Compounds comprising cleavable linker and uses thereof

Abstract

Provided herein are compounds including cleavable linkers, uses thereof, and intermediate compounds for preparing the same. In particular, are disclosed conjugates of Formula (I’): (see formula I’) where CB is a targeting moiety; each D-L has the structure of Formula (I"): (see formula I”) where Q is an active agent; Z' is a linking group; L’ is a spacer moiety attached to the SO₂ via a heteroatom; X and Y’ are positioned on adjacent atoms of Ar; TG is a triggering group that, when activated, generates an N, O, or S atom capable of reacting with the SO₂ to displace (Q)q-(L’)w and form a 5-6-membered ring including X-SO₂ and the intervening atoms of Ar. Additional substitutes and attributes are described herein.

Description

COMPOUNDS COMPRISING CLEAVABLE LINKER AND USES THEREOF RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 62 / 597,226, filed on December 11, 2017, and Korean Patent Application No. 10-2017-0084805, filed on July 4, 2017. BACKGROUND Antibody-drug conjugates (ADCs) are emerging as a powerful class of anti-tumor agents with efficacy across a range of cancers. ADCs are commonly composed of three distinct features: a cell-binding agent or targeting moiety; a linker; and a cytotoxic agent. The linker component of ADC is an important feature in developing targeted anti-cancer agents that possess a desirable target-specificity, i.e., high activity in tumor cells, but with low activity in healthy cells. Therefore, there is a need for improved linkers useful for preparing ADCs. SUMMARY Provided herein are conjugates of Formula (I'): <com:Math><semantics>(D−L)n−(CB)cb<annotation encoding="application / x-tex">(D-L)_n-(CB)_{cb}< / annotation>< / semantics>< / com:Math> (I') or a pharmaceutically acceptable salt thereof, wherein: CB is a targeting moiety; cb and n are each independently integers having a value of 1 to about 20, preferably from 1 to about 10; each D-L independently is a group having the structure of Formula (I"): [Image disponible dans le document PDF, Image available in the PDF document] (I") Q is an active agent linked to L' via a heteroatom, preferably O or N; Z' is a linking group; L' is a spacer moiety attached to the SO<com:Sub>2< / com:Sub> via a heteroatom selected from O, S, and N, preferably O or N, and is selected such that cleavage of the bond between L' and SO<com:Sub>2< / com:Sub> promotes cleavage of the bond between L' and Q to release the active agent; X is <com:Math><semantics>−O−<annotation encoding="application / x-tex">-O_{-}< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−C(Rb)2−<annotation encoding="application / x-tex">-C(R^b)_{2-}< / annotation>< / semantics>< / com:Math>, or <com:Math><semantics>−N(Rc)−<annotation encoding="application / x-tex">-N(R^c)_{-}< / annotation>< / semantics>< / com:Math>, preferably <com:Math><semantics>−O−<annotation encoding="application / x-tex">-O_{-}< / annotation>< / semantics>< / com:Math>; Ar represents a ring, such as aryl, heteroaryl, cycloalkyl, or heterocycloalkyl, preferably aryl or heteroaryl; Y' is <com:Math><semantics>−(CRb2)yN(Ra1)<annotation encoding="application / x-tex">-(CR^{b_2})_yN(R^{a_1})< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−(CRb2)yO<annotation encoding="application / x-tex">-(CR^{b_2})_yO< / annotation>< / semantics>< / com:Math>, or <com:Math><semantics>−(CRb2)yS<annotation encoding="application / x-tex">-(CR^{b_2})_yS< / annotation>< / semantics>< / com:Math>, positioned such that the N, O, or S atom is attached to TG if y is 1; X and Y' are positioned on adjacent atoms of Ar; TG is a triggering group that, when activated, generates an N, O, or S atom capable of reacting with the <com:Math><semantics>SO2<annotation encoding="application / x-tex">SO_2< / annotation>< / semantics>< / com:Math> to displace <com:Math><semantics>(Q)q<annotation encoding="application / x-tex">(Q)_q< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>(L′)w<annotation encoding="application / x-tex">(L')_w< / annotation>< / semantics>< / com:Math> and form a 5- or 6-membered ring including X-<com:Math><semantics>SO2<annotation encoding="application / x-tex">SO_2< / annotation>< / semantics>< / com:Math> and the intervening atoms of Ar; q is an integer having a value from 1 to about 20, preferably from 1 to about 10; w, x, and y are each independently an integer having a value of 0 or 1; each R<com:Sup>a< / com:Sup> and R<com:Sup>c< / com:Sup> is independently hydrogen or lower alkyl; and each R<com:Sup>b< / com:Sup> is independently hydrogen or lower alkyl; or two R<com:Sup>b< / com:Sup>, together with the atom to which they are attached, form a 3-5-membered ring, preferably a 3-4-membered ring; provided that when w is 0, q is 1. The present invention also relates to compositions (e.g., pharmaceutical compositions) comprising a compound of Formula (I') and a carrier (e.g., a pharmaceutically acceptable carrier). In one aspect, the invention provides conjugates of Formula (I'), and compositions comprising such conjugates, e.g., for use in therapy, imaging, as sensors, as molecular switches, as molecular machines, and / or as nanomachines. In another aspect, the invention further provides conjugates of Formula (I') and pharmaceutical compositions thereof, for use in a method for delivering an active agent to a cell, wherein the targeting moiety is selected to bind to a molecule associated with a target cell. In particular, the present compounds, conjugates, and compositions may be useful for inhibiting abnormal cell growth or treating a proliferative disorder in a mammal (e.g., a human), such as where the target cell is a cancer cell and the targeting moiety is selected to bind to a molecule associated with the cancer cell (and not associated with healthy cells, or at least preferentially associated with tumor cells rather than healthy cells). The present conjugates of Formula (I') and pharmaceutical compositions thereof may be useful for treating conditions such as cancer, rheumatoid arthritis, multiple sclerosis, graft versus host disease (GVHD), transplant rejection, lupus, myositis, infection, immune deficiency such as AIDS, and inflammatory diseases in a mammal (e.g., human). BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows results of an enzymatic cleavage assay of Compound A-1. FIG. 2 shows results of an enzymatic cleavage assay of Compound A-2. FIG. 3 shows results of an enzymatic cleavage assay of Compound A-3. FIG. 4 shows results of an enzymatic cleavage assay of Compound A-4. FIG. 5 shows results of an enzymatic cleavage assay of Compound B-1. FIG. 6 shows results of an enzymatic cleavage assay of Compound B-3. FIG. 7 shows results of an enzymatic cleavage assay (pH 7.4) of Compound B-2. FIG. 8 shows results of an enzymatic cleavage assay (pH 5.0) of Compound B-2. FIG. 9 shows results of an enzymatic cleavage assay of Compound B-4. FIG. 10 shows results of an enzymatic cleavage assay of Compound C-3. FIG. 11 shows results of stability analysis of Compound A-1. FIG. 12 shows results of in vitro analysis of Compound D-1-AB. FIG. 13 shows results of in vivo test of Compound D-1-AB, D-2-AB, D-8-AB, and D-16- AB. DETAILED DESCRIPTION The present invention relates to compounds and conjugates comprising a cleavable linker and uses thereof. Representative compounds and conjugates disclosed herein comprise an active agent (e.g., a chemical factor, a biological factor, a hormone, an oligonucleotide, a drug, a toxin, a ligand, a probe for detection, etc.) having a desired function or activity, a functional group that undergoes a chemical reaction (e.g., a physicochemical reaction and / or a biological reaction) under predetermined conditions to release a nucleophilic heteroatom, and an SO<com:Sub>2< / com:Sub> functional group positioned proximal to the nucleophilic heteroatom so that it can react with the nucleophilic heteroatom in an intramolecular cyclization reaction to release the active agent. In some embodiments, the compounds and conjugates disclosed herein further comprise a targeting moiety (e.g., oligopeptide, polypeptide, antibody, etc.) having binding specificity for a desired target receptor or other molecule associated with a target cell. Definitions The meaning of the term "alkyl" is understood in the art. For example, "alkyl" used alone or as part of a larger moiety, such as "alkoxy", "haloalkyl", "cycloalkyl", "heterocycloalkyl", and the like, may refer to a straight chain or branched hydrocarbon which is completely saturated. Typically, a straight chain or branched alkyl group is an acyclic group having from 1 to about 20 carbon atoms, preferably from 1 to about 10 carbon atoms, unless otherwise defined. Examples of straight chain and branched alkyl groups include, but are not limited to, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n- heptyl, and n-octyl. A C<com:Sub>1< / com:Sub>–C<com:Sub>6< / com:Sub> straight chain or branched alkyl group is also referred to as a "lower alkyl" group. Alkyl groups having two open valences are sometimes referred to with an "ene" suffix, as in alkylene. Exemplary alkylene groups include methylene, ethylene, propylene, and the like. Moreover, the term "alkyl" (or "lower alkyl") may include both "unsubstituted alkyls" and "substituted alkyls", the latter of which refers to alkyl moieties having substituents replacing a hydrogen on one or more carbons of the hydrocarbon backbone. Such substituents, if not otherwise specified, can include, for example, a halogen, a hydroxyl, a carbonyl (such as a carboxyl, an alkoxycarbonyl, a formyl, or an acyl), a thiocarbonyl (such as a thioester, a thioacetate, or a thioformate), an alkoxyl, a phosphoryl, a phosphate, a phosphonate, a phosphinate, an amino, an amido, an amidine, an imine, a cyano, a nitro, an azido, a sulfhydryl, an alkylthio, a sulfate, a sulfonate, a sulfamoyl, a sulfonamido, a sulfonyl, a heterocyclyl, an aralkyl, or an aromatic or heteroaromatic moiety. The skilled artisan will understand that the moieties substituted on the hydrocarbon chain can themselves be substituted, if appropriate. For example, the substituents of a substituted alkyl may include substituted and unsubstituted forms of alkyl, amino, azido, imino, amido, phosphoryl (including phosphonate and phosphinate), sulfonyl (including sulfate, sulfonamido, sulfamoyl and sulfonate), and silyl groups, as well as ethers, alkylthios, carbonyls (including ketones, aldehydes, carboxylates, and esters), -CF<com:Sub>3< / com:Sub>, -CN and the like. Exemplary substituted alkyls are described below. Cycloalkyls can be further substituted with alkyls, alkenyls, alkoxys, alkylthios, aminoalkyls, carbonyl-substituted alkyls, - CF<com:Sub>3< / com:Sub>, -CN, and the like. The term "<com:Math><semantics>Cx<annotation encoding="application / x-tex">C_x< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>Cy<annotation encoding="application / x-tex">C_y< / annotation>< / semantics>< / com:Math>" when used in conjunction with a chemical moiety, such as, for example, acyl, acyloxy, alkyl, alkenyl, alkynyl, or alkoxy may include groups that contain from x to y carbons in the chain, wherein "x" and "y" are integers selected from 1 to about 20, and wherein x is an integer of lesser value than y, and x and y are not the same value. For example, the term "C<com:Sub>x< / com:Sub>-C<com:Sub>y< / com:Sub>-alkyl" refers to substituted or unsubstituted saturated hydrocarbon groups, including straight-chain alkyl and branched-chain alkyl groups that contain from x to y number of carbons in the chain, including haloalkyl groups such as trifluoromethyl and 2,2,2- tirfluoroethyl, etc. The terms "C<com:Sub>2< / com:Sub>-C<com:Sub>y< / com:Sub>-alkenyl" and "C<com:Sub>2< / com:Sub>-C<com:Sub>y< / com:Sub>-alkynyl" refer to substituted or unsubstituted unsaturated aliphatic groups analogous in length and possible substitution to the alkyls described above, but that contain at least one double or triple bond respectively. As applied to heteroalkyls, "<com:Math><semantics>Cx<annotation encoding="application / x-tex">C_x< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>Cy<annotation encoding="application / x-tex">C_y< / annotation>< / semantics>< / com:Math>" indicates that the group contains from x to y number of carbons and heteroatoms in the chain. As applied to carbocyclic structures, such as aryl and cycloalkyl groups, "C<com:Sub>x< / com:Sub>-C<com:Sub>y< / com:Sub>" indicates that the ring comprises x to y number of carbon atoms in the ring. The meaning of the term "alkoxy" is understood in the art, and, for example, may refer to an alkyl group, preferably a lower alkyl group, having an oxygen attached thereto. Representative alkoxy groups include methoxy, ethoxy, propoxy, tert-butoxy and the like. The terms "hal", "halo", and "halogen" are used interchangeably throughout, and refer to fluorine or fluoro (F), chlorine or chloro (Cl), bromine or bromo (Br), or iodine or iodo (I). The meaning of the term "cycloalkyl" is understood in the art, and, for example, may refer to a substituted or unsubstituted cyclic hydrocarbon which is completely saturated. Cycloalkyl includes monocyclic and bicyclic rings. Typically, a monocyclic cycloalkyl group has from 3 to about 10 carbon atoms, more typically 3 to 8 carbon atoms, unless otherwise defined. The second ring of a bicyclic cycloalkyl may be selected from saturated, unsaturated, and aromatic rings. Cycloalkyl includes bicyclic molecules in which one, two, or three or more atoms are shared between the two rings. The term "fused cycloalkyl" refers to a bicyclic cycloalkyl in which each of the rings shares two adjacent atoms with the other ring. The second ring of a fused bicyclic cycloalkyl may be selected from saturated, unsaturated and aromatic rings. A "cycloalkenyl" group is a cyclic hydrocarbon containing one or more double bonds. The meaning of the term "aryl" is understood in the art, and, for example, may refer to substituted or unsubstituted single-ring aromatic groups in which each atom of the ring is carbon. Preferably, the ring is a 5- to 7-membered ring, more preferably a 6-membered ring. The term "aryl" also includes polycyclic ring systems having two or more cyclic rings in which two or more carbons are common to two adjoining rings wherein at least one of the rings is aromatic, e.g., the other cyclic rings can be cycloalkyls, cycloalkenyls, cycloalkyls, aryls, heteroaryls, and / or heterocyclyls. Aryl groups include benzene, naphthalene, phenanthrene, phenol, aniline, and the like. The meaning of the terms "heterocyclyl" and "heterocycle" are understood in the art, and, for example, may refer to substituted or unsubstituted non-aromatic ring structures, preferably 3- to 10-membered rings, more preferably 3- to 7-membered rings, whose ring structures include at least one heteroatom, preferably one to four heteroatoms, more preferably one or two heteroatoms. Such heterocycles also include polycyclic ring systems having two or more cyclic rings in which two or more carbons are common to two adjoining rings wherein at least one of the rings is heterocyclic, e.g., the other cyclic rings can be cycloalkyls, cycloalkenyls, cycloalkyls, aryls, heteroaryls, and / or heterocyclyls. Heterocyclyl groups include, for example, piperidine, piperazine, pyrrolidine, morpholine, lactones, lactams, and the like. The meaning of the term "heteroaryl" is understood in the art, and, for example, may refer to substituted or unsubstituted aromatic single ring structures, preferably 5- to 7-membered rings, more preferably 5- to 6-membered rings, whose ring structures include at least one heteroatom, preferably one to four heteroatoms, more preferably one or two heteroatoms. The terms "heteroaryl" and "hetaryl" also include polycyclic ring systems having two or more cyclic rings in which two or more carbons are common to two adjoining rings wherein at least one of the rings is heteroaromatic, e.g., the other cyclic rings can be cycloalkyls, cycloalkenyls, cycloalkyls, aryls, heteroaryls, and / or heterocyclyls. Heteroaryl groups include, for example, pyrrole, furan, thiophene, imidazole, oxazole, thiazole, pyrazole, pyridine, pyrazine, pyridazine, and pyrimidine, and the like. The term "substituted" refers to moieties having substituents replacing a hydrogen on one or more carbons or heteroatoms of the moiety. The skilled artisan will understand that "substitution" or "substituted with" includes the implicit proviso that such substitution is in accordance with permitted valence of the substituted atom and the substituent, and that the substitution results in a stable compound, e.g., which does not spontaneously undergo transformation such as by rearrangement, cyclization, elimination, etc. As used herein, the term "substituted" is contemplated to include all permissible substituents of organic compounds. In some embodiments, the permissible substituents include acyclic and cyclic, branched and unbranched, carbocyclic and heterocyclic, aromatic and non-aromatic substituents of organic compounds. The permissible substituents can be one or more and the same or different for appropriate organic compounds. For purposes of this invention, the heteroatoms such as nitrogen may have hydrogen substituents and / or any permissible substituents of organic compounds described herein which satisfy the valences of the heteroatoms. Substituents can include any substituents described herein, such as, for example, a halogen, a hydroxyl, a carbonyl (such as a carboxyl, an alkoxycarbonyl, a formyl, or an acyl), a thiocarbonyl (such as a thioester, a thioacetate, or a thioformate), an alkoxyl, a phosphoryl, a phosphate, a phosphonate, a phosphinate, an amino, an amido, an amidine, an imine, a cyano, a nitro, an azido, a sulfhydryl, an alkylthio, a sulfate, a sulfonate, a sulfamoyl, a sulfonamido, a sulfonyl, a heterocyclyl, an alkyl, an aralkyl, or an aromatic or heteroaromatic moiety. The skilled artisan will understand that substituents can themselves be substituted, if appropriate. Unless specifically stated as "unsubstituted", references to chemical moieties herein are understood to include substituted variants. For example, reference to an "aryl" group or moiety implicitly includes both substituted and unsubstituted variants. The term "subject" to which administration is contemplated includes, for example, humans (i.e., a male or female of any age group, e.g., a pediatric subject (e.g., infant, child, adolescent) or adult subject (e.g., young adult, middle-aged adult or senior adult)) and / or other primates (e.g., cynomolgus monkeys, rhesus monkeys); mammals, including commercially relevant mammals such as cattle, pigs, horses, sheep, goats, cats, and / or dogs; and / or birds, including commercially relevant birds such as chickens, ducks, geese, quail, and / or turkeys. Preferred subjects are humans. As used herein, a therapeutic that "prevents" a disorder or condition can, for example, refer to a compound that, in a statistical sample, reduces the occurrence of the disorder or condition in the treated sample relative to an untreated control sample, or delays the onset or reduces the severity of one or more symptoms of the disorder or condition relative to the untreated control sample. The term "treating" includes prophylactic and / or therapeutic treatments. The term "prophylactic or therapeutic" treatment is art-recognized and includes administration to the host of one or more of the subject compositions. If it is administered prior to clinical manifestation of the unwanted condition (e.g., disease or other unwanted state of the host animal) then the treatment is prophylactic (i.e., it protects the host against developing the unwanted condition), whereas if it is administered after manifestation of the unwanted condition, the treatment is therapeutic, (i.e., it is intended to diminish, ameliorate, or stabilize the existing unwanted condition or side effects thereof). In certain embodiments, compounds and conjugates disclosed herein may be used alone or conjointly administered with another type of therapeutic compound or agent. As used herein, the phrase "conjoint administration" refers to any form of administration of two or more different therapeutic compounds such that the second compound is administered while the previously administered therapeutic compound is still effective in the body (e.g., the two compounds are simultaneously effective in the subject, which may include synergistic effects of the two compounds). For example, the different therapeutic compounds and conjugates can be administered either in the same formulation or in a separate formulation, either concomitantly or sequentially. In certain embodiments, the different therapeutic compounds and conjugates can be administered within one hour, 12 hours, 24 hours, 36 hours, 48 hours, 72 hours, or a week of one another. Thus, a subject who receives such treatment can benefit from a combined effect of different therapeutic compounds and conjugates. The terms "abnormal cell growth" and "proliferative disorder" are used interchangeably in this application. "Abnormal cell growth," as used herein, unless otherwise indicated, refers to cell growth that is independent of normal regulatory mechanisms (e.g., loss of contact inhibition). This includes, for example, the abnormal growth of: (1) tumor cells (tumors) that proliferate by expressing a mutated tyrosine kinase or over-expression of a receptor tyrosine kinase; (2) benign and malignant cells of other proliferative diseases in which aberrant tyrosine kinase activation occurs; (3) any tumors that proliferate by receptor tyrosine kinases; (4) any tumors that proliferate by aberrant serine / threonine kinase activation; and (5) benign and malignant cells of other proliferative diseases in which aberrant serine / threonine kinase activation occurs. The terms "cancer" and "cancerous" refer to or describe the physiological condition in mammals that is typically characterized by unregulated cell growth. A "tumor" comprises one or more cancerous cells. Examples of cancer include, but are not limited to, carcinoma, lymphoma, blastoma, sarcoma, and leukemia or lymphoid malignancies. More particular examples of such cancers include squamous cell cancer (e.g., epithelial squamous cell cancer), lung cancer including small-cell lung cancer, non-small cell lung cancer ("NSCLC"), adenocarcinoma of the lung and squamous carcinoma of the lung, cancer of the peritoneum, hepatocellular cancer, gastric or stomach cancer including gastrointestinal cancer, pancreatic cancer, glioblastoma, cervical cancer, ovarian cancer, liver cancer, bladder cancer, hepatoma, breast cancer, colon cancer, rectal cancer, colorectal cancer, endometrial or uterine carcinoma, salivary gland carcinoma, kidney or renal cancer, prostate cancer, vulval cancer, thyroid cancer, hepatic carcinoma, anal carcinoma, penile carcinoma, acute leukemia, as well as head / brain and neck cancer. Compounds and Conjugates of the Invention The present disclosure provides conjugates of Formula (I'): [Image disponible dans le document PDF, Image available in the PDF document] (I') or a pharmaceutically acceptable salt thereof, wherein: CB is a targeting moiety; cb and n are each independently integers having a value of 1 to about 20, preferably from 1 to about 10; each D-L independently is a group having the structure of Formula (I"): [Image disponible dans le document PDF, Image available in the PDF document] <Formule mathématique disponible dans le document PDF, Math available in the PDF document>$(I^{"})$ each Q is, independently, an active agent linked to L' via a heteroatom, preferably O or N; Z' is a linking group; L' is a spacer moiety attached to the SO<com:Sub>2< / com:Sub> via a heteroatom selected from O, S, and N, preferably O or N, and is selected such that cleavage of the bond between L' and SO<com:Sub>2< / com:Sub> promotes cleavage of the bond between L' and Q to release the active agent; X is <com:Math><semantics>−O−<annotation encoding="application / x-tex">-O_{-}< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−C(Rb)2−<annotation encoding="application / x-tex">-C(R^b)_{2-}< / annotation>< / semantics>< / com:Math>, or <com:Math><semantics>−N(Rc)−<annotation encoding="application / x-tex">-N(R^c)_{-}< / annotation>< / semantics>< / com:Math>, preferably <com:Math><semantics>−O−<annotation encoding="application / x-tex">-O_{-}< / annotation>< / semantics>< / com:Math>; Ar represents a ring, such as aryl, heteroaryl, cycloalkyl, or heterocycloalkyl, preferably aryl or heteroaryl; Y' is <com:Math><semantics>−(CRb2)yN(Ra1)<annotation encoding="application / x-tex">-(CR^{b_2})_yN(R^{a_1})< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−(CRb2)yO<annotation encoding="application / x-tex">-(CR^{b_2})_yO< / annotation>< / semantics>< / com:Math>, or <com:Math><semantics>−(CRb2)yS<annotation encoding="application / x-tex">-(CR^{b_2})_yS< / annotation>< / semantics>< / com:Math>, positioned such that the N, O, or S atom is attached to TG if y is 1; X and Y' are positioned on adjacent atoms of Ar; TG is a triggering group that, when activated, generates an N, O, or S atom capable of reacting with the <com:Math><semantics>SO2<annotation encoding="application / x-tex">SO_2< / annotation>< / semantics>< / com:Math> to displace <com:Math><semantics>(Q)q<annotation encoding="application / x-tex">(Q)_q< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>(L′)w<annotation encoding="application / x-tex">(L')_w< / annotation>< / semantics>< / com:Math> and form a 5-6-membered ring including X-SO<com:Sup>2< / com:Sup> and the intervening atoms of Ar; q is an integer having a value from 1 to about 20, preferably from 1 to about 10; w, x, and y are each independently an integer having a value of 0 or 1; each R<com:Sup>a< / com:Sup> and R<com:Sup>c< / com:Sup> is independently hydrogen or lower alkyl; and each R<com:Sup>b< / com:Sup> is independently hydrogen or lower alkyl; or two R<com:Sup>b< / com:Sup>, together with the atom to which they are attached, form a 3-5-membered ring, preferably a 3-4-membered ring, provided that when w is 0, q is 1. Each active agent can be any suitable active agent, as described in greater detail below. While many traditional conjugation methods require having certain functional groups, such as amines or hydroxyl groups, to form a stable linkage, the disclosure herein provides strategies for forming connections using functional groups, such as phenols and tertiary amines, to form stable linkages in the conjugates disclosed herein, while still permitting release under the predetermined conditions that activate the triggering group. Many suitable triggering groups are known in the art, and exemplary triggering groups and the conditions that activate them are discussed below, such as moieties described for Y below. Some triggering groups include the N, O, or S atom, but in a non-nucleophilic form. For example, an NO<com:Sub>2< / com:Sub> group is a triggering group that, under reductive conditions, is reduced to an NH<com:Sub>2< / com:Sub> or NHOH group that can react with the SO<com:Sub>2< / com:Sub>, and an acetate group is a triggering group that, under hydrolytic conditions, is hydrolyzed to a hydroxyl group that can react with the SO<com:Sub>2< / com:Sub>. Other triggering groups do not include the N, O, or S atom, but when activated are converted to a nucleophilic N, O, or S atom. For example, a boronate group is a triggering group that, under oxidative conditions (such as peroxide), is converted to a hydroxyl group that can react with the SO<com:Sub>2< / com:Sub>. Preferably, the triggering group is selected such that the conditions that activate it do so selectively, without cleaving or degrading other portions of the conjugate, such as the targeting moiety. Once the nucleophilic N, O, or S atom is generated, that atom intramolecularly attacks the <com:Math><semantics>SO2<annotation encoding="application / x-tex">SO_2< / annotation>< / semantics>< / com:Math> moiety to form a ring, expelling the moiety <com:Math><semantics>(Q)q<annotation encoding="application / x-tex">(Q)_q< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>(L′)w<annotation encoding="application / x-tex">(L')_w< / annotation>< / semantics>< / com:Math>-H, where the H is bonded to the heteroatom of Q or L' that was formerly attached to the SO<com:Sub>2< / com:Sub> moiety. In embodiments where w is 0, q is 1 and Q is directly attached to the SO<com:Sub>2< / com:Sub> via a heteroatom. Accordingly, activating the triggering group generates a nucleophilic heteroatom that intramolecularly attacks the SO<com:Sub>2< / com:Sub> moiety to form a ring, expelling the active agent Q-H, where the H is bonded to the heteroatom formerly attached to SO<com:Sub>2< / com:Sub>. In embodiments where w is 1, L' may be selected to permit attachment of multiple occurrences of Q, which may be the same or different. Accordingly, each instance of Q is indirectly attached to the SO<com:Sub>2< / com:Sub> via a spacer moiety. In such embodiments, activating the triggering group generates a nucleophilic heteroatom that intramolecularly attacks the SO<com:Sub>2< / com:Sub> moiety to form a ring, expelling the moiety (Q)<com:Sub>q< / com:Sub>-L'-H, where the H is bonded to the heteroatom in L' that was formerly attached to SO<com:Sub>2< / com:Sub>. In such embodiments, the released heteroatom triggers an intramolecular reaction that expels the active agent(s) Q (such as if Q has a tertiary amine that was attached to L' as a quarternary ammonium) or Q-H. For example, the heteroatom may undergo an intramolecular cyclization reaction with an ester moiety formed with a hydroxyl of Q-H, forming a ring and ejecting the active agent Q-H. Alternatively, the heteroatom may undergo an intramolecular tautomerization that expels the active agent Q or Q-H. Ar can be any suitable ring, including a ring of a bicycle or other polycycle, so that the moieties that undergo intramolecular cyclization are held in close proximity to facilitate that reaction after activation of the triggering group. The planar character of aromatic and heteroaromatic rings is preferred, as the rigid geometry of substituents on such rings ensures favorable placement of the reactive moieties, although other types of rings, such as cycloalkenyl or heterocycloalkenyl, can enforce similar geometries. A five- or six-membered ring, and / or the number or identities of heteroatoms in the ring, and / or substituents (e.g., electron-donating or electron-withdrawing substituents) on other the ring, may be selected to modulate the rate of cyclization based on the resulting bond angles of the ring. Similarly, the more flexible conformations of cycloalkyl and heterocyclyl rings can be useful when it is desired to slow the rate of intramolecular cyclization. Z' can be any suitable linking group that connects Ar to one or more CB groups. Typically, the linking group should be sufficiently hydrophilic to promote water-solubility and discourage aggregation of the conjugate, such as by including moieties such as polyethylene glycol moieties, peptide sequences, charge-bearing moieties (such as carboxylates, amines, nitrogen-containing rings, etc.), etc. to balance the hydrophobic character of any alkyl chains that may be included. Because it is often advantageous to prepare conjugates in a modular fashion, Z' may contain a linking unit, a functional group that results from the conjugation of one reactive moiety to another. Representative linking units are discussed in greater detail below (e.g., in connection with the variable Z), and common linking groups include amides, triazoles, oximes, carbamates, etc. Representative Z' groups include L1'-Z groups as discussed in greater detail below. In some embodiments, all of the D-L groups attached to each CB are identical, while in other embodiments, each CB may be attached to two or more distinct D-L groups. For example, some D-L groups may have a triggering group that is activated under a first condition, while other D-L groups may have a triggering group that is activated under a second condition, so that, for example, one active agent can be selectively released under the first condition, but a second active agent can be selectively released under the second condition. The disclosure also provides compounds that may serve as intermediates or reagents in the formation of group D-L in formula (I'), as described in Formula (I''). Thus, in some embodiments, provided herein are compounds of Formula (Ia): [Image disponible dans le document PDF, Image available in the PDF document] (Ia) or a pharmaceutically acceptable salt thereof, wherein: each Q is, independently, an active agent linked to L' via a heteroatom, preferably O or N; Z' is absent or a linking group; L' is a spacer moiety attached to the SO<com:Sub>2< / com:Sub> via a heteroatom selected from O, S, and N, preferably O or N, and is selected such that cleavage of the bond between L' and SO<com:Sub>2< / com:Sub> promotes cleavage of the bond between L' and Q to release the active agent; X is -O-, -CR<com:Sup>a< / com:Sup><com:Sub>2< / com:Sub>-, or -NR'-, preferably -O-; Ar represents a ring, such as aryl, heteroaryl, cycloalkyl, or heterocycloalkyl, preferably aryl or heteroaryl; Y' is <com:Math><semantics>−(CRb2)yN(Ra1)<annotation encoding="application / x-tex">-(CR^{b_2})_yN(R^{a_1})< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−(CRb2)yO<annotation encoding="application / x-tex">-(CR^{b_2})_yO< / annotation>< / semantics>< / com:Math>, or <com:Math><semantics>−(CRb2)yS<annotation encoding="application / x-tex">-(CR^{b_2})_yS< / annotation>< / semantics>< / com:Math>, positioned such that the N, O, or S atom is attached to TG if y is 1; X and Y' are positioned on adjacent atoms of Ar; TG is a triggering group that, when activated, generates an N, O, or S atom capable of reacting with the <com:Math><semantics>SO2<annotation encoding="application / x-tex">SO_2< / annotation>< / semantics>< / com:Math> to displace <com:Math><semantics>(Q)q<annotation encoding="application / x-tex">(Q)_q< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>(L′)w<annotation encoding="application / x-tex">(L')_w< / annotation>< / semantics>< / com:Math> and form a 5-6-membered ring including X-SO<com:Sup>2< / com:Sup> and the intervening atoms of Ar; q is an integer having a value from 1 to about 20, preferably from 1 to about 10; w, x, and y are each independently an integer having a value of 0 or 1; each R<com:Sup>a< / com:Sup> and R<com:Sup>c< / com:Sup> is independently hydrogen or lower alkyl; and each R<com:Sup>b< / com:Sup> is independently hydrogen or lower alkyl; or two R<com:Sup>b< / com:Sup>, together with the carbon atom to which they are attached, form a 3-5-membered ring, preferably a 3-4-membered ring. In certain embodiments of Formulas (I') and (Ia), -Y' is -(CH<com:Sub>2< / com:Sub>)<com:Sub>y< / com:Sub>NR"-, -(CH<com:Sub>2< / com:Sub>)<com:Sub>y< / com:Sub>O- or - (CH<com:Sub>2< / com:Sub>)<com:Sub>y< / com:Sub>S-, positioned such that the N, O, or S atom is attached to TG if y is 1; R" is hydrogen or <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math>-alkyl; and y is an integer having a value of 0 or 1. In some such embodiments, TG is a <com:Math><semantics>β<annotation encoding="application / x-tex">\beta< / annotation>< / semantics>< / com:Math>- galactoside, <com:Math><semantics>β<annotation encoding="application / x-tex">\beta< / annotation>< / semantics>< / com:Math>-glucuronide, or a combination of <com:Math><semantics>β<annotation encoding="application / x-tex">\beta< / annotation>< / semantics>< / com:Math>-galactoside and <com:Math><semantics>β<annotation encoding="application / x-tex">\beta< / annotation>< / semantics>< / com:Math>-glucuronide. In some embodiments of Formulas (I') and (Ia), (L')<com:Sub>w< / com:Sub> links each Q to the -SO<com:Sub>2< / com:Sub>-; and each Q is an active agent linked to one of the L' groups through a heteroatom, preferably O or N, and forming an -O-, an -OC(O)-, an -OC(O)O- or an -OC(O)NH- linkage including the heteroatom of Q. In other embodiments, <com:Math><semantics>(Q)q<annotation encoding="application / x-tex">(Q)_q< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>(L′)w<annotation encoding="application / x-tex">(L')_w< / annotation>< / semantics>< / com:Math>- is selected from: [Image disponible dans le document PDF, Image available in the PDF document] wherein: Q is an active agent linked to L' through a heteroatom, preferably O or N, <com:Math><semantics>X4<annotation encoding="application / x-tex">X^4< / annotation>< / semantics>< / com:Math> is absent or forms an -O-, an -OC(O)-, an -OC(O)O- or an -OC(O)NH- linkage including the heteroatom of Q; <com:Math><semantics>X1<annotation encoding="application / x-tex">X^1< / annotation>< / semantics>< / com:Math> is -O- or -NR<com:Sup>a< / com:Sup>-; <com:Math><semantics>X2<annotation encoding="application / x-tex">X^2< / annotation>< / semantics>< / com:Math> is -O-, -OC(O)-, -OC(O)O- or -OC(O)NH-; <com:Math><semantics>X3<annotation encoding="application / x-tex">X^3< / annotation>< / semantics>< / com:Math> is <com:Math><semantics>−OC(=O)<annotation encoding="application / x-tex">-OC(=O)< / annotation>< / semantics>< / com:Math>-; w' is an integer having a value of 1, 2, 3, 4, or 5; R<com:Sup>9< / com:Sup> and R<com:Sup>10< / com:Sup> are each independently hydrogen, alkyl, aryl, or heteroaryl, wherein alkyl, aryl, and heteroaryl are unsubstituted or substituted with one or more substituents, e.g., selected from alkyl, <com:Math><semantics>−(CH2)uNH2<annotation encoding="application / x-tex">-(CH_2)_uNH_2< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−(CH2)uNRu1Ru2<annotation encoding="application / x-tex">-(CH_2)_uNR^{u1}R^{u2}< / annotation>< / semantics>< / com:Math>, and <com:Math><semantics>−(CH2)uSO2Ru3<annotation encoding="application / x-tex">-(CH_2)_uSO_2R^{u3}< / annotation>< / semantics>< / com:Math>; R<com:Sup>u1< / com:Sup>, R<com:Sup>u2< / com:Sup>, and R<com:Sup>u3< / com:Sup> are each independently hydrogen, alkyl, aryl, or heteroaryl; and u is an integer having a value of 1 to about 10. In some such embodiments, <com:Math><semantics>(Q)q<annotation encoding="application / x-tex">(Q)_q< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>(L′)w<annotation encoding="application / x-tex">(L')_w< / annotation>< / semantics>< / com:Math>- is selected from: [Image disponible dans le document PDF, Image available in the PDF document] Further, the invention provides intermediates for preparing conjugates according to Formula (I') or compounds according to Formula (Ia), wherein (Q)<com:Sub>q< / com:Sub>-(L')<com:Sub>w< / com:Sub> in those Formulas is replaced by a leaving group, such as a halogen (preferably fluorine), to permit attachment of <com:Math><semantics>(Q)q<annotation encoding="application / x-tex">(Q)_q< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>(L′)w<annotation encoding="application / x-tex">(L')_w< / annotation>< / semantics>< / com:Math>. In certain such embodiments, Z' includes a reactive group (e.g., a precursor group, as discussed in greater detail below with respect to Z) that can be used to attach the compound to a triggering agent, such as a CB (e.g., to prepare a compound of Formula (I') as discussed in greater detail above), to a solid surface (e.g., to form a solid-supported array, or sensor particles), or to any other molecule or support of interest. In certain preferred embodiments, the compound [Image disponible dans le document PDF, Image available in the PDF document] of Formula (I') is selected from: ·<com:Br / >• [Image disponible dans le document PDF, Image available in the PDF document] wherein: <com:Math><semantics>R1<annotation encoding="application / x-tex">R^1< / annotation>< / semantics>< / com:Math> is <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math> alkyl; and R<com:Sup>21< / com:Sup> and R<com:Sup>22< / com:Sup> are each independently hydrogen or C<com:Sub>1< / com:Sub>–C<com:Sub>6< / com:Sub>-alkyl. In other embodiments, the compound of Formula (I') is selected from: [Image disponible dans le document PDF, Image available in the PDF document] , In still other embodiments, the compound of Formula (I') is selected from: [Image disponible dans le document PDF, Image available in the PDF document] 5 [Image disponible dans le document PDF, Image available in the PDF document] In other embodiments, the compound of Formula (I') is selected from: [Image disponible dans le document PDF, Image available in the PDF document] × In certain preferred embodiments, Z is a linking group having a structure of Formula (F), (G), (H), (J), (K), (L), (M), or (N): [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] (N) wherein: * is the point of attachment to CB; ** is point of attachment to Ar; R<com:Sup>e< / com:Sup> is alkyl; [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] W<com:Sup>b1< / com:Sup> and W<com:Sup>b2< / com:Sup> are each independently -C(O)NH-, -NHC(O)-, . L<com:Sup>2< / com:Sup> is an optionally present spacer moiety, and may be further substituted with one or more substituents, such as C<com:Sub>1< / com:Sub>-C<com:Sub>6< / com:Sub> alkyl, C<com:Sub>5< / com:Sub>-C<com:Sub>14< / com:Sub> aryl, and C<com:Sub>3< / com:Sub>-C<com:Sub>8< / com:Sub> heteroaryl, wherein the alkyl, aryl and heteroaryl may be further substituted, e.g., with one or more substituents selected from the group consisting of C<com:Sub>1< / com:Sub>-C<com:Sub>10< / com:Sub> alkyl, -(CH<com:Sub>2< / com:Sub>)<com:Sub>u< / com:Sub>NH<com:Sub>2< / com:Sub>, -(CH<com:Sub>2< / com:Sub>)<com:Sub>u< / com:Sub>NR<com:Sup>u1< / com:Sup>R<com:Sup>u2< / com:Sup>, - (CH<com:Sub>2< / com:Sub>)<com:Sub>u< / com:Sub>CO<com:Sub>2< / com:Sub>H, -(CH<com:Sub>2< / com:Sub>)<com:Sub>u< / com:Sub>CO<com:Sub>2< / com:Sub>R<com:Sup>u1< / com:Sup>, and -(CH<com:Sub>2< / com:Sub>)<com:Sub>u< / com:Sub>SO<com:Sub>2< / com:Sub>R<com:Sup>u3< / com:Sup>, wherein R<com:Sup>u1< / com:Sup>, R<com:Sup>u2< / com:Sup>, and R<com:Sup>u3< / com:Sup> are each independently hydrogen, C<com:Sub>1< / com:Sub>-C<com:Sub>15< / com:Sub> alkyl, C<com:Sub>6< / com:Sub>-C<com:Sub>20< / com:Sub> aryl or C<com:Sub>3< / com:Sub>-C<com:Sub>10< / com:Sub> heteroaryl; and u is an integer having a value of 1 to about 10; R<com:Sup>12< / com:Sup> is hydrogen, C<com:Sub>1< / com:Sub>-C<com:Sub>8< / com:Sub> alkyl, or an amino acid moiety, such as a naural amino acid moiety; b, c, d, e, g, h, o, and qq are each independently an integer having a value of 1 to about 10; and s' is an integer having a value of 1 to about 10. In other embodiments, Z is a linking group having a structure of Formula (F'), (G'), (H'), <com:Math><semantics>(J′),(K′),(L′),(M′),or(N′)<annotation encoding="application / x-tex">(J'), (K'), (L'), (M'), or (N')< / annotation>< / semantics>< / com:Math>: [Image disponible dans le document PDF, Image available in the PDF document] 1 1 . [Image disponible dans le document PDF, Image available in the PDF document] (N') In certain preferred embodiments, CB is selected from: [Image disponible dans le document PDF, Image available in the PDF document] In certain preferred embodiments, <com:Math><semantics>(Q)q<annotation encoding="application / x-tex">(Q)_q< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>(L′)w<annotation encoding="application / x-tex">(L')_w< / annotation>< / semantics>< / com:Math> is selected from: [Image disponible dans le document PDF, Image available in the PDF document] 4 [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] Also provided herein are compounds of Formula (I): [Image disponible dans le document PDF, Image available in the PDF document] (I) or a pharmaceutically acceptable salt thereof, wherein: X is -O-, -CH<com:Sub>2< / com:Sub>- or -NR'-; R' is hydrogen, <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math>-alkyl, <com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C14<annotation encoding="application / x-tex">C_{14}< / annotation>< / semantics>< / com:Math>-aryl, or <com:Math><semantics>C2<annotation encoding="application / x-tex">C_2< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C20<annotation encoding="application / x-tex">C_{20}< / annotation>< / semantics>< / com:Math>-heteroaryl; Ar is a C<com:Sub>5< / com:Sub>–C<com:Sub>20< / com:Sub>-aromatic ring, a C<com:Sub>2< / com:Sub>–C<com:Sub>20< / com:Sub>-heteroaromatic ring, a C<com:Sub>2< / com:Sub>–C<com:Sub>30< / com:Sub>-fused ring, or a C<com:Sub>5< / com:Sub>–C<com:Sub>20< / com:Sub>- aromatic ring-C<com:Sub>2< / com:Sub>-C<com:Sub>20< / com:Sub>-heteroaromatic ring; R is a substituent on Ar or -L<com:Sup>1< / com:Sup>'-Z-(CB)<com:Sub>cb< / com:Sub>, preferably -L<com:Sup>1< / com:Sup>'-Z-(CB)<com:Sub>cb< / com:Sub>; <com:Math><semantics>L1<annotation encoding="application / x-tex">L^{1}< / annotation>< / semantics>< / com:Math> is <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C200<annotation encoding="application / x-tex">C_{200}< / annotation>< / semantics>< / com:Math>-alkylene or <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C200<annotation encoding="application / x-tex">C_{200}< / annotation>< / semantics>< / com:Math> alkylene further comprising at least one of a peptide bond, an amino bond, an ether bond, a triazole bond, a tetrazole bond, a sugar bond, a sulfonamide bond, a phosphonate bond, a sulfo bond, or a dendrimer structure; Z is a linking unit connecting CB and L1' or a reactive group (e.g., that enables connection to CB); CB is a targeting moiety, such as a ligand having a property in which it binds to a receptor; cb is an integer having a value of 0, 1, or 2; n is an integer having a value of 1, 2, 3, or 4; [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] , [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] <com:Math><semantics>R1<annotation encoding="application / x-tex">R^1< / annotation>< / semantics>< / com:Math> is <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math> alkyl; r is an integer having a value of 1, 2, 3, 4, or 5; <com:Math><semantics>Ar1<annotation encoding="application / x-tex">Ar^1< / annotation>< / semantics>< / com:Math> is <com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C20<annotation encoding="application / x-tex">C_{20}< / annotation>< / semantics>< / com:Math> arylene; <com:Math><semantics>R2<annotation encoding="application / x-tex">R^2< / annotation>< / semantics>< / com:Math> and <com:Math><semantics>R3<annotation encoding="application / x-tex">R^3< / annotation>< / semantics>< / com:Math> are each independently hydrogen, <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math>-alkyl, <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math>-alkoxy, or hydroxy; <com:Math><semantics>Ra<annotation encoding="application / x-tex">R^a< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>Rb<annotation encoding="application / x-tex">R^b< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>Rc<annotation encoding="application / x-tex">R^c< / annotation>< / semantics>< / com:Math>, and <com:Math><semantics>Rd<annotation encoding="application / x-tex">R^d< / annotation>< / semantics>< / com:Math> are each independently hydrogen or <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math> alkyl; Y' is <com:Math><semantics>−(CH2)xNR″<annotation encoding="application / x-tex">-(CH_2)_xNR''< / annotation>< / semantics>< / com:Math>-, <com:Math><semantics>−(CH2)xO<annotation encoding="application / x-tex">-(CH_2)_xO< / annotation>< / semantics>< / com:Math>-, or <com:Math><semantics>−(CH2)xS<annotation encoding="application / x-tex">-(CH_2)_xS< / annotation>< / semantics>< / com:Math>-; R" is hydrogen or C<com:Sub>1< / com:Sub>-C<com:Sub>6< / com:Sub> alkyl; x is an integer having a value of 0 or 1; TG is a triggering group; Q is <com:Math><semantics>−Q1<annotation encoding="application / x-tex">-Q^{1}< / annotation>< / semantics>< / com:Math> or <com:Math><semantics>−L′−(Q1)w<annotation encoding="application / x-tex">-L'-(Q^{1})_{w}< / annotation>< / semantics>< / com:Math>; L' is a C<com:Sub>7< / com:Sub>–C<com:Sub>30< / com:Sub>-hydrocarbon spacer having -O- or -NR'''- at one end and -O-, -OC(O)-, - O(CO)O-, -OC(O)NR'''- or -OC(O)NR<com:Sup>4< / com:Sup>CH<com:Sub>2< / com:Sub>O- at the other end, wherein -O-, -OC(O)-, -O(CO)O- or -OC(O)NR'''- may be further included in the C<com:Sub>7< / com:Sub>-C<com:Sub>30< / com:Sub> hydrocarbon spacer, the C<com:Sub>7< / com:Sub>-C<com:Sub>30< / com:Sub> hydrocarbon spacer being further substituted with one or more substituents, such as C<com:Sub>1< / com:Sub>-C<com:Sub>6< / com:Sub> alkyl, C<com:Sub>5< / com:Sub>-C<com:Sub>14< / com:Sub> aryl, and C<com:Sub>3< / com:Sub>-C<com:Sub>8< / com:Sub> heteroaryl, wherein the alkyl, aryl and heteroaryl may be further substituted, e.g., with one or more substituents selected from the group consisting of C<com:Sub>1< / com:Sub>-C<com:Sub>10< / com:Sub> alkyl, -(CH<com:Sub>2< / com:Sub>)<com:Sub>u< / com:Sub>NH<com:Sub>2< / com:Sub>, -(CH<com:Sub>2< / com:Sub>)<com:Sub>u< / com:Sub>NR<com:Sup>ul< / com:Sup>R<com:Sup>u2< / com:Sup>, -(CH<com:Sub>2< / com:Sub>)<com:Sub>u< / com:Sub>CO<com:Sub>2< / com:Sub>H, - (CH<com:Sub>2< / com:Sub>)<com:Sub>u< / com:Sub>CO<com:Sub>2< / com:Sub>R<com:Sup>u1< / com:Sup>, and -(CH<com:Sub>2< / com:Sub>)<com:Sub>u< / com:Sub>SO<com:Sub>2< / com:Sub>R<com:Sup>u3< / com:Sup>, wherein R<com:Sup>u1< / com:Sup>, R<com:Sup>u2< / com:Sup>, and R<com:Sup>u3< / com:Sup> are each independently hydrogen, C<com:Sub>1< / com:Sub>-C<com:Sub>15< / com:Sub> alkyl, C<com:Sub>6< / com:Sub>-C<com:Sub>20< / com:Sub> aryl or C<com:Sub>3< / com:Sub>-C<com:Sub>10< / com:Sub> heteroaryl; and u is an integer having a value of 1 to about 10; Q<com:Sup>1< / com:Sup> is an active agent including at least one functional group of -OH, -NH-, -NR<com:Sub>5< / com:Sub>R<com:Sub>6< / com:Sub>, -SH, - <com:Math><semantics>SO2NH2<annotation encoding="application / x-tex">SO_2NH_2< / annotation>< / semantics>< / com:Math>, or -COOH; R<com:Sup>4< / com:Sup> is hydrogen, C<com:Sub>1< / com:Sub>–C<com:Sub>6< / com:Sub>-alkyl, C<com:Sub>5< / com:Sub>–C<com:Sub>14< / com:Sub>-aryl, or C<com:Sub>3< / com:Sub>–C<com:Sub>8< / com:Sub>-heteroaryl, wherein alkyl, aryl, and heteroaryl are substituted or unsubstituted; R<com:Sup>5< / com:Sup> and R<com:Sup>6< / com:Sup> are each independently hydrogen, C<com:Sub>1< / com:Sub>–C<com:Sub>6< / com:Sub>-alkyl, C<com:Sub>3< / com:Sub>–C<com:Sub>9< / com:Sub>-cycloalkyl or C<com:Sub>5< / com:Sub>–C<com:Sub>10< / com:Sub>- heteroaryl, wherein heteroaryl is substituted or unsubstituted; R''' and R''' are each independently hydrogen or C<com:Sub>1< / com:Sub>–C<com:Sub>6< / com:Sub>-alkyl; and w is an integer having a value of 1, 2, 3, 4, or 5. In some embodiments, the compound of Formula (I) comprises a functional group (e.g., Y) capable of inducing intramolecular cyclization by external stimulation. In certain embodiments, said functional group is introduced at an ortho-position with respect to X. In some embodiments, R' is <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>—<com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math>-alkyl, <com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math>—<com:Math><semantics>C14<annotation encoding="application / x-tex">C_{14}< / annotation>< / semantics>< / com:Math>-aryl, or <com:Math><semantics>C2<annotation encoding="application / x-tex">C_2< / annotation>< / semantics>< / com:Math>—<com:Math><semantics>C20<annotation encoding="application / x-tex">C_{20}< / annotation>< / semantics>< / com:Math>-heteroaryl. In some embodiments, Ar is a <com:Math><semantics>C5<annotation encoding="application / x-tex">C_5< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>C20<annotation encoding="application / x-tex">C_{20}< / annotation>< / semantics>< / com:Math>-aromatic ring, a <com:Math><semantics>C2<annotation encoding="application / x-tex">C_2< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>C20<annotation encoding="application / x-tex">C_{20}< / annotation>< / semantics>< / com:Math>-heteroaromatic ring, a <com:Math><semantics>C2<annotation encoding="application / x-tex">C_2< / annotation>< / semantics>< / com:Math>- C<com:Sub>30< / com:Sub>-fused ring, or a C<com:Sub>5< / com:Sub>-C<com:Sub>20< / com:Sub>-aromatic ring-C<com:Sub>2< / com:Sub>-C<com:Sub>20< / com:Sub>-heteroaromatic ring. For example, Ar may be a benzene ring, a naphthalene ring, a pyridine ring, or a quinolone ring. Preferably, Ar is a benzene ring or a naphthalene ring. In some embodiments, the compound of Formula (I) is a compound having a structure according to Formula (II): [Image disponible dans le document PDF, Image available in the PDF document] (II) or a pharmaceutically acceptable salt thereof. In other embodiments, the compound of Formula (I) is a compound having a structure according to Formula (III): [Image disponible dans le document PDF, Image available in the PDF document] (III) or a pharmaceutically acceptable salt thereof. In some embodiments, the compound is a compound of Formula (I), (II), or (III), wherein R is selected from hydrogen, halogen (hal), aldehyde, acetal, ketal, -R*, -OR*, -SR*, - <com:Math><semantics>NR*R**,−C(hal)3,−CN,−OCN,−SCN,−N=C=O,−NCS,−NO,−NO2,−N3,−NC,−C(O)R*,−<annotation encoding="application / x-tex">NR*R**, -C(hal)_3, -CN, -OCN, -SCN, -N=C=O, -NCS, -NO, -NO_2, -N_3, -NC, -C(O)R*, -< / annotation>< / semantics>< / com:Math> <com:Math><semantics>OC(O)R*<annotation encoding="application / x-tex">OC(O)R^*< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−OS(O)R*<annotation encoding="application / x-tex">-OS(O)R^*< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−S(O)2R*<annotation encoding="application / x-tex">-S(O)_2R^*< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−S(O)2OR*<annotation encoding="application / x-tex">-S(O)_2OR^*< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−OS(O)OR*<annotation encoding="application / x-tex">-OS(O)OR^*< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−OS(O)2OR*<annotation encoding="application / x-tex">-OS(O)_2OR^*< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−S(O)NR*R**<annotation encoding="application / x-tex">-S(O)NR^*R^{**}< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−OS(O)2OR*<annotation encoding="application / x-tex">-OS(O)_2OR^*< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−OS(O)2OR*<annotation encoding="application / x-tex">-OS(O)_2OR^*< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−OS(O)2OR*<annotation encoding="application / x-tex">-OS(O)_2OR^*< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−OS(O)2OR*<annotation encoding="application / x-tex">-OS(O)_2OR^*< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−OS(O)2OR*<annotation encoding="application / x-tex">-OS(O)_2OR^*< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−OS(O)2OR*<annotation encoding="application / x-tex">-OS(O)_2OR^*< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−OS(O)2OR*<annotation encoding="application / x-tex">-OS(O)_2OR^*< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−OS(O<annotation encoding="application / x-tex">-OS(O< / annotation>< / semantics>< / com:Math> <com:Math><semantics>S(O)2NR*R**,−S(O)R*,−OP(O)(OR*)2,−P(O)(OR*)2,−OP(OR*)2,−OP(OR*)2,−OP(OR*)2,−OP(OR*)2,−OP(OR*)2,−OP(OR*)2,−OP(OR*)2,−OP(OR*)2,−OP(OR*)2,−OP(OR*)2,−OP(OR*)2,−OP(OR*)2,−OP(OR*)2,−OP(OR*)2,<annotation encoding="application / x-tex">S(O)_2NR*R**, -S(O)R*, -OP(O)(OR*)_2, -P(O)(OR*)_2, -OP(OR*)_2, -OP(OR*)_2, -OP(OR*)_2, -OP(OR*)_2, -OP(OR*)_2, -OP(OR*)_2, -OP(OR*)_2, -OP(OR*)_2, -OP(OR*)_2, -OP(OR*)_2, -OP(OR*)_2, -OP(OR*)_2, -OP(OR*)_2, -OP(OR*)_2,< / annotation>< / semantics>< / com:Math> <com:Math><semantics>OP(O)(OR*)N(R**)2<annotation encoding="application / x-tex">OP(O)(OR^*)N(R^{**})_2< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−PR*<annotation encoding="application / x-tex">-PR^*< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−P(O)2<annotation encoding="application / x-tex">-P(O)_2< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−P(O)R*<annotation encoding="application / x-tex">-P(O)R^*< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−C(O)hal<annotation encoding="application / x-tex">-C(O)hal< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−C(S)R*<annotation encoding="application / x-tex">-C(S)R^*< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−CO2R*<annotation encoding="application / x-tex">-CO_2R^*< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−C(S)OR*<annotation encoding="application / x-tex">-C(S)OR^*< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−C(S)OR*<annotation encoding="application / x-tex">-C(S)OR^*< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−C(S)OR*<annotation encoding="application / x-tex">-C(S)OR^*< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−C(S)OR*<annotation encoding="application / x-tex">-C(S)OR^*< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−C(S)OR*<annotation encoding="application / x-tex">-C(S)OR^*< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−C(S)OR*<annotation encoding="application / x-tex">-C(S)OR^*< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−C(S)OR*<annotation encoding="application / x-tex">-C(S)OR^*< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−C(S)OR*<annotation encoding="application / x-tex">-C(S)OR^*< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−C(S)OR*<annotation encoding="application / x-tex">-C(S)OR^*< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−C(S)OR*<annotation encoding="application / x-tex">-C(S)OR^*< / annotation>< / semantics>< / com:Math> C(O)SR*, -C(S)SR*, -C(O)NR*R**, -C(S)NR*R**, -C(=NR*)NR*R**, -NR*C(O)R**, - NR*S(O)<com:Sub>2< / com:Sub>OR**, -NR*S(O)R**, -NR*C(O)NR**, -SS-R*, or -R*SSR**, wherein: R* and R** are each independently hydrogen, C<com:Sub>1< / com:Sub>-C<com:Sub>18< / com:Sub> alkyl, C<com:Sub>6< / com:Sub>-C<com:Sub>20< / com:Sub> aryl, C<com:Sub>3< / com:Sub>-C<com:Sub>15< / com:Sub> heterocycle or C<com:Sub>3< / com:Sub>-C<com:Sub>20< / com:Sub> heteroaryl. In some embodiments, the compound is a compound of Formula (I), (II), or (III), wherein R is hydrogen or *-(La-A<com:Sub>1< / com:Sub>-Lb-Lc-Z)<com:Sub>m< / com:Sub>-CB; wherein: <com:Math><semantics>La<annotation encoding="application / x-tex">L^a< / annotation>< / semantics>< / com:Math> is a single bond or <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C20<annotation encoding="application / x-tex">C_{20}< / annotation>< / semantics>< / com:Math>-alkylene; [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] R* is hydrogen, <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C18<annotation encoding="application / x-tex">C_{18}< / annotation>< / semantics>< / com:Math>-alkyl, <com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C20<annotation encoding="application / x-tex">C_{20}< / annotation>< / semantics>< / com:Math>-aryl, <com:Math><semantics>C3<annotation encoding="application / x-tex">C_3< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C15<annotation encoding="application / x-tex">C_{15}< / annotation>< / semantics>< / com:Math>-heterocycle, or <com:Math><semantics>C3<annotation encoding="application / x-tex">C_3< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>C20<annotation encoding="application / x-tex">C_{20}< / annotation>< / semantics>< / com:Math> heteroaryl; a is an integer having a value of 1 to about 20; L<com:Sup>c< / com:Sup> is a single bond or C<com:Sub>1< / com:Sub>–C<com:Sub>20< / com:Sub>-alkylene; n is an integer having a value of 1 or 2; and Z is a linking unit connecting CB and L<com:Sup>c< / com:Sup>; or Z is a precursor selected from isocyanide, isothiocyanide, 2-pyridyl disulfide, haloacetamide (- NHC(O)CH<com:Sub>2< / com:Sub>-hal), maleimide, diene, alkene, halide, tosylate (TsO<com:Sup>-< / com:Sup>), aldehyde, sulfonate [Image disponible dans le document PDF, Image available in the PDF document] <com:Math><semantics>(R−SO3−),<annotation encoding="application / x-tex">(R-SO_3^-),< / annotation>< / semantics>< / com:Math> , phosphonic acid (- P(=O)(OH)<com:Sub>2< / com:Sub>), ketone, C<com:Sub>8< / com:Sub>-C<com:Sub>10< / com:Sub> cycloalkynyl, -OH, -NHOH, -NHNH<com:Sub>2< / com:Sub>, -SH, carboxylic acid (-COOH), acetylene (-C<com:Math><semantics>≡<annotation encoding="application / x-tex">\equiv< / annotation>< / semantics>< / com:Math>CH), azide (-N<com:Sub>3< / com:Sub>), amino (-NH<com:Sub>2< / com:Sub>), sulfonic acid (-SO<com:Sub>3< / com:Sub>H), an alkynone derivative (-C(O)C<com:Math><semantics>≡<annotation encoding="application / x-tex">\equiv< / annotation>< / semantics>< / com:Math>C-R<com:Sup>a< / com:Sup>, wherein R<com:Sup>a< / com:Sup> is C<com:Sub>1< / com:Sub>-C<com:Sub>10< / com:Sub>-alkyl), and dihydrogen phosphate <com:Math><semantics>(−OP(=O)(OH)2)<annotation encoding="application / x-tex">(-OP(=O)(OH)_2)< / annotation>< / semantics>< / com:Math>; CB is a targeting moiety, such as a ligand capable of binding to a receptor; and m is an integer having a value of 0, 1, or 2. In some embodiments, the compound is a compound of Formula (I), (II), or (III), wherein R is hydrogen or *-La-A1-Lb-Lc-Z; wherein: <com:Math><semantics>La<annotation encoding="application / x-tex">L^a< / annotation>< / semantics>< / com:Math> is a single bond or <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C20<annotation encoding="application / x-tex">C_{20}< / annotation>< / semantics>< / com:Math>-alkylene; [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] R* is hydrogen, <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C18<annotation encoding="application / x-tex">C_{18}< / annotation>< / semantics>< / com:Math>-alkyl, <com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C20<annotation encoding="application / x-tex">C_{20}< / annotation>< / semantics>< / com:Math>-aryl, <com:Math><semantics>C3<annotation encoding="application / x-tex">C_3< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C15<annotation encoding="application / x-tex">C_{15}< / annotation>< / semantics>< / com:Math>-heterocycle, or <com:Math><semantics>C3<annotation encoding="application / x-tex">C_3< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C20<annotation encoding="application / x-tex">C_{20}< / annotation>< / semantics>< / com:Math>-heteroaryl; a is an integer having a value of 1 to about 20; L<com:Sup>c< / com:Sup> is a single bond or C<com:Sub>1< / com:Sub>–C<com:Sub>20< / com:Sub>-alkylene; n is an integer having a value of 1 or 2; and Z is a precursor selected from isocyanide, isothiocyanide, 2-pyridyl disulfide, haloacetamide (- NHC(O)CH<com:Sub>2< / com:Sub>-hal), maleimide, diene, alkene, halide, tosylate (TsO<com:Sup>-< / com:Sup>), aldehyde, sulfonate [Image disponible dans le document PDF, Image available in the PDF document] <com:Math><semantics>(R−SO3−),<annotation encoding="application / x-tex">(R-SO_3^-),< / annotation>< / semantics>< / com:Math> , phosphonic acid (- P(=O)(OH)<com:Sub>2< / com:Sub>), ketone, C<com:Sub>8< / com:Sub>-C<com:Sub>10< / com:Sub> cycloalkynyl, -OH, -NHOH, -NHNH<com:Sub>2< / com:Sub>, -SH, carboxylic acid (-COOH), acetylene (-C<com:Math><semantics>≡<annotation encoding="application / x-tex">\equiv< / annotation>< / semantics>< / com:Math>CH), azide (-N<com:Sub>3< / com:Sub>), amino (-NH<com:Sub>2< / com:Sub>), sulfonic acid (-SO<com:Sub>3< / com:Sub>H), an alkynone derivative (-C(O)C<com:Math><semantics>≡<annotation encoding="application / x-tex">\equiv< / annotation>< / semantics>< / com:Math>C-R<com:Sup>a< / com:Sup>, wherein R<com:Sup>a< / com:Sup> is C<com:Sub>1< / com:Sub>-C<com:Sub>10< / com:Sub>-alkyl), and dihydrogen phosphate <com:Math><semantics>(−OP(=O)(OH)2)<annotation encoding="application / x-tex">(-OP(=O)(OH)_2)< / annotation>< / semantics>< / com:Math>. In some embodiments, the compound is a compound of Formula (I), (II), or (III), wherein R is <com:Math><semantics>(−La−A1−Lb−Lc−Z)m<annotation encoding="application / x-tex">(-L^a-A_1-L^b-L^c-Z)_m< / annotation>< / semantics>< / com:Math>-CB; wherein: L<com:Sup>a< / com:Sup> is a single bond or C<com:Sub>1< / com:Sub>–C<com:Sub>20< / com:Sub>-alkylene; [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] R* is hydrogen, <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C18<annotation encoding="application / x-tex">C_{18}< / annotation>< / semantics>< / com:Math>-alkyl, <com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C20<annotation encoding="application / x-tex">C_{20}< / annotation>< / semantics>< / com:Math>-aryl, <com:Math><semantics>C3<annotation encoding="application / x-tex">C_3< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C15<annotation encoding="application / x-tex">C_{15}< / annotation>< / semantics>< / com:Math>-heterocycle, or <com:Math><semantics>C3<annotation encoding="application / x-tex">C_3< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C20<annotation encoding="application / x-tex">C_{20}< / annotation>< / semantics>< / com:Math>-heteroaryl; a is an integer having a value of 1 to about 20; L<com:Sup>c< / com:Sup> is a single bond or C<com:Sub>1< / com:Sub>–C<com:Sub>20< / com:Sub>-alkylene; n is an integer having a value of 1 or 2; Z is a linking unit connecting CB and L<com:Sup>c< / com:Sup>; CB is a targeting moiety, such as a ligand having a property in which it binds to a receptor; and m is an integer having a value of 1 to 2. In some embodiments, the compound is a compound of Formula (I), (II), or (III), wherein L' is a C<com:Sub>7< / com:Sub>–C<com:Sub>30< / com:Sub> hydrocarbon spacer further comprising -O-, -OC(O)-, -O(CO)O- or - OC(O)NR"."-. In some embodiments, the compound is a compound of Formula (I), (II), or (III), wherein Q is <com:Math><semantics>−L′−(Q1)w<annotation encoding="application / x-tex">-L'-(Q^1)_w< / annotation>< / semantics>< / com:Math> selected from: [Image disponible dans le document PDF, Image available in the PDF document] wherein: Q<com:Sup>1< / com:Sup> is an active agent comprising at least one functional group selected from -OH, -NR<com:Sup>5< / com:Sup>R<com:Sup>6< / com:Sup>, -SH, and -COOH; <com:Math><semantics>Q2<annotation encoding="application / x-tex">Q^2< / annotation>< / semantics>< / com:Math> is an active agent comprising -NR<com:Sup>5< / com:Sup>R<com:Sup>6< / com:Sup>; <com:Math><semantics>X1<annotation encoding="application / x-tex">X^1< / annotation>< / semantics>< / com:Math> is -O- or -NR'''-; X<com:Sup>2< / com:Sup> and X<com:Sup>4< / com:Sup> are each independently absent or selected from -O-, -OC(O)-, -OC(O)O-, and - OC(O)NH-; <com:Math><semantics>X3<annotation encoding="application / x-tex">X^3< / annotation>< / semantics>< / com:Math> is <com:Math><semantics>−OC(=O)<annotation encoding="application / x-tex">-OC(=O)< / annotation>< / semantics>< / com:Math>-; <com:Math><semantics>R5<annotation encoding="application / x-tex">R^5< / annotation>< / semantics>< / com:Math> and <com:Math><semantics>R6<annotation encoding="application / x-tex">R^6< / annotation>< / semantics>< / com:Math> are the same as defined above; R<com:Sup>9< / com:Sup> and R<com:Sup>10< / com:Sup> are each independently hydrogen, C<com:Sub>1< / com:Sub>-C<com:Sub>6< / com:Sub> alkyl, C<com:Sub>6< / com:Sub>-C<com:Sub>14< / com:Sub> aryl or C<com:Sub>3< / com:Sub>-C<com:Sub>9< / com:Sub> heteroaryl, the alkyl, aryl, and heteroaryl of the R<com:Sub>9< / com:Sub> and R<com:Sub>10< / com:Sub> may be further substituted with one or more substituents selected from the group consisting of <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>C10<annotation encoding="application / x-tex">C_{10}< / annotation>< / semantics>< / com:Math> alkyl, -(CH<com:Sub>2< / com:Sub>)<com:Sub>u< / com:Sub>NH<com:Sub>2< / com:Sub>, - (CH<com:Sub>2< / com:Sub>)<com:Sub>u< / com:Sub>NR<com:Sup>u1< / com:Sup>R<com:Sup>u2< / com:Sup>, and -(CH<com:Sub>2< / com:Sub>)<com:Sub>u< / com:Sub>SO<com:Sub>2< / com:Sub>R<com:Sup>u3< / com:Sup>, and the R<com:Sup>u1< / com:Sup>, R<com:Sup>u2< / com:Sup>, and R<com:Sup>u3< / com:Sup> are each independently hydrogen, C<com:Sub>1< / com:Sub>-C<com:Sub>15< / com:Sub> alkyl, C<com:Sub>6< / com:Sub>-C<com:Sub>20< / com:Sub> aryl or C<com:Sub>3< / com:Sub>-C<com:Sub>10< / com:Sub> heteroaryl; and u is an integer having a value of 1 to about 10; R"' is hydrogen or <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math>-alkyl; and w is an integer having a value of 1, 2, 3, 4, or 5. In certain embodiments, -L'-(Q¹)<com:Sub>w< / com:Sub> is selected from [Image disponible dans le document PDF, Image available in the PDF document] The at least one functional group of Q, Q<com:Sup>1< / com:Sup>, or Q<com:Sup>2< / com:Sup> selected from -OH, -NR<com:Sup>5< / com:Sup>R<com:Sup>6< / com:Sup>, -SH, and - COOH serves as a connection point of the active agent to L'. The functional group may exist as part of an ester, thioester, carbonate, carbamate, amide, sulfonamide, sulfonate, sulfate, or other suitable linkage; that is, the -OH, -NR<com:Sup>5< / com:Sup>R<com:Sup>6< / com:Sup>, -SH, and -COOH moiety does not exist as such while the active agent is part of the conjugate. In some embodiments, Q<com:Sup>2< / com:Sup> is an active agent comprising -NR<com:Sup>5< / com:Sup>R<com:Sup>6< / com:Sup>, wherein the active agent is capable of binding in a quaternary amine structure, for instance the -NR<com:Sup>5< / com:Sup>R<com:Sup>6< / com:Sup> moiety in the active agent is capable of forming a quaternary amine linkage with L'. In some embodiments of Formulas (I"), (Ia), (I), (II), and (III), R<com:Sup>4< / com:Sup> is substituted alkyl, aryl, or heteroaryl. In some such embodiments, R<com:Sup>4< / com:Sup> is substituted with one or more substituents selected from <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C10<annotation encoding="application / x-tex">C_{10}< / annotation>< / semantics>< / com:Math> alkyl, -(CH<com:Sub>2< / com:Sub>)<com:Sub>u< / com:Sub>NH<com:Sub>2< / com:Sub>, -(CH<com:Sub>2< / com:Sub>)<com:Sub>u< / com:Sub>NR<com:Sup>u1< / com:Sup>R<com:Sup>u2< / com:Sup>, -(CH<com:Sub>2< / com:Sub>)<com:Sub>u< / com:Sub>CO<com:Sub>2< / com:Sub>H, -(CH<com:Sub>2< / com:Sub>)<com:Sub>u< / com:Sub>CO<com:Sub>2< / com:Sub>R<com:Sup>u1< / com:Sup>, and - (CH<com:Sub>2< / com:Sub>)<com:Sub>u< / com:Sub>SO<com:Sub>2< / com:Sub>R<com:Sup>u3< / com:Sup>, wherein R<com:Sup>u1< / com:Sup>, R<com:Sup>u2< / com:Sup>, and R<com:Sup>u3< / com:Sup> are each independently hydrogen, C<com:Sub>1< / com:Sub>–C<com:Sub>15< / com:Sub>-alkyl, C<com:Sub>6< / com:Sub>– <com:Math><semantics>C20<annotation encoding="application / x-tex">C_{20}< / annotation>< / semantics>< / com:Math>-aryl, or <com:Math><semantics>C3<annotation encoding="application / x-tex">C_3< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>C10<annotation encoding="application / x-tex">C_{10}< / annotation>< / semantics>< / com:Math>-heteroaryl; and u is an integer having a value of 1 to about 10. In some embodiments of Formulas (I"), (Ia), (I), (II), and (III), R<com:Sup>5< / com:Sup> and / or R<com:Sup>6< / com:Sup> is heteroaryl substituted with -NR<com:Sup>7< / com:Sup>R<com:Sup>8< / com:Sup>, wherein R<com:Sup>7< / com:Sup> and R<com:Sup>8< / com:Sup> are each independently hydrogen, C<com:Sub>1< / com:Sub>–C<com:Sub>6< / com:Sub>- alkyl, C<com:Sub>3< / com:Sub>–C<com:Sub>9< / com:Sub>-cycloalkyl, or C<com:Sub>5< / com:Sub>–C<com:Sub>14< / com:Sub>-aryl. In some embodiments of Formulas (I"), (Ia), (I), (II), and (III), Q or -(L')w-(Q)q is selected from: [Image disponible dans le document PDF, Image available in the PDF document] - - [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] No. In certain embodiments, provided herein is a compound of Formula (I), (II), or (III), wherein: [Image disponible dans le document PDF, Image available in the PDF document] <com:Math><semantics>R1<annotation encoding="application / x-tex">R^1< / annotation>< / semantics>< / com:Math> is <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math> alkyl; r is an integer having a value of 1, 2, 3, 4, or 5; Ar<com:Sup>1< / com:Sup> is phenylene, biphenylene, or naphthylene; <com:Math><semantics>R2<annotation encoding="application / x-tex">R^2< / annotation>< / semantics>< / com:Math> and <com:Math><semantics>R3<annotation encoding="application / x-tex">R^3< / annotation>< / semantics>< / com:Math> are each independently hydrogen, <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math>-alkyl, <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math>-alkoxy, or hydroxy; Y' is <com:Math><semantics>−(CH2)xNR″<annotation encoding="application / x-tex">-(CH_2)_xNR''< / annotation>< / semantics>< / com:Math>-, <com:Math><semantics>−(CH2)xO<annotation encoding="application / x-tex">-(CH_2)_xO< / annotation>< / semantics>< / com:Math>- or <com:Math><semantics>−(CH2)xS<annotation encoding="application / x-tex">-(CH_2)_xS< / annotation>< / semantics>< / com:Math>-; R" is hydrogen or C<com:Sub>1< / com:Sub>–C<com:Sub>6< / com:Sub>-alkyl; x is an integer having a value of 0 or 1; R" is hydrogen or C<com:Sub>1< / com:Sub>–C<com:Sub>6< / com:Sub>-alkyl; and TG is a triggering group, such as a <com:Math><semantics>β<annotation encoding="application / x-tex">\beta< / annotation>< / semantics>< / com:Math>-galactoside, <com:Math><semantics>β<annotation encoding="application / x-tex">\beta< / annotation>< / semantics>< / com:Math>-glucuronide, or a combination of <com:Math><semantics>β<annotation encoding="application / x-tex">\beta< / annotation>< / semantics>< / com:Math>- galactoside and β-glucuronide. In certain embodiments, the compound of Formula (I), (II), or (III) is selected from: [Image disponible dans le document PDF, Image available in the PDF document] wherein: <com:Math><semantics>R1<annotation encoding="application / x-tex">R^1< / annotation>< / semantics>< / com:Math> is <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math> alkyl; <com:Math><semantics>R21<annotation encoding="application / x-tex">R^{21}< / annotation>< / semantics>< / com:Math> and <com:Math><semantics>R22<annotation encoding="application / x-tex">R^{22}< / annotation>< / semantics>< / com:Math> are each independently hydrogen or acetyl; R is hydrogen, *-La-A<com:Sub>1< / com:Sub>-Lb-Lc-Z, or a group having a structure of Formula (F), (G), (H), <com:Math><semantics>(J),(K),(L),(M),or(N)<annotation encoding="application / x-tex">(J), (K), (L), (M), or (N)< / annotation>< / semantics>< / com:Math>: [Image disponible dans le document PDF, Image available in the PDF document] L<com:Sup>a< / com:Sup> is a single bond or C<com:Sub>1< / com:Sub>-C<com:Sub>20< / com:Sub> alkylene; [Image disponible dans le document PDF, Image available in the PDF document] <com:Math><semantics>Lb<annotation encoding="application / x-tex">L^b< / annotation>< / semantics>< / com:Math> is <com:Math><semantics>−(CH2CH2O)a<annotation encoding="application / x-tex">-(CH_2CH_2O)_a< / annotation>< / semantics>< / com:Math>- or <com:Math><semantics>−(CH2)a<annotation encoding="application / x-tex">-(CH_2)_a< / annotation>< / semantics>< / com:Math>-; a is an integer having a value of 1 to about 20; <com:Math><semantics>Lc<annotation encoding="application / x-tex">L^{c}< / annotation>< / semantics>< / com:Math> is <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>C20<annotation encoding="application / x-tex">C_{20}< / annotation>< / semantics>< / com:Math> alkylene; X" is -O-, -S-, -NH-, or -CH<com:Sub>2< / com:Sub>-; [Image disponible dans le document PDF, Image available in the PDF document] W<com:Sup>b1< / com:Sup> and W<com:Sup>b2< / com:Sup> are each independently -C(O)NH-, -NHC(O)-, R<com:Sup>12< / com:Sup> is hydrogen, C<com:Sub>1< / com:Sub>-C<com:Sub>8< / com:Sub> alkyl, an amino acid moiety, -(CH<com:Sub>2< / com:Sub>)<com:Sub>s< / com:Sub>COR<com:Sup>13< / com:Sup>, or -(CH<com:Sub>2< / com:Sub>)<com:Sub>p< / com:Sub>NR<com:Sup>14< / com:Sup>R<com:Sup>15< / com:Sup>; <com:Math><semantics>R13<annotation encoding="application / x-tex">R^{13}< / annotation>< / semantics>< / com:Math> is OH or <com:Math><semantics>−NH(CH2)s′(X″CH2CH2)s″Z<annotation encoding="application / x-tex">-NH(CH_2)_{s'}(X''CH_2CH_2)_{s''}Z< / annotation>< / semantics>< / com:Math>; R<com:Sup>14< / com:Sup> and R<com:Sup>15< / com:Sup> are each independently hydrogen or -(C(O)(CH<com:Sub>2< / com:Sub>)<com:Sub>s'< / com:Sub>(X"CH<com:Sub>2< / com:Sub>CH<com:Sub>2< / com:Sub>)<com:Sub>s"< / com:Sub>Z)<com:Sub>m< / com:Sub>-CB; X" is -O-, -S-, -NH-, or -CH<com:Sub>2< / com:Sub>-; <com:Math><semantics>Re<annotation encoding="application / x-tex">R^e< / annotation>< / semantics>< / com:Math> is <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C8<annotation encoding="application / x-tex">C_8< / annotation>< / semantics>< / com:Math>-alkyl or -(<com:Math><semantics>L1′<annotation encoding="application / x-tex">L^{1'}< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>Z<annotation encoding="application / x-tex">Z< / annotation>< / semantics>< / com:Math>)<com:Sub>m< / com:Sub>-<com:Math><semantics>CB<annotation encoding="application / x-tex">CB< / annotation>< / semantics>< / com:Math>; <com:Math><semantics>X4<annotation encoding="application / x-tex">X^4< / annotation>< / semantics>< / com:Math> is <com:Math><semantics>−NHC(O)−(CH2)g−NH−<annotation encoding="application / x-tex">-NHC(O)-(CH_2)_g-NH-< / annotation>< / semantics>< / com:Math> or <com:Math><semantics>−C(O)NH−(CH2)h−NH−<annotation encoding="application / x-tex">-C(O)NH-(CH_2)_h-NH-< / annotation>< / semantics>< / com:Math>; b, c, d, e, g, h, o, and q are each independently an integer having a value of 1 to about 10; p is an integer having a value of 1 to about 10; s and s" are each independently an integer having a value of 0 to about 10; s' is an integer having a value of 1 to about 10; m is an integer having a value of 0 or 1; Z is isocyanide, isothiocyanide, 2-pyridyl disulfide, haloacetamide (-NHC(O)CH<com:Sub>2< / com:Sub>-hal), maleimide, diene, alkene, halide, tosylate (TsO<com:Sup>-< / com:Sup>), aldehyde, sulfonate (R-SO<com:Sub>3< / com:Sub><com:Sup>-< / com:Sup>), [Image disponible dans le document PDF, Image available in the PDF document] , phosphonic acid <com:Math><semantics>(−P(=O)(OH)2)<annotation encoding="application / x-tex">(-P(=O)(OH)_2)< / annotation>< / semantics>< / com:Math>, ketone, C<com:Sub>8< / com:Sub>–C<com:Sub>10< / com:Sub>-cycloalkynyl, -OH, -NHOH, -NHNH<com:Sub>2< / com:Sub>, -SH, carboxylic acid (-COOH), acetylene (-C≡CH), azide (-N<com:Sub>3< / com:Sub>), amino (-NH<com:Sub>2< / com:Sub>), sulfonic acid (-SO<com:Sub>3< / com:Sub>H), an alkynone derivative (-C(O)C<com:Math><semantics>≡<annotation encoding="application / x-tex">\equiv< / annotation>< / semantics>< / com:Math>C-R<com:Sup>a< / com:Sup>, wherein R<com:Sup>a< / com:Sup> is C<com:Sub>1< / com:Sub>-C<com:Sub>10< / com:Sub> alkyl), or dihydrogen phosphate (- <com:Math><semantics>OP(=O)(OH)2);<annotation encoding="application / x-tex">OP(=O)(OH)_2);< / annotation>< / semantics>< / com:Math> CB is a ligand selected from: [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] Q is selected from: [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] 5 . Release of the Active Agent As described above, in certain embodiments, the compounds and conjugates disclosed herein are capable of dissociating one or more active agents (represented by Q, Q<com:Sup>1< / com:Sup>, Q<com:Sup>2< / com:Sup>) through an intramolecular cyclization reaction following a chemical reaction that activates the triggering group. In certain embodiments, the chemical reaction is a physicochemical reaction and / or a biochemical reaction. In some embodiments, the compounds and conjugates disclosed herein comprise a nucleophilic functional group (Y or Y') introduced at an adjacent atom on Ar with respect to X (e.g., O). Typically, the nucleophilic functional group is masked by a triggering group (TG), as further detailed below. Upon activation, the triggering group releases the nucleophilic functional group to react with the nearby SO<com:Sub>2< / com:Sub> moiety in an intramolecular cyclization, ultimately releasing the one or more active agents <com:Math><semantics>(Q,Q1, or Q2)<annotation encoding="application / x-tex">(Q, Q^1, \text{ or } Q^2)< / annotation>< / semantics>< / com:Math>. In some such embodiments, one or more active agents are released through an intramolecular cyclization reaction after a chemical reaction, a physicochemical reaction and / or a biochemical reaction (see, for example, Reaction Scheme 1), or the active agent is released through 1,6-elimination or 1,4-elimination after the intramolecular cyclization reaction (see, for example, Reaction Scheme 2). As an example, the mechanism when Y is -Y'-TG is shown in Reaction Scheme 1: Reaction Scheme 1: [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] In some embodiments, Q<com:Sup>1< / com:Sup> when released is an active agent comprising at least one functional group selected from -OH, -NH-, -SH and -COOH. According to these embodiments, as further described herein, Q<com:Sup>1< / com:Sup> is conjugated to a compound as described herein by the -OH, - NH-, -SH and -COOH, for instance through a functional group selected from ester, amide, thioester, carbamate, urea, oxime, hydrazone, etc. In some such embodiments, <com:Math><semantics>Q2<annotation encoding="application / x-tex">Q^2< / annotation>< / semantics>< / com:Math> is used in place of <com:Math><semantics>Q1<annotation encoding="application / x-tex">Q^1< / annotation>< / semantics>< / com:Math>, and <com:Math><semantics>Q2<annotation encoding="application / x-tex">Q^2< / annotation>< / semantics>< / com:Math> is an amine group-containing drug. In other embodiments, <com:Math><semantics>Q2<annotation encoding="application / x-tex">Q^2< / annotation>< / semantics>< / com:Math> is an active agent capable of binding with an ammonium unit. In still other embodiments, <com:Math><semantics>Q2<annotation encoding="application / x-tex">Q^2< / annotation>< / semantics>< / com:Math> is capable of being dissociated in its original form having an amine group upon release of Q<com:Sup>2< / com:Sup> release, wherein the active agent may be a drug, a toxin, an affinity ligand, a probe for detection, or a combination thereof. In some embodiments, the compounds and conjugates disclosed herein are chemically and physiologically stable. In some such embodiments, the compounds and conjugates disclosed herein reach a desired target cell in a state wherien there is little dissociation of the active agent in the blood, thereby selectively releasing the drug. Triggering Groups (TGs) In some embodiments, the conjugates of the present invention include a triggering group (TG). TGs are groups capable of being cleaved, preferably selectively cleaved, by a chemical reaction, such as a biological reaction. Generally, triggering groups serve to mask the nucleophilic nature of the Y or Y' group, thereby providing stability (e.g., by preventing self- immolation or intramolecular cyclization prior to the conjugate reaching a target location or experiencing a predetermined trigger condition) to the compounds and conjugates disclosed herein. Upon activation, the triggering group releases the nucleophilic Y or Y' group and allows for self-immolation or intramolecular cyclization to occur, as described above. In some embodiments, the TG comprises a sequence (such as a peptide sequence) or a moiety recognized by TEV, trypsin, thrombin, cathepsin B, cathespin D, cathepsin K, caspase 1, matrix metalloproteinase (MMP), and the like, which can be hydrolyzed by an enzyme (e.g., an oxidoreductase, a transferase, a hydrolase, a lyase, an isomerase, a ligase, etc.) and / or may include a moiety selected from a phosphodiester, a phospholipid, an ester, a β-galactose, a β- glucose, a fucose, an oligosugar, and the like. In some embodiments, the TG comprises a reactive chemical moiety or functional group that can be cleaved under nucleophilic reagent conditions (e.g., a silyl ether, a 2-N-acyl nitrobenzenesulfonamide, an unsaturated vinyl sulfide, a sulfonamide after activation, a malondialdehyde-indole derivative, a levulinoyl ester, a hydrazone, or an acyl hydrazone). In some embodiments, the TG may comprise a reactive chemical moiety or functional group that can be cleaved under basic reagent conditions (e.g., a 2-cyanoethyl ester, an ethylene glycolyl disuccinate, a 2-sulfonylethyl ester, an alkyl thioester, or a thiophenyl ester). In some embodiments, the TG may comprise a reactive chemical moiety or functional group that can be cleaved by photo-irradiation (e.g., 2-nitrobenzyl derivative, phenacyl ester, 8- quinolinyl benzenesulfonate, coumarin, phosphotriester, bis-arylhydrazone, or bimane bi- thiopropionic acid derivative). In some embodiments, the TG may comprise a reactive chemical moiety or functional group that can be cleaved by reducing agent conditions (e.g., hydroxylamine, disulfide, levulinate, nitro, or 4-nitrobenzyl derivative). In some embodiments, the TG may comprise a reactive chemical moiety or a functional group that can be cleaved using acidic conditions (e.g., saccharides, tert-butylcarbamate analogue, dialkyl or diaryl dialkoxysilane, orthoester, acetal, aconityl, hydrazone, β- thiopropionate, phosphoramidate, imine, trityl, vinyl ether, polyketal, and alkyl 2- (diphenylphosphino)benzoate derivative; alkyl ester, 8-hydroxyquinoline ester, and picolinate ester). In some embodiments, the TG may comprise a reactive chemical moiety or functional group that can be cleaved under oxidative conditions (e.g., a boronate, a vicinal diol, paramethoxybenzyl derivative, or a selenium compound). In certain preferred embodiments, the TG comprises a saccharide, which can be cleaved under acidic or enzymatic conditions. In certain preferred embodiments, the triggering group is - NO<com:Sub>2< / com:Sub>, which can be cleaved under reducing conditions. In certain preferred embodiments, the triggering group is a boronate, which can be cleaved under oxidative conditions. In certain preferred embodiments, the triggering group is an ester, which can be cleaved under acidic, basic, or enzymatic conditions. In certain preferred embodiments, the triggering group is a hydrazone, which can be cleaved under nucleophilic conditions or under acidic conditions. In certain preferred embodiments, the triggering group is a hydroxylamine, which can be cleaved under reducing conditions. Saccharide Triggering Groups In some embodiments, the compounds and conjugates disclosed herein comprise a saccharide triggering group, for instance a triggering group selected from: [Image disponible dans le document PDF, Image available in the PDF document] wherein each R<com:Sup>21< / com:Sup> is independently hydrogen or is selected such that O-R<com:Sup>21< / com:Sup> is a hydroxy protecting group (e.g., acetyl); and R<com:Sup>22< / com:Sup> is hydrogen or lower alkyl (e.g., C<com:Sub>1< / com:Sub>–C<com:Sub>6< / com:Sub>-alkyl). In certain embodiments, the hydroxy protecting group is capable of being used in organic synthesis, including but not limited to: methyl ether, methoxymethyl ether, methylthiomethyl ether, 2- methoxyethoxymethyl ether, bis(2-chloroethoxy)methyl ether, tetrahydropyranyl ether, tetrahydrothiopyranyl ether, 4-methoxytetrahydropyranyl ether, 4-methoxytetrahydrothiopyranyl ether, tetrahydrofuranyl ether, 1-ethoxyethyl ether, 1-methyl-1-methoxyethyl ether, 2- (phenylselenyl)ethyl ether, t-butyl ether, allyl ether, benzyl ether, o-nitrobenzyl ether, triphenyl methyl ether, α-naphthyldiphenyl methyl ether, p-methoxyphenyldiphenylmethyl ether, 9-(9- phenyl-10-oxo)anthryl ether, trimethylsilyl ether, isopropyldimethylsilyl ether, t- butyldimethylsilyl ether, t-butyldiphenylsilyl ether, tribenzylsilyl ether, triisopropylsilyl ether, formate ester, acetate ester, trichloroacetate ester, phenoxyacetate ester, isobutyrate ester, pivaloate ester, adamantoate ester, benzoate ester, 2,4,6-trimethylbenzoate ester, methyl carbonate, 2,2,2-trichloroethyl carbonate, allyl carbonate, p-nitrophenyl carbonate, benzyl carbonate, p-nitrobenzyl carbonate, S-benzylthiocarbonate, N-phenylcarbamate, nitrate ester, 2,4-dinitrophenylsulfenate ester, etc., but is not limited thereto. Protecting Groups as Triggering Groups In some embodiments, TG is a group that is capable of being cleaved by a chemical reaction, a physicochemical reaction, and / or a biological reaction. In certain embodiments, TG is a protecting group. In some such embodiments, the protecting group is an amine group protecting group, an alcohol protecting group, or a thiol protecting group. Amine Protecting Groups In certain embodiments, the amine protecting group is a general protecting group that is capable of being used in organic synthesis, including but not limited to: m-nitrophenyl carbamate, 3,5-dimethoxybenzyl carbamate, o-nitrobenzyl carbamate, phenyl(o- nitrophenyl)methyl carbamate, alkyl carbamate, 9-fluorenylmethyl carbamate, 2,2,2- trichloroethyl carbamate, 2-trimethylsilylethyl carbamate(Teoc), t-butyl carbamate(Boc), vinyl carbamate (Voc), allyl carbamate (Alloc), 1-isopropylallyl carbamate (Ipaoc), 8-quinolyl carbamate, N-hydroxypiperidinyl carbamate, benzyl carbamate, p-methoxybenzyl carbamate, p- nitrobenzyl carbamate, diphenyl methyl carbamate, acetamide, chloroacetamide, trichloroacetamide, phenylacetamide, benzamide, N-phthalimide, N-2,3-diphenylmaleimide, N- 2,5-dimethylpyrrole, N-1,1-dimethylthiomethyleneamine, N-benzylideneamine, benzenesulfenamide, o-nitrobenzenesulfenamide, triphenylmethylsulfenamide, p- toluenesulfonamide, methanesulfonamide, etc., but is not limited thereto. Alcohol Protecting Groups In certain embodiments, the alcohol protecting group is a general protecting group that is capable of being used in organic synthesis, including but not limited to: methyl ether, methoxymethyl ether (MOM ether), benzyloxymethyl ether (BOM ether), 2- (trimethylsilyl)ethoxymethyl ether (SEM ether), phenylthiomethyl ether (PTM ether), 2,2- dichloro-1,1-difluoroethyl ether, p-bromophenacyl ether, chloropropylmethyl ether, isopropyl ether, cyclohexyl ether, 4-methoxybenzyl, 2,6-dichlorobenzyl ether, 4- (dimethylaminocarbonyl)benzyl ether, 9-anthrylmethyl ether, 4-picolyl ether, methylthiomethyl ether (MTM ether), 2-methoxyethoxymethyl ether (MEM ether), bis(2-chloroethoxy)methyl ether, tetrahydropyranyl ether (THP ether), tetrahydrothiopyranyl ether, 4- methoxytetrahydropyranyl ether, 4-methoxytetrahydrothiopyranyl ether, tetrahydrofuranyl ether, 1-ethoxyethyl ether, 1-methyl-1-methoxyethyl ether, 2-(phenylselenyl)ethyl ether), t-butyl ether, allyl ether, benzyl ether, o-nitrobenzyl ether, triphenylmethyl ether, <com:Math><semantics>α<annotation encoding="application / x-tex">\alpha< / annotation>< / semantics>< / com:Math>-naphthyldiphenylmethyl ether, p-methoxyphenyldiphenylmethyl ether, 9-(9-phenyl-10-oxo)anthryl ether, trimethylsilyl ether (TMS ether), isopropyldimethylsilyl ether, t-butyldimethylsilyl ether (TBDMS ether), t- butyldiphenyl silyl ether, tribenzylsilyl ether, triisopropylsilyl ether, formate ester, acetate ester, trichloroacetate ester, phenoxyacetate ester, isobutyrate ester, pivaloate ester, adamantoate ester, benzoate ester, 2,4,6-trimethylbenzoate(Mesitoate) ester, methyl carbonate, 2,2,2-trichloroethyl carbonate, allyl carbonate, p-nitrophenyl carbonate, benzyl carbonate, p-nitrobenzyl carbonate, S-benzyl thiocarbonate, N-phenylcarbamate, nitrate ester, 2,4-dinitrophenylsulfenate ester, dimethylphosphinyl ester (DMP ester), dimethylthiophosphinyl ester (MPT ester), aryl methanesulfonate, aryl toluenesulfonate, etc., but is not limited thereto. Thiol Protecting Groups In certain embodiments, the thiol protecting group is capable of being used in organic synthesis, including but not limited to: S-benzyl thioether, S-p-methoxybenzyl thioether, S-o- or p-hydroxyl or acetoxybenzyl thioether, S-p-nitrobenzyl thioether, S-4-picolyl thioether, S-2- picolyl N-oxide thioether, S-9-anthrylmethyl thioether, S-9-fluorenylmethyl thioether, S- methoxymethyl monothioacetal, A-acetyl derivative, S-benzoyl derivative, S-(N- ethylcarbamate), S-(N-methoxymethylcarbamate), etc., but is not limited thereto. Linking Group In some embodiments, the compounds and conjugates disclosed herein comprise a linking group connecting each CB and Ar through a covalent bond. Typical linking groups are stable, non-hydrolyzable moieties, such as, for example a <com:Math><semantics>C10<annotation encoding="application / x-tex">C_{10}< / annotation>< / semantics>< / com:Math>—<com:Math><semantics>C100<annotation encoding="application / x-tex">C_{100}< / annotation>< / semantics>< / com:Math> linear or branched, saturated or unsaturated alkylene. In certain embodiments, the linking unit satisfies at least two, and more preferably at least three, out of four of the following criteria: (i) at least one -CH<com:Sub>2< / com:Sub>- in the alkylene moiety is substituted with (i.e., is replaced by) one or more heteroatoms selected from -NH-, -C(=O), -O-, -S- and -P-; (ii) at least one heteroarylene is included in the alkylene moiety; (iii) at least one amino acid moiety, sugar bond, peptide bond, or amide bond is included in the alkylene moiety; and (iv) the alkylene may be further substituted with one or more substituents selected from the group consisting of C<com:Sub>1< / com:Sub>-C<com:Sub>20< / com:Sub> alkyl, C<com:Sub>6< / com:Sub>-C<com:Sub>20< / com:Sub> aryl C<com:Sub>1< / com:Sub>-C<com:Sub>8< / com:Sub> alkyl, -(CH<com:Sub>2< / com:Sub>)<com:Sub>s< / com:Sub>COOH, and -(CH<com:Sub>2< / com:Sub>)<com:Sub>p< / com:Sub>NH<com:Sub>2< / com:Sub>, wherein s is an integer having a value of 0 to 10, and p is an integer having a value of 1 to about 10. In certain embodiments, the linking unit comprises at least two, and more preferably at least three, of the following: (i) at least one heteroatom selected from -NH-, -C(=O), -O-, -S- and -P-; (ii) at least one heteroarylene; (iii) at least one amino acid moiety, sugar bond, peptide bond, or amide bond; and (iv) the alkylene may be further substituted with one or more substituents selected from the group consisting of C<com:Sub>1< / com:Sub>-C<com:Sub>20< / com:Sub> alkyl, C<com:Sub>6< / com:Sub>-C<com:Sub>20< / com:Sub> aryl C<com:Sub>1< / com:Sub>-C<com:Sub>8< / com:Sub> alkyl, -(CH<com:Sub>2< / com:Sub>)<com:Sub>s< / com:Sub>COOH, and -(CH<com:Sub>2< / com:Sub>)<com:Sub>p< / com:Sub>NH<com:Sub>2< / com:Sub>, wherein s is an integer having a value of 0 to 10, and p is an integer having a value of 1 to about 10. In other embodiments, the linking group connecting each CB and Ar comprises a functional group produced through a click chemical reaction. In alternative embodiments, the linking unit comprises a reactive functional group capable of participating in a click chemical reaction. A click chemical reaction is a reaction that can be performed under mild conditions, and is extremely selective for functional groups that are not commonly found in biological molecules (e.g., an azide group, an acetylene group, etc.). Accordingly, this reaction can be carried out in the presence of complex triggering groups, targeting moieties, etc. Further, click chemistry has high reaction specificity. For example, the click chemical reaction between an azide group and an acetylene group proceeds selectively without interference from other functional groups present in the molecule. For example, azide-acetylene click chemistry may afford a triazole moiety in high yield. Thus, in some embodiments, the linking group connecting each CB and Ar comprises [Image disponible dans le document PDF, Image available in the PDF document] <Formule mathématique disponible dans le document PDF, Math available in the PDF document display="block"> \label{eq:ch2} \begin{tabular}{l} \begin{tabular}{l} \begin{tabular}{l} \begin{tabular}{l} \begin{tabular}{l} \begin{tabular}{l} \begin{tabular}{l} \begin{tabular}{l} \begin{tabular}{l} \begin{tabular}{l} \begin{tabula NR<com:Sup>23< / com:Sup>C(O)-, -NR<com:Sup>24< / com:Sup>SO<com:Sub>2< / com:Sub>-, or -SO<com:Sub>2< / com:Sub>NR<com:Sup>25< / com:Sup>-, R<com:Sup>21< / com:Sup> to R<com:Sup>25< / com:Sup> may be each independently hydrogen, (C<com:Sub>1< / com:Sub>- <com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math>)alkyl, <com:Math><semantics>(C1−C6)<annotation encoding="application / x-tex">(C_1-C_6)< / annotation>< / semantics>< / com:Math>alkyl<com:Math><semantics>(C6−C20)<annotation encoding="application / x-tex">(C_6-C_{20})< / annotation>< / semantics>< / com:Math>aryl, or <com:Math><semantics>(C1−C6)<annotation encoding="application / x-tex">(C_1-C_6)< / annotation>< / semantics>< / com:Math>alkyl<com:Math><semantics>(C3−C20)<annotation encoding="application / x-tex">(C_3-C_{20})< / annotation>< / semantics>< / com:Math>heteroaryl, r may be an integer having a value of 1 to about 10, p may be an integer having a value of 0 to about 10, q may be an integer having a value of 1 to about 10, and L" may be a single bond. In other embodiments, the linking unit connecting each CB and Ar is a linking group represented by Formula (A): [Image disponible dans le document PDF, Image available in the PDF document] (A) wherein: * is the point of attachment to CB; ** is point of attachment to Ar; <com:Math><semantics>Wa1<annotation encoding="application / x-tex">W^{a1}< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>Wa2<annotation encoding="application / x-tex">W^{a2}< / annotation>< / semantics>< / com:Math>, and <com:Math><semantics>Wa3<annotation encoding="application / x-tex">W^{a3}< / annotation>< / semantics>< / com:Math> are each independently -NH-, -C(=O)-, or (-CH<com:Sub>2< / com:Sub>-)<com:Sub>b< / com:Sub>; W<com:Sup>b1< / com:Sup> is an amide bond or triazolylene; P<com:Sup>1< / com:Sup> is a linker connecting W<com:Sup>a3< / com:Sup> and Y<com:Sup>2< / com:Sup>, and is an amino acid moiety, a peptide bond, or an amide bond; L<com:Sup>c< / com:Sup> is alkylene; <com:Math><semantics>Y2<annotation encoding="application / x-tex">Y^2< / annotation>< / semantics>< / com:Math> is a single bond, <com:Math><semantics>−Wa4<annotation encoding="application / x-tex">-W^{a4}< / annotation>< / semantics>< / com:Math>-(CH<com:Sub>2< / com:Sub>)<com:Sub>c< / com:Sub>-<com:Math><semantics>Wb2<annotation encoding="application / x-tex">W^{b2}< / annotation>< / semantics>< / com:Math>-(CH<com:Sub>2< / com:Sub>)<com:Sub>d< / com:Sub>-<com:Math><semantics>Wa5<annotation encoding="application / x-tex">W^{a5}< / annotation>< / semantics>< / com:Math>-, or <com:Math><semantics>−Wa6<annotation encoding="application / x-tex">-W^{a6}< / annotation>< / semantics>< / com:Math>-(CH<com:Sub>2< / com:Sub>)<com:Sub>e< / com:Sub>-<com:Math><semantics>CReRf<annotation encoding="application / x-tex">CR^eR^f< / annotation>< / semantics>< / com:Math>-X-; <com:Math><semantics>Re<annotation encoding="application / x-tex">R^e< / annotation>< / semantics>< / com:Math> is <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>C8<annotation encoding="application / x-tex">C_8< / annotation>< / semantics>< / com:Math> alkyl or <com:Math><semantics>CB<annotation encoding="application / x-tex">CB< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>Wa7<annotation encoding="application / x-tex">W_{a7}< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>Y3<annotation encoding="application / x-tex">Y_3< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>Wc1<annotation encoding="application / x-tex">W_{c1}< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>(CH2)f<annotation encoding="application / x-tex">(CH_2)_f< / annotation>< / semantics>< / com:Math>-; <com:Math><semantics>Rf<annotation encoding="application / x-tex">R^{f}< / annotation>< / semantics>< / com:Math> is B-W<com:Sup>a7< / com:Sup>-Y<com:Sup>3< / com:Sup>-W<com:Sup>c1< / com:Sup>-(CH<com:Sub>2< / com:Sub>)<com:Sub>f< / com:Sub>-; X is <com:Math><semantics>−NHC(=O)−(CH2)g−Wa8−or−C(=O)NH−(CH2)h−Wa9−<annotation encoding="application / x-tex">-NHC(=O)-(CH_2)_g-W^{a8}- or -C(=O)NH-(CH_2)_h-W^{a9}-< / annotation>< / semantics>< / com:Math>; W<com:Sup>a4< / com:Sup>, W<com:Sup>a5< / com:Sup>, W<com:Sup>a6< / com:Sup>, W<com:Sup>a7< / com:Sup>, W<com:Sup>a8< / com:Sup>, and W<com:Sup>a9< / com:Sup> are each independently -NH-, -C(=O)-, or -CH<com:Sub>2< / com:Sub>-; W<com:Sup>b2< / com:Sup> is an amide bond or triazolylene; <com:Math><semantics>Wc1<annotation encoding="application / x-tex">W^{c1}< / annotation>< / semantics>< / com:Math> is -NHC(=O)- or -C(=O)NH-; <com:Math><semantics>Y3<annotation encoding="application / x-tex">Y^3< / annotation>< / semantics>< / com:Math> is -(CH<com:Sub>2< / com:Sub>)<com:Sub>i< / com:Sub>-(X'CH<com:Sub>2< / com:Sub>CH<com:Sub>2< / com:Sub>)<com:Sub>i< / com:Sub>-(CH<com:Sub>2< / com:Sub>)<com:Sub>k< / com:Sub>-; X' is -O-, -S-, -NH-, or -CH<com:Sub>2< / com:Sub>-; CB is the same as defined above; b, c, d, e, f, g, h, i, and j are each independently an integer having a value of 1 to about 10; k and y are each independently an integer having a value of 0 to about 10; <com:Math><semantics>Y1<annotation encoding="application / x-tex">Y^1< / annotation>< / semantics>< / com:Math> is <com:Math><semantics>−(CH2)q−(CH2CH2X″)o<annotation encoding="application / x-tex">-(CH_2)_q-(CH_2CH_2X'')_o< / annotation>< / semantics>< / com:Math> or <com:Math><semantics>−(CH2)q−(X″CH2CH2)o<annotation encoding="application / x-tex">-(CH_2)_q-(X''CH_2CH_2)_o< / annotation>< / semantics>< / com:Math>; X" is -O-, -S-, -NH-, or -CH<com:Sub>2< / com:Sub>-; and o and q are an integer having a value of 1 to about 10. In some embodiments, <com:Math><semantics>P1<annotation encoding="application / x-tex">P^1< / annotation>< / semantics>< / com:Math> comprises at least one unit represented by Formula (B) or (C): [Image disponible dans le document PDF, Image available in the PDF document] (B) [Image disponible dans le document PDF, Image available in the PDF document] wherein: <com:Math><semantics>R12<annotation encoding="application / x-tex">R^{12}< / annotation>< / semantics>< / com:Math> is hydrogen, <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C8<annotation encoding="application / x-tex">C_8< / annotation>< / semantics>< / com:Math>-alkyl, an amino acid side chain, such as a natural amino acid side chain (e.g., H, methyl, isopropyl, isobutyl, sec-butyl, S-methyl thioether, benzyl, indole, pyrollidine, pyrroline, hydroxymethyl, tyrosyl, lysyl, imidazole, glycyl, glutamyl, carbamoylbutanoic acid, carboxamide, aspartic acid, 1-hydroxyethyl, and 2- hydroxyethyl), <com:Math><semantics>−(CH2)sCOR13<annotation encoding="application / x-tex">-(CH_2)_sCOR^{13}< / annotation>< / semantics>< / com:Math> or <com:Math><semantics>−(CH2)pNR14R15<annotation encoding="application / x-tex">-(CH_2)_pNR^{14}R^{15}< / annotation>< / semantics>< / com:Math>; <com:Math><semantics>R13<annotation encoding="application / x-tex">R^{13}< / annotation>< / semantics>< / com:Math> is OH or -NH(CH<com:Sub>2< / com:Sub>)<com:Sub>s'< / com:Sub>(X"CH<com:Sub>2< / com:Sub>CH<com:Sub>2< / com:Sub>)<com:Sub>s"< / com:Sub>Z; R<com:Sup>14< / com:Sup> and R<com:Sup>15< / com:Sup> are each independently hydrogen or –(C(O)(CH<com:Sub>2< / com:Sub>)<com:Sub>s< / com:Sub>·(X''CH<com:Sub>2< / com:Sub>CH<com:Sub>2< / com:Sub>)<com:Sub>s< / com:Sub>·Z)<com:Sub>m< / com:Sub>-CB; X" is -O-, -S-, -NH-, or -CH<com:Sub>2< / com:Sub>-; Z and CB are the same as defined above; p is an integer having a value of 1 to about 10; s and s" are an integer having a value of 0 to about 10; s' is an integer having a value of 1 to about 10; and m is an integer having a value of 0 or 1. In some embodiments of formula (B) or (C): R<com:Sup>12< / com:Sup> is hydrogen, alkyl, an amino acid side chain, -(CH<com:Sub>2< / com:Sub>)<com:Sub>s< / com:Sub>C(O)R<com:Sup>13< / com:Sup> or -(CH<com:Sub>2< / com:Sub>)<com:Sub>p< / com:Sub>NR<com:Sup>14< / com:Sup>R<com:Sup>15< / com:Sup>; p is an integer having a value of 1 to about 10; s is an integer having a value of 0 to about 10; <com:Math><semantics>R13<annotation encoding="application / x-tex">R^{13}< / annotation>< / semantics>< / com:Math> is OH or <com:Math><semantics>−NH(CH2)s′(X‴CH2CH2)s″Z″−(CB)m<annotation encoding="application / x-tex">-NH(CH_2)_{s'}(X'''CH_2CH_2)_{s''}Z''-(CB)_{m}< / annotation>< / semantics>< / com:Math>; R<com:Sup>14< / com:Sup> and R<com:Sup>15< / com:Sup> are each independently hydrogen or -C(O)(CH<com:Sub>2< / com:Sub>)<com:Sub>s< / com:Sub>'(X'''CH<com:Sub>2< / com:Sub>CH<com:Sub>2< / com:Sub>)<com:Sub>s< / com:Sub>"Z''-(CB)<com:Sub>m< / com:Sub>; s" is an integer having a value of 0 to about 10; s' is an integer having a value of 1 to about 10; m is an integer having a value of 0 or 1; X''' is <com:Math><semantics>−O−<annotation encoding="application / x-tex">-O_{-}< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−S−<annotation encoding="application / x-tex">-S_{-}< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−NH−<annotation encoding="application / x-tex">-NH_{-}< / annotation>< / semantics>< / com:Math>, or <com:Math><semantics>−CH2−<annotation encoding="application / x-tex">-CH_{2-}< / annotation>< / semantics>< / com:Math>; and <com:Math><semantics>Z″<annotation encoding="application / x-tex">Z''< / annotation>< / semantics>< / com:Math> is a linking group connecting CB to the remainder of <com:Math><semantics>R14<annotation encoding="application / x-tex">R^{14}< / annotation>< / semantics>< / com:Math> or <com:Math><semantics>R15<annotation encoding="application / x-tex">R^{15}< / annotation>< / semantics>< / com:Math>; or <com:Math><semantics>Z″<annotation encoding="application / x-tex">Z''< / annotation>< / semantics>< / com:Math> is a linking group comprising a reactive group. In some such embodiments of formula (B) or (C): <com:Math><semantics>R13<annotation encoding="application / x-tex">R^{13}< / annotation>< / semantics>< / com:Math> is OH or <com:Math><semantics>−NH(CH2)s′(X‴CH2CH2)s″Z″<annotation encoding="application / x-tex">-NH(CH_2)_{s'}(X'''CH_2CH_2)_{s''}Z''< / annotation>< / semantics>< / com:Math>; R<com:Sup>14< / com:Sup> and R<com:Sup>15< / com:Sup> are each independently hydrogen or -C(O)(CH<com:Sub>2< / com:Sub>)<com:Sub>s'< / com:Sub>(X'''CH<com:Sub>2< / com:Sub>CH<com:Sub>2< / com:Sub>)<com:Sub>s''< / com:Sub>Z''; and Z'' is a reactive precursor of a linking unit selected from isocyanide, isothiocyanide, 2-pyridyl disulfide, haloacetamide (-NHC(O)CH<com:Sub>2< / com:Sub>-hal), maleimide, diene, alkene, halide, tosylate [Image disponible dans le document PDF, Image available in the PDF document] (TsO<com:Sup>-< / com:Sup>), aldehyde, sulfonate (R-SO<com:Sub>3< / com:Sub><com:Sup>-< / com:Sup>), , phosphonic acid <com:Math><semantics>(−P(=O)(OH)2)<annotation encoding="application / x-tex">(-P(=O)(OH)_2)< / annotation>< / semantics>< / com:Math>, ketone, <com:Math><semantics>C8−C10<annotation encoding="application / x-tex">C_8-C_{10}< / annotation>< / semantics>< / com:Math> cycloalkynyl, <com:Math><semantics>−OH<annotation encoding="application / x-tex">-OH< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−NHOH<annotation encoding="application / x-tex">-NHOH< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−NHNH2<annotation encoding="application / x-tex">-NHNH_2< / annotation>< / semantics>< / com:Math>, -SH, carboxylic acid (-COOH), acetylene (-C≡CH), azide (-N<com:Sub>3< / com:Sub>), amino (-NH<com:Sub>2< / com:Sub>), sulfonic acid (-SO<com:Sub>3< / com:Sub>H), an alkynone derivative (-C(O)C<com:Math><semantics>≡<annotation encoding="application / x-tex">\equiv< / annotation>< / semantics>< / com:Math>C-R<com:Sup>a< / com:Sup>, wherein R<com:Sup>a< / com:Sup> is C<com:Sub>1< / com:Sub>-C<com:Sub>10< / com:Sub>-alkyl), and dihydrogen phosphate <com:Math><semantics>(−OP(=O)(OH)2)<annotation encoding="application / x-tex">(-OP(=O)(OH)_2)< / annotation>< / semantics>< / com:Math>. In other such embodiments of formula (B) or (C): <com:Math><semantics>R13<annotation encoding="application / x-tex">R^{13}< / annotation>< / semantics>< / com:Math> is OH or <com:Math><semantics>−NH(CH2)s′(X‴CH2CH2)s″Z″CB<annotation encoding="application / x-tex">-NH(CH_2)_{s'}(X'''CH_2CH_2)_{s''}Z''CB< / annotation>< / semantics>< / com:Math>; R<com:Sup>14< / com:Sup> and R<com:Sup>15< / com:Sup> are each independently hydrogen or -C(O)(CH<com:Sub>2< / com:Sub>)<com:Sub>s'< / com:Sub>(X'''CH<com:Sub>2< / com:Sub>CH<com:Sub>2< / com:Sub>)<com:Sub>s''< / com:Sub>Z''CB; and Z'' is a linking unit connecting CB to the remainder of R<com:Sup>14< / com:Sup> or R<com:Sup>15< / com:Sup> formed from a precursor selected from isocyanide, isothiocyanide, 2-pyridyl disulfide, haloacetamide (- NHC(O)CH<com:Sub>2< / com:Sub>-hal), maleimide, diene, alkene, halide, tosylate (TsO<com:Sup>-< / com:Sup>), aldehyde, sulfonate [Image disponible dans le document PDF, Image available in the PDF document] <com:Math><semantics>(R−SO3−),<annotation encoding="application / x-tex">(R-SO_3^-),< / annotation>< / semantics>< / com:Math> , phosphonic acid (- P(=O)(OH)<com:Sub>2< / com:Sub>), ketone, C<com:Sub>8< / com:Sub>-C<com:Sub>10< / com:Sub> cycloalkynyl, -OH, -NHOH, -NHNH<com:Sub>2< / com:Sub>, -SH, carboxylic acid (-COOH), acetylene (-C<com:Math><semantics>≡<annotation encoding="application / x-tex">\equiv< / annotation>< / semantics>< / com:Math>CH), azide (-N<com:Sub>3< / com:Sub>), amino (-NH<com:Sub>2< / com:Sub>), sulfonic acid (-SO<com:Sub>3< / com:Sub>H), an alkynone derivative (-C(O)C<com:Math><semantics>≡<annotation encoding="application / x-tex">\equiv< / annotation>< / semantics>< / com:Math>C-R<com:Sup>a< / com:Sup>, wherein R<com:Sup>a< / com:Sup> is C<com:Sub>1< / com:Sub>-C<com:Sub>10< / com:Sub>-alkyl), and dihydrogen phosphate <com:Math><semantics>(−OP(=O)(OH)2)<annotation encoding="application / x-tex">(-OP(=O)(OH)_2)< / annotation>< / semantics>< / com:Math>. In some embodiments, <com:Math><semantics>Y2<annotation encoding="application / x-tex">Y^2< / annotation>< / semantics>< / com:Math> is a single bond or is selected from: [Image disponible dans le document PDF, Image available in the PDF document] wherein: <com:Math><semantics>Wb2<annotation encoding="application / x-tex">W^{b2}< / annotation>< / semantics>< / com:Math> is <com:Math><semantics>−C(O)NH<annotation encoding="application / x-tex">-C(O)NH< / annotation>< / semantics>< / com:Math>-, <com:Math><semantics>−NHC(O)<annotation encoding="application / x-tex">-NHC(O)< / annotation>< / semantics>< / com:Math>-, <com:Math><semantics>N=N<annotation encoding="application / x-tex">N=N< / annotation>< / semantics>< / com:Math> , or <com:Math><semantics>N=N<annotation encoding="application / x-tex">N=N< / annotation>< / semantics>< / com:Math> [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] c, d, e, f, g, h, i, and j are each independently an integer having a value of 1 to about 10; X'' is -O-, -S-, -NH-, or -CH<com:Sub>2< / com:Sub>-; and L<com:Sup>1< / com:Sup>, Z, m, and B are the same as defined above. In certain embodiments, the linking unit connecting each CB and Ar is a linking group comprising (CH<com:Sub>2< / com:Sub>)<com:Sub>b< / com:Sub>, L<com:Sup>c< / com:Sup>, (P<com:Sup>1< / com:Sup>)<com:Sub>a< / com:Sub>, W<com:Sup>a1< / com:Sup>, W<com:Sup>a2< / com:Sup>, W<com:Sup>a3< / com:Sup>, Y<com:Sup>1< / com:Sup>, and Y<com:Sup>2< / com:Sup> groups connected to each other by covalent bonds, wherein: W<com:Sup>a1< / com:Sup>, W<com:Sup>a2< / com:Sup>, and W<com:Sup>a3< / com:Sup> are each independently -NH-, -C(O)-, or -CH<com:Sub>2< / com:Sub>-; W<com:Sup>b1< / com:Sup> is an amide bond or triazolylene; <com:Math><semantics>P1<annotation encoding="application / x-tex">P^1< / annotation>< / semantics>< / com:Math> is an amide bond, an amino acid residue, or a peptide; L° is alkylene; [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] <com:Math><semantics>Y2<annotation encoding="application / x-tex">Y^2< / annotation>< / semantics>< / com:Math> is a single bond or a group selected from: [Image disponible dans le document PDF, Image available in the PDF document] W<com:Sup>b2< / com:Sup> is an amide bond or triazolylene; a is 0 to 10; b, c, and d are each independently an integer having a value of 1 to about 10; and o and q are each independently an integer having a value of 1 to about 10. In some embodiments, <com:Math><semantics>R12<annotation encoding="application / x-tex">R^{12}< / annotation>< / semantics>< / com:Math> is a natural amino acid side chain. In other embodiments, <com:Math><semantics>R12<annotation encoding="application / x-tex">R^{12}< / annotation>< / semantics>< / com:Math> is non-natural amino acid side chain. In some embodiments, the linking unit connecting each CB and Ar is a linking group represented by Formula (A): [Image disponible dans le document PDF, Image available in the PDF document] (A) wherein: * is the point of attachment to CB; and ** is point of attachment to Ar. In some such embodiments, P<com:Sup>1< / com:Sup> is [Image disponible dans le document PDF, Image available in the PDF document] wherein: R<com:Sup>12< / com:Sup> is hydrogen, alkyl, an amino acid side chain, -(CH<com:Sub>2< / com:Sub>)<com:Sub>s< / com:Sub>COOH or -(CH<com:Sub>2< / com:Sub>)<com:Sub>p< / com:Sub>NH<com:Sub>2< / com:Sub>; p is an integer having a value of 1 to about 10; and s and s" are each independently an integer having a value of 0 to about 10. In some embodiments <com:Math><semantics>P1<annotation encoding="application / x-tex">P^1< / annotation>< / semantics>< / com:Math> is [Image disponible dans le document PDF, Image available in the PDF document] wherein: R<com:Sup>12< / com:Sup> is hydrogen, alkyl, an amino acid side chain, -(CH<com:Sub>2< / com:Sub>)<com:Sub>s< / com:Sub>C(O)R<com:Sup>13< / com:Sup> or -(CH<com:Sub>2< / com:Sub>)<com:Sub>p< / com:Sub>NR<com:Sup>14< / com:Sup>R<com:Sup>15< / com:Sup>; p is an integer having a value of 1 to about 10; s is an integer having a value of 0 to about 10; <com:Math><semantics>R13<annotation encoding="application / x-tex">R^{13}< / annotation>< / semantics>< / com:Math> is OH or <com:Math><semantics>−NH(CH2)s′(X‴CH2CH2)s″Z″−(CB)m′<annotation encoding="application / x-tex">-NH(CH_2)_{s'}(X'''CH_2CH_2)_{s''}Z''-(CB)_{m'}< / annotation>< / semantics>< / com:Math>; R<com:Sup>14< / com:Sup> and R<com:Sup>15< / com:Sup> are each independently hydrogen or -C(O)(CH<com:Sub>2< / com:Sub>)<com:Sub>s'< / com:Sub>(X'''CH<com:Sub>2< / com:Sub>CH<com:Sub>2< / com:Sub>)<com:Sub>s''< / com:Sub>Z''-(CB)<com:Sub>m< / com:Sub>; s" is an integer having a value of 0 to about 10; s' is an integer having a value of 1 to about 10; m is an integer having a value of 0 or 1; X''' is -O-, -S-, -NH-, or -CH<com:Sub>2< / com:Sub>-; and <com:Math><semantics>Z″<annotation encoding="application / x-tex">Z''< / annotation>< / semantics>< / com:Math> is a linking group connecting CB to the remainder of <com:Math><semantics>R14<annotation encoding="application / x-tex">R^{14}< / annotation>< / semantics>< / com:Math> or <com:Math><semantics>R15<annotation encoding="application / x-tex">R^{15}< / annotation>< / semantics>< / com:Math>; or <com:Math><semantics>Z″<annotation encoding="application / x-tex">Z''< / annotation>< / semantics>< / com:Math> is a linking group comprising a reactive group. In some such embodiments of P<com:Sup>1< / com:Sup>: <com:Math><semantics>R13<annotation encoding="application / x-tex">R^{13}< / annotation>< / semantics>< / com:Math> is OH or <com:Math><semantics>−NH(CH2)s′(X‴CH2CH2)s″Z″;<annotation encoding="application / x-tex">-NH(CH_2)_{s'}(X'''CH_2CH_2)_{s''}Z'';< / annotation>< / semantics>< / com:Math> R<com:Sup>14< / com:Sup> and R<com:Sup>15< / com:Sup> are each independently hydrogen or -C(O)(CH<com:Sub>2< / com:Sub>)<com:Sub>s'< / com:Sub>(X'''CH<com:Sub>2< / com:Sub>CH<com:Sub>2< / com:Sub>)<com:Sub>s''< / com:Sub>Z''; and Z' is a reactive precursor of a linking unit selected from isocyanide, isothiocyanide, 2-pyridyl disulfide, haloacetamide (-NHC(O)CH<com:Sub>2< / com:Sub>-hal), maleimide, diene, alkene, halide, tosylate [Image disponible dans le document PDF, Image available in the PDF document] (TsO<com:Sup>-< / com:Sup>), aldehyde, sulfonate (R-SO<com:Sub>3< / com:Sub><com:Sup>-< / com:Sup>), , phosphonic acid <com:Math><semantics>(−P(=O)(OH)2)<annotation encoding="application / x-tex">(-P(=O)(OH)_2)< / annotation>< / semantics>< / com:Math>, ketone, <com:Math><semantics>C8−C10<annotation encoding="application / x-tex">C_8-C_{10}< / annotation>< / semantics>< / com:Math> cycloalkynyl, <com:Math><semantics>−OH<annotation encoding="application / x-tex">-OH< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−NHOH<annotation encoding="application / x-tex">-NHOH< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−NHNH2<annotation encoding="application / x-tex">-NHNH_2< / annotation>< / semantics>< / com:Math>, -SH, carboxylic acid (-COOH), acetylene (-C≡CH), azide (-N<com:Sub>3< / com:Sub>), amino (-NH<com:Sub>2< / com:Sub>), sulfonic acid (-SO<com:Sub>3< / com:Sub>H), an alkynone derivative (-C(O)C<com:Math><semantics>≡<annotation encoding="application / x-tex">\equiv< / annotation>< / semantics>< / com:Math>C-R<com:Sup>a< / com:Sup>, wherein R<com:Sup>a< / com:Sup> is C<com:Sub>1< / com:Sub>-C<com:Sub>10< / com:Sub>-alkyl), and dihydrogen phosphate <com:Math><semantics>(−OP(=O)(OH)2)<annotation encoding="application / x-tex">(-OP(=O)(OH)_2)< / annotation>< / semantics>< / com:Math>. In other such embodiments of <com:Math><semantics>P1<annotation encoding="application / x-tex">P^1< / annotation>< / semantics>< / com:Math>: <com:Math><semantics>R13<annotation encoding="application / x-tex">R^{13}< / annotation>< / semantics>< / com:Math> is OH or <com:Math><semantics>−NH(CH2)s′(X‴CH2CH2)s″Z″CB<annotation encoding="application / x-tex">-NH(CH_2)_{s'}(X'''CH_2CH_2)_{s''}Z''CB< / annotation>< / semantics>< / com:Math>; R<com:Sup>14< / com:Sup> and R<com:Sup>15< / com:Sup> are each independently hydrogen or -C(O)(CH<com:Sub>2< / com:Sub>)<com:Sub>s'< / com:Sub>(X'''CH<com:Sub>2< / com:Sub>CH<com:Sub>2< / com:Sub>)<com:Sub>s''< / com:Sub>Z''CB; and <com:Math><semantics>Z″<annotation encoding="application / x-tex">Z''< / annotation>< / semantics>< / com:Math> is a linking unit connecting CB to the remainder of <com:Math><semantics>R14<annotation encoding="application / x-tex">R^{14}< / annotation>< / semantics>< / com:Math> or <com:Math><semantics>R15<annotation encoding="application / x-tex">R^{15}< / annotation>< / semantics>< / com:Math> formed from a precursor selected from isocyanide, isothiocyanide, 2-pyridyl disulfide, haloacetamide (- NHC(O)CH<com:Sub>2< / com:Sub>-hal), maleimide, diene, alkene, halide, tosylate (TsO<com:Sup>-< / com:Sup>), aldehyde, sulfonate [Image disponible dans le document PDF, Image available in the PDF document] <com:Math><semantics>(R−SO3−),<annotation encoding="application / x-tex">(R-SO_3^-),< / annotation>< / semantics>< / com:Math> , phosphonic acid (- P(=O)(OH)<com:Sub>2< / com:Sub>), ketone, C<com:Sub>8< / com:Sub>-C<com:Sub>10< / com:Sub> cycloalkynyl, -OH, -NHOH, -NHNH<com:Sub>2< / com:Sub>, -SH, carboxylic acid (-COOH), acetylene (-C<com:Math><semantics>≡<annotation encoding="application / x-tex">\equiv< / annotation>< / semantics>< / com:Math>CH), azide (-N<com:Sub>3< / com:Sub>), amino (-NH<com:Sub>2< / com:Sub>), sulfonic acid (-SO<com:Sub>3< / com:Sub>H), an alkynone derivative (-C(O)C<com:Math><semantics>≡<annotation encoding="application / x-tex">\equiv< / annotation>< / semantics>< / com:Math>C-R<com:Sup>a< / com:Sup>, wherein R<com:Sup>a< / com:Sup> is C<com:Sub>1< / com:Sub>-C<com:Sub>10< / com:Sub>-alkyl), and dihydrogen phosphate <com:Math><semantics>(−OP(=O)(OH)2)<annotation encoding="application / x-tex">(-OP(=O)(OH)_2)< / annotation>< / semantics>< / com:Math>. In alternative embodiments, the linking unit connecting CB and Ar is a linking group represented by Formula (F), (G), (H), (J), (K), (L), (M), or (N): [Image disponible dans le document PDF, Image available in the PDF document] ¥ . ż - - wherein: R<com:Sup>e< / com:Sup> is alkyl; [Image disponible dans le document PDF, Image available in the PDF document] e, g, and h are each independently an integer having a value of 1 to about 10; and s' is an integer having a value of 1 to about 10. In some embodiments of Formula (F), (G), (H), (I), (J), (K), (L), or (M): R<com:Sup>12< / com:Sup> is hydrogen, alkyl, an amino acid side chain, -(CH<com:Sub>2< / com:Sub>)<com:Sub>s< / com:Sub>C(O)R<com:Sup>13< / com:Sup> or -(CH<com:Sub>2< / com:Sub>)<com:Sub>p< / com:Sub>NR<com:Sup>14< / com:Sup>R<com:Sup>15< / com:Sup>; p is an integer having a value of 1 to about 10; s is an integer having a value of 0 to about 10; [Image disponible dans le document PDF, Image available in the PDF document] R<com:Sup>14< / com:Sup> and R<com:Sup>15< / com:Sup> are each independently hydrogen or -C(O)(CH<com:Sub>2< / com:Sub>)<com:Sub>s'< / com:Sub>(X'''CH<com:Sub>2< / com:Sub>CH<com:Sub>2< / com:Sub>)<com:Sub>s''< / com:Sub>Z''-(CB)<com:Sub>m< / com:Sub>; s" is an integer having a value of 0 to about 10; s' is an integer having a value of 1 to about 10; m is an integer having a value of 0 or 1; [Image disponible dans le document PDF, Image available in the PDF document] Z'' is a linking group connecting CB to the remainder of <com:Math><semantics>ℝ14<annotation encoding="application / x-tex">\mathbb{R}^{14}< / annotation>< / semantics>< / com:Math> or <com:Math><semantics>ℝ15<annotation encoding="application / x-tex">\mathbb{R}^{15}< / annotation>< / semantics>< / com:Math>; or Z'' is a linking group comprising a reactive group. In some such embodiments of Formula (F), (G), (H), (I), (J), (K), (L), or (M): <com:Math><semantics>R13<annotation encoding="application / x-tex">R^{13}< / annotation>< / semantics>< / com:Math> is OH or <com:Math><semantics>−NH(CH2)s′(X‴CH2CH2)s″Z″<annotation encoding="application / x-tex">-NH(CH_2)_{s'}(X'''CH_2CH_2)_{s''}Z''< / annotation>< / semantics>< / com:Math>; R<com:Sup>14< / com:Sup> and R<com:Sup>15< / com:Sup> are each independently hydrogen or -C(O)(CH<com:Sub>2< / com:Sub>)<com:Sub>s'< / com:Sub>(X'''CH<com:Sub>2< / com:Sub>CH<com:Sub>2< / com:Sub>)<com:Sub>s''< / com:Sub>Z''; and Z'' is a reactive precursor of a linking unit selected from isocyanide, isothiocyanide, 2-pyridyl disulfide, haloacetamide (-NHC(O)CH<com:Sub>2< / com:Sub>-hal), maleimide, diene, alkene, halide, tosylate [Image disponible dans le document PDF, Image available in the PDF document] (TsO<com:Sup>-< / com:Sup>), aldehyde, sulfonate (R-SO<com:Sub>3< / com:Sub><com:Sup>-< / com:Sup>), , phosphonic acid (-P(=O)(OH)<com:Sub>2< / com:Sub>), ketone, C<com:Sub>8< / com:Sub>-C<com:Sub>10< / com:Sub> cycloalkynyl, -OH, -NHOH, -NHNH<com:Sub>2< / com:Sub>, -SH, carboxylic acid (-COOH), acetylene (-C≡CH), azide (-N<com:Sub>3< / com:Sub>), amino (-NH<com:Sub>2< / com:Sub>), sulfonic acid (-SO<com:Sub>3< / com:Sub>H), an alkynone derivative (-C(O)C<com:Math><semantics>≡<annotation encoding="application / x-tex">\equiv< / annotation>< / semantics>< / com:Math>C-R<com:Sup>a< / com:Sup>, wherein R<com:Sup>a< / com:Sup> is C<com:Sub>1< / com:Sub>-C<com:Sub>10< / com:Sub>-alkyl), and dihydrogen phosphate <com:Math><semantics>(−OP(=O)(OH)2)<annotation encoding="application / x-tex">(-OP(=O)(OH)_2)< / annotation>< / semantics>< / com:Math>. In some such embodiments of Formula (F), (G), (H), (I), (J), (K), (L), or (M): <com:Math><semantics>R13<annotation encoding="application / x-tex">R^{13}< / annotation>< / semantics>< / com:Math> is OH or <com:Math><semantics>−NH(CH2)s′(X‴CH2CH2)s″Z″CB;<annotation encoding="application / x-tex">-NH(CH_2)_{s'}(X'''CH_2CH_2)_{s''}Z''CB;< / annotation>< / semantics>< / com:Math> R<com:Sup>14< / com:Sup> and R<com:Sup>15< / com:Sup> are each independently hydrogen or -C(O)(CH<com:Sub>2< / com:Sub>)<com:Sub>s'< / com:Sub>(X'''CH<com:Sub>2< / com:Sub>CH<com:Sub>2< / com:Sub>)<com:Sub>s''< / com:Sub>Z''CB; and <com:Math><semantics>Z″<annotation encoding="application / x-tex">Z''< / annotation>< / semantics>< / com:Math> is a linking unit connecting CB to the remainder of <com:Math><semantics>R14<annotation encoding="application / x-tex">R^{14}< / annotation>< / semantics>< / com:Math> or <com:Math><semantics>R15<annotation encoding="application / x-tex">R^{15}< / annotation>< / semantics>< / com:Math> formed from a precursor selected from isocyanide, isothiocyanide, 2-pyridyl disulfide, haloacetamide (- NHC(O)CH<com:Sub>2< / com:Sub>-hal), maleimide, diene, alkene, halide, tosylate (TsO<com:Sup>-< / com:Sup>), aldehyde, sulfonate [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] <com:Math><semantics>(R−SO3−),<annotation encoding="application / x-tex">(R-SO_3^-),< / annotation>< / semantics>< / com:Math> 2 , phosphonic acid (- P(=O)(OH)<com:Sub>2< / com:Sub>), ketone, C<com:Sub>8< / com:Sub>-C<com:Sub>10< / com:Sub> cycloalkynyl, -OH, -NHOH, -NHNH<com:Sub>2< / com:Sub>, -SH, carboxylic acid (-COOH), acetylene (-C<com:Math><semantics>≡<annotation encoding="application / x-tex">\equiv< / annotation>< / semantics>< / com:Math>CH), azide (-N<com:Sub>3< / com:Sub>), amino (-NH<com:Sub>2< / com:Sub>), sulfonic acid (-SO<com:Sub>3< / com:Sub>H), an alkynone derivative (-C(O)C<com:Math><semantics>≡<annotation encoding="application / x-tex">\equiv< / annotation>< / semantics>< / com:Math>C-R<com:Sup>a< / com:Sup>, wherein R<com:Sup>a< / com:Sup> is C<com:Sub>1< / com:Sub>-C<com:Sub>10< / com:Sub>-alkyl), and dihydrogen phosphate <com:Math><semantics>(−OP(=O)(OH)2)<annotation encoding="application / x-tex">(-OP(=O)(OH)_2)< / annotation>< / semantics>< / com:Math>. Targeting Moieties The compounds and conjugates of the present invention can further comprise a ligand or targeting moiety, CB. In some embodiments, the ligand or targeting moiety is any molecular recognition element, which can undergo a specific interaction with at least one other molecular through, e.g., noncovalent bonding such as hydrogen bonding, metal coordination, hydrophobic forces, van der Waals forces, <com:Math><semantics>π<annotation encoding="application / x-tex">\pi< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>π<annotation encoding="application / x-tex">\pi< / annotation>< / semantics>< / com:Math> interactions, halogen bonding, electrostatic, and / or electromagnetic effects. In certain embodiments, CB is selected from a nanoparticle, an immunoglobulin, a nucleic acid, a protein, an oligopeptide, a polypeptide, an antibody, a fragment of an antigenic polypeptide, a repebody, and the like. The compounds and conjugates of the present invention may comprise one or more targeting moieties. That is, the variable cb may have an integer value selected from 1, 2, 3, 4, 5, 1-10, or 1-20. In some embodiments, CB comprises two or more independently selected natural amino acids or non-natural amino acids conjugated by covalent bonds (e.g., peptide bonds), and the peptide may include 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or more natural amino acids or non-natural amino acids that are conjugated by peptide bonds. In some embodiments, the ligand comprises shorter amino acid sequences (e.g., fragments of natural proteins or synthetic polypeptide fragments) as well as full-length proteins (e.g., pre-engineered proteins). In some embodiments, CB is selected from an antibody, a hormone, a drug, an antibody analogue (e.g., non-IgG), protein, an oligopeptide, a polypeptide, etc., which bind to a receptor. In certain embodiments, CB selectively targets the drug in a specific organ, tissue, or cell. In other embodiments, CB specifically binds to a receptor over-expressed in cancer cells as compared to normal cells, and may be classified into a monoclonal antibody (mAb) or an antibody fragment and a low-molecular non-antibody. Preferably, CB is selected from peptides, tumor cell-specific peptides, tumor cell-specific aptamers, tumor cell-specific carbohydrates, tumor cell-specific monoclonal antibodies, polyclonal antibodies, and antibody fragments that are identified in a library screen. Exemplary ligands or targeting moieties include, but are not limited to, carnitine, inositol, lipoic acid, pyridoxal, ascorbic acid, niacin, pantothenic acid, folic acid, riboflavin, thiamine, biotin, vitamin B<com:Sub>12< / com:Sub>, other water-soluble vitamins (vitamin B), fat-soluble vitamins (vitamin A, D, E, K), RGD (Arg-Gly-Asp), NGR (Asn-Gly-Arg), transferein, VIP (vasoactive intestinal peptide) receptor, APRPG (Ala-Pro-Arg-Pro-Gly) peptide, TRX-20 (thioredoxin-20), integrin, nucleolin, aminopeptidase N (CD13), endoglin, vascular epithelial growth factor receptor, low density lipoprotein receptor, transferrin receptor, somatostatin receptor, bombesin, neuropeptide Y, luteinizing hormone releasing hormone receptor, folic acid receptor, epidermal growth factor receptor, transforming growth factor, fibroblast growth factor receptor, asialoglycoprotein receptor, galectin-3 receptor, E-selectin receptor, hyaluronic acid receptor, prostate-specific membrane antigen (PSMA), cholecystokinin A receptor, cholecystokinin B receptor, discoidin domain receptor, mucin receptor, opioid receptor, plasminogen receptor, bradykinin receptor, insulin receptor, insulin-like growth factor receptor, angiotensin AT1 receptor, angiotensin AT2 receptor, granulocyte macrophage colony stimulating factor receptor (GM-CSF receptor), galactosamine receptor, sigma-2 receptor, delta-like 3 (DLL-3), aminopeptidase P, melanotransferrin, leptin, tetanus toxin Tet1, tetanus toxin G23, RVG (Rabies Virus Glycoprotein) peptide, HER2 (human epidermal growth factor receptor 2), GPNMB (glycoprotein non-metastatic b), Ley, CA6, CanAng, SLC44A4(Solute carrier family 44 member 4), CEACAM5 (Carcinoembryonic antigen-related cell adhesion molecule 5), Nectin-4, Carbonic Anhydrase 9, TNNB2, 5T4, CD30, CD37, CD74, CD70, PMEL17, EphA2(EphrinA2 receptor), Trop-2, SC-16, Tissue factor, ENPP-3(AGS-16), SLITRK6 (SLIT and NTRK like family member 6), CD27, Lewis Y antigen, LIV1, GPR161 (G Protein-Coupled Receptor 161), PBR (peripheral-type benzodiazeoine receptor), MERTK (Mer receptor tyrosine kinase) receptor, CD71, LLT1 (Lectin-like transcript 1 or CLED2D), interleukin-22 receptor, sigma 1 receptor, peroxisome proliferator-activated receptor, DLL3, C4.4a, cKIT, EphrinA, CTLA4 (Cytotoxic T-Lymphocyte Associated Protein 4), FGFR2b (fibroblast growth factor receptor 2b), N-acetylcholine receptor, gonadotropin releasing hormone receptor, gastrin-releasing peptide receptor, bone morphogenetic protein receptor-type 1B (BMPR1B), E16 (LAT1, SLC7A5), STEAP1 (six transmembrane epithelial antigen of prostate), 0772P (CA125, MUC16), MPF (MSLN, mesothelin), Napi3b (SLC34A2), Sema5b (semaphorin 5b), ETBR(Endothelin type B receptor), MSG783(RNF124), STEAP2 (six transmembrane epithelial antigen of prostate 2), TrpM4 (transient receptor potential cation 5 channel, subfamily M, member 4), CRIPTO (teratocarcinoma-derived growth factor), CD21, CD79b, FcRH2 (IFGP4), HER2 (ErbB2), NCA (CEACM6), MDP (DPEP1), IL20R-alpha (IN20Ra), Brevican (BCAN), EphB2R, ASLG659 (B7h), CD276, PSCA (prostate stem cell antigen precursor), GEDA, BAFF-R (BR3), CD22 (BL- CAM), CD79a, CXCR5, HLA-DOB, P2X5, CD72, LY64, FcRH1, IRTA2, TENB2, SSTR2, SSTR5, SSTR1, SSTR3, SSTR4, ITGAV (Integrin, alpha 5), ITGB6 (Integrin, beta 6), MET, MUC1, EGFRvIII, CD33, CD19, IL2RA (interleukin 2 receptor, alpha), AXL, BCMA, CTA (cancer tetis antigens), CD174, CLEC14A, GPR78, CD25, CD32, LGR5 (GPR49), CD133 (Prominin), ASG5, ENPP3 (ectonucleotide Pyrophosphatase / Phosphodiesterase 3), PRR4 (proline-rich protein 4), GCC (guanylate cyclase 2C), Liv-1 (SLC39A6), CD56, CanAg, TIM-1, RG-1, B7-H4, PTK7, CD138, Claudins, Her3 (ErbB3), RON (MST1R), CD20, TNC (Tenascin C), FAP, DKK-1, CD52, CS1 (SLAMF7), Annexin A1, V-CAM, gp100, MART-1, MAGE-1 (melanoma antigen-encoding gene-1), MAGE-3 (melanoma-associated antigen 3), BAGE, GAGE-1, MUM-1(multiple myeloma oncogene 1), CDK4, TRP-1(gp75), TAG-72 (tumor- associated glycoprotein-72), ganglioside GD2, GD3, GM2, GM3, VEP8, VEP9, My1, VIM-D5, D156-22, OX40, RNAK, PD-L1, TNFR1, TNFR2, etc. Targets In some embodiments, the target or targets of the molecular recognition element are specifically associated with one or more particular cell or tissue types. In some embodiments, targets are specifically associated with one or more particular disease states. In some embodiments, targets are specifically associated with one or more particular developmental stages. For example, a cell type specific marker is typically expressed at levels at least 2 fold greater in that cell type than in a reference population of cells. In some embodiments, the cell type specific marker is present at levels at least 3 fold, at least 4 fold, at least 5 fold, at least 6 fold, at least 7 fold, at least 8 fold, at least 9 fold, at least 10 fold, at least 50 fold, at least 100 fold, or at least 1,000 fold greater than its average expression in a reference population. Detection or measurement of a cell type specific marker may make it possible to distinguish the cell type or types of interest from cells of many, most, or all other types. In some embodiments, a target can comprise a protein, a carbohydrate, a lipid, and / or a nucleic acid, as described herein. In some embodiments, a substance is considered to be "targeted" if it specifically binds to a targeting moiety, such as a nucleic acid targeting moiety. In some embodiments, a targeting moiety, such as a nucleic acid targeting moiety, specifically binds to a target under stringent conditions. In certain embodiments, the conjugates and compounds described herein comprise a targeting moiety that specifically binds to one or more targets (e.g., antigens) associated with an organ, tissue, cell, extracellular matrix component, and / or intracellular compartment. In some embodiments, the conjugates and compounds described herein comprise a targeting moiety that specifically binds to targets associated with a particular organ or organ system. In some embodiments, the conjugates and compounds described herein comprise a targeting moiety that specifically binds to one or more intracellular targets (e.g., organelle, intracellular protein). In some embodiments, the conjugates and compounds described herein comprise a targeting moiety which specifically binds to targets associated with diseased organs, tissues, cells, extracellular matrix components, and / or intracellular compartments. In some embodiments, the conjugates and compounds described herein comprise a targeting moiety that specifically binds to targets associated with particular cell types (e.g., endothelial cells, cancer cells, malignant cells, prostate cancer cells, etc.). In some embodiments, the conjugates and compounds described herein comprise a targeting moiety that binds to a target that is specific for one or more particular tissue types (e.g., liver tissue vs. prostate tissue). In some embodiments, the conjugates and compounds described herein comprise a targeting moiety that binds to a target that is specific for one or more particular cell types (e.g., T cells vs. B cells). In some embodiments, the conjugates and compounds described herein comprise a targeting moiety that binds to a target that is specific for one or more particular disease states (e.g., tumor cells vs. healthy cells). In some embodiments, the conjugates and compounds described herein comprise a targeting moiety that binds to a target that is specific for one or more particular developmental stages (e.g., stem cells vs. differentiated cells). In some embodiments, a target may be a marker that is exclusively or primarily associated with one or a few cell types, with one or a few diseases, and / or with one or a few developmental stages. A cell type specific marker is typically expressed at levels at least 2 fold greater in that cell type than in a reference population of cells which may consist, for example, of a mixture containing cells from a plurality (e.g., 5–10 or more) of different tissues or organs in approximately equal amounts. In some embodiments, the cell type specific marker is present at levels at least 3 fold, at least 4 fold, at least 5 fold, at least 6 fold, at least 7 fold, at least 8 fold, at least 9 fold, at least 10 fold, at least 50 fold, at least 100 fold, or at least 1000 fold greater than its average expression in a reference population. Detection or measurement of a cell type specific marker may make it possible to distinguish the cell type or types of interest from cells of many, most, or all other types. In some embodiments, a target comprises a protein, a carbohydrate, a lipid, and / or a nucleic acid. In some embodiments, a target comprises a protein and / or characteristic portion thereof, such as a tumor marker, integrin, cell surface receptor, transmembrane protein, intercellular protein, ion channel, membrane transporter protein, enzyme, antibody, chimeric protein, glycoprotein, etc. In some embodiments, a target comprises a carbohydrate and / or characteristic portion thereof, such as a glycoprotein, sugar (e.g., monosaccharide, disaccharide, polysaccharide), glycocalyx (i.e., the carbohydrate-rich peripheral zone on the outside surface of most eukaryotic cells), etc. In some embodiments, a target comprises a lipid and / or characteristic portion thereof, such as an oil, fatty acid, glyceride, hormone, steroid (e.g., cholesterol, bile acid), vitamin (e.g., vitamin E), phospholipid, sphingolipid, lipoprotein, etc. In some embodiments, a target comprises a nucleic acid and / or characteristic portion thereof, such as a DNA nucleic acid; RNA nucleic acid; modified DNA nucleic acid; modified RNA nucleic acid; nucleic acid that includes any combination of DNA, RNA, modified DNA, and modified RNA. Numerous markers are known in the art. Typical markers include cell surface proteins, e.g., receptors. Exemplary receptors include, but are not limited to, the transferrin receptor; LDL receptor; growth factor receptors such as epidermal growth factor receptor family members (e.g., EGFR, Her2, Her3, Her4) or vascular endothelial growth factor receptors, cytokine receptors, cell adhesion molecules, integrins, selectins, and CD molecules. The marker can be a molecule that is present exclusively or in higher amounts on a malignant cell, e.g., a tumor antigen. Nanoparticles In some embodiments, the targeting moiety comprises a particle (e.g., target particle), preferably a nanoparticle, optionally a targeted nanoparticle attached to a targeting molecule that can binds specifically or preferably to a target. In some embodiments, the targeting particle by itself guides the compound of the present invention (such as by enrichment in tumor cells or tissue) and there is no additional targeting molecules attached therein. By "nanoparticle" herein is meant any particle having a diameter of less than 1000 nm. In some embodiments, a therapeutic agent and / or targeting molecule can be associated with the body of the particle, for instance in a polymeric matrix. In some embodiments, the targeting molecule can be covalently associated with the surface of the polymeric matrix. In some embodiments, the covalent association is mediated by a linker. In some embodiments, the therapeutic agent can be associated with the surface of, encapsulated within, surrounded by, and / or dispersed throughout the polymeric matrix. See, for example, US Pat. No. 8,246,968. In general, nanoparticles of the present invention comprise any type of particle. Any particle can be used in accordance with the present invention. In some embodiments, particles are biodegradable and biocompatible. In general, a biocompatible substance is not toxic to cells. In some embodiments, a substance is considered to be biocompatible if its addition to cells results in less than a certain threshold of cell death. In some embodiments, a substance is considered to be biocompatible if its addition to cells does not induce adverse effects. In general, a biodegradable substance is one that undergoes breakdown under physiological conditions over the course of a therapeutically relevant time period (e.g., weeks, months, or years). In some embodiments, a biodegradable substance is a substance that can be broken down by cellular machinery. In some embodiments, a biodegradable substance is a substance that can be broken down by chemical processes. In some embodiments, a particle is a substance that is both biocompatible and biodegradable. In some embodiments, a particle is a substance that is biocompatible, but not biodegradable. In some embodiments, a particle is a substance that is biodegradable, but not biocompatible. It is often desirable to use a population of particles that is relatively uniform in terms of size, shape, and / or composition so that each particle has similar properties. For example, at least 80%, at least 90%, or at least 95% of the particles may have a diameter or greatest dimension that falls within 5%, 10%, or 20% of the average diameter or greatest dimension. In some embodiments, a population of particles may be heterogeneous with respect to size, shape, and / or composition. A variety of different particles can be used in accordance with the present invention. In some embodiments, particles are spheres or spheroids. In some embodiments, particles are spheres or spheroids. In some embodiments, particles are flat or plate-shaped. In some embodiments, particles are cubes or cuboids. In some embodiments, particles are ovals or ellipses. In some embodiments, particles are cylinders, cones, or pyramids. In some embodiments, particles are microparticles (e.g., microspheres). In general, a "microparticle" refers to any particle having a diameter of less than 1000 µm. In some embodiments, particles are picoparticles (e.g., picospheres). In general, a "picoparticle" refers to any particle having a diameter of less than 1 nm. In some embodiments, particles are liposomes. In some embodiments, particles are micelles. Particles can be solid or hollow and can comprise one or more layers (e.g., nanoshells, nanorings). In some embodiments, each layer has a unique composition and unique properties relative to the other layer(s). For example, particles may have a core / shell structure, wherein the core is one layer and the shell is a second layer. Particles may comprise a plurality of different layers. In some embodiments, one layer may be substantially crosslinked, a second layer is not substantially cross-linked, and so forth. In some embodiments, one, a few, or all of the different layers may comprise one or more therapeutic or diagnostic agents to be delivered. In some embodiments, one layer comprises an agent to be delivered, a second layer does not comprise an agent to be delivered, and so forth. In some embodiments, each individual layer comprises a different agent or set of agents to be delivered. In some embodiments, a particle is porous, by which is meant that the particle contains holes or channels, which are typically small compared with the size of a particle. For example a particle may be a porous silica particle, e.g., a mesoporous silica nanoparticle or may have a coating of mesoporous silica (Lin et al., 2005, J. Am. Chem. Soc, 17:4570). Particles may have pores ranging from about 1 nm to about 50 nm in diameter, e.g., between about 1 and 20 nm in diameter. Between about 10% and 95% of the volume of a particle may consist of voids within the pores or channels. Particles may have a coating layer. Use of a biocompatible coating layer can be advantageous, e.g., if the particles contain materials that are toxic to cells. Suitable coating materials include, but are not limited to, natural proteins such as bovine serum albumin (BSA), biocompatible hydrophilic polymers such as polyethylene glycol (PEG) or a PEG derivative, phospholipid-(PEG), silica, lipids, polymers, carbohydrates such as dextran, other nanoparticles that can be associated with inventive nanoparticles, etc. Coatings may be applied or assembled in a variety of ways such as by dipping, using a layer-by-layer technique, by self-assembly, conjugation, etc. Self-assembly refers to a process of spontaneous assembly of a higher order structure that relies on the natural attraction of the components of the higher order structure (e.g., molecules) for each other. It typically occurs through random movements of the molecules and formation of bonds based on size, shape, composition, or chemical properties. Examples of polymers include polyalkylenes (e.g., polyethylenes), polycarbonates (e.g., poly(1,3-dioxan-2-one)), polyanhydrides (e.g., poly(sebacic anhydride)), polyhydroxyacids (e.g., poly(3-hydroxyalkanoate)), polyfumarates, polycaprolactones, polyamides (e.g., polycaprolactam), polyacetals, polyethers, polyesters (e.g., polylactide, polyglycolide), poly(orthoesters), polyvinyl alcohols, polyurethanes, polyphosphazenes, polyacrylates, polymethacrylates, polycyanoacrylates, polyureas, polystyrenes, and polyamines. In some embodiments, polymers in accordance with the present invention include polymers which have been approved for use in humans by the U.S. Food and Drug Administration (FDA) under 21 C.F.R. §177.2600, including but not limited to polyesters (e.g., polylactic acid, polyglycolic acid, poly(lactic-co-glycolic acid), polycaprolactone, polyvalerolactone, poly(l,3-dioxan-2-one)); polyanhydrides (e.g., poly(sebacic anhydride)); polyethers (e.g., polyethylene glycol); polyurethanes; polymethacrylates; polyacrylates; and polycyanoacrylates. In some embodiments, particles can be non-polymeric particles (e.g., metal particles, quantum dots, ceramic particles, polymers comprising inorganic materials, bone-derived materials, bone substitutes, viral particles, etc.). In some embodiments, a therapeutic or diagnostic agent to be delivered can be associated with the surface of such a non-polymeric particle. In some embodiments, a non-polymeric particle is an aggregate of non-polymeric components, such as an aggregate of metal atoms (e.g., gold atoms). In some embodiments, a therapeutic or diagnostic agent to be delivered can be associated with the surface of and / or encapsulated within, surrounded by, and / or dispersed throughout an aggregate of non-polymeric components. Particles (e.g., nanoparticles, microparticles) may be prepared using any method known in the art. For example, particulate formulations can be formed by methods as nanoprecipitation, flow focusing fluidic channels, spray drying, single and double emulsion solvent evaporation, solvent extraction, phase separation, milling, microemulsion procedures, microfabrication, nanofabrication, sacrificial layers, simple and complex coacervation, and other suitable methods. Alternatively or additionally, aqueous and organic solvent syntheses for monodisperse semiconductor, conductive, magnetic, organic, and other nanoparticles have been described (Pellegrino et al., 2005, Small, 1:48; Murray et al., 2000, Ann. Rev. Mat. Sci., 30:545; and Trindade et al., 2001, Chem. Mat., 13:3843). Methods for making microparticles for delivery of encapsulated agents are described in the literature (see, e.g., Doubrow, Ed., "Microcapsules and Nanoparticles in Medicine and Pharmacy," CRC Press, Boca Raton, 1992; Mathiowitz et al., 1987, J. Control. Release, 5:13; Mathiowitz et al., 1987, Reactive Polymers, <com:Math><semantics>δ<annotation encoding="application / x-tex">\delta< / annotation>< / semantics>< / com:Math>: 275; and Mathiowitz et al., 1988, J. Appl. Polymer Sci., 35:755). Nucleic Acid Targeting Moieties In some embodiments, the targeting moiety comprises an nucleic acid targeting moiety. In general, a nucleic acid targeting moiety is any polynucleotide that binds to a component associated with an organ, tissue, cell, extracellular matrix component, and / or intracellular compartment (the target). In some embodiments, nucleic acid targeting moieties are aptamers. An aptamer is typically a polynucleotide that binds to a specific target structure that is associated with a particular organ, tissue, cell, extracellular matrix component, and / or intracellular compartment. In general, the targeting function of the aptamer is based on the three-dimensional structure of the aptamer. In some embodiments, binding of an aptamer to a target is typically mediated by the interaction between the two- and / or three-dimensional structures of both the aptamer and the target. In some embodiments, binding of an aptamer to a target is not solely based on the primary sequence of the aptamer, but depends on the three-dimensional structure(s) of the aptamer and / or target. In some embodiments, aptamers bind to their targets via complementary Watson-Crick base pairing which is interrupted by structures (e.g., hairpin loops) that disrupt base pairing. In some embodiments, nucleic acid targeting moieties are spiegelmers (PCT Publications WO 98 / 08856, WO 02 / 100442, and WO 06 / 117217). In general, spiegelmers are synthetic, mirror-image nucleic acids that can specifically bind to a target (i.e., mirror image aptamers). Spiegelmers are characterized by structural features that make them not susceptible to exo- and endo-nucleases. One of ordinary skill in the art will recognize that any nucleic acid targeting moiety (e.g., aptamer or spiegelmer) that is capable of specifically binding to a target can be used in accordance with the present invention. In some embodiments, nucleic acid targeting moieties to be used in accordance with the present invention may target a marker associated with a disease, disorder, and / or condition. In some embodiments, nucleic acid targeting moieties to be used in accordance with the present invention may target cancer-associated targets. In some embodiments, nucleic acid targeting moieties to be used in accordance with the present invention may target tumor markers. Any type of cancer and / or any tumor marker may be targeted using nucleic acid targeting moieties in accordance with the present invention. To give but a few examples, nucleic acid targeting moieties may target markers associated with prostate cancer, lung cancer, breast cancer, colorectal cancer, bladder cancer, pancreatic cancer, endometrial cancer, ovarian cancer, bone cancer, esophageal cancer, liver cancer, stomach cancer, brain tumors, cutaneous melanoma, and / or leukemia. Nucleic acids of the present invention (including nucleic acid nucleic acid targeting moieties and / or functional RNAs to be delivered, e.g., RNAi-inducing entities, ribozymes, tRNAs, etc., described in further detail below) may be prepared according to any available technique including, but not limited to chemical synthesis, enzymatic synthesis, enzymatic or chemical cleavage of a longer precursor, etc. Methods of synthesizing RNAs are known in the art (see, e.g., Gait, M. J. (ed.) Oligonucleotide synthesis: a practical approach, Oxford [Oxfordshire], Washington, D.C.: IRL Press, 1984; and Herdewijn, P. (ed.) Oligonucleotide synthesis: methods and applications, Methods in molecular biology, v. 288 (Clifton, NJ.) Totowa, N.J.: Humana Press, 2005). The nucleic acid that forms the nucleic acid nucleic acid targeting moiety may comprise naturally occurring nucleosides, modified nucleosides, naturally occurring nucleosides with hydrocarbon linkers (e.g., an alkylene) or a polyether linker (e.g., a PEG linker) inserted between one or more nucleosides, modified nucleosides with hydrocarbon or PEG linkers inserted between one or more nucleosides, or a combination of thereof. In some embodiments, nucleotides or modified nucleotides of the nucleic acid nucleic acid targeting moiety can be replaced with a hydrocarbon linker or a polyether linker provided that the binding affinity and selectivity of the nucleic acid nucleic acid targeting moiety is not substantially reduced by the substitution (e.g., the dissociation constant of the nucleic acid nucleic acid targeting moiety for the target should not be greater than about <com:Math><semantics>1×10−3<annotation encoding="application / x-tex">1 \times 10^{-3}< / annotation>< / semantics>< / com:Math> M). It will be appreciated by those of ordinary skill in the art that nucleic acids in accordance with the present invention may comprise nucleotides entirely of the types found in naturally occurring nucleic acids, or may instead include one or more nucleotide analogs or have a structure that otherwise differs from that of a naturally occurring nucleic acid. U.S. Pat. Nos. 6,403,779; 6,399,754; 6,225,460; 6,127,533; 6,031,086; 6,005,087; 5,977,089; and references therein disclose a wide variety of specific nucleotide analogs and modifications that may be used. See Crooke, S. (ed.) Antisense Drug Technology: Principles, Strategies, and Applications (1 st ed), Marcel Dekker; ISBN: 0824705661; 1st edition (2001) and references therein. For example, 2'-modifications include halo, alkoxy and allyloxy groups. In some embodiments, the 2'-OH group is replaced by a group selected from H, OR, R, halo, SH, SR, NH<com:Sub>2< / com:Sub>, NHR, NR<com:Sub>2< / com:Sub> or CN, wherein R is C<com:Sub>1< / com:Sub>-C<com:Sub>6< / com:Sub> alkyl, alkenyl, or alkynyl, and halo is F, CI, Br, or I. Examples of modified linkages include phosphorothioate and 5'-N-phosphoramidite linkages. Nucleic acids comprising a variety of different nucleotide analogs, modified backbones, or non- naturally occurring internucleoside linkages can be utilized in accordance with the present invention. Nucleic acids of the present invention may include natural nucleosides (i.e., adenosine, thymidine, guanosine, cytidine, uridine, deoxyadenosine, deoxythymidine, deoxyguanosine, and deoxycytidine) or modified nucleosides. Examples of modified nucleotides include base modified nucleoside (e.g., aracytidine, inosine, isoguanosine, nebularine, pseudouridine, 2,6-diaminopurine, 2-aminopurine, 2- thiothymidine, 3-deaza-5-azacytidine, 2'- deoxyuridine, 3-nitorpyrrole, 4-methylindole, 4-thiouridine, 4-thiothymidine, 2-aminoadenosine, 2-thiothymidine, 2-thiouridine, 5-bromocytidine, 5-iodouridine, inosine, 6-azauridine, 6- chloropurine, 7-deazaadenosine, 7-deazaguanosine, 8-azaadenosine, 8- azidoadenosine, benzimidazole, Ml-methyladenosine, pyrrolo-pyrimidine, 2-amino-6-chloropurine, 3- methyl adenosine, 5-propynylcytidine, 5-propynyluridine, 5-bromouridine, 5-fluorouridine, 5- methylcytidine, 7-deazaadenosine, 7-deazaguanosine, 8-oxoadenosine, 8-oxoguanosine, 0(6)- methylguanine, and 2-thiocytidine), chemically or biologically modified bases (e.g., methylated bases), modified sugars (e.g., 2'-fluororibose, 2'-aminoribose, 2'-azidoribose, 2'-O- methylribose, L-enantiomeric nucleosides arabinose, and hexose), modified phosphate groups (e.g., phosphorothioates and 5'-N- phosphoramidite linkages), and combinations thereof. Natural and modified nucleotide monomers for the chemical synthesis of nucleic acids are readily available. In some cases, nucleic acids comprising such modifications display improved properties relative to nucleic acids consisting only of naturally occurring nucleotides. In some embodiments, nucleic acid modifications described herein are utilized to reduce and / or prevent digestion by nucleases (e.g., exonucleases, endonucleases, etc.). For example, the structure of a nucleic acid may be stabilized by including nucleotide analogs at the 3' end of one or both strands order to reduce digestion. Modified nucleic acids need not be uniformly modified along the entire length of the molecule. Different nucleotide modifications and / or backbone structures may exist at various positions in the nucleic acid. One of ordinary skill in the art will appreciate that the nucleotide analogs or other modification(s) may be located at any position(s) of a nucleic acid such that the function of the nucleic acid is not substantially affected. To give but one example, modifications may be located at any position of a nucleic acid targeting moiety such that the ability of the nucleic acid targeting moiety to specifically bind to the target is not substantially affected. The modified region may be at the 5'-end and / or the 3'-end of one or both strands. For example, modified nucleic acid targeting moieties in which approximately 1-5 residues at the 5' and / or 3' end of either of both strands are nucleotide analogs and / or have a backbone modification have been employed. The modification may be a 5' or 3' terminal modification. One or both nucleic acid strands may comprise at least 50% unmodified nucleotides, at least 80% unmodified nucleotides, at least 90% unmodified nucleotides, or 100% unmodified nucleotides. Nucleic acids in accordance with the present invention may, for example, comprise a modification to a sugar, nucleoside, or internucleoside linkage such as those described in U.S. Patent Application Publications 2003 / 0175950, 2004 / 0192626, 2004 / 0092470, 2005 / 0020525, and 2005 / 0032733. The present invention encompasses the use of any nucleic acid having any one or more of the modification described therein. For example, a number of terminal conjugates, e.g., lipids such as cholesterol, lithocholic acid, aluric acid, or long alkyl branched chains have been reported to improve cellular uptake. Analogs and modifications may be tested using, e.g., using any appropriate assay known in the art, for example, to select those that result in improved delivery of a therapeutic or diagnostic agent, improved specific binding of an nucleic acid targeting moiety to a target, etc. In some embodiments, nucleic acids in accordance with the present invention may comprise one or more non-natural nucleoside linkages. In some embodiments, one or more internal nucleotides at the 3'-end, 5'-end, or both 3'- and 5'- ends of the nucleic acid targeting moiety are inverted to yield a linkage such as a 3'-3' linkage or a 5'-5' linkage. In some embodiments, nucleic acids in accordance with the present invention are not synthetic, but are naturally-occurring entities that have been isolated from their natural environments. Any method can be used to design novel nucleic acid targeting moieties (see, e.g., U.S. Pat. Nos. 6,716,583; 6,465,189; 6,482,594; 6,458,543; 6,458,539; 6,376,190; 6,344,318; 6,242,246; 6,184,364; 6,001,577; 5,958,691; 5,874,218; 5,853,984; 5,843,732; 5,843,653; 5,817,785; 5,789,163; 5,763,177; 5,696,249; 5,660,985; 5,595,877; 5,567,588; and 5,270,163; and U.S. Patent Application Publications 2005 / 0069910, 2004 / 0072234, 2004 / 0043923, 2003 / 0087301, 2003 / 0054360, and 2002 / 0064780). Nucleic acid targeting moieties that bind to a protein, a carbohydrate, a lipid, and / or a nucleic acid can be designed and / or identified. In some embodiments, nucleic acid targeting moieties can be designed and / or identified for use in the complexes of the invention that bind to proteins and / or characteristic portions thereof, such as tumor-markers, integrins, cell surface receptors, transmembrane proteins, intercellular proteins, ion channels, membrane transporter proteins, enzymes, antibodies, chimeric proteins etc. In some embodiments, nucleic acid targeting moieties can be designed and / or identified for use in the complexes of the invention that bind to carbohydrates and / or characteristic portions thereof, such as glycoproteins, sugars (e.g., monosaccharides, disaccharides and polysaccharides), glycocalyx (i.e., the carbohydrate - rich peripheral zone on the outside surface of most eukaryotic cells) etc. In some embodiments, nucleic acid targeting moieties can be designed and / or identified for use in the complexes of the invention that bind to lipids and / or characteristic portions thereof, such as oils, saturated fatty acids, unsaturated fatty acids, glycerides, hormones, steroids (e.g., cholesterol, bile acids), vitamins (e.g., vitamin E), phospholipids, sphingolipids, lipoproteins etc. In some embodiments, nucleic acid targeting moieties can be designed and / or identified for use in the complexes of the invention that bind to nucleic acids and / or characteristic portions thereof, such as DNA nucleic acids; RNA nucleic acids; modified DNA nucleic acids; modified RNA nucleic acids; and nucleic acids that include any combination of DNA, RNA, modified DNA, and modified RNA; etc. Nucleic acid targeting moieties (e.g., aptamers or spiegelmers) may be designed and / or identified using any available method. In some embodiments, nucleic acid targeting moieties are designed and / or identified by identifying nucleic acid targeting moieties from a candidate mixture of nucleic acids. Methods of Preparing the Compounds of the Invention The compounds and conjugates disclosed herein can be prepared via simple preparation methods (see, e.g., Examples 1–78). Such preparation methods enable easy purification. Thus, also provided herein are methods for preparing the compounds of the invention. For example, compounds of the invention can be prepared as shown in any one of Reaction Schemes 3, 4, 5, 6, or 7: Reaction Scheme 3: [Image disponible dans le document PDF, Image available in the PDF document] Reaction Scheme 4: [Image disponible dans le document PDF, Image available in the PDF document] Reaction Scheme 5: [Image disponible dans le document PDF, Image available in the PDF document] Reaction Scheme 6: [Image disponible dans le document PDF, Image available in the PDF document] Reaction Scheme 7: [Image disponible dans le document PDF, Image available in the PDF document] wherein X, Y, Ar, R, and n are the same as defined above. Also provided herein are methods for preparing a compound, comprising reacting a compound of Formula (IIc): [Image disponible dans le document PDF, Image available in the PDF document] (IIc) or a pharmaceutically acceptable salt thereof, with a sulfonyl halide: [Image disponible dans le document PDF, Image available in the PDF document] to provide a compound of Formula (Iaa): [Image disponible dans le document PDF, Image available in the PDF document] (Iaa) or a pharmaceutically acceptable salt thereof, wherein: X<com:Sup>a< / com:Sup> is halogen (preferably fluorine), each R<com:Sup>11< / com:Sup> independently represents an alkyl, aryl, aralkyl, or alkoxy substituent, and the remaining groups may be selected according to any definition provided herein. For example, in certain such embodiments, Q is an active agent linked to L' by a heteroatom, preferably O or N; Z' is absent or a linking group comprising at least one reactive group, such as a precursor described above in connection with Z; L' is a spacer moiety attached to the SO<com:Sub>2< / com:Sub> via a heteroatom selected from O, S, and N, preferably O or N, and is selected such that cleavage of the bond between L' and SO<com:Sub>2< / com:Sub> promotes cleavage of the bond between L' and Q to release the active agent; Ar is aryl, heteroaryl, cycloalkyl, or heterocycloalkyl, preferably aryl or heteroaryl; Y' is <com:Math><semantics>−(CRb2)yN(Ra1)<annotation encoding="application / x-tex">-(CR^{b_2})_yN(R^{a_1})< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−(CRb2)yO<annotation encoding="application / x-tex">-(CR^{b_2})_yO< / annotation>< / semantics>< / com:Math>, or <com:Math><semantics>−(CRb2)yS<annotation encoding="application / x-tex">-(CR^{b_2})_yS< / annotation>< / semantics>< / com:Math>, such that the N, O, or S atom is attached to TG if y is 1; O and Y' are positioned on adjacent atoms of Ar; TG is a triggering group that, when activated, results in formation of an N, O, or S atom capable of reacting with the SO<com:Sub>2< / com:Sub> to displace (Q)<com:Sub>q< / com:Sub>-(L')<com:Sub>w< / com:Sub> and form a 5-6-membered ring including X-SO<com:Sup>2< / com:Sup> and the intervening atoms of Ar; w, x, and y are each independently an integer having a value of 0 or 1; each R<com:Sup>a< / com:Sup> and R<com:Sup>c< / com:Sup> is independently hydrogen or lower alkyl; and each R<com:Sup>b< / com:Sup> is independently hydrogen or lower alkyl; or two R<com:Sup>b< / com:Sup>, together with the carbon atom to which they are attached, form a 3-5-membered ring, preferably a 3-4-membered ring. The reactive group of the linking group can be a moiety capable of participating in 1,3- dipolar cycloaddition reactions, hetero-Diels-Alder reactions, nucleophilic substitution reactions, non-aldol type carbonyl reactions, additions to carbon-carbon multiple bonds, oxidation reactions, click reactions, or any other intermolecular coupling reaction. Preferably, the reactive group is selected to participate in a selective reaction with a reacting partner that is not common in biological molecules, such as a 1,3-dipolar cycloaddition, hetero-Diels-Alder, oxime / hydrazone condensation, or click reaction. In certain preferred embodiments, the linking group may comprise an alkyne or azide (which react to form a triazole), an alkyne and a nitrile oxide (which react to form an isoxazole), or a carbonyl (e.g., an aldehyde or ketone) or a hydrazine or hydroxylamine (which react to form an oxime or a hydrazone). In other embodiments, provided herein are methods for preparing a compound, comprising: (a) reacting a compound of Formula (IIa): (Y')<com:Sub>x< / com:Sub>TG<com:Br / >HO−År−Z' (IIa) or a pharmaceutically acceptable salt thereof, with 1,1'-sulfonylbis(1H-imidazole): [Image disponible dans le document PDF, Image available in the PDF document] to provide a compound of Formula (IIbb): [Image disponible dans le document PDF, Image available in the PDF document] (IIbb) or a pharmaceutically acceptable salt thereof, wherein the variables may be selected according to any definition provided herein. For example, in certain such embodiments, Z' is absent or a linking group comprising a reactive group as discussed in greater detail above; Ar is aryl, heteroaryl, cycloalkyl, or heterocycloalkyl, preferably aryl or heteroaryl; Y' is <com:Math><semantics>−(CRb2)yN(Ra1)<annotation encoding="application / x-tex">-(CR^{b_2})_yN(R^{a_1})< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−(CRb2)yO<annotation encoding="application / x-tex">-(CR^{b_2})_yO< / annotation>< / semantics>< / com:Math>, or <com:Math><semantics>−(CRb2)yS<annotation encoding="application / x-tex">-(CR^{b_2})_yS< / annotation>< / semantics>< / com:Math>, positioned such that the N, O, or S atom is attached to TG if y is 1; -SO<com:Sub>2< / com:Sub>- and Y' are positioned on adjacent atoms of Ar; TG is a triggering group that, when activated, results in formation of an N, O, or S atom capable of reacting with the SO<com:Sub>2< / com:Sub> to displace (Q)<com:Sub>q< / com:Sub>-(L')<com:Sub>w< / com:Sub> and form a 5-6-membered ring including X-SO<com:Sup>2< / com:Sup> and the intervening atoms of Ar; w, x, and y are each independently an integer having a value of 0 or 1; each R<com:Sup>a< / com:Sup> and R<com:Sup>c< / com:Sup> is independently hydrogen or lower alkyl; and each R<com:Sup>b< / com:Sup> is independently hydrogen or lower alkyl; or two R<com:Sup>b< / com:Sup>, together with the carbon atom to which they are attached, form a 3-5-membered ring, preferably a 3-4-membered ring. A compound of Formula (IIbb) may then be further reacted with a compound of Formula (Ia'), Q-(L')<com:Sub>w< / com:Sub>-H, or a pharmaceutically acceptable salt thereof, to provide a compound (Ia): [Image disponible dans le document PDF, Image available in the PDF document] (Ia) or a pharmaceutically acceptable salt thereof, wherein the variables may be selected according to any definition provided herein. For example, in certain embodiments, X is O; Q is an active agent linked to L' by a heteroatom, preferably O or N; L' is a linking group attached to the SO<com:Sub>2< / com:Sub> via a heteroatom selected from O, S, and N, preferably O or N, and is selected such that cleavage of the bond between L' and SO<com:Sub>2< / com:Sub> promotes cleavage of the bond between L' and Q to release the active agent; and w is 0 or 1. In some embodiments, the methods utilize an intermediate compound of Formula (IIa), (IIb), or (IIc) to provide a compound of Formula (Iaa), wherein Ar, TG, Y'Z' and Ra are as defined above for the conjugates of Formula (I') or the compounds of Formula (Ia). The invention further provides the compounds described above, which are useful in these methods. Intermediate Compounds In some embodiments, the compounds and conjugates disclosed herein can be prepared by a method that utilizes an intermediate compound having the structure according to Formula (IV): [Image disponible dans le document PDF, Image available in the PDF document] (IV) or a pharmaceutically acceptable salt thereof, wherein: W is hydrogen, <com:Math><semantics>−SiR16R17R18<annotation encoding="application / x-tex">-SiR^{16}R^{17}R^{18}< / annotation>< / semantics>< / com:Math> or <com:Math><semantics>−SO2<annotation encoding="application / x-tex">-SO_2< / annotation>< / semantics>< / com:Math>-G; <com:Math><semantics>R16<annotation encoding="application / x-tex">R^{16}< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>R17<annotation encoding="application / x-tex">R^{17}< / annotation>< / semantics>< / com:Math>, and <com:Math><semantics>R18<annotation encoding="application / x-tex">R^{18}< / annotation>< / semantics>< / com:Math> are each independently <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math>-alkyl; G is halogen (preferably fluorine), imidazole, or N-methyl imidazolium; R is a substituent or <com:Math><semantics>−L1′−Z<annotation encoding="application / x-tex">-L^{1'}-Z< / annotation>< / semantics>< / com:Math>; <com:Math><semantics>L1<annotation encoding="application / x-tex">L^{1}< / annotation>< / semantics>< / com:Math> is a <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C200<annotation encoding="application / x-tex">C_{200}< / annotation>< / semantics>< / com:Math>-alkylene that optionally comprises at least one of a peptide bond, an amino bond, an ether bond, a triazole bond, a tetrazole bond, a sugar bond, a sulfonamide bond, a phosphonate bond, a sulfo bond, or a dendrimer structure; Z is a precursor selected from isocyanide, isothiocyanide, 2-pyridyl disulfide, haloacetamide (- NHC(O)CH<com:Sub>2< / com:Sub>-hal), maleimide, diene, alkene, halide, tosylate (TsO<com:Sup>-< / com:Sup>), aldehyde, sulfonate [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] <com:Math><semantics>(R−SO3−),<annotation encoding="application / x-tex">(R-SO_3^-),< / annotation>< / semantics>< / com:Math> , phosphonic acid (- > P(=O)(OH)<com:Sub>2< / com:Sub>), ketone, C<com:Sub>8< / com:Sub>-C<com:Sub>10< / com:Sub> cycloalkyl, -OH, -NHOH, -NHNH<com:Sub>2< / com:Sub>, -SH, carboxylic acid (- COOH), acetylene (-C<com:Math><semantics>≡<annotation encoding="application / x-tex">\equiv< / annotation>< / semantics>< / com:Math>CH), azide (-N<com:Sub>3< / com:Sub>), amino (-NH<com:Sub>2< / com:Sub>), sulfonic acid (-SO<com:Sub>3< / com:Sub>H), an alkynone derivative (-C(O)C<com:Math><semantics>≡<annotation encoding="application / x-tex">\equiv< / annotation>< / semantics>< / com:Math>C-R<com:Sup>a< / com:Sup>, wherein R<com:Sup>a< / com:Sup> is C<com:Sub>1< / com:Sub>-C<com:Sub>10< / com:Sub> alkyl), and dihydrogen phosphate <com:Math><semantics>(−OP(=O)(OH)2)<annotation encoding="application / x-tex">(-OP(=O)(OH)_2)< / annotation>< / semantics>< / com:Math>; n is an integer having a value of 1 to 4; [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] <com:Math><semantics>R1<annotation encoding="application / x-tex">R^1< / annotation>< / semantics>< / com:Math> is <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math> alkyl; r is an integer of 1 to 5; <com:Math><semantics>Ar1<annotation encoding="application / x-tex">Ar^1< / annotation>< / semantics>< / com:Math> is <com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C20<annotation encoding="application / x-tex">C_{20}< / annotation>< / semantics>< / com:Math>-arylene; <com:Math><semantics>R2<annotation encoding="application / x-tex">R^2< / annotation>< / semantics>< / com:Math> and <com:Math><semantics>R3<annotation encoding="application / x-tex">R^3< / annotation>< / semantics>< / com:Math> are each independently hydrogen, <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math>-alkyl, <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math>-alkoxy, or hydroxy; R<com:Sup>a< / com:Sup>, R<com:Sup>b< / com:Sup>, R<com:Sup>c< / com:Sup>, and R<com:Sup>d< / com:Sup> are each independently hydrogen or C<com:Sub>1< / com:Sub>-C<com:Sub>6< / com:Sub> alkyl; [Image disponible dans le document PDF, Image available in the PDF document] R" is hydrogen or <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math> alkyl; x is an integer of 0 or 1; and TG is a triggering group. In some embodiments, the compounds and conjugates disclosed herein can be prepared by a method that utilizes an intermediate compound having the structure according to Formula (V): [Image disponible dans le document PDF, Image available in the PDF document] (V) or a pharmaceutically acceptable salt thereof, wherein: <com:Math><semantics>W,L1<annotation encoding="application / x-tex">W, L^{1}< / annotation>< / semantics>< / com:Math>, and Z are the same as defined for Formula (IV); and TG is a triggering group, such as a <com:Math><semantics>β<annotation encoding="application / x-tex">\beta< / annotation>< / semantics>< / com:Math>-galactoside, <com:Math><semantics>β<annotation encoding="application / x-tex">\beta< / annotation>< / semantics>< / com:Math>-glucuronide, or a combination of <com:Math><semantics>β<annotation encoding="application / x-tex">\beta< / annotation>< / semantics>< / com:Math>- galactoside and <com:Math><semantics>β<annotation encoding="application / x-tex">\beta< / annotation>< / semantics>< / com:Math> -glucuronide. In other embodiments, the compounds and conjugates disclosed herein can be prepared by a method that utilizes an intermediate compound having the structure according to Formula (VI): [Image disponible dans le document PDF, Image available in the PDF document] (VI) or a pharmaceutically acceptable salt thereof, wherein: W is the same as defined for Formula (IV); Y is <com:Math><semantics>−NO2<annotation encoding="application / x-tex">-NO_2< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−OC(O)(CH2)rC(O)R1<annotation encoding="application / x-tex">-OC(O)(CH_2)_rC(O)R^1< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−O(CH2)r−Ar1−NO2<annotation encoding="application / x-tex">-O(CH_2)_r-Ar^1-NO_2< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−NHOH<annotation encoding="application / x-tex">-NHOH< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−NHNH2<annotation encoding="application / x-tex">-NHNH_2< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−BR2R3<annotation encoding="application / x-tex">-BR^2R^3< / annotation>< / semantics>< / com:Math>, or <com:Math><semantics>−O−TG<annotation encoding="application / x-tex">-O-TG< / annotation>< / semantics>< / com:Math>; <com:Math><semantics>R1<annotation encoding="application / x-tex">R^1< / annotation>< / semantics>< / com:Math> is <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math>-alkyl, such as <com:Math><semantics>NO2<annotation encoding="application / x-tex">NO_2< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−OC(O)(CH2)rC(O)R1<annotation encoding="application / x-tex">-OC(O)(CH_2)_rC(O)R^1< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−O(CH2)r<annotation encoding="application / x-tex">-O(CH_2)_r< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>Ar1<annotation encoding="application / x-tex">Ar^1< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>NO2<annotation encoding="application / x-tex">NO_2< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−NHOH<annotation encoding="application / x-tex">-NHOH< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−NHNH2<annotation encoding="application / x-tex">-NHNH_2< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−<annotation encoding="application / x-tex">-< / annotation>< / semantics>< / com:Math> <com:Math><semantics>BR2R3<annotation encoding="application / x-tex">BR^2R^3< / annotation>< / semantics>< / com:Math>, or -O-TG; <com:Math><semantics>R1<annotation encoding="application / x-tex">R^1< / annotation>< / semantics>< / com:Math> is <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math>-alkyl; r is an integer of 1 to 5; Ar<com:Sup>1< / com:Sup> is phenylene, biphenylene, or naphthalene; <com:Math><semantics>R2<annotation encoding="application / x-tex">R^2< / annotation>< / semantics>< / com:Math> and <com:Math><semantics>R3<annotation encoding="application / x-tex">R^3< / annotation>< / semantics>< / com:Math> are each independently hydrogen, <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math>-alkyl, <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math>-alkoxy, or hydroxy; R<com:Sup>a< / com:Sup>, R<com:Sup>b< / com:Sup>, R<com:Sup>c< / com:Sup>, and R<com:Sup>d< / com:Sup> are each independently hydrogen or C<com:Sub>1< / com:Sub>–C<com:Sub>6< / com:Sub>-alkyl; and TG is a triggering group, <com:Math><semantics>β<annotation encoding="application / x-tex">\beta< / annotation>< / semantics>< / com:Math>-galactoside, <com:Math><semantics>β<annotation encoding="application / x-tex">\beta< / annotation>< / semantics>< / com:Math>-glucuronide, or a combination of <com:Math><semantics>β<annotation encoding="application / x-tex">\beta< / annotation>< / semantics>< / com:Math>-galactoside and <com:Math><semantics>β<annotation encoding="application / x-tex">\beta< / annotation>< / semantics>< / com:Math>- glucuronide. Also provided herein are intermediate compounds of Formula (IIa), (IIb), or (IIc): [Image disponible dans le document PDF, Image available in the PDF document] (IIa) [Image disponible dans le document PDF, Image available in the PDF document] (IIb) [Image disponible dans le document PDF, Image available in the PDF document] (IIc) or a pharmaceutically acceptable salt thereof, wherein: G is halogen, imidazole, or N-methyl imidazolium; each <com:Math><semantics>R11<annotation encoding="application / x-tex">R^{11}< / annotation>< / semantics>< / com:Math> is independently <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math>-alkyl; Ar is aryl, heteroaryl, cycloalkyl, or heterocycloalkyl; TG is a triggering group that, when activated, results in formation of an N, O, or S atom capable of forming a 5-6-membered ring including X-SO<com:Sup>2< / com:Sup> and the intervening atoms of Ar; Y' is -(CR<com:Sup>b< / com:Sup><com:Sub>2< / com:Sub>)<com:Sub>y< / com:Sub>N(R<com:Sup>a< / com:Sup>)-, -(CR<com:Sup>b< / com:Sup><com:Sub>2< / com:Sub>)<com:Sub>y< / com:Sub>O-, or -(CR<com:Sup>b< / com:Sup><com:Sub>2< / com:Sub>)<com:Sub>y< / com:Sub>S-, positioned such that the N, O, or S atom is attached to TG if y is 1; O and Y' are positioned on adjacent atoms of Ar; x and y are each independently an integer having a value of 0 or 1; Z' is absent or a linking unit comprising, e.g., a reactive or binding unit; and each R<com:Sup>a< / com:Sup> is independently hydrogen or alkyl; or two R<com:Sup>a< / com:Sup>, together with the carbon atom to which they are attached, form a three-membered ring. In some embodiments, the intermediate compound is a compound of Formula (IIa), (IIb), or (IIc), wherein Ar, TG, Y' Z' and R<com:Sup>a< / com:Sup> are as defined above for the conjugates of Formula (I') or the compounds of Formula (Ia). In preferred embodiments, the intermediate compound is a compound of Formula (IIa), (IIb), or (IIc), wherein Ar is aryl (e.g., phenyl or naphthyl). In some embodiments, provided herein is an intermediate compound is a compound of Formula (IIa), (IIb), or (IIc), wherein Z' is a linking group comprising one or more groups selected from isocyanide, isothiocyanide, 2-pyridyl disulfide, haloacetamide (-NHC(O)CH<com:Sub>2< / com:Sub>-halo), maleimide, diene, alkene, halide, tosylate (TsO), aldehyde, sulfonate (R- [Image disponible dans le document PDF, Image available in the PDF document] <com:Math><semantics>SO3−<annotation encoding="application / x-tex">SO_3^-< / annotation>< / semantics>< / com:Math>), , phosphonic acid <com:Math><semantics>(−P(=O)(OH)2)<annotation encoding="application / x-tex">(-P(=O)(OH)_2)< / annotation>< / semantics>< / com:Math>, ketone, C<com:Sub>8< / com:Sub>-C<com:Sub>10< / com:Sub> cycloalkynyl, -OH, -NHOH, -NHNH<com:Sub>2< / com:Sub>, -SH, carboxylic acid (-COOH), acetylene (-C≡CH), azide (-N<com:Sub>3< / com:Sub>), amino (-NH<com:Sub>2< / com:Sub>), sulfonic acid (-SO<com:Sub>3< / com:Sub>H), an alkynone derivative (-C(O)C≡C- <com:Math><semantics>Ra<annotation encoding="application / x-tex">R^{a}< / annotation>< / semantics>< / com:Math>), and dihydrogen phosphate (-OP(=O)(OH)<com:Sub>2< / com:Sub>. In other embodiments, the intermediate compound is a compound of Formula (IIa), (IIb), or (IIc), wherein x is 0. In some such embodiments, TG is -NO<com:Sub>2< / com:Sub>, -OC(O)(CH<com:Sub>2< / com:Sub>)<com:Sub>r< / com:Sub>C(O)R<com:Sup>1< / com:Sup>, -NHOH, [Image disponible dans le document PDF, Image available in the PDF document] <com:Math><semantics>−NHNH2<annotation encoding="application / x-tex">-NHNH_2< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−BR2R3<annotation encoding="application / x-tex">-BR^2R^3< / annotation>< / semantics>< / com:Math>, , such as <com:Math><semantics>NO2<annotation encoding="application / x-tex">NO_2< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−OC(O)(CH2)rC(O)R1<annotation encoding="application / x-tex">-OC(O)(CH_2)_rC(O)R^1< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−NHNH2<annotation encoding="application / x-tex">-NHNH_2< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−BR2R3<annotation encoding="application / x-tex">-BR^2R^3< / annotation>< / semantics>< / com:Math>, [Image disponible dans le document PDF, Image available in the PDF document] , wherein: <com:Math><semantics>R1<annotation encoding="application / x-tex">R^1< / annotation>< / semantics>< / com:Math> is <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math> alkyl; <com:Math><semantics>R2<annotation encoding="application / x-tex">R^2< / annotation>< / semantics>< / com:Math> and <com:Math><semantics>R3<annotation encoding="application / x-tex">R^3< / annotation>< / semantics>< / com:Math> are each independently hydrogen, <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math> alkyl, <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math> alkoxy, or hydroxy; <com:Math><semantics>R4<annotation encoding="application / x-tex">R^4< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>R5<annotation encoding="application / x-tex">R^5< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>R6<annotation encoding="application / x-tex">R^6< / annotation>< / semantics>< / com:Math>, and <com:Math><semantics>R7<annotation encoding="application / x-tex">R^7< / annotation>< / semantics>< / com:Math> are each independently hydrogen or <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math> alkyl; and r is an integer having a value of 1, 2, 3, 4, or 5. In alternative embodiments, the intermediate compound is a compound of Formula (IIa), (IIb), or (IIc), wherein TG is a triggering group comprising <com:Math><semantics>β<annotation encoding="application / x-tex">\beta< / annotation>< / semantics>< / com:Math>-galactoside, <com:Math><semantics>β<annotation encoding="application / x-tex">\beta< / annotation>< / semantics>< / com:Math>-glucuronide, or a combination of <com:Math><semantics>β<annotation encoding="application / x-tex">\beta< / annotation>< / semantics>< / com:Math>-galactoside and <com:Math><semantics>β<annotation encoding="application / x-tex">\beta< / annotation>< / semantics>< / com:Math>-glucuronide. In particular embodiments, the intermediate compound is: [Image disponible dans le document PDF, Image available in the PDF document] or a pharmaceutically acceptable salt thereof. In certain other embodiments, the intermediate compound is: [Image disponible dans le document PDF, Image available in the PDF document] / ~ ■ ... or a pharmaceutically acceptable salt thereof. Antibody-Drug Conjugates (ADCs) In some embodiments, CB is an antibody, and Q is a drug. Accordingly, the compounds and conjugates disclosed herein may be used to conjugate an antibody to a drug moiety to form an antibody-drug conjugate (ADC). Antibody-drug conjugates (ADCs) may increase therapeutic efficacy in treating disease, e.g., cancer, due to the ability of the ADC to selectively deliver one or more drug moiety(s) to target tissues, such as a tumor-associated antigen. Thus, in certain embodiments, the invention provides ADCs for therapeutic use, e.g., treatment of cancer. ADCs of the invention comprise an antibody linked to one or more drug moieties. The specificity of the ADC is defined by the specificity of the antibody. In one embodiment, an antibody is linked to one or more cytotoxic drug(s), which is delivered internally to a cancer cell. Examples of drugs that may be used in the ADC of the invention are provided below. The terms "drug", "agent", and "drug moiety" are used interchangeably herein. The terms "linked" and "conjugated" are also used interchangeably herein and indicate that the antibody and moiety are covalently linked. In some embodiments, the ADC has the following formula (Formula VII): [Image disponible dans le document PDF, Image available in the PDF document] wherein Ab is the antibody and (D-L) is a Linker-Drug moiety. The Linker-Drug moiety is made of a linker L and a drug moiety D. The drug moiety may have, for example, cytostatic, cytotoxic, or otherwise therapeutic activity against a target cell. n is an integer having a value of 1 to about 20, preferably from 1 to about 10. Preferably, D-L is has the structure of Formula (I''): [Image disponible dans le document PDF, Image available in the PDF document] Q is an active agent linked to L' by a heteroatom, preferably O or N; Z' is a linking group; L' is a spacer moiety attached to the SO<com:Sub>2< / com:Sub> via a heteroatom selected from O, S, and N, preferably O or N, and is selected such that cleavage of the bond between L' and SO<com:Sub>2< / com:Sub> promotes cleavage of the bond between L' and Q to release the active agent; X is <com:Math><semantics>−O<annotation encoding="application / x-tex">-O< / annotation>< / semantics>< / com:Math>-, <com:Math><semantics>−C(Rb)2<annotation encoding="application / x-tex">-C(R^b)_2< / annotation>< / semantics>< / com:Math>-, or <com:Math><semantics>−N(Rc)<annotation encoding="application / x-tex">-N(R^c)< / annotation>< / semantics>< / com:Math>-, preferably <com:Math><semantics>−O<annotation encoding="application / x-tex">-O< / annotation>< / semantics>< / com:Math>-; Ar is aryl, heteroaryl, cycloalkyl, or heterocycloalkyl, preferably aryl or heteroaryl; Y' is <com:Math><semantics>−(CRb2)yN(Ra1)<annotation encoding="application / x-tex">-(CR^{b_2})_yN(R^{a_1})< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−(CRb2)yO<annotation encoding="application / x-tex">-(CR^{b_2})_yO< / annotation>< / semantics>< / com:Math>, or <com:Math><semantics>−(CRb2)yS<annotation encoding="application / x-tex">-(CR^{b_2})_yS< / annotation>< / semantics>< / com:Math>, positioned such that the N, O, or S atom is attached to TG if y is 1; X and Y' are positioned on adjacent atoms of Ar; TG is a triggering group that, when activated, results in formation of an N, O, or S atom capable of reacting with the SO<com:Sub>2< / com:Sub> to displace (Q)<com:Sub>q< / com:Sub>-(L')<com:Sub>w< / com:Sub> and form a 5-6-membered ring including X-SO<com:Sup>2< / com:Sup> and the intervening atoms of Ar; w, x, and y are each independently an integer having a value of 0 or 1; each R<com:Sup>a< / com:Sup> and R<com:Sup>c< / com:Sup> is independently hydrogen or lower alkyl; and each R<com:Sup>b< / com:Sup> is independently hydrogen or lower alkyl; or two R<com:Sup>b< / com:Sup>, together with the atom to which they are attached, form a 3-5-membered ring, preferably a 3-4-membered ring. In some embodiments, n has a value ranging from 1 to 8, 1 to 7, 1 to 6, 1 to 5, 1 to 4, 1 to 3, 1 to 2, or is an integer having a value of 1. When cb is 1 and n is 1, the drug-to-antibody ratio (DAR) of an ADC is equivalent to the number of drugs present in (D-L). When cb is other than 1, the drug-to-antibody ratio (DAR) of an ADC is equivalent to ratio of the number of drugs present in (D-L) to the number of antibodies present in the conjugate. Exemplary Drugs for Conjugation The ADCs of the invention provide a targeted therapy that may, for example, reduce the side effects often seen with anti-cancer therapies, as the one or more active agent(s) or drug(s) is delivered to a specific cell. For example, the drug may be selected from the group consisting of erlotinib (TARCEVA; Genentech / OSI Pharm.); bortezomib (VELCADE; MilleniumPharm.); fulvestrant (FASLODEX; AstraZeneca); sutent (SU11248; Pfizer); letrozole (FEMARA; Novartis); imatinib mesylate (GLEEVEC; Novartis); PTK787 / ZK 222584 (Novartis); oxaliplatin (Eloxatin; Sanofi); 5-fluorouracil (5-FU); leucovorin; rapamycin (Sirolimus, RAPAMUNE; Wyeth); lapatinib (TYKERB, GSK572016; GlaxoSmithKline); lonafarnib (SCH 66336); sorafenib (BAY43-9006; Bayer Labs.); gefitinib (IRESSA; Astrazeneca); AG1478, AG1571 (SU 5271; Sugen); alkylating agent (e.g., thiotepa or CYTOXAN® cyclophosphamide); alkyl sulfonate (e.g., busulfan, improsulfan or piposulfan); aziridine (e.g., benzodopa, carboquone, meturedopa or uredopa); ethylenimine, methylmelamine, altretamine, triethylenemelamine, triethylenephosphoramide, triethylenethiophosphoramide, trimethylolmelamine; acetogenins (e.g., bullatacin or bullatacinone); camptothecin including synthetic analogue topotecan; bryostatin; callystatin; CC- 1065 (including adozelesin, carzelesin or bizelesin synthetic analogues thereof); cryptophycins (e.g., cryptophycin 1 or cryptophycin 8); dolastatin; duocarmycin (including a synthetic analogue, KW-2189, and CB1-TM1); eleutherobin; pancratistatin; sarcodictyin; spongistatin; nitrogen mustard (e.g., chlorambucil, chlornaphazine, cholophosphamide, estramustine, ifosfamide, mechlorethamine, mechlorethamine oxide hydrochloride, melphalan, novembichin, phenesterine, prednimustine, trofosfamide or uracil mustard); nitrousurea (e.g., carmustine, chlorozotocin, fotemustine, lomustine, nimustine or ranimnustine); antibiotics (e.g., calicheamicin selected from calicheamycin gamma1 I and calicheamycin omega I 1 or dynemic in including dynemic in A as enediyne antibiotics); bisphosphonate (e.g., clodronate); esperamicin, neocarzinostatin chromophore or related chromoprotein enediyne antibiotic chromophores, aclacinomycin, actinomycin, antramycin, azaserine, bleomycin, cactinomycin, carabicin, carninomycin, carzinophilin, chromomycin, dactinomycin, daunorubicin, detorubucin, 6-diazo-5-oxo-L-norleucine, ADRLIMYCIN® doxorubicin (e.g., morpholino-doxorubicin, cyanomorpholino-doxorubicin, 2-pyrrolino-doxorubucin, liposomal doxorubicin or deoxydoxorubicin), epirubicin, esorubicin, marcellomycin, mitomycin (e.g., mitomycin C, mycophenolic acid, nogalamycin, olivomycin, peplomycin, potfiromycin, puromycin, quelamycin, rodorubicin, streptomigrin, streptozocin, tubercidin, ubenimex, zinostatin or zorubicin); anti-metabolites (e.g., 5-fluorouracil (5-FU)); folic acid analogues (e.g., denopterin, methotrexate, pteropterin or trimetrexate); purine analogs (e.g., fludarabine, 6-mercaptopurine, thiamiprine or thiguanine); pyrimidine analogs (e.g., ancitabine, azacitidine, 6-azauridine, carmofur, cytarabine, dideoxyuridine, doxifluridine, enocitabine or floxuridine); androgen (e.g., calusterone, dromostanolone propionate, epitiostanol, mepitiostane or testolactone); anti-adrenal (e.g., aminoglutethimide, mitotane or trilostane); folic acid replenisher (e.g., folinic acid); aceglatone; aldophosphamide glycoside; aminolevulinic acid; eniluracil; amsacrine; bestrabucil; bisantrene; edatraxate; defofamine; demecolcine; diaziquone; elfornithine; elliptinium acetate; epothilone; etoglucid; gallium nitrate; hydroxyurea; lentinan; lonidainine; maytansinoid (e.g., maytansine or ansamitocin; trichothecene (e.g., T-2 toxin, verracurin A, roridin A or anguidine); mitoguazone; mitoxantrone; mopidanmol; nitraerine; pentostatin; phenamet; pirarubicin; losoxantrone; 2-ethylhydrazide; procarbazine; PSK® polysaccharide; razoxane; rhizoxin; sizofiran; spirogermanium; tenuazonic acid; triaziquone; 2,2',2"-trichlorotriethylamine; trichothecene (particularly, T-2 toxin, verracurin A, roridin A or anguidine); urethane; vindesine; dacarbazine; mannomustine; mitobronitol; mitolactol; pipobroman; gacytosine; arabinoside ('Ara-C'); cyclophosphamide; thiotepa; taxoids (e.g., TAXOL® paclitaxel (Bristol-Myers Squibb Oncology, Princeton, N. J.), ABRAXANE<com:Sup>TM< / com:Sup> cremophor-free, albumin-engineered nanoparticle formulation of paclitaxel, American Pharmaceutical Partners, Schaumber, Ill. or TAXOTERE® dox etaxel ((Rhone-Poulenc Rorer, Antony, France))); chloranbucil; gemcitabine; 6-thioguanine; mercaptopurine; platinum analog (e.g., cisplatin or carboplatin); vinblastine; platinum; etoposide, ifosfamide; mitoxantrone; vincristine; NAVELBINE® vinorelbine; novantrone; teniposide; edatrexate; daunomycin; aminopterin; xeloda; ibandronate; CPT-11; topoisomerase inhibitor RFS 2000; difluoromethylornithine (DFMO); retinoid (e.g., retinoic acid); capecitabine; and a pharmaceutically acceptable salt thereof, a solvate thereof, an acid thereof or a derivative thereof. Mitotic Inhibitors In some embodiments, linkers of the invention may be used to conjugate an antibody to one or more mitotic inhibitor(s) to form an ADC for the treatment of cancer. The term "mitotic inhibitor", as used herein, refers to a cytotoxic and / or therapeutic agent that blocks mitosis or cell division, a biological process particularly important to cancer cells. A mitotic inhibitor disrupts microtubules such that cell division is prevented, often by affecting microtubule polymerization or microtubule depolymerization. Thus, in certain embodiments, an antibody is conjugated to one or more mitotic inhibitor(s) that disrupts microtubule formation by inhibiting tubulin polymerization. In one embodiment, the mitotic inhibitor used in the ADCs of the invention is Taxol® (paclitaxel), Taxotere® (docetaxel), or Ixempra® (ixabepilone). Examples of mitotic inhibitors that may be used in the ADCs disclosed herein are provided below. Included in the genus of mitotic inhibitors are auristatins, described above. Auristatins The linkers of the invention may be used to conjugate an antibody to at least one auristatin. Auristatins represent a group of dolastatin analogs that have generally been shown to possess anticancer activity by interfering with microtubule dynamics and GTP hydrolysis, thereby inhibiting cellular division. For example, Auristatin E (U.S. Pat. No. 5,635,483) is a synthetic analogue of the marine natural product dolastatin 10, a compound that inhibits tubulin polymerization by binding to the same site on tubulin as the anticancer drug vincristine (G. R. Pettit, Prog. Chem. Org. Nat. Prod, 70: 1-79 (1997)). Dolastatin 10, auristatin PE, and auristatin E are linear peptides having four amino acids, three of which are unique to the dolastatin class of compounds. Exemplary embodiments of the auristatin subclass of mitotic inhibitors include, but are not limited to, monomethyl auristatin D (MMAD or auristatin D derivative), monomethyl auristatin E (MMAE or auristatin E derivative), monomethyl auristatin F (MMAF or auristatin F derivative), auristatin F phenylenediamine (AFP), auristatin EB (AEB), auristatin EFP (AEFP), and 5-benzoylvaleric acid-AE ester (AEVB). The synthesis and structure of auristatin derivatives are described in U.S. Patent Application Publication Nos. 2003-0083263, 2005-0238649 and 2005-0009751; International Patent Publication No. WO 04 / 010957, International Patent Publication No. WO 02 / 088172, and U.S. Pat. Nos. 6,323,315; 6,239,104; 6,034,065; 5,780,588; 5,665,860; 5,663,149; 5,635,483; 5,599,902; 5,554,725; 5,530,097; 5,521,284; 5,504,191; 5,410,024; 5,138,036; 5,076,973; 4,986,988; 4,978,744; 4,879,278; 4,816,444; and 4,486,414 Dolastatins The linkers of the invention may be used to conjugate an antibody to at least one dolastatin to form an ADC. Dolastatins are short peptidic compounds isolated from the Indian Ocean sea hare Dolabella auricularia (see Pettit et al., J. Am. Chem. Soc., 1976, 98, 4677). Examples of dolastatins include dolastatin 10 and dolatstin 15. Dolastatin 15, a seven-subunit depsipeptide derived from Dolabella auricularia, and is a potent antimitotic agent structurally related to the antitubulin agent dolastatin 10, a five-subunit peptide obtained from the same organism. Thus, in one embodiment, the ADC of the invention comprises an antibody, a linker as described herein, and at least one dolastatin. Auristatins, described above, are synthetic derivatives of dolastatin 10. Maytansinoids The linkers of the invention may be used to conjugate an antibody to at least one maytansinoid to form an ADC. Maytansinoids are potent antitumor agents that were originally isolated from members of the higher plant families Celastraceae, Rhamnaceae and Euphorbiaceae, as well as some species of mosses (Kupchan et al, J. Am. Chem. Soc. 94:1354- 1356

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[1990] ). Evidence suggests that may tansinoids inhibit mitosis by inhibiting polymerization of the microtubule protein tubulin, thereby preventing formation of microtubules (see, e.g., U.S. Pat. No. 6,441,163 and Remillard et al., Science, 189, 1002-1005 (1975)). Maytansinoids have been shown to inhibit tumor cell growth in vitro using cell culture models, and in vivo using laboratory animal systems. Moreover, the cytotoxicity of maytansinoids is 1,000-fold greater than conventional chemotherapeutic agents, such as, for example, methotrexate, daunorubicin, and vincristine (see, e.g., U.S. Pat. No. 5,208,020). Maytansinoids to include maytansine, maytansinol, C-3 esters of maytansinol, and other maytansinol analogues and derivatives (see, e.g., U.S. Pat. Nos. 5,208,020 and 6,441,163). C-3 esters of maytansinol can be naturally occurring or synthetically derived. Moreover, both naturally occurring and synthetic C-3 may tansinol esters can be classified as a C-3 ester with simple carboxylic acids, or a C-3 ester with derivatives of N-methyl-L-alanine, the latter being more cytotoxic than the former. Synthetic may tansinoid analogues are described in, for example, Kupchan et al., J. Med. Chem., 21, 31-37 (1978). Suitable may tansinoids for use in ADCs of the invention can be isolated from natural sources, synthetically produced, or semi-synthetically produced. Moreover, the may tansinoid can be modified in any suitable manner, so long as sufficient cytotoxicity is preserved in the ultimate conjugate molecule. The structure of an exemplary may tansinoid, mertansine (DM1), is provided below. [Image disponible dans le document PDF, Image available in the PDF document] Mertansine (DM1) Representative examples of may tansinoids include, but are not limited, to DM1 (N2'- deacetyl-N2'-(3-mercapto-1-oxopropyl)-maytansine; also referred to as mertansine, drug maytansinoid 1; ImmunoGen, Inc.; see also Chari et al. (1992) Cancer Res 52:127), DM2, DM3 (N2'-deacetyl-N2'-(4-mercapto-1-oxopentyl)-maytansine), DM4 (4-methyl-4-mercapto-1- oxopentyl)-maytansine) and maytansinol (a synthetic maytansinoid analog). Other examples of may tansinoids are described in U.S. Pat. No. 8,142,784. Ansamitocins are a group of maytansinoid antibiotics that have been isolated from various bacterial sources. These compounds have potent antitumor activities. Representative examples include, but are not limited to ansamitocin P1, ansamitocin P2, ansamitocin P3, and ansamitocin P4. Plant Alkaloids The linkers of the invention may be used to conjugate an antibody to at least one plant alkaloid, e.g., a taxane or vinca alkaloid. Plant alkaloids are chemotherapy treatments derived made from certain types of plants. The vinca alkaloids are made from the periwinkle plant catharanthus rosea), whereas the taxanes are made from the bark of the Pacific Yew tree taxus). Both the vinca alkaloids and taxanes are also known as antimicrotubule agents, and are described in more detail below. Taxanes The linkers of the invention may be used to conjugate an antibody to at least one taxane. The term "tax ane" as used herein refers to the class of antineoplastic agents having a mechanism of microtubule action and having a structure that includes the taxane ring structure and a stereospecific side chain that is required for cytostatic activity. Also included within the term "taxane" are a variety of known derivatives, including both hydrophilic derivatives, and hydrophobic derivatives. Taxane derivatives include, but not limited to, galactose and mannose derivatives described in International Patent Application No. WO 99 / 18113; piperazino and other derivatives described in WO 99 / 14209; taxane derivatives described in WO 99 / 09021, WO 98 / 22451, and U.S. Pat. No. 5,869,680; 6-thio derivatives described in WO 98 / 28288; sulfenamide derivatives described in U.S. Pat. No. 5,821,263; and taxol derivative described in U.S. Pat. No. 5,415,869. Taxane compounds have also previously been described in U.S. Pat. Nos. 5,641,803, 5,665,671, 5,380,751, 5,728,687, 5,415,869, 5,407,683, 5,399,363, 5,424,073, 5,157,049, 5,773,464, 5,821,263, 5,840,929, 4,814,470, 5,438,072, 5,403,858, 4,960,790, 5,433,364, 4,942,184, 5,362,831, 5,705,503, and 5,278,324. Further examples of taxanes include, but are not limited to, docetaxel (Taxotere<com:Sup>®< / com:Sup>; Sanofi Aventis), paclitaxel (Abraxane<com:Sup>®< / com:Sup> or Taxol<com:Sup>®< / com:Sup>; Abraxis Oncology), and nanoparticle paclitaxel (ABI-007 / Abraxene®; Abraxis Bioscience). In one embodiment, the linkers of the invention may be used to conjugate an antibody to at least one docetaxel. In one embodiment, the linkers of the invention may be used to conjugate an antibody to at least one paclitaxel. Vinca Alkaloids In one embodiment, the linkers of the invention may be used to conjugate an antibody to at least one vinca alkaloid. Vinca alkaloids are a class of cell-cycle-specific drugs that work by inhibiting the ability of cancer cells to divide by acting upon tubulin and preventing the formation of microtubules. Examples of vinca alkaloids that may be used in the ADCs of the invention include, but are not limited to, vindesine sulfate, vincristine, vinblastine and vinorelbine. Antitumor Antibiotics The linkers of the invention may be used to conjugate an antibody to one or more antitumor antibiotic(s) for the treatment of cancer. As used herein, the term "antitumor antibiotic" means an antineoplastic drug that blocks cell growth by interfering with DNA and is made from a microorganism. Often, antitumor antibiotics either break up DNA strands or slow down or stop DNA synthesis. Examples of antitumor antibiotics that may be included in the ADCs disclosed herein include, but are not limited to, actinomycines (e.g., pyrrolo[2,1- c][1,4]benzodiazepines), anthracyclines, calicheamicins, and duocarmycins, described in more detail below. Actinomycines The linkers of the invention may be used to conjugate an antibody to at least one actinomycine. Actinomycines are a subclass of antitumor antibiotics isolated from bacteria of the genus Streptomyces. Representative examples actinomycines include, but are not limited to, actinomycin D (Cosmegen [also known as actinomycin, dactinomycin, actinomycin IV, actinomycin C1], Lundbeck, Inc.), anthramycin, chicamycin A, DC-81, mazethramycin, neothramycin A, neothramycin B, porothramycin, prothracarcin B, SG2285, sibanomicin, sibiromycin and tomaymycin. In one embodiment, D is pyrrolobenzodiazepine (PBD). Examples of PBDs include, but are not limited to, anthramycin, chicamycin A, DC-81, mazethramycin, neothramycin A, neothramycin B, porothramycin, prothracarcin B, SG2000 (SJG-136), SG2202 (ZC-207), SG2285 (ZC-423), sibanomicin, sibiromycin and tomaymycin. Thus, in one embodiment, D is actinomycine, e.g., actinomycin D, or PBD, e.g., a pyrrolobenzodiazepine (PBD) dimer. The structures of PBDs can be found, for example, in U.S. Patent Application Pub. Nos. 2013 / 0028917 and 2013 / 0028919, and in WO 2011 / 130598 A1. The generic structure of a PBD is provided below. [Image disponible dans le document PDF, Image available in the PDF document] PBDs differ in the number, type and position of substituents, in both their aromatic A rings and pyrrolo C rings, and in the degree of saturation of the C ring. In the B-ring, there is generally an imine (N=C), a carbinolamine (NH—CH(OH)), or a carbinolamine methyl ether (NH—CH(OMe)) at the N10-C11 position which is the electrophilic centre responsible for alkylating DNA. All of the known natural products have an (S)-configuration at the chiral C11a position which provides them with a right-handed twist when viewed from the C ring towards the A ring. Further examples of PBDs which may be conjugated to antibodies via the linkers disclosed herein can be found, for example, in U.S. Patent Application Publication Nos. 2013 / 0028917 A1 and 2013 / 0028919 A1, in U.S. Pat. No. 7,741,319 B2, and in WO 2011 / 130598 A1 and WO 2006 / 111759 A1. Anthracyclines The linkers of the invention may be used to conjugate an antibody to at least one anthracycline. Anthracyclines are a subclass of antitumor antibiotics isolated from bacteria of the genus Streptomyces. Representative examples include, but are not limited to daunorubicin (Cerubidine, Bedford Laboratories), doxorubicin (Adriamycin, Bedford Laboratories; also referred to as doxorubicin hydrochloride, hydroxydaunorubicin, and Rubex), epirubicin (Ellence, Pfizer), and idarubicin (Idamycin; Pfizer Inc.). Thus, in one embodiment, D is anthracycline, e.g., doxorubicin. Calicheamicins The linkers of the invention may be used to conjugate an antibody to at least one calicheamicin. Calicheamicins are a family of enediyne antibiotics derived from the soil organism Micromonospora echinospora. Calicheamicins bind the minor groove of DNA and induce double-stranded DNA breaks, resulting in cell death with a 100 fold increase over other chemotherapeutics (Damle et al. (2003) Curr Opin Pharmacol 3:386). Preparation of calicheamicins that may be used as drug conjugates in the invention have been described, see U.S. Pat. Nos. 5,712,374; 5,714,586; 5,739,116; 5,767,285; 5,770,701; 5,770,710; 5,773,001; and 5,877,296. Structural analogues of calicheamicin which may be used include, but are not limited to, γ1 I, α2 I, α3 I, N-acetyl-γ1 I, PSAG and θI 1 (Hinman et al., Cancer Research 53:3336-3342 (1993), Lode et al., Cancer Research 58:2925-2928 (1998) and the aforementioned U.S. Pat. Nos. 5,712,374; 5,714,586; 5,739,116; 5,767,285; 5,770,701; 5,770,710; 5,773,001; and 5,877,296). Thus, in one embodiment, D is calicheamicin. Duocarmycins The linkers of the invention may be used to conjugate an antibody to at least one duocarmycin. Duocarmycins are a subclass of antitumor antibiotics isolated from bacteria of the genus Streptomyces. (see Nagamura and Saito (1998) Chemistry of Heterocyclic Compounds, Vol. 34, No. 12). Duocarmycins bind to the minor groove of DNA and alkylate the nucleobase adenine at the N3 position (Boger (1993) Pure and Appl Chem 65(6):1123; and Boger and Johnson (1995) PNAS USA 92:3642). Synthetic analogs of duocarmycins include, but are not limited to, adozelesin, bizelesin, and carzelesin. Thus, in one embodiment, the D is duocarmycin. Other Antitumor Antibiotics In addition to the foregoing, additional antitumor antibiotics that may be used in the ADCs of the invention include bleomycin (Blenoxane, Bristol-Myers Squibb), mitomycin, and plicamycin (also known as mithramycin). Immunomodulating Agents In some embodiments, the linkers of the invention may be used to conjugate an antibody to at least one immunomodulating agent. As used herein, the term "immunomodulating agent" refers to an agent that can stimulate or modify an immune response. In one embodiment, an immunomodulating agent is an immunostimuator which enhances a subject's immune response. In some embodiments, an immunomodulating agent is an immunosuppressant, which prevents or decreases a subject's immune response. An immunomodulating agent may modulate myeloid cells (monocytes, macrophages, dendritic cells, megakaryocytes and granulocytes) or lymphoid cells (T cells, B cells and natural killer (NK) cells) and any further differentiated cell thereof. Representative examples include, but are not limited to, bacillus calmette-guerin (BCG) and levamisole (Ergamisol). Other examples of immunomodulating agents that may be used in the ADCs of the invention include, but are not limited to, cancer vaccines, cytokines, and immunomodulating gene therapy. Cancer Vaccines The linkers of the invention may be used to conjugate an antibody to a cancer vaccine. As used herein, the term "cancer vaccine" refers to a composition (e.g., a tumor antigen and a cytokine) that elicits a tumor-specific immune response. The response is elicited from the subject's own immune system by administering the cancer vaccine, or, in the case of the instant invention, administering an ADC comprising anantibody and a cancer vaccine. In preferred embodiments, the immune response results in the eradication of tumor cells in the body (e.g., primary or metastatic tumor cells). The use of cancer vaccines generally involves the administration of a particular antigen or group of antigens that are, for example, present on the surface a particular cancer cell, or present on the surface of a particular infectious agent shown to facilitate cancer formation. In some embodiments, the use of cancer vaccines is for prophylactic purposes, while in other embodiments, the use is for therapeutic purposes. Non-limiting examples of cancer vaccines that may be used in the ADCs disclosed herein include, recombinant bivalent human papillomavirus (HPV) vaccine types 16 and 18 vaccine (Cervarix, GlaxoSmithKline), recombinant quadrivalent human papillomavirus (HPV) types 6, 11, 16, and 18 vaccine (Gardasil, Merck & Company), and sipuleucel-T (Provenge, Dendreon). Thus, in one embodiment, D is a cancer vaccine that is either an immunostimulator or is an immunosuppressant. Cytokines The linkers of the invention may be used to conjugate an antibody at least one cytokine. The term "cytokine" generally refers to proteins released by one cell population which act on another cell as intercellular mediators. Cytokines directly stimulate immune effector cells and stromal cells at the tumor site and enhance tumor cell recognition by cytotoxic effector cells (Lee and Margolin (2011) Cancers 3:3856). Numerous animal tumor model studies have demonstrated that cytokines have broad anti-tumor activity and this has been translated into a number of cytokine-based approaches for cancer therapy (Lee and Margoli, supra). Recent years have seen a number of cytokines, including GM-CSF, IL-7, IL-12, IL-15, IL-18 and IL-21, enter clinical trials for patients with advanced cancer (Lee and Margoli, supra). Examples of cytokines that may be used in the ADCs of the invention include, but are not limited to, parathyroid hormone; thyroxine; insulin; proinsulin; relaxin; prorelaxin; glycoprotein hormones such as follicle stimulating hormone (FSH), thyroid stimulating hormone (TSH), and luteinizing hormone (LH); hepatic growth factor; fibroblast growth factor; prolactin; placental lactogen; tumor necrosis factor; mullerian-inhibiting substance; mouse gonadotropin-associated peptide; inhibin; activin; vascular endothelial growth factor; integrin; thrombopoietin (TPO); nerve growth factors such as NGF; platelet-growth factor; transforming growth factors (TGFs); insulin-like growth factor-I and -II; erythropoietin (EPO); osteoinductive factors; interferons such as interferon <com:Math><semantics>α<annotation encoding="application / x-tex">\alpha< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>β<annotation encoding="application / x-tex">\beta< / annotation>< / semantics>< / com:Math>, and <com:Math><semantics>γ<annotation encoding="application / x-tex">\gamma< / annotation>< / semantics>< / com:Math>, colony stimulating factors (CSFs); granulocyte-macrophage-C-SF (GM-CSF); and granulocyte-CSF (G-CSF); interleukins (ILs) such as IL-1, IL-la, IL-2, IL-3, IL- 4, IL-5, IL-6, IL-7, IL-8, IL-9, IL-11, IL-12; tumor necrosis factor; and other polypeptide factors including LIF and kit ligand (KL). As used herein, the term cytokine includes proteins from natural sources or from recombinant cell culture and biologically active equivalents of the native sequence cytokines. Thus, in one embodiment, D is a cytokine. Colony-Stimulating Factors (CSFs) The linkers of the invention may be used to conjugate an antibody to at least one colony stimulating factor (CSF). Colony stimulating factors (CSFs) are growth factors that assist the bone marrow in making red blood cells. Because some cancer treatments (e.g., chemotherapy) can affect white blood cells (which help fight infection), colony-stimulating factors may be introduced to help support white blood cell levels and strengthen the immune system. Colony- stimulating factors may also be used following a bone marrow transplant to help the new marrow start producing white blood cells. Representative examples of CSFs that may be used in ADCs disclosed herein include, but are not limited to erythropoietin (Epoetin), filgrastim (Neopogen (also known as granulocyte colony-stimulating factor (G-CSF); Amgen, Inc.), sargramostim (leukine (granulocyte-macrophage colony-stimulating factor and GM-CSF); Genzyme Corporation), promegapoietin, and Oprelvekin (recombinant IL-11; Pfizer, Inc.). Thus, in one embodiment, D is a CSF. Gene Therapy The linkers of the invention may be used to conjugate an antibody to at least one nucleic acid (directly or indirectly via a carrier) for gene therapy. Gene therapy generally refers to the introduction of genetic material into a cell whereby the genetic material is designed to treat a disease. As it pertains to immunomoduatory agents, gene therapy is used to stimulate a subject's natural ability to inhibit cancer cell proliferation or kill cancer cells. In one embodiment, the ADC of the invention comprises a nucleic acid encoding a functional, therapeutic gene that is used to replace a mutated or otherwise dysfuntional (e.g., truncated) gene associated with cancer. In other embodiments, the ADC of the invention comprises a nucleic acid that encodes for or otherwise provides for the production of a therapeutic protein to treat cancer. The nucleic acid that encodes the therapeutic gene may be directly conjugated to the antibody, or alternatively, may be conjugated to the antibody through a carrier. Examples of carriers that may be used to deliver a nucleic acid for gene therapy include, but are not limited to, viral vectors or liposomes. Alkylating Agents The linkers of the invention may be used to conjugate an antibody to one or more alkylating agent(s). Alkylating agents are a class of antineoplastic compounds that attaches an alkyl group to DNA. Examples of alkylating agents that may be used in the ADCs of the invention include, but are not limited to, alkyl sulfonates, ethylenimimes, methylamine derivatives, epoxides, nitrogen mustards, nitrosoureas, triazines and hydrazines. Alkyl Sulfonates The linkers of the invention may be used to conjugate an antibody to at least one alkyl sulfonate. Alkyl sulfonates are a subclass of alkylating agents with a general formula: R—SO<com:Sub>2< / com:Sub>— O—R<com:Sup>1< / com:Sup>, wherein R and R<com:Sup>1< / com:Sup> are typically alkyl or aryl groups. A representative example of an alkyl sulfonate is busulfan (Myleran<com:Sup>®< / com:Sup>, GlaxoSmithKline; Busulfex IV<com:Sup>®< / com:Sup>, PDL BioPharma, Inc.). Nitrogen Mustards The linkers of the invention may be used to conjugate an antibody to at least one nitrogen mustard. Representative examples of this subclass of anti-cancer compounds include, but are not limited to chlorambucil (Leukeran®, GlaxoSmithKline), cyclophosphamide (Cytoxan®, Bristol- Myers Squibb; Neosar, Pfizer, Inc.), estramustine (estramustine phosphate sodium or Estracyt<com:Sup>®< / com:Sup>), Pfizer, Inc.), ifosfamide (Ifex<com:Sup>®< / com:Sup>, Bristol-Myers Squibb), mechlorethamine (Mustargen<com:Sup>®< / com:Sup>, Lundbeck Inc.), and melphalan (Alkeran® or L-Pam® or phenylalanine mustard; GlaxoSmithKline). Nitrosoureas The linkers of the invention may be used to conjugate an antibody to at least one nitrosourea. Nitrosoureas are a subclass of alkylating agents that are lipid soluble. Representative examples include, but are not limited to, carmustine (BCNU [also known as BiCNU, N,N-bis(2- chloroethyl)-N-nitrosourea, or 1,3-bis(2-chloroethyl)-1-nitrosoureal, Bristol-Myers Squibb), fotemustine (also known as Muphoran®), lomustine (CCNU or 1-(2-chloro-ethyl)-3-cyclohexyl- 1-nitrosourea, Bristol-Myers Squibb), nimustine (also known as ACNU), and streptozocin (Zanosar<com:Sup>®< / com:Sup>, Teva Pharmaceuticals). Triazines and Hydrazines The linkers of the invention may be used to conjugate an antibody to at least one triazine or hydrazine. Triazines and hydrazines are a subclass of nitrogen-containing alkylating agents. In some embodiments, these compounds spontaneously decompose or can be metabolized to produce alkyl diazonium intermediates that facilitate the transfer of an alkyl group to nucleic acids, peptides, and / or polypeptides, thereby causing mutagenic, carcinogenic, or cytotoxic effects. Representative examples include, but are not limited to dacarbazine (DTIC-Dome, Bayer Healthcare Pharmaceuticals Inc.), procarbazine (Mutalane<com:Sup>®< / com:Sup>, Sigma-Tau Pharmaceuticals, Inc.), and temozolomide (Temodar<com:Sup>®< / com:Sup>, Schering Plough). Other Alkylating Agents The linkers of the invention may be used to conjugate an antibody to at least one ethylenimine, methylamine derivative, or epoxide. Ethylenimines are a subclass of alkylating agents that typically containing at least one aziridine ring. Epoxides represent a subclass of alkylating agents that are characterized as cyclic ethers with only three ring atoms. Representatives examples of ethylenimines include, but are not limited to thiopeta (Thioplex, Amgen), diaziquone (also known as aziridinyl benzoquinone (AZQ)), and mitomycin C. Mitomycin C is a natural product that contains an aziridine ring and appears to induce cytoxicity through cross-linking DNA (Dorr R T, et al. Cancer Res. 1985; 45:3510; Kennedy K A, et al Cancer Res. 1985; 45:3541). Representative examples of methylamine derivatives and their analogs include, but are not limited to, altretamine (Hexalen, MGI Pharma, Inc.), which is also known as hexamethylamine and hexastat. Representative examples of epoxides of this class of anti-cancer compound include, but are not limited to dianhydrogalactitol. Dianhydrogalactitol (1,2:5,6-dianhydrodulcitol) is chemically related to the aziridines and generally facilitate the transfer of an alkyl group through a similar mechanism as described above. Dibromodulcitol is hydrolyzed to dianhydrogalactitol and thus is a pro-drug to an epoxide (Sellei C, et al. Cancer Chemother Rep. 1969; 53:377). Antiangiogenic Agents In some embodiments, the linkers of the invention may be used to conjugate an antibody to at least one antiangiogenic agent. Antiangiogenic agents inhibit the growth of new blood vessels. Antiangiogenic agents exert their effects in a variety of ways. In some embodiments, these agents interfere with the ability of a growth factor to reach its target. For example, vascular endothelial growth factor (VEGF) is one of the primary proteins involved in initiating angiogenesis by binding to particular receptors on a cell surface. Thus, certain antiangiogenic agents, that prevent the interaction of VEGF with its cognate receptor, prevent VEGF from initiating angiogenesis. In other embodiments, these agents interfere with intracellular signaling cascades. For example, once a particular receptor on a cell surface has been triggered, a cascade of other chemical signals is initiated to promote the growth of blood vessels. Thus, certain enzymes, for example, some tyrosine kinases, that are known to facilitate intracellular signaling cascades that contribute to, for example, cell proliferation, are targets for cancer treatment. In other embodiments, these agents interfere with intercellular signaling cascades. Yet, in other embodiments, these agents disable specific targets that activate and promote cell growth or by directly interfering with the growth of blood vessel cells. Angiogenesis inhibitory properties have been discovered in more than 300 substances with numerous direct and indirect inhibitory effects. Representative examples of antiangiogenic agents that may be used in the ADCs of the invention include, but are not limited to, angiostatin, ABX EGF, C1-1033, PKI-166, EGF vaccine, EKB-569, GW2016, ICR-62, EMD 55900, CP358, PD153035, AG1478, IMC-C225 (Erbitux, ZD1839 (Iressa), OSI-774, Erlotinib (tarceva), angiostatin, arrestin, endostatin, BAY 12-9566 and w / fluorouracil or doxorubicin, canstatin, carboxyamidotriozole and with paclitaxel, EMD121974, S-24, vitaxin, dimethylxanthenone acetic acid, IM862, Interleukin-12, Interleukin- 2, NM-3, HuMV833, PTK787, RhuMab, angiozyme (ribozyme), IMC-1C11, Neovastat, marimstat, prinomastat, BMS-275291, COL-3, MM1270, SU101, SU6668, SU11248, SU5416, with paclitaxel, with gemcitabine and cisplatin, and with irinotecan and cisplatin and with radiation, tecogalan, temozolomide and PEG interferon α2b, tetrathiomolybdate, TNP-470, thalidomide, CC-5013 and with taxotere, tumstatin, 2-methoxyestradiol, VEGF trap, mTOR inhibitors (deforolimus, everolimus (Afinitor, Novartis Pharmaceutical Corporation), and temsirolimus (Torisel, Pfizer, Inc.)), tyrosine kinase inhibitors (e.g., erlotinib (Tarceva, Genentech, Inc.), imatinib (Gleevec, Novartis Pharmaceutical Corporation), gefitinib (Iressa, AstraZeneca Pharmaceuticals), dasatinib (Sprycel, Brystol-Myers Squibb), sunitinib (Sutent, Pfizer, Inc.), nilotinib (Tasigna, Novartis Pharmaceutical Corporation), lapatinib (Tykerb, GlaxoSmithKline Pharmaceuticals), sorafenib (Nexavar, Bayer and Onyx), phosphoinositide 3- kinases (PI3K). Antimetabolites The linkers of the invention may be used to conjugate an antibody to at least one antimetabolite. Antimetabolites are types of chemotherapy treatments that are very similar to normal substances within the cell. When the cells incorporate an antimetabolite into the cellular metabolism, the result is negative for the cell, e.g., the cell is unable to divide. Antimetabolites are classified according to the substances with which they interfere. Examples of antimetabolies that may be used in the ADCs of the invention include, but are not limited to, a folic acid antagonist (e.g., methotrexate), a pyrimidine antagonist (e.g., 5-Fluorouracil, Foxuridine, Cytarabine, Capecitabine, and Gemcitabine), a purine antagonist (e.g., 6-Mercaptopurine and 6- Thioguanine) and an adenosine deaminase inhibitor (e.g., Cladribine, Fludarabine, Nelarabine and Pentostatin), as described in more detail below. Antifolates The linkers of the invention may be used to conjugate an antibody to at least one antifolate. Antifolates are a subclass of antimetabolites that are structurally similar to folate. Representative examples include, but are not limited to, methotrexate, 4-amino-folic acid (also known as aminopterin and 4-aminopteroic acid), lometrexol (LMTX), pemetrexed (Alimpta, Eli Lilly and Company), and trimetrexate (Neutrexin, Ben Venue Laboratories, Inc.) Purine Antagonists The linkers of the invention may be used to conjugate an antibody to at least one purine antagonist. Purine analogs are a subclass of antimetabolites that are structurally similar to the group of compounds known as purines. Representative examples of purine antagonists include, but are not limited to, azathioprine (Azasan, Salix; Imuran, GlaxoSmithKline), cladribine (Leustatin [also known as 2-CdA], Janssen Biotech, Inc.), mercaptopurine (Purinethol [also known as 6-mercaptoethanol], GlaxoSmithKline), fludarabine (Fludara, Genzyme Corporation), pentostatin (Nipent, also known as 2'-deoxycoformycin (DCF)), 6-thioguanine (Lanvis [also known as thioguanine], GlaxoSmithKline). Pyrimidine Antagonists The linkers of the invention may be used to conjugate an antibody to at least one pyrimidine antagonist. Pyrimidine antagonists are a subclass of antimetabolites that are structurally similar to the group of compounds known as purines. Representative examples of pyrimidine antagonists include, but are not limited to azacitidine (Vidaza, Celgene Corporation), capecitabine (Xeloda, Roche Laboratories), Cytarabine (also known as cytosine arabinoside and arabinosylcytosine, Bedford Laboratories), decitabine (Dacogen, Eisai Pharmaceuticals), 5- fluorouracil (Adrucil, Teva Pharmaceuticals; Efudex, Valeant Pharmaceuticals, Inc), 5-fluoro-2'- deoxyuridine 5'-phosphate (FdUMP), 5-fluorouridine triphosphate, and gemcitabine (Gemzar, Eli Lilly and Company). Boron-Containing Agents The linkers of the invention may be used to conjugate an antibody to at least one boron containing agent. Boron-containing agents comprise a class of cancer therapeutic compounds which interfere with cell proliferation. Representative examples of boron containing agents include, but are not limited, to borophycin and bortezomib (Velcade, Millenium Pharmaceuticals). Chemoprotective Agents The linkers of the invention may be used to conjugate an antibody to at least one chemoprotective agent. Chemoprotective drugs are a class of compounds, which help protect the body against specific toxic effects of chemotherapy. Chemoprotective agents may be administered with various chemotherapies in order to protect healthy cells from the toxic effects of chemotherapy drugs, while simultaneously allowing the cancer cells to be treated with the administered chemotherapeutic. Representative chemoprotective agents include, but are not limited to amifostine (Ethyol, Medimmune, Inc.), which is used to reduce renal toxicity associated with cumulative doses of cisplatin, dexrazoxane (Totect, Apricus Pharma; Zinecard), for the treatment of extravasation caused by the administration of anthracycline (Totect), and for the treatment of cardiac-related complications caused by the administration of the antitumor antibiotic doxorubicin (Zinecard), and mesna (Mesnex, Bristol-Myers Squibb), which is used to prevent hemorrhagic cystitis during chemotherapy treatment with ifocfamide. Hormone Agents The linkers of the invention may be used to conjugate an antibody to at least one hormone agent. A hormone agent (including synthetic hormones) is a compound that interferes with the production or activity of endogenously produced hormones of the endocrine system. In some embodiments, these compounds interfere with cell growth or produce a cytotoxic effect. Non-limiting examples include androgens, estrogens, medroxyprogesterone acetate (Provera, Pfizer, Inc.), and progestins. Antihormone Agents The linkers of the invention may be used to conjugate an antibody to at least one antihormone agent. An "antihormone" agent is an agent that suppresses the production of and / or prevents the function of certain endogenous hormones. In one embodiment, the antihormone agent interferes with the activity of a hormone selected from the group comprising androgens, estrogens, progesterone, and goanadotropin-releasing hormone, thereby interfering with the growth of various cancer cells. Representative examples of antihormone agents include, but are not limited to, aminoglutethimide, anastrozole (Arimidex, AstraZeneca Pharmaceuticals), bicalutamide (Casodex, AstraZeneca Pharmaceuticals), cyproterone acetate (Cyprostat, Bayer PLC), degarelix (Firmagon, Ferring Pharmaceuticals), exemestane (Aromasin, Pfizer Inc.), flutamide (Drogenil, Schering-Plough Ltd), fulvestrant (Faslodex, AstraZeneca Pharmaceuticals), goserelin (Zolodex, AstraZeneca Pharmaceuticals), letrozole (Femara, Novartis Pharmaceuticals Corporation), leuprolide (Prostap), lupron, medroxyprogesterone acetate (Provera, Pfizer Inc.), Megestrol acetate (Megace, Bristol-Myers Squibb Company), tamoxifen (Nolvadex, AstraZeneca Pharmaceuticals), and triptorelin (Decapetyl, Ferring). Corticosteroids The linkers of the invention may be used to conjugate an antibody to at least one corticosteroid. Corticosteroids may be used in the ADCs of the invention to decrease inflammation. An example of a corticosteroid includes, but is not limited to, a glucocorticoid, for example, prednisone (Deltasone, Pharmacia & Upjohn Company, a division of Pfizer, Inc.). Photoactive Therapeutic Agents The linkers of the invention may be used to conjugate an antibody to at least one photoactive therapeutic agent. Photoactive therapeutic agents include compounds that can be deployed to kill treated cells upon exposure to electromagnetic radiation of a particular wavelength. Therapeutically relevant compounds absorb electromagnetic radiation at wavelengths which penetrate tissue. In preferred embodiments, the compound is administered in a non-toxic form that is capable of producing a photochemical effect that is toxic to cells or tissue upon sufficient activation. In other preferred embodiments, these compounds are retained by cancerous tissue and are readily cleared from normal tissues. Non-limiting examples include various chromagens and dyes. Oligonucleotides The linkers of the invention may be used to conjugate an antibody to at least one oligonucleotide. Oligonucleotides are made of short nucleic acid chains that work by interfering with the processing of genetic information. In some embodiments, the oligonucleotides for use in ADCs are unmodified single-stranded and / or double-stranded DNA or RNA molecules, while in other embodiments, these therapeutic oligonucleotides are chemically-modified single-stranded and / or double-stranded DNA or RNA molecules. In one embodiment, the oligonucleotides used in the ADCs are relatively short (19-25 nucleotides) and hybridize to a unique nucleic acid sequence in the total pool of nucleic acid targets present in cells. Some of the important oligonucleotide technologies include the antisense oligonucleotides (including RNA interference (RNAi)), aptamers, CpG oligonucleotides, and ribozymes. Antisense Oligonucleotides The linkers of the invention may be used to conjugate an antibody to at least one antisense oligonucleotide. Antisense oligonucleotides are designed to bind to RNA through Watson-Crick hybridization. In some embodiments the antisense oligonucleotide is complementary to a nucleotide encoding a region, domain, portion, or segment of the conjugated antibody. In some embodiments, the antisense oligonucleotide comprises from about 5 to about 100 nucleotides, from about 10 to about 50 nucleotides, from about 12 to about 35, and from about 18 to about 25 nucleotides There are multiple mechanisms that can be exploited to inhibit the function of the RNA once the oligonucleotide binds to the target RNA (Crooke ST. (1999). Biochim. Biophys. Acta, 1489, 30-42). The best-characterized antisense mechanism results in cleavage of the targeted RNA by endogenous cellular nucleases, such as RNase H or the nuclease associated with the RNA interference mechanism. However, oligonucleotides that inhibit expression of the target gene by non-catalytic mechanisms, such as modulation of splicing or translation arrest, can also be potent and selective modulators of gene function. Another RNase-dependent antisense mechanism that has recently received much attention is RNAi (Fire et al. (1998). Nature, 391, 806-811; Zamore PD. (2002). Science, 296, 1265-1269.). RNA interference (RNAi) is a post-transcriptional process where a double stranded RNA inhibits gene expression in a sequence specific fashion. In some embodiments, the RNAi effect is achieved through the introduction of relatively longer double-stranded RNA (dsRNA), while in preferred embodiments, this RNAi effect is achieved by the introduction of shorter double-stranded RNAs, e g small interfering RNA (siRNA) and / or microRNA (miRNA). In yet another embodiment, RNAi can also be achieved by introducing of plasmid that generate dsRNA complementary to target gene. In each of the foregoing embodiments, the double-stranded RNA is designed to interfere with the gene expression of a particular the target sequence within cells. Generally, the mechanism involves conversion of dsRNA into short RNAs that direct ribonucleases to homologous mRNA targets (summarized, Ruvkun, Science 2294:797 (2001)), which then degrades the corresponding endogenous mRNA, thereby resulting in the modulation of gene expression. Notably, dsRNA has been reported to have anti-proliferative properties, which makes it possible also to envisage therapeutic applications (Aubel et al., Proc. Natl. Acad. Sci., USA 88:906 (1991)). For example, synthetic dsRNA has been shown to inhibit tumor growth in mice (Levy et al. Proc. Nat. Acad. Sci. USA, 62:357-361 (1969)), is active in the treatment of leukemic mice (Zeleznick et al., Proc. Soc. Exp. Biol. Med. 130:126-128 (1969)), and inhibits chemically induced tumorigenesis in mouse skin (Gelboin et al., Science 167:205- 207 (1970)). Thus, in preferred embodiments, the invention provides for the use of antisense oligonucleotides in ADCs for the treatment of breast cancer. In other embodiments, the invention provides compositions and methods for initiating antisense oligonucleotide treatment, wherein dsRNA interferes with target cell expression of EGFR at the mRNA level. dsRNA, as used above, refers to naturally-occurring RNA, partially purified RNA, recombinantly produced RNA, synthetic RNA, as well as altered RNA that differs from naturally-occurring RNA by the inclusion of non-standard nucleotides, non-nucleotide material, nucleotide analogs (e.g. locked nucleic acid (LNA)), deoxyribonucleotides, and any combination thereof. RNA of the invention need only be sufficiently similar to natural RNA that it has the ability to mediate the antisense oligonucleotide-based modulation described herein. Aptamers The linkers of the invention may be used to conjugate an antibody to at least one aptamer. An aptamer is a nucleic acid molecule that has been selected from random pools based on its ability to bind other molecules. Like antibodies, aptamers can bind target molecules with extraordinary affinity and specificity. In many embodiments, aptamers assume complex, sequence-dependent, three-dimensional shapes that allow them to interact with a target protein, resulting in a tightly bound complex analogous to an antibody-antigen interaction, thereby interfering with the function of said protein. The particular capacity of aptamers to bind tightly and specifically to their target protein underlines their potential as targeted molecular therapies. CpG Oligonucleotides The linkers of the invention may be used to conjugate an antibody to at least one CpG oligonucleotide. Bacterial and viral DNA are known to be a strong activators of both the innate and specific immunity in humans. These immunologic characteristics have been associated with unmethylated CpG dinucleotide motifs found in bacterial DNA. Owing to the fact that these motifs are rare in humans, the human immune system has evolved the ability to recognize these motifs as an early indication of infection and subsequently initiate immune responses. Therefore, oligonucleotides containing this CpG motif can be exploited to initiate an antitumor immune response. Ribozymes The linkers of the invention may be used to conjugate an antibody to at least one ribozyme. Ribozymes are catalytic RNA molecules ranging from about 40 to 155 nucleotides in length. The ability of ribozymes to recognize and cut specific RNA molecules makes them potential candidates for therapeutics. A representative example includes angiozyme. Radionuclide Agents (Radioactive Isotopes) The linkers of the invention may be used to conjugate an antibody to at least one radionuclide agent. Radionuclide agents comprise agents that are characterized by an unstable nucleus that is capable of undergoing radioactive decay. The basis for successful radionuclide treatment depends on sufficient concentration and prolonged retention of the radionuclide by the cancer cell. Other factors to consider include the radionuclide half-life, the energy of the emitted particles, and the maximum range that the emitted particle can travel. In preferred embodiments, the therapeutic agent is a radionuclide selected from the group consisting of 111In, 177Lu, 212Bi, 213Bi, 211At, 62Cu, 64Cu, 67Cu, 90Y, 125I, 131I, 32P, 33P, 47Sc, 111Ag, 67Ga, 142Pr, 153Sm, 161Tb, 166Dy, 166Ho, 186Re, 188Re, 189Re, 212Pb, 223Ra, 225Ac, 59Fe, 75Se, 77As, 89Sr, 99Mo, 105Rh, 109Pd, 143Pr, 149Pm, 169Er, 194Ir, 198Au, 199Au, and 211Pb. Also preferred are radionuclides that substantially decay with Auger-emitting particles. For example, Co-58, Ga-67, Br-80m, Tc-99m, Rh-103m, Pt-109, In-111 1, Sb-119, 1-125, Ho-161, Os-189m and Ir-192. Decay energies of useful beta-particle-emitting nuclides are preferably Dy-152, At- 211, Bi-212, Ra-223, Rn-219, Po-215, Bi-211, Ac-225, Fr-221, At-217, Bi-213 and Fm-255. Decay energies of useful alpha-particle-emitting radionuclides are preferably 2,000-10,000 keV, more preferably 3,000-8,000 keV, and most preferably 4,000-7,000 keV. Additional potential radioisotopes of use include 11C, 13N, 150, 75Br, 198Au, 95Ru, 97Ru, 103Ru, 105Ru, 107Hg, 203Hg, 121mTe, 122mTe, 125mTe, 165Tm, 167Tm, 168Tm, 197Pt, 109Pd, 105Rh, 142Pr, 143Pr, 161Tb, 166Ho, 199Au, 57Co, 58Co, 51Cr, 59Fe, 75Se, 201Tl, 225Ac, 76Br, 169Yb, and the like. Radiosensitizers The linkers of the invention may be used to conjugate an antibody to at least one radiosensitizer. The term "radiosensitizer," as used herein, is defined as a molecule, preferably a low molecular weight molecule, administered to animals in therapeutically effective amounts to increase the sensitivity of the cells to be radiosensitized to electromagnetic radiation and / or to promote the treatment of diseases that are treatable with electromagnetic radiation. Radiosensitizers are agents that make cancer cells more sensitive to radiation therapy, while typically having much less of an effect on normal cells. Thus, the radiosensitizer can be used in combination with a radiolabeled antibody or ADC. The addition of the radiosensitizer can result in enhanced efficacy when compared to treatment with the radiolabeled antibody or antibody fragment alone. Radiosensitizers are described in D. M. Goldberg (ed.), Cancer Therapy with Radiolabeled Antibodies, CRC Press (1995). Examples of radiosensitizers include gemcitabine, 5-fluorouracil, taxane, and cisplatin. Radiosensitizers may be activated by the electromagnetic radiation of X-rays. Representative examples of X-ray activated radiosensitizers include, but are not limited to, the following: metronidazole, misonidazole, desmethylmisonidazole, pimonidazole, etanidazole, nimorazole, mitomycin C, RSU 1069, SR 4233, E09, RB 6145, nicotinamide, 5- bromodeoxyuridine (BUdR), 5-iododeoxyuridine (IUdR), bromodeoxycytidine, fluorodeoxyuridine (FUdR), hydroxyurea, cisplatin, and therapeutically effective analogs and derivatives of the same. Alternatively, radiosensitizers may be activated using photodynamic therapy (PDT). Representative examples of photodynamic radiosensitizers include, but are not limited to, hematoporphyrin derivatives, Photofrin(r), benzoporphyrin derivatives, NPe6, tin etioporphyrin (SnET2), pheoborbide a, bacteriochlorophyll a, naphthalocyanines, phthalocyanines, zinc phthalocyanine, and therapeutically effective analogs and derivatives of the same. Topoisomerase Inhibitors The linkers of the invention may be used to conjugate an antibody to at least one topoisomerase inhibitor. Topoisomerase inhibitors are chemotherapy agents designed to interfere with the action of topoisomerase enzymes (topoisomerase I and II), which are enzymes that control the changes in DNA structure by catalyzing then breaking and rejoining of the phosphodiester backbone of DNA strands during the normal cell cycle. Representative examples of DNA topoisomerase I inhibitors include, but are not limited to, camptothecins and its derivatives irinotecan (CPT-11, Camptosar, Pfizer, Inc.) and topotecan (Hycamtin, GlaxoSmithKline Pharmaceuticals). Representative examples of DNA topoisomerase II inhibitors include, but are not limited to, amsacrine, daunorubicin, doxotrubicin, epipodophyllotoxins, ellipticines, epirubicin, etoposide, razoxane, and teniposide. Tyrosine Kinase Inhibitors The linkers of the invention may be used to conjugate an antibody to at least one tyrosine kinase inhibitor. Tyrosine kinases are enzymes within the cell that function to attach phosphate groups to the amino acid tyrosine. By blocking the ability of protein tyrosine kinases to function, tumor growth may be inhibited. Examples of tyrosine kinases that may be used on the ADCs of the invention include, but are not limited to, Axitinib, Bosutinib, Cediranib, Dasatinib, Erlotinib, Gefitinib, Imatinib, Lapatinib, Lestaurtinib, Nilotinib, Semaxanib, Sunitinib, and Vandetanib. Other Agents Examples of other agents that may be used in the ADCs of the invention include, but are not limited to, abrin (e.g. abrin A chain), alpha toxin, Aleurites fordii proteins, amatoxin, crotin, curcin, dianthin proteins, diptheria toxin (e.g. diphtheria A chain and nonbinding active fragments of diphtheria toxin), deoxyribonuclease (Dnase), gelonin, mitogellin, modeccin A chain, momordica charantia inhibitor, neomycin, onconase, phenomycin, Phytolaca americana proteins (PAPI, PAPII, and PAP-S), pokeweed antiviral protein, Pseudomonas endotoxin, Pseudomonas exotoxin (e.g. exotoxin A chain (from Pseudomonas aeruginosa)), restrictocin, ricin A chain, ribonuclease (Rnase), sapaonaria officinalis inhibitor, saporin, alpha-sarcin, Staphylcoccal enterotoxin-A, tetanus toxin, cisplatin, carboplatin, and oxaliplatin (Eloxatin, Sanofi Aventis), proteasome inhibitors (e.g. PS-341 [bortezomib or Velcade]), HDAC inhibitors (vorinostat (Zolinza, Merck & Company, Inc.)), belinostat, entinostat, mocetinostat, and panobinostat), COX-2 inhibitors, substituted ureas, heat shock protein inhibitors (e.g. Geldanamycin and its numerous analogs), adrenocortical suppressants, and the tricothecenes. (See, for example, WO 93 / 21232). Other agents also include asparaginase (Espar, Lundbeck Inc.), hydroxyurea, levamisole, mitotane (Lysodren, Bristol-Myers Squibb), and tretinoin (Renova, Valeant Pharmaceuticals Inc.). It should be noted that the aforementioned groups of drug moieties that may be used in the ADCs of the invention are not exclusive, in that certain examples of drugs may be found in more than one category, e.g., ansamitocins are both mitotic inhibitors and antitumor antibiotics. All stereoisomers of the above drug moieties are contemplated for the compounds of the invention, i.e. any combination of R and S configurations at the chiral carbons of D. A "detectable moiety" or a "marker" refers to a composition that is detectable by spectroscopic, photochemical, biochemical, immunochemical, radioactive or chemical means. For example, a useful label includes <com:Sup>32< / com:Sup>P, <com:Sup>35< / com:Sup>S, fluorescent dyes, electron-dense reagents, enzymes (e.g., enzymes that are generally used in ELISA), biotin-streptavidin, dioxigenin, hapten, and proteins for which antisera or monoclonal antibodies are available, or nucleic acid molecules with a sequence complementary to a target. The detectable moiety often generates a measurable signal, e.g., a radioactive signal, a color signal or a fluorescent signal, which is usable to quantify an amount of the detectable moiety that binds in the sample. Quantification of the signal may be accomplished by, for example, scintillation counting, density gauge, flow cell analysis, ELISA, or direct analysis by mass spectroscopy of circular or subsequently digested peptides (one or more peptides may be assayed). Those skilled in the art are familiar with techniques and detection means for a label compound of interest. These techniques and methods are conventional and well known in the art. The probe for detection refers to (i) a material capable of providing a detectable signal, (ii) a material capable of interacting with a first probe or a second probe to change a detectable signal provided by the first probe or the second probe, such as fluorescence resonance energy transfer (FRET), (iii) a material capable of stabilizing an interaction with an antigen or a ligand or increasing binding affinity, (iv) a material capable of affecting electric mobility or cell- invasive action by physical parameters such as charge, hydrophobicity, etc., or (v) a material capable of adjusting ligand affinity, antigen-antibody binding or ion complex formation. Antibodies The antibody of an ADC may be any antibody that binds, typically but not necessarily specifically, an antigen expressed on the surface of a target cell of interest. The antigen need not, but in some embodiments, is capable of internalizing an ADC bound thereto into the cell. Target cells of interest may include cells where induction of apoptosis is desirable. Target antigens may be any protein, glycoprotein, polysaccharide, lipoprotein, etc. expressed on the target cell of interest, but will typically be proteins that are either uniquely expressed on the target cell and not on normal or healthy cells, or that are over-expressed on the target cell as compared to normal or healthy cells, such that the ADCs selectively target specific cells of interest, such as, for example, tumor cells. As will be appreciated by skilled artisans, the specific antigen, and hence antibody, selected will depend upon the identity of the desired target cell of interest. In specific embodiments, the antibody of the ADC is an antibody suitable for administration to humans. Antibodies (Abs) and immunoglobulins (Igs) are glycoproteins having the same structural characteristics. While antibodies exhibit binding specificity to a specific target, immunoglobulins include both antibodies and other antibody-like molecules which lack target specificity. Native antibodies and immunoglobulins are usually heterotetrameric glycoproteins of about 150,000 daltons, composed of two identical light (L) chains and two identical heavy (H) chains. Each heavy chain has at one end a variable domain (VH) followed by a number of constant domains. Each light chain has a variable domain at one end (VL) and a constant domain at its other end. References to "VH" refer to the variable region of an immunoglobulin heavy chain of an antibody, including the heavy chain of an Fv, scFv, or Fab. References to "VL" refer to the variable region of an immunoglobulin light chain, including the light chain of an Fv, scFv, dsFv or Fab. The term "antibody" herein is used in the broadest sense and refers to an immunoglobulin molecule that specifically binds to, or is immunologically reactive with, a particular antigen, and includes polyclonal, monoclonal, genetically engineered and otherwise modified forms of antibodies, including but not limited to murine, chimeric antibodies, humanized antibodies, heteroconjugate antibodies (e.g., bispecific antibodies, diabodies, triabodies, and tetrabodies), and antigen binding fragments of antibodies, including e.g., Fab', F(ab')2, Fab, Fv, rIgG, and scFv fragments. The term "scFv" refers to a single chain Fv antibody in which the variable domains of the heavy chain and the light chain from a traditional antibody have been joined to form one chain. Antibodies may be murine, human, humanized, chimeric, or derived from other species. An antibody is a protein generated by the immune system that is capable of recognizing and binding to a specific antigen. (Janeway, C., Travers, P., Walport, M., Shlomchik (2001) Immuno Biology, 5th Ed., Garland Publishing, New York). A target antigen generally has numerous binding sites, also called epitopes, recognized by CDRs on multiple antibodies. Each antibody that specifically binds to a different epitope has a different structure. Thus, one antigen may have more than one corresponding antibody. An antibody includes a full-length immunoglobulin molecule or an immunologically active portion of a full-length immunoglobulin molecule, i.e., a molecule that contains an antigen binding site that immunospecifically binds an antigen of a target of interest or part thereof, such targets including but not limited to, cancer cell or cells that produce autoimmune antibodies associated with an autoimmune disease. The immunoglobulin disclosed herein can be of any type (e.g., IgG, IgE, IgM, IgD, and IgA), class (e.g., IgG1, IgG2, IgG3, IgG4, IgA1 and IgA2) or subclass of immunoglobulin molecule. The immunoglobulins can be derived from any species. In one aspect, however, the immunoglobulin is of human, murine, or rabbit origin. The term "antibody fragment" refers to a portion of a full-length antibody, generally the target binding or variable region. Examples of antibody fragments include Fab, Fab', F(ab')2 and Fy fragments. An "Fy" fragment is the minimum antibody fragment which contains a complete target recognition and binding site. This region consists of a dimer of one heavy and one light chain variable domain in a tight, non-covalent association (VH-VL dimer). It is in this configuration that the three CDRs of each variable domain interact to define a target binding site on the surface of the VH-VL dimer. Often, the six CDRs confer target binding specificity to the antibody. However, in some instances even a single variable domain (or half of an Fv comprising only three CDRs specific for a target) can have the ability to recognize and bind target. "Single- chain Fv" or "scFv" antibody fragments comprise the VH and VL domains of an antibody in a single polypeptide chain. Generally, the Fv polypeptide further comprises a polypeptide linker between the VH and VL domains which enables the scFv to form the desired structure for target binding. "Single domain antibodies" are composed of a single VH or VL domains which exhibit sufficient affinity to the target. In a specific embodiment, the single domain antibody is a camelized antibody (see, e.g., Riechmann, 1999, Journal of Immunological Methods 231:25-38). The Fab fragment contains the constant domain of the light chain and the first constant domain (CH1) of the heavy chain. Fab' fragments differ from Fab fragments by the addition of a few residues at the carboxyl terminus of the heavy chain CH1 domain including one or more cysteines from the antibody hinge region. F(ab') fragments are produced by cleavage of the disulfide bond at the hinge cysteines of the F(ab')2 pepsin digestion product. Additional chemical couplings of antibody fragments are known to those of ordinary skill in the art. Both the light chain and the heavy chain variable domains have complementarity determining regions (CDRs), also known as hypervariable regions. The more highly conserved portions of variable domains are called the framework (FR). As is known in the art, the amino acid position / boundary delineating a hypervariable region of an antibody can vary, depending on the context and the various definitions known in the art. Some positions within a variable domain may be viewed as hybrid hypervariable positions in that these positions can be deemed to be within a hypervariable region under one set of criteria while being deemed to be outside a hypervariable region under a different set of criteria. One or more of these positions can also be found in extended hypervariable regions. The CDRs in each chain are held together in close proximity by the FR regions and, with the CDRs from the other chain, contribute to the formation of the target binding site of antibodies (see Kabat et al., Sequences of Proteins of Immunological Interest (National Institute of Health, Bethesda, Md. 1987). As used herein, numbering of immunoglobulin amino acid residues is done according to the immunoglobulin amino acid residue numbering system of Kabat et al., unless otherwise indicated. In certain embodiments, the antibodies of the ADCs of the present disclosure are monoclonal antibodies. The term "monoclonal antibody" (mAb) refers to an antibody that is derived from a single copy or clone, including e.g., any eukaryotic, prokaryotic, or phage clone, and not the method by which it is produced. Preferably, a monoclonal antibody of the disclosure exists in a homogeneous or substantially homogeneous population. Monoclonal antibody includes both intact molecules, as well as, antibody fragments (such as, for example, Fab and F(ab')2 fragments), which are capable of specifically binding to a protein. Fab and F(ab')2 fragments lack the Fc fragment of intact antibody, clear more rapidly from the circulation of the animal, and may have less non-specific tissue binding than an intact antibody (Wahl et al., 1983, J. Nucl. Med 24:316). Monoclonal antibodies useful with the present disclosure can be prepared using a wide variety of techniques known in the art including the use of hybridoma, recombinant, and phage display technologies, or a combination thereof. The antibodies of the disclosure include chimeric, primatized, humanized, or human antibodies. While in most instances antibodies are composed of only the genetically-encoded amino acids, in some embodiments non-encoded amino acids may be incorporated at specific. Examples of non-encoded amino acids that may be incorporated into antibodies for use in controlling stoichiometry and attachment location, as well as methods for making such modified antibodies are discussed in Tian et al., 2014, Proc Nat'l Acad Sci USA 111(5):1766-1771 and Axup et al., 2012, Proc Nat'l Acad Sci USA 109(40):16101-16106. In certain embodiments, the antibody of the ADCs described herein is a chimeric antibody. The term "chimeric" antibody as used herein refers to an antibody having variable sequences derived from a non-human immunoglobulin, such as rat or mouse antibody, and human immunoglobulin constant regions, typically chosen from a human immunoglobulin template. Methods for producing chimeric antibodies are known in the art. See, e.g., Morrison, 1985, Science 229(4719):1202-7; Oi et al., 1986, BioTechniques 4:214-221; Gillies et al., 1985, J. Immunol. Methods 125:191-202; U.S. Pat. Nos. 5,807,715; 4,816,567; and 4,816397. In certain embodiments, the antibody of the ADCs described herein is a humanized antibody. "Humanized" forms of non-human (e.g., murine) antibodies are chimeric immunoglobulins, immunoglobulin chains or fragments thereof (such as Fv, Fab, Fab', F(ab')2 or other target-binding subdomains of antibodies), which contain minimal sequences derived from non-human immunoglobulin. In general, the humanized antibody will comprise substantially all of at least one, and typically two, variable domains, in which all or substantially all of the CDR regions correspond to those of a non-human immunoglobulin and all or substantially all of the FR regions are those of a human immunoglobulin sequence. The humanized antibody can also comprise at least a portion of an immunoglobulin constant region (Fc), typically that of a human immunoglobulin consensus sequence. Methods of antibody humanization are known in the art. See, e.g., Riechmann et al., 1988, Nature 332:323-7; U.S. Pat. Nos. 5,530,101; 5,585,089; 5,693,761; 5,693,762; and U.S. Pat. No. 6,180,370 to Queen et al.; EP239400; PCT publication WO 91 / 09967; U.S. Pat. No. 5,225,539; EP592106; EP519596; Padlan, 1991, Mol. Immunol., 28:489-498; Studnicka et al., 1994, Prot. Eng. 7:805-814; Roguska et al., 1994, Proc. Natl. Acad Sci. USA 91:969-973; and U.S. Pat. No. 5,565,332. In certain embodiments, the antibody of the ADCs described herein is a human antibody. Completely "human" antibodies can be desirable for the the rapeutic treatment of human patients. As used herein, "human antibodies" include antibodies having the amino acid sequence of a human immunoglobulin and include antibodies isolated from human immunoglobulin libraries or from animals transgenic for one or more human immunoglobulin and that do not express endogenous immunoglobulins. Human antibodies can be made by a variety of methods known in the art including phage display methods using antibody libraries derived from human immunoglobulin sequences. See U.S. Pat. Nos. 4,444,887 4,716,111, 6,114,598, 6,207,418, 6,235,883, 7,227,002, 8,809,151 and U.S. Published Application No. 2013 / 189218. Human antibodies can also be produced using transgenic mice which are incapable of expressing functional endogenous immunoglobulins, but which can express human immunoglobulin genes. See, e.g., U.S. Pat. Nos. 5,413,923; 5,625,126; 5,633,425; 5,569,825; 5,661,016; 5,545,806; 5,814,318; 5,885,793; 5,916,771; 5,939,598; 7,723,270; 8,809,051 and U.S. Published Application No. 2013 / 117871. In addition, companies such as Medarex (Princeton, N.J.), Astellas Pharma (Deerfield, Ill.), and Regeneron (Tarrytown, N.Y.) can be engaged to provide human antibodies directed against a selected antigen using technology similar to that described above. Completely human antibodies that recognize a selected epitope can be generated using a technique referred to as "guided selection." In this approach a selected non-human monoclonal antibody, e.g., a mouse antibody, is used to guide the selection of a completely human antibody recognizing the same epitope (Jespers et al., 1988, Biotechnology 12:899-903). In certain embodiments, the antibody of the ADCs described herein is a primatized antibody. The term "primatized antibody" refers to an antibody comprising monkey variable regions and human constant regions. Methods for producing primatized antibodies are known in the art. See, e.g., U.S. Pat. Nos. 5,658,570; 5,681,722; and 5,693,780. In certain embodiments, the antibody of the ADCs described herein is a bispecific antibody or a dual variable domain antibody (DVD). Bispecific and DVD antibodies are monoclonal, often human or humanized, antibodies that have binding specificities for at least two different antigens. DVDs are described, for example, in U.S. Pat. No. 7,612,181. In certain embodiments, the antibody of the ADCs described herein is a derivatized antibody. For example, but not by way of limitation, derivatized antibodies are typically modified by glycosylation, acetylation, pegylation, phosphorylation, amidation, derivatization by known protecting / blocking groups, proteolytic cleavage, linkage to a cellular ligand or other protein, etc. Any of numerous chemical modifications can be carried out by known techniques, including, but not limited to, specific chemical cleavage, acetylation, formylation, metabolic synthesis of tunicamycin, etc. Additionally, the derivative can contain one or more non-natural amino acids, e.g., using ambrx technology (see, e.g., Wolfson, 2006, Chem. Biol. 13(10):1011- 2). In certain embodiments, the antibody of the ADCs described herein has a sequence that has been modified to alter at least one constant region-mediated biological effector function relative to the corresponding wild type sequence. For example, in some embodiments, the antibody can be modified to reduce at least one constant region-mediated biological effector function relative to an unmodified antibody, e.g., reduced binding to the Fc receptor (FcR). FcR binding can be reduced by mutating the immunoglobulin constant region segment of the antibody at particular regions necessary for FcR interactions (see, e.g., Canfield and Morrison, 1991, J. Exp. Med 173:1483-1491; and Lund et al., 1991, J. Immunol. 147:2657-2662). In certain embodiments, the antibody of the ADCs described herein is modified to acquire or improve at least one constant region-mediated biological effector function relative to an unmodified antibody, e.g., to enhance FcyR interactions (see, e.g., US 2006 / 0134709). For example, an antibody with a constant region that binds FcyRIIA, FcyRIIB and / or FcyRIIIA with greater affinity than the corresponding wild type constant region can be produced according to the methods described herein. In certain specific embodiments, the antibody of the ADCs described herein is an antibody that binds tumor cells, such as an antibody against a cell surface receptor or a tumor- associated antigen (TAA). In attempts to discover effective cellular targets for cancer diagnosis and therapy, researchers have sought to identify transmembrane or otherwise tumor-associated polypeptides that are specifically expressed on the surface of one or more particular type(s) of cancer cell as compared to on one or more normal non-cancerous cell(s). Often, such tumor- associated polypeptides are more abundantly expressed on the surface of the cancer cells as compared to the surface of the no-cancerous cells. Such cell surface receptor and tumor- associated antigens are known in the art, and can prepared for use in generating antibodies using methods and information which are well known in the art. Exemplary Cell Surface Receptors and TAAs Examples of cell surface receptor and TAAs to which the antibody of the ADCs described herein may be targeted include, but are not limited to, the various receptors and TAAs listed below in Table 1. For convenience, information relating to these antigens, all of which are known in the art, is listed below and includes names, alternative names, Genbank accession numbers and primary reference(s), following nucleic acid and protein sequence identification conventions of the National Center for Biotechnology Information (NCBI). Nucleic acid and protein sequences corresponding to the listed cell surface receptors and TAAs are available in public databases such as GenBank. Table 1 [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] Exemplary Antibodies Exemplary antibodies to be used with ADCs of the disclosure include but are not limited to 3F8 (GD2), Abagovomab (CA-125 (imitation)), Adecatumumab (EpCAM), Afutuzumab (CD20), Alacizumab pegol (VEGFR2), ALD518 (IL-6), Alemtuzumnab (CD52), Altumomab pentetate (CEA), Amatuximab (Mesothelin), Anatumomnab mafenatox (TAG-72), Apolizumab (HLA-DR), Arcitumomab (CEA), Bavituximab (Phosphatidylserine), Bectumomab (CD22), Belimumab (BAFF), Besilesomab (CEA-related antigen), Bevacizumab (VEGF-A), Bivatuzumab mertansine (CD44 v6), Blinatumomab (CD19), Brentuximab vedotin ((CD30 (TNFRSF8)), Cantuzumab mertansine (Mucin CanAg), Cantuzumab ravtansine (MUC1), Capromab pendetide (Prostatic carcinoma cells), Carlumab (MCP-1), Catumaxomab (EpCAM, CD3), CC49 (Tag-72), cBR96-DOX ADC (Lewis-Y antigen), Cetuximab (EGFR), Citatuzumab bogatox (EpCAM), Cixutumumab (IGF-1 receptor), Clivatuzumab tetraxetan(MUC1), Conatumumab (TRAIL-E2), Dacetuzumab (CD40), Dalotuzumab (Insulin-like growth factor 1 receptor), Deratumumab ((CD38 (cyclic ADP ribose hydrolase)), Demcizumab (DLL4), Denosumab (RANKL), Detumomab (B-lymphoma cell), Drozitumab (DR5), Dusigitumab (ILGF2), Ecromeximab (D3 ganglioside), Eculizumab (C5), Edrecolomab (EpCAM), Elotuzumab (SLAMF7), Elsilimomab (IL-6), Enavatuzumab (TWEAK receptor), Enoticumab (DLL4), Ensituximab (5AC), Epitumomab cituxetan (Episialin), Epratuzumab (CD22), Ertumaxomab ((HER2 / neu, CD3)), Etancizumab (Integrin ανβ3), Farletuzumab (Folate receptor 1), FBTA05 (CD20), Ficlatuzumab (HGF), Figitumumab (IGF-1 receptor), Flanvotumab ((TYRP1 (glycoprotein 75)), Fresolimumab (TGF-1), Galiximab (CD80), Ganitumab (IGF-I), Gemtuzumab ozogamicin (CD33), Girentuximab ((Carbonic anhydrase 9 (CA-IX)), Glembatumumab vedotin (GPNMB), Ibritumomab tiuxetan (CD20) Icrucumab (VEGFR-1), Igovomab (CA-125), IMAB362 (CLDN18.2), Imgatuzumab (EGFR), Indatuximab ravtansine (SDC1), Intetumumab (CD51), Inotuzumab ozogamicin (CD22), Ipilimumab (CD152), Iratumumab ((CD30 (TNFRSF8)), Labetuzumab (CEA), Lambrolizumab (PDCD1), Lexatumumab (TRAIL-R2), Lintuzumab (CD33), Lorvotuzumab mertansine (CD56), Lucatumumab (CD40), Lumiliximab ((CD23 (IgE receptor)), Mapatumumab (TRAIL-R1), Margetuximab (ch4DS), Matuzumab (EGFR), Milatuzumab (CD74), Mitumomab (GD3 ganglioside), Mogamulizumab (CCR4), Moxetumomab pasudotox (CD22), Nacolomab tafenatox (C2-42 antigen), Naptumomab estafenatox (5T4), Narnatumab (RON), Natalizumab (integrin α4), Necitumumab (EGFR), Nesvacumab (angiopoietin 2), Nimotuzumab (EGFR), Nivolumab (IgG4), Ocaratuzumab (CD20), Ofatumumab (CD20), Olaratumab (PDGF-R α), Onartuzumab (Human scatter factor receptor kinase), Ontuxizumab (TEM1), Oportuzumab monato (EpCAM), Oregovomab (CA-125), Otlertuzumab (CD37), Panitumumab (EGFR) Pankomab (Tumor specific glycosylation of MUC1), Parsatuzumab (EGFL7), Patritumab (HER3), Pemtumomab (MUC1), Pertuzumab (HER2 / neu), Pidilizumab (PD-1), Pinatuzumab vedotin (CD22), Pritumumab (Vimentin), Racotumomab (N-glycolylneuraminic acid), Radretumab (Fibronectin extra domain-B), Ramucirumab (VEGFR2), Rilotumumab (HGF), Rituximab (CD20), Robatumumab (IGF-1 receptor), Samalizumab (CD200), Satumomab pendetide (TAG-72), Seribantumab (ERBB3), Sibrotuzumab (FAP), SGN-CD19A (CD19), SGN-CD33A (CD33), Siltuximab (IL-6), Solitomab (EpCAM), Sonepcizumab (Sphingosine-1- phosphate), Tabalumb (BAFF), Tacatuzumab tetraxetan (Alpha-fetoprotein), Taplitumomab paptox (CD19), Tenatumomab (Tenascin C), Teprotumumab (CD221), TGN1412 (CD28), Ticilimumab (CTLA-4), Tigatuzumab (TRAIL-R2), TNX-650 (IL-13), Tovetumab (CD40a), Trastuzumab (HER2 / neu), TRBS07 (GD2), Tremelimumab (CTLA-4), Tucotuzumab celmoleukin (EpCAM), Ublituximab (MS4A), Urelumab (4-1BB), Vandetanib (VEGF), Vantictumab (Frizzled receptor), Volociximab (integrin α5β1), Vorsetuzumab mafodotin (CD70), Votumumab (Tumor antigen CTAA16.88), Zalutumumab (EGFR), Zanolimumab (CD4), and Zatuximab (HER1). Methods of Making Antibodies The antibody of an ADC can be prepared by recombinant expression of immunoglobulin light and heavy chain genes in a host cell. For example, to express an antibody recombinantly, a host cell is transfected with one or more recombinant expression vectors carrying DNA fragments encoding the immunoglobulin light and heavy chains of the antibody such that the light and heavy chains are expressed in the host cell and, optionally, secreted into the medium in which the host cells are cultured, from which medium the antibodies can be recovered. Standard recombinant DNA methodologies are used to obtain antibody heavy and light chain genes, incorporate these genes into recombinant expression vectors and introduce the vectors into host cells, such as those described in Molecular Cloning; A Laboratory Manual, Second Edition (Sambrook, Fritsch and Maniatis (eds), Cold Spring Harbor, N. Y., 1989), Current Protocols in Molecular Biology (Ausubel, F. M. et al., eds., Greene Publishing Associates, 1989) and in U.S. Pat. No. 4,816,397. In one embodiment, the Fc variant antibodies are similar to their wild-type equivalents but for changes in their Fc domains. To generate nucleic acids encoding such Fc variant antibodies, a DNA fragment encoding the Fc domain or a portion of the Fc domain of the wild- type antibody (referred to as the "wild-type Fc domain") can be synthesized and used as a template for mutagenesis to generate an antibody as described herein using routine mutagenesis techniques; alternatively, a DNA fragment encoding the antibody can be directly synthesized. Once DNA fragments encoding wild-type Fc domains are obtained, these DNA fragments can be further manipulated by standard recombinant DNA techniques, for example, to convert the constant region genes to full-length antibody chain genes. In these manipulations, a CH-encoding DNA fragment is operatively linked to another DNA fragment encoding another protein, such as an antibody variable region or a flexible linker. The term "operatively linked," as used in this context, is intended to mean that the two DNA fragments are joined such that the amino acid sequences encoded by the two DNA fragments remain in-frame. To express the Fc variant antibodies, DNAs encoding par...

Claims

CLAIMS 1. A conjugate of Formula (I'): [Image disponible dans le document PDF, Image available in the PDF document] <com:Math><semantics>(𝑰′)<annotation encoding="application / x-tex">(\mathbf{I'})< / annotation>< / semantics>< / com:Math> or a pharmaceutically acceptable salt thereof, wherein: CB is a targeting moiety; cb and n are each independently integers having a value of 1 to about 20; each D-L independently is a group having the structure of Formula (I"): [Image disponible dans le document PDF, Image available in the PDF document] each Q is independently an active agent linked to L' by a heteroatom; Z' is a linking group; L' is a spacer moiety attached to the SO<com:Sub>2< / com:Sub> via a heteroatom selected from O, S, and N, and is selected such that cleavage of the bond between L' and SO<com:Sub>2< / com:Sub> promotes cleavage of the bond between L' and Q to release the active agent; [Image disponible dans le document PDF, Image available in the PDF document] Ar represents aryl or heteroaryl; Y' is <com:Math><semantics>−(CRb2)yN(Ra)<annotation encoding="application / x-tex">-(CR^{b_2})_yN(R^{a})< / annotation>< / semantics>< / com:Math>-, <com:Math><semantics>−(CRb2)yO<annotation encoding="application / x-tex">-(CR^{b_2})_yO< / annotation>< / semantics>< / com:Math>-, or <com:Math><semantics>−(CRb2)yS<annotation encoding="application / x-tex">-(CR^{b_2})_yS< / annotation>< / semantics>< / com:Math>-, positioned such that the N, O, or S atom is attached to TG if y is 1; X and Y' are positioned on adjacent atoms of Ar; TG is a triggering group that, when activated, generates an N, O, or S atom capable of reacting with the SO<com:Sub>2< / com:Sub> to displace (Q)<com:Sub>q< / com:Sub>-(L')<com:Sub>w< / com:Sub> and form a 5-6-membered ring including X-SO<com:Sub>2< / com:Sub> and the intervening atoms of Ar; q is an integer having a value from 1 to about 20; w, x, and y are each independently an integer having a value of 0 or 1; each R<com:Sup>a< / com:Sup> and R<com:Sup>c< / com:Sup> is independently hydrogen or lower alkyl; and each R<com:Sup>b< / com:Sup> is independently hydrogen or lower alkyl; or two R<com:Sup>b< / com:Sup>, together with the atom to which they are attached, form a 3-5-membered ring; provided that when w is 0, q is 1.

2. The conjugate of claim 1, wherein X is -O-.

3. The conjugate of claim 1 or 2, wherein Ar is aryl.

4. The conjugate of claim 3, wherein Ar is phenyl or naphthyl.

5. The conjugate of any one of claims 1–4, wherein Z' is a <com:Math><semantics>C10<annotation encoding="application / x-tex">C_{10}< / annotation>< / semantics>< / com:Math>–<com:Math><semantics>C100<annotation encoding="application / x-tex">C_{100}< / annotation>< / semantics>< / com:Math> linear or branched, saturated or unsaturated alkylene moiety comprising at least two of the following: (i) at least one heteroatom selected from -NH-, -C(=O), -O-, -S- and -P-; (ii) at least one heteroarylene; (iii) at least one amino acid moiety, sugar bond, peptide bond, or amide bond; and (iv) one or more substituents selected from the group consisting of C<com:Sub>1< / com:Sub>-C<com:Sub>20< / com:Sub> alkyl, C<com:Sub>6< / com:Sub>-C<com:Sub>20< / com:Sub> aryl C<com:Sub>1< / com:Sub>-C<com:Sub>8< / com:Sub> alkyl, -(CH<com:Sub>2< / com:Sub>)<com:Sub>s< / com:Sub>COOH, and -(CH<com:Sub>2< / com:Sub>)<com:Sub>p< / com:Sub>NH<com:Sub>2< / com:Sub>, s is an integer having a value of 0 to 10, and p is an integer having a value of 1 to about 10.

6. The conjugate of any one of claims 1–4, wherein Z' comprises a functional group that can be produced through a click chemical reaction.

7. The conjugate of any one of claims 1–4, wherein Z' comprises: [Image disponible dans le document PDF, Image available in the PDF document] , , [Image disponible dans le document PDF, Image available in the PDF document] wherein: each V is independently a single bond, -O-, -S-, -NR<com:Sup>21< / com:Sup>-, -C(O)NR<com:Sup>22< / com:Sup>-, -NR<com:Sup>23< / com:Sup>C(O)-, -NR<com:Sup>24< / com:Sup>SO<com:Sub>2< / com:Sub>-, or - [Image disponible dans le document PDF, Image available in the PDF document] R<com:Sup>21< / com:Sup>, R<com:Sup>22< / com:Sup>, R<com:Sup>23< / com:Sup>, R<com:Sup>24< / com:Sup>, and R<com:Sup>25< / com:Sup> are each independently hydrogen, (C<com:Sub>1< / com:Sub>-C<com:Sub>6< / com:Sub>)alkyl, (C<com:Sub>1< / com:Sub>-C<com:Sub>6< / com:Sub>)alkyl(C<com:Sub>6< / com:Sub>-C<com:Sub>20< / com:Sub>)aryl, [Image disponible dans le document PDF, Image available in the PDF document] r is an integer having a value of 1 to about 10; p is an integer having a value of 0 to about 10; q is an integer having a value of 1 to about 10; and L" is a single bond.

8. The conjugate of any one of claims 1–4, wherein Z' is a linking group connecting CB and Ar comprising (CH<com:Sub>2< / com:Sub>)<com:Sub>b< / com:Sub>, L<com:Sup>c< / com:Sup>, (P<com:Sup>1< / com:Sup>)<com:Sub>a< / com:Sub>, W<com:Sup>a1< / com:Sup>, W<com:Sup>a2< / com:Sup>, W<com:Sup>a3< / com:Sup>, W<com:Sup>b1< / com:Sup>, Y<com:Sup>1< / com:Sup>, and Y<com:Sup>2< / com:Sup> groups connected to each other in a linear chain by covalent bonds, wherein: W<com:Sup>a1< / com:Sup>, W<com:Sup>a2< / com:Sup>, and W<com:Sup>a3< / com:Sup> are each independently -NH-, -C(O)-, or -CH<com:Sub>2< / com:Sub>-; W<com:Sup>b1< / com:Sup> is an amide bond or triazolylene; P<com:Sup>1< / com:Sup> is an amide bond, an amino acid residue, or a peptide; L<com:Sup>c< / com:Sup> is alkylene; [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] <com:Math><semantics>Y2<annotation encoding="application / x-tex">Y^2< / annotation>< / semantics>< / com:Math> is a single bond or a group selected from: [Image disponible dans le document PDF, Image available in the PDF document] W<com:Sup>b2< / com:Sup> is an amide bond or triazolylene; a is 0 to 10; b, c, and d are each independently an integer having a value of 1 to about 10; and o and q are each independently an integer having a value of 1 to about 10.

9. The conjugate of claim 8, wherein Z' is a linking group of Formula (A): [Image disponible dans le document PDF, Image available in the PDF document] (A) wherein: * is the point of attachment to CB; and ** is point of attachment to Ar.

10. The conjugate of claim 8 or 9, wherein <com:Math><semantics>P1<annotation encoding="application / x-tex">P^1< / annotation>< / semantics>< / com:Math> is [Image disponible dans le document PDF, Image available in the PDF document] wherein: R<com:Sup>12< / com:Sup> is hydrogen, alkyl, an amino acid side chain, -(CH<com:Sub>2< / com:Sub>)<com:Sub>s< / com:Sub>C(O)R<com:Sup>13< / com:Sup> or -(CH<com:Sub>2< / com:Sub>)<com:Sub>p< / com:Sub>NR<com:Sup>14< / com:Sup>R<com:Sup>15< / com:Sup>; p is an integer having a value of 1 to about 10; s is an integer having a value of 0 to about 10; [Image disponible dans le document PDF, Image available in the PDF document] R<com:Sup>14< / com:Sup> and R<com:Sup>15< / com:Sup> are each independently hydrogen or -C(O)(CH<com:Sub>2< / com:Sub>)<com:Sub>s'< / com:Sub>(X'''CH<com:Sub>2< / com:Sub>CH<com:Sub>2< / com:Sub>)<com:Sub>s''< / com:Sub>Z''-(CB)<com:Sub>m< / com:Sub>; s" is an integer having a value of 0 to about 10; s' is an integer having a value of 1 to about 10; m is an integer having a value of 0 or 1; [Image disponible dans le document PDF, Image available in the PDF document] Z'' is a linking group connecting CB to the remainder of R<com:Sup>14< / com:Sup> or R<com:Sup>15< / com:Sup>; or Z'' is a linking group comprising a reactive group.

11. The conjugate of any one of claims <com:Math><semantics>8−10<annotation encoding="application / x-tex">8-10< / annotation>< / semantics>< / com:Math>, wherein Z' is a linking group of Formula (F'), <com:Math><semantics>(G′),(H′),(J′),(K′),(L′),(M′),or(N′)<annotation encoding="application / x-tex">(G'), (H'), (J'), (K'), (L'), (M'), or (N')< / annotation>< / semantics>< / com:Math>: [Image disponible dans le document PDF, Image available in the PDF document] (J') [Image disponible dans le document PDF, Image available in the PDF document] wherein: R<com:Sup>e< / com:Sup> is alkyl; L<com:Sup>2< / com:Sup> is a spacer moiety, unsubstituted or substituted with one or more C<com:Sub>1< / com:Sub>-C<com:Sub>6< / com:Sub> alkyl, C<com:Sub>5< / com:Sub>-C<com:Sub>14< / com:Sub> aryl, and C<com:Sub>3< / com:Sub>- C<com:Sub>8< / com:Sub> heteroaryl, wherein the alkyl, aryl and heteroaryl are unsubstituted or substituted with one or more substituents selected from C<com:Sub>1< / com:Sub>-C<com:Sub>10< / com:Sub> alkyl, -(CH<com:Sub>2< / com:Sub>)<com:Sub>u< / com:Sub>NH<com:Sub>2< / com:Sub>, -(CH<com:Sub>2< / com:Sub>)<com:Sub>u< / com:Sub>NR<com:Sup>u1< / com:Sup>R<com:Sup>u2< / com:Sup>, - (CH<com:Sub>2< / com:Sub>)<com:Sub>u< / com:Sub>CO<com:Sub>2< / com:Sub>H, -(CH<com:Sub>2< / com:Sub>)<com:Sub>u< / com:Sub>CO<com:Sub>2< / com:Sub>R<com:Sup>u1< / com:Sup>, and -(CH<com:Sub>2< / com:Sub>)<com:Sub>u< / com:Sub>SO<com:Sub>2< / com:Sub>R<com:Sup>u3< / com:Sup>, wherein R<com:Sup>u1< / com:Sup>, R<com:Sup>u2< / com:Sup>, and R<com:Sup>u3< / com:Sup> are each independently hydrogen, C<com:Sub>1< / com:Sub>-C<com:Sub>15< / com:Sub> alkyl, C<com:Sub>6< / com:Sub>-C<com:Sub>20< / com:Sub> aryl or C<com:Sub>3< / com:Sub>-C<com:Sub>10< / com:Sub> heteroaryl; and u is an integer having a value of 1 to 10; [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] <com:Math><semantics>Wb1<annotation encoding="application / x-tex">W^{b1}< / annotation>< / semantics>< / com:Math> and <com:Math><semantics>Wb2<annotation encoding="application / x-tex">W^{b2}< / annotation>< / semantics>< / com:Math> are each independently -C(O)NH-, -NHC(O)-, <com:Math><semantics>N=N<annotation encoding="application / x-tex">N=N< / annotation>< / semantics>< / com:Math> , or <com:Math><semantics>N=N<annotation encoding="application / x-tex">N=N< / annotation>< / semantics>< / com:Math> R<com:Sup>12< / com:Sup> is hydrogen, alkyl, an amino acid side chain, -(CH<com:Sub>2< / com:Sub>)<com:Sub>s< / com:Sub>C(O)R<com:Sup>13< / com:Sup> or -(CH<com:Sub>2< / com:Sub>)<com:Sub>p< / com:Sub>NR<com:Sup>14< / com:Sup>R<com:Sup>15< / com:Sup>; [Image disponible dans le document PDF, Image available in the PDF document] R<com:Sup>14< / com:Sup> and R<com:Sup>15< / com:Sup> are each independently hydrogen or -C(O)(CH<com:Sub>2< / com:Sub>)<com:Sub>s'< / com:Sub>(X'''CH<com:Sub>2< / com:Sub>CH<com:Sub>2< / com:Sub>)<com:Sub>s''< / com:Sub>Z''-(CB)<com:Sub>m< / com:Sub>; s and s' are each independently an integer having a value of 0 to about 10; m is an integer having a value of 0 or 1; X''' is -O-, -S-, -NH-, or -CH<com:Sub>2< / com:Sub>-; and Z'' is a linking group connecting CB to the remainder of R<com:Sup>14< / com:Sup> or R<com:Sup>15< / com:Sup>; or Z'' is a linking group comprising a reactive group; and a, b, c, d, e, g, h, o, p, and qq are each independently an integer having a value of 1 to about 10; and s' is an integer having a value of 1 to about 10.

12. The conjugate of any one of claims 1–11, wherein TG is a reactive chemical moiety or functional group that can be cleaved by nucleophilic reagent conditions, basic reagent conditions, photo-irradiation, reducing agent conditions, acidic conditions, enzymatic conditions, or oxidative conditions.

13. The conjugate of any one of claims <com:Math><semantics>1−12<annotation encoding="application / x-tex">1-12< / annotation>< / semantics>< / com:Math>, wherein TG is selected from: [Image disponible dans le document PDF, Image available in the PDF document] wherein: each R<com:Sup>21< / com:Sup> is independently hydrogen or acetyl; and <com:Math><semantics>R22<annotation encoding="application / x-tex">R^{22}< / annotation>< / semantics>< / com:Math> is hydrogen or lower alkyl.

14. The conjugate of any one of claims <com:Math><semantics>1−11<annotation encoding="application / x-tex">1-11< / annotation>< / semantics>< / com:Math>, wherein x is 0.

15. The conjugate of claim 14, wherein TG is selected from -NO<com:Sub>2< / com:Sub>, -C(O)-(CH<com:Sub>2< / com:Sub>)<com:Sub>2< / com:Sub>C(O)-alkyl, and nitrobenzyl.

16. The conjugate of any one of claims 1–15, wherein Q is a chemical factor, a biological factor, a hormone, an oligonucleotide, a drug, a toxin, an affinity ligand, a probe for detection, or a combination thereof.

17. The conjugate of any one of claims 16, wherein Q is a drug selected from a cytokine, an immunomodulatory compound, an anti-cancer agent, an anti-viral agent, an anti-bacterial agent, an anti-fungal agent, an anthelmintic agent, or a combination thereof.

18. The conjugate of any one of claims 1–12, wherein <com:Math><semantics>(Q)q<annotation encoding="application / x-tex">(Q)_q< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>(L′)w<annotation encoding="application / x-tex">(L')_w< / annotation>< / semantics>< / com:Math>- is selected from: [Image disponible dans le document PDF, Image available in the PDF document] wherein: <com:Math><semantics>X1<annotation encoding="application / x-tex">X^1< / annotation>< / semantics>< / com:Math> is -O- or -NR<com:Sup>a< / com:Sup>-, wherein R<com:Sup>a< / com:Sup> is hydrogen or C<com:Sub>1< / com:Sub>-C<com:Sub>6< / com:Sub> alkyl; X<com:Sup>2< / com:Sup> and X<com:Sup>4< / com:Sup> are each independently absent or -C(O)-, or -C(O)O-; <com:Math><semantics>X3<annotation encoding="application / x-tex">X^3< / annotation>< / semantics>< / com:Math> is <com:Math><semantics>−OC(=O)<annotation encoding="application / x-tex">-OC(=O)< / annotation>< / semantics>< / com:Math>-; w' is an integer having a value of 1, 2, 3, 4, or 5; and R<com:Sup>9< / com:Sup> and R<com:Sup>10< / com:Sup> are each independently hydrogen, alkyl, aryl, or heteroaryl, wherein alkyl, aryl, and heteroaryl are unsubstituted or substituted with one or more substituents.

19. The conjugate of claim 18, wherein <com:Math><semantics>(Q)q<annotation encoding="application / x-tex">(Q)_q< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>(L′)w<annotation encoding="application / x-tex">(L')_w< / annotation>< / semantics>< / com:Math>- is selected from: [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] wherein * represents the point of attachment of <com:Math><semantics>(Q)q<annotation encoding="application / x-tex">(Q)_q< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>(L′)w<annotation encoding="application / x-tex">(L')_w< / annotation>< / semantics>< / com:Math> to -SO<com:Sub>2< / com:Sub>-.

20. The conjugate of any one of claims 1–19, wherein the targeting moiety is a nanoparticle, an immunoglobulin, a nucleic acid, a protein, an oligopeptide, a polypeptide, an antibody, a fragment of an antigenic polypeptide, or a repebody.

21. The conjugate of claim 20, wherein the targeting moiety is an antibody selected from an intact polyclonal antibody, an intact monoclonal antibody, an antibody fragment, a single chain Fv (scFv) mutant, a multispecific antibody, a bispecific antibody, a chimeric antibody, a humanized antibody, a human antibody, a fusion protein comprising an antigenic determinant portion of an antibody, and other modified immunoglobulin molecules comprising antigen recognition sites.

22. The conjugate of claim 20, wherein the antibody is selected from Muromonab-CD3, Abciximab, Rituximab, Daclizumab, Palivizumab, Infliximab, Trastuzumab (herceptin), Etanercept, Basiliximab, Gemtuzumab ozogamicin, Alemtuzumab, Ibritumomab tiuxetan, Adalimumab, Alefacept, Omalizumab, Efalizumab, Tositumomab-I<com:Sup>131< / com:Sup>, Cetuximab, Bevacizumab, Natalizumab, Ranibizumab, Panitumumab, Eculizumab, Rilonacept, Certolizumab pegol, Romiplostim, AMG- 531, CNTO-148, CNTO-1275, ABT-874, LEA-29Y, Belimumab, TACI-Ig, Second generation anti- CD20, ACZ-885, Tocilizumab, Atlizumab, Mepolizumab, Pertuzumab, Humax CD20, Tremelimumab (CP-675 206), Ticilimumab, MDX-010, IDEC-114, Inotuzumab ozogamycin, HuMax EGFR, Aflibercept, HuMax-CD4, Ala-Ala, ChAglyCD3, TRX4, Catumaxomab, IGN101, MT-201, Pregovomab, CH-14.18, WX-G250, AMG-162, AAB-001, Motavizumab, MEDI-524, Efumgumab, Aurograb, Raxibacumab, Third generation anti-CD20, LY2469298, and Veltuzumab.

23. A compound of Formula (Ia): [Image disponible dans le document PDF, Image available in the PDF document] (Ia) or a pharmaceutically acceptable salt thereof, wherein: each Q is independently an active agent linked to L' by a heteroatom; Z' is absent or a linking group; L' is a linking group attached to the SO<com:Sub>2< / com:Sub> via a heteroatom selected from O, S, and N, and is selected such that cleavage of the bond between L' and SO<com:Sub>2< / com:Sub> promotes cleavage of the bond between L' and Q to release the active agent; X is -O-, <com:Math><semantics>−CR2a<annotation encoding="application / x-tex">-CR^{a}_{2}< / annotation>< / semantics>< / com:Math>-, or <com:Math><semantics>−NRc<annotation encoding="application / x-tex">-NR^{c}< / annotation>< / semantics>< / com:Math>-; Ar represents aryl or heteroaryl; Y' is <com:Math><semantics>−(CRb2)yN(Ra)<annotation encoding="application / x-tex">-(CR^{b_2})_yN(R^{a})< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−(CRb2)yO<annotation encoding="application / x-tex">-(CR^{b_2})_yO< / annotation>< / semantics>< / com:Math>-, or <com:Math><semantics>−(CRb2)yS<annotation encoding="application / x-tex">-(CR^{b_2})_yS< / annotation>< / semantics>< / com:Math>-, positioned such that the N, O, or S atom is attached to TG if y is 1; X and Y' are positioned on adjacent atoms of Ar; TG is a triggering group that, when activated, generates an N, O, or S atom capable of reacting with the SO<com:Sub>2< / com:Sub> to displace (Q)<com:Sub>q< / com:Sub>-(L')<com:Sub>w< / com:Sub> and form a 5-6-membered ring including X-SO<com:Sub>2< / com:Sub> and the intervening atoms of Ar; q is an integer having a value from 1 to about 20; w, x, and y are each independently an integer having a value of 0 or 1; each R<com:Sup>a< / com:Sup> and R<com:Sup>c< / com:Sup> is independently hydrogen or lower alkyl; and each R<com:Sup>b< / com:Sup> is independently hydrogen or lower alkyl; or two R<com:Sup>b< / com:Sup>, together with the carbon atom to which they are attached, form a 3-5-membered ring; provided that when w is 0, q is 1.

24. The compound of claim 23, wherein X is -O-.

25. The compound of claim 23 or 24, wherein Ar is aryl.

26. The compound of claim 25, wherein Ar is phenyl or naphthyl.

27. The compound of any one of claims 23–26, wherein Z' is a linking group comprising one or more groups selected from isocyanide, isothiocyanide, 2-pyridyl disulfide, haloacetamide (- NHC(O)CH<com:Sub>2< / com:Sub>-halo), maleimide, diene, alkene, halide, tosylate (TsO<com:Sup>-< / com:Sup>), aldehyde, sulfonate (R-SO<com:Sub>3< / com:Sub><com:Sup>-< / com:Sup>), [Image disponible dans le document PDF, Image available in the PDF document] , phosphonic acid <com:Math><semantics>(−P(=O)(OH)2)<annotation encoding="application / x-tex">(-P(=O)(OH)_2)< / annotation>< / semantics>< / com:Math>, ketone, <com:Math><semantics>C8<annotation encoding="application / x-tex">C_8< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>C10<annotation encoding="application / x-tex">C_{10}< / annotation>< / semantics>< / com:Math> cycloalkynyl, -OH, -NHOH, -NHNH<com:Sub>2< / com:Sub>, -SH, carboxylic acid (-COOH), acetylene (-C≡CH), azide (- <com:Math><semantics>N3<annotation encoding="application / x-tex">N_3< / annotation>< / semantics>< / com:Math>), amino (-NH<com:Sub>2< / com:Sub>), sulfonic acid (-SO<com:Sub>3< / com:Sub>H), an alkynone derivative (-C(O)C<com:Math><semantics>≡<annotation encoding="application / x-tex">\equiv< / annotation>< / semantics>< / com:Math>C-R<com:Sup>a< / com:Sup>), and dihydrogen phosphate <com:Math><semantics>(−OP(=O)(OH)2)<annotation encoding="application / x-tex">(-OP(=O)(OH)_2)< / annotation>< / semantics>< / com:Math>.

28. The compound of any one of claims <com:Math><semantics>23−27<annotation encoding="application / x-tex">23-27< / annotation>< / semantics>< / com:Math>, wherein x is 0.

29. The compound of claim 28, wherein TG is <com:Math><semantics>−NO2<annotation encoding="application / x-tex">-NO_2< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−OC(O)(CH2)rC(O)R1<annotation encoding="application / x-tex">-OC(O)(CH_2)_rC(O)R^1< / annotation>< / semantics>< / com:Math>, [Image disponible dans le document PDF, Image available in the PDF document] <com:Math><semantics>−NHNH2<annotation encoding="application / x-tex">-NHNH_2< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−BR2R3<annotation encoding="application / x-tex">-BR^2R^3< / annotation>< / semantics>< / com:Math>, or , wherein: <com:Math><semantics>R1<annotation encoding="application / x-tex">R^1< / annotation>< / semantics>< / com:Math> is <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math> alkyl; <com:Math><semantics>R2<annotation encoding="application / x-tex">R^2< / annotation>< / semantics>< / com:Math> and <com:Math><semantics>R3<annotation encoding="application / x-tex">R^3< / annotation>< / semantics>< / com:Math> are each independently hydrogen, <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math> alkyl, <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math> alkoxy, or hydroxy; <com:Math><semantics>R4<annotation encoding="application / x-tex">R^4< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>R5<annotation encoding="application / x-tex">R^5< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>R6<annotation encoding="application / x-tex">R^6< / annotation>< / semantics>< / com:Math>, and <com:Math><semantics>R7<annotation encoding="application / x-tex">R^7< / annotation>< / semantics>< / com:Math> are each independently hydrogen or <com:Math><semantics>C1<annotation encoding="application / x-tex">C_1< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>C6<annotation encoding="application / x-tex">C_6< / annotation>< / semantics>< / com:Math> alkyl; and r is an integer having a value of 1, 2, 3, 4, or 5.

30. The compound of any one of claims 23–27, wherein TG is selected from: [Image disponible dans le document PDF, Image available in the PDF document] wherein: each R<com:Sup>21< / com:Sup> is independently hydrogen or acetyl; and <com:Math><semantics>R22<annotation encoding="application / x-tex">R^{22}< / annotation>< / semantics>< / com:Math> is hydrogen or lower alkyl.

31. The compound of any one of claims 23–27, wherein TG is selected from -NO<com:Sub>2< / com:Sub>, -C(O)- <com:Math><semantics>(CH2)2C(O)<annotation encoding="application / x-tex">(CH2)2C(O)< / annotation>< / semantics>< / com:Math>-alkyl, and nitrobenzyl.

32. The compound of any one of claims 23–31, wherein <com:Math><semantics>(Q)q<annotation encoding="application / x-tex">(Q)_q< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>(L′)w<annotation encoding="application / x-tex">(L')_w< / annotation>< / semantics>< / com:Math>- is selected from: [Image disponible dans le document PDF, Image available in the PDF document] wherein: <com:Math><semantics>X1<annotation encoding="application / x-tex">X^1< / annotation>< / semantics>< / com:Math> is -O- or -NR<com:Sup>a< / com:Sup>-, wherein R<com:Sup>a< / com:Sup> is hydrogen or C<com:Sub>1< / com:Sub>-C<com:Sub>6< / com:Sub> alkyl; <com:Math><semantics>X2<annotation encoding="application / x-tex">X^2< / annotation>< / semantics>< / com:Math> and <com:Math><semantics>X4<annotation encoding="application / x-tex">X^4< / annotation>< / semantics>< / com:Math> are each independently absent or <com:Math><semantics>C(O)<annotation encoding="application / x-tex">C(O)< / annotation>< / semantics>< / com:Math>-, <com:Math><semantics>−C(O)O<annotation encoding="application / x-tex">-C(O)O< / annotation>< / semantics>< / com:Math>-, or <com:Math><semantics>−C(O)NH<annotation encoding="application / x-tex">-C(O)NH< / annotation>< / semantics>< / com:Math>-; <com:Math><semantics>X3<annotation encoding="application / x-tex">X^3< / annotation>< / semantics>< / com:Math> is <com:Math><semantics>−OC(=O)<annotation encoding="application / x-tex">-OC(=O)< / annotation>< / semantics>< / com:Math>-; w' is an integer having a value of 1, 2, 3, 4, or 5; and R<com:Sup>9< / com:Sup> and R<com:Sup>10< / com:Sup> are each independently hydrogen, alkyl, aryl or heteroaryl, wherein alkyl, aryl, and heteroaryl are optionally substituted with one or more substituents.

33. The compound of claim 32, wherein <com:Math><semantics>(Q)q<annotation encoding="application / x-tex">(Q)_q< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>(L′)w<annotation encoding="application / x-tex">(L')_w< / annotation>< / semantics>< / com:Math>- is selected from: [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] wherein * represents the point of attachment of <com:Math><semantics>(Q)q<annotation encoding="application / x-tex">(Q)_q< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>(L′)w<annotation encoding="application / x-tex">(L')_w< / annotation>< / semantics>< / com:Math>- to -SO<com:Sub>2< / com:Sub>-.

34. The compound of any one of claims 23–33, wherein Q is a chemical factor, a biological factor, a hormone, an oligonucleotide, a drug, a toxin, an affinity ligand, a probe for detection, or a combination thereof.

35. The compound claim 34, wherein Q is a drug selected from a cytokine, an immunomodulatory compound, an anti-cancer agent, an anti-viral agent, an anti-bacterial agent, an anti-fungal agent, an anthelmintic agent, or a combination thereof.

36. A method of preparing a conjugate, comprising reacting the compound of any one of claims 23–35 with a targeting moiety.

37. The method of claim 36, wherein the targeting moiety is a nanoparticle, an immunoglobulin, a nucleic acid, a protein, an oligopeptide, a polypeptide, an antibody, a fragment of an antigenic polypeptide, or a repebody.

38. The method of claim 37, wherein the targeting moiety is an antibody selected from an intact polyclonal antibody, an intact monoclonal antibody, an antibody fragment, a single chain Fv (scFv) mutant, a multispecific antibody, a bispecific antibody, a chimeric antibody, a humanized antibody, a human antibody, a fusion protein comprising an antigenic determinant portion of an antibody, and other modified immunoglobulin molecules comprising antigen recognition sites.

39. The method of claim 37, wherein the antibody is selected from Muromonab-CD3, Abciximab, Rituximab, Daclizumab, Palivizumab, Infliximab, Trastuzumab (herceptin), Etanercept, Basiliximab, Gemtuzumab ozogamicin, Alemtuzumab, Ibritumomab tiuxetan, Adalimumab, Alefacept, Omalizumab, Efalizumab, Tositumomab-I<com:Sup>131< / com:Sup>, Cetuximab, Bevacizumab, Natalizumab, Ranibizumab, Panitumumab, Eculizumab, Rilonacept, Certolizumab pegol, Romiplostim, AMG- 531, CNTO-148, CNTO-1275, ABT-874, LEA-29Y, Belimumab, TACI-Ig, Second generation anti- CD20, ACZ-885, Tocilizumab, Atlizumab, Mepolizumab, Pertuzumab, Humax CD20, Tremelimumab (CP-675 206), Ticilimumab, MDX-010, IDEC-114, Inotuzumab ozogamycin, HuMax EGFR, Aflibercept, HuMax-CD4, Ala-Ala, ChAglyCD3, TRX4, Catumaxomab, IGN101, MT-201, Pregovomab, CH-14.18, WX-G250, AMG-162, AAB-001, Motavizumab, MEDI-524, Efumgumab, Aurograb, Raxibacumab, Third generation anti-CD20, LY2469298, and Veltuzumab.

40. A pharmaceutical composition comprising a conjugate of any one of claims 1–22 and a pharmaceutically acceptable carrier or excipient.

41. An imaging compound comprising a conjugate of any one of claims 1–22.

42. A method for imaging comprising contacting a material with the imaging compound of claim 41.

43. A sensor compound comprising a conjugate of any one of claims 1–22.

44. A method of detecting comprising contacting a material with the sensor compound of claim 43.

45. A molecular switch, molecular machine, or nanomachine comprising a conjugate of any one of claims 1–22.

46. A method for moving portions of a molecular device, comprising mixing in a solution, (1) the molecular switch, molecular machine, or nanomachine of claim 45; and (2) an activating agent that activates the triggering group.

47. Use of a conjugate of any one of claims 1–22 to deliver an active agent to a cell, wherein the targeting moiety is selected to bind to a molecule associated with said cell.

48. The use of claim 47, wherein the cell is a cancer cell and the targeting moiety is selected to bind to a molecule associated with the cancer cell.

49. The use of a conjugate of any one of claims 1–22 to treat a disease.

50. The use of claim 49, wherein the disease is an autoimmune disease, an infectious disease, or a tumor.

51. The use of claim 49, wherein the disease is an autoimmune disorder, a chronic inflammatory condition, a hyperproliferative disorder, a viral infection, osteoarthritis, or atherosclerosis.

52. The use of claim 49, wherein the disease is a cancer.

53. The use of claim 52, wherein the disease is a cancer selected from carcinoma, lymphoma, blastoma, sarcoma, leukemia, or a lymphoid malignancy.

54. The use of claim 53, wherein the cancer is squamous cell cancer, lung cancer, cancer of the peritoneum, hepatocellular cancer, gastric or stomach cancer, pancreatic cancer, glioblastoma, cervical cancer, ovarian cancer, liver cancer, bladder cancer, hepatoma, breast cancer, colon cancer, rectal cancer, colorectal cancer, endometrial or uterine carcinoma, salivary gland carcinoma, kidney or renal cancer, prostate cancer, vulval cancer, thyroid cancer, hepatic carcinoma, anal carcinoma, penile carcinoma, acute leukemia, or head / brain and neck cancer.

55. The use of claim 54, wherein the cancer is cervical carcinoma.

56. A compound that is: [Image disponible dans le document PDF, Image available in the PDF document] or a pharmaceutically acceptable salt thereof.

57. A method for preparing a compound, comprising reacting a compound of Formula (IIc): [Image disponible dans le document PDF, Image available in the PDF document] (IIc) or a pharmaceutically acceptable salt thereof, with a sulfonyl halide: [Image disponible dans le document PDF, Image available in the PDF document] to provide a compound of Formula (Iaa): [Image disponible dans le document PDF, Image available in the PDF document] (Iaa) or a pharmaceutically acceptable salt thereof, wherein: X<com:Sup>a< / com:Sup> is halogen; each R<com:Sup>11< / com:Sup> is independently alkyl, aryl, aralkyl, or alkoxy; each Q is independently an active agent linked to L' by a heteroatom; Z' is absent or a linking group; L' is a linking group attached to the SO<com:Sub>2< / com:Sub> via a heteroatom selected from O, S, and N, and is selected such that cleavage of the bond between L' and SO<com:Sub>2< / com:Sub> promotes cleavage of the bond between L' and Q to release the active agent; Ar represents aryl or heteroaryl; Y' is <com:Math><semantics>−(CRb2)yN(Ra)<annotation encoding="application / x-tex">-(CR^{b_2})_yN(R^a)< / annotation>< / semantics>< / com:Math>-, <com:Math><semantics>−(CRb2)yO<annotation encoding="application / x-tex">-(CR^{b_2})_yO< / annotation>< / semantics>< / com:Math>-, or <com:Math><semantics>−(CRb2)yS<annotation encoding="application / x-tex">-(CR^{b_2})_yS< / annotation>< / semantics>< / com:Math>-, such that the N, O, or S atom is attached to TG if y is 1; O and Y' are positioned on adjacent atoms of Ar; TG is a triggering group that, when activated, generates an N, O, or S atom capable of reacting with the SO<com:Sub>2< / com:Sub> to displace (Q)<com:Sub>q< / com:Sub>-(L')<com:Sub>w< / com:Sub> and form a 5-6-membered ring including O-SO<com:Sub>2< / com:Sub> and the intervening atoms of Ar; q is an integer having a value from 1 to about 20; w, x, and y are each independently an integer having a value of 0 or 1; each R<com:Sup>a< / com:Sup> is independently hydrogen or lower alkyl; and each R<com:Sup>b< / com:Sup> is independently hydrogen or lower alkyl; or two R<com:Sup>b< / com:Sup>, together with the carbon atom to which they are attached, form a 3-5-membered ring; provided that when w is 0, q is 1.

58. The method of claim 57, wherein Z' is a linking group comprising one or more groups selected from isocyanide, isothiocyanide, 2-pyridyl disulfide, haloacetamide (-NHC(O)CH<com:Sub>2< / com:Sub>-halo), maleimide, diene, alkene, halide, tosylate (TsO<com:Sup>-< / com:Sup>), aldehyde, sulfonate (R-SO<com:Sub>3< / com:Sub><com:Sup>-< / com:Sup>), [Image disponible dans le document PDF, Image available in the PDF document] , phosphonic acid (-P(=O)(OH)<com:Sub>2< / com:Sub>), ketone, <com:Math><semantics>C8<annotation encoding="application / x-tex">C_8< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>C10<annotation encoding="application / x-tex">C_{10}< / annotation>< / semantics>< / com:Math> cycloalkynyl, -OH, -NHOH, -NHNH<com:Sub>2< / com:Sub>, -SH, carboxylic acid (-COOH), acetylene (-C≡CH), azide (- <com:Math><semantics>N3<annotation encoding="application / x-tex">N_3< / annotation>< / semantics>< / com:Math>), amino (-NH<com:Sub>2< / com:Sub>), sulfonic acid (-SO<com:Sub>3< / com:Sub>H), an alkynone derivative (-C(O)C<com:Math><semantics>≡<annotation encoding="application / x-tex">\equiv< / annotation>< / semantics>< / com:Math>C-R<com:Sup>a< / com:Sup>), and dihydrogen phosphate <com:Math><semantics>(−OP(=O)(OH)2)<annotation encoding="application / x-tex">(-OP(=O)(OH)_2)< / annotation>< / semantics>< / com:Math>.

59. A method for preparing a compound, comprising: (a) reacting a compound of Formula (IIa): [Image disponible dans le document PDF, Image available in the PDF document] (IIa) or a pharmaceutically acceptable salt thereof, with 1,1'-sulfonylbis(1H-imidazole): [Image disponible dans le document PDF, Image available in the PDF document] to provide a compound of Formula (IIbb): [Image disponible dans le document PDF, Image available in the PDF document] (IIbb) or a pharmaceutically acceptable salt thereof, wherein: Z' is a linking group comprising one or more groups selected from isocyanide, isothiocyanide, 2- pyridyl disulfide, haloacetamide (-NHC(O)CH<com:Sub>2< / com:Sub>-halo), maleimide, diene, alkene, halide, [Image disponible dans le document PDF, Image available in the PDF document] tosylate (TsO<com:Sup>-< / com:Sup>), aldehyde, sulfonate (R-SO<com:Sub>3< / com:Sub><com:Sup>-< / com:Sup>), [Image disponible dans le document PDF, Image available in the PDF document] , phosphonic acid <com:Math><semantics>(−P(=O)(OH)2)<annotation encoding="application / x-tex">(-P(=O)(OH)_2)< / annotation>< / semantics>< / com:Math>, ketone, <com:Math><semantics>C8<annotation encoding="application / x-tex">C_8< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>C10<annotation encoding="application / x-tex">C_{10}< / annotation>< / semantics>< / com:Math> cycloalkynyl, - OH, -NHOH, -NHNH<com:Sub>2< / com:Sub>, -SH, carboxylic acid (-COOH), acetylene (-C≡CH), azide (-N<com:Sub>3< / com:Sub>), amino (-NH<com:Sub>2< / com:Sub>), sulfonic acid (-SO<com:Sub>3< / com:Sub>H), an alkynone derivative (-C(O)C≡C-R<com:Sup>a< / com:Sup>), and dihydrogen phosphate <com:Math><semantics>(−OP(=O)(OH)2)<annotation encoding="application / x-tex">(-OP(=O)(OH)_2)< / annotation>< / semantics>< / com:Math>; Ar represents aryl or heteroaryl; Y' is <com:Math><semantics>−(CRb2)yN(Ra)<annotation encoding="application / x-tex">-(CR^{b_2})_yN(R^{a})< / annotation>< / semantics>< / com:Math>, <com:Math><semantics>−(CRb2)yO<annotation encoding="application / x-tex">-(CR^{b_2})_yO< / annotation>< / semantics>< / com:Math>, or <com:Math><semantics>−(CRb2)yS<annotation encoding="application / x-tex">-(CR^{b_2})_yS< / annotation>< / semantics>< / com:Math>, positioned such that the N, O, or S atom is attached to TG if y is 1; O and Y' are positioned on adjacent atoms of Ar; TG is a triggering group that, when activated, generates an N, O, or S atom capable of reacting with the SO<com:Sub>2< / com:Sub> to form a 5-6-membered ring including O-SO<com:Sub>2< / com:Sub> and the intervening atoms of Ar; x and y are each independently an integer having a value of 0 or 1; each R<com:Sup>a< / com:Sup> is independently hydrogen or lower alkyl; and each R<com:Sup>b< / com:Sup> is independently hydrogen or lower alkyl; or two R<com:Sup>b< / com:Sup>, together with the carbon atom to which they are attached, form a 3-5-membered ring.

60. The method of claim 59, wherein the compound of Formula (IIbb) is further reacted with a compound of Formula (Ia'), (Q)<com:Sub>q< / com:Sub>-(L')<com:Sub>w< / com:Sub>-H, or a pharmaceutically acceptable salt thereof, to provide a compound (Iaa): [Image disponible dans le document PDF, Image available in the PDF document] (Iaa) or a pharmaceutically acceptable salt thereof, wherein: each Q is, independently, an active agent linked to L' by a heteroatom, wherein Q is displaced upon activation of TG; L' is a spacer moiety attached to the SO<com:Sub>2< / com:Sub> via a heteroatom selected from O, S, and N, and is selected such that cleavage of the bond between L' and SO<com:Sub>2< / com:Sub> promotes cleavage of the bond between L' and Q to release the active agent; and q is an integer having a value from 1 to about 20; w is an integer having a value of 0 or 1; provided that when w is 0, q is 1.

61. The method of any one of claims 58-60, wherein Ar is aryl.

62. The method of claim 61, wherein Ar is phenyl or naphthyl.

63. The method of any one of claims 57-62, wherein TG is selected from: [Image disponible dans le document PDF, Image available in the PDF document] wherein: each R<com:Sup>21< / com:Sup> is independently hydrogen or acetyl; and <com:Math><semantics>R22<annotation encoding="application / x-tex">R^{22}< / annotation>< / semantics>< / com:Math> is hydrogen or lower alkyl.

64. The method of any one of claims 57, 58, and 60-63, excluding dependency from claim 59, wherein <com:Math><semantics>(Q)q<annotation encoding="application / x-tex">(Q)_q< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>(L′)w<annotation encoding="application / x-tex">(L')_w< / annotation>< / semantics>< / com:Math>- is selected from: [Image disponible dans le document PDF, Image available in the PDF document] wherein: <com:Math><semantics>X1<annotation encoding="application / x-tex">X^1< / annotation>< / semantics>< / com:Math> is -O- or -NR<com:Sup>a< / com:Sup>-, wherein R<com:Sup>a< / com:Sup> is hydrogen or C<com:Sub>1< / com:Sub>-6 alkyl; X<com:Sup>2< / com:Sup> and X<com:Sup>4< / com:Sup> are each independently absent or C(O)-, -C(O)O-, or -C(O)NH-; <com:Math><semantics>X3<annotation encoding="application / x-tex">X^{3}< / annotation>< / semantics>< / com:Math> is -OC(=O)-; w' is an integer having a value of 1, 2, 3, 4, or 5; R<com:Sup>9< / com:Sup> and R<com:Sup>10< / com:Sup> are each independently hydrogen, alkyl, aryl or heteroaryl, wherein alkyl, aryl, and heteroaryl are optionally substituted with one or more substituents selected from alkyl, - [Image disponible dans le document PDF, Image available in the PDF document] R<com:Sup>u1< / com:Sup>, R<com:Sup>u2< / com:Sup>, and R<com:Sup>u3< / com:Sup> are each independently hydrogen, alkyl, aryl, or heteroaryl; and u is an integer having a value of 1 to about 10.

65. The method of claim 64, wherein <com:Math><semantics>(Q)q<annotation encoding="application / x-tex">(Q)_q< / annotation>< / semantics>< / com:Math>-<com:Math><semantics>(L′)w<annotation encoding="application / x-tex">(L')_w< / annotation>< / semantics>< / com:Math>- is selected from: [Image disponible dans le document PDF, Image available in the PDF document] • • [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] [Image disponible dans le document PDF, Image available in the PDF document] wherein * represents the point of attachment of Q-(L')<com:Sub>w< / com:Sub>- to -SO<com:Sub>2< / com:Sub>-.

66. The method of any one of claims 57, 58, and 60-63, excluding dependency from claim 59, wherein Q is a chemical factor, a biological factor, a hormone, an oligonucleotide, a drug, a toxin, an affinity ligand, a probe for detection, or a combination thereof.

67. The method of claim 66, wherein Q is a drug selected from a cytokine, an immunomodulatory compound, an anti-cancer agent, an anti-viral agent, an anti-bacterial agent, an anti-fungal agent, an anthelmintic agent, or a combination thereof.

68. The method of any one of claims 57, 58, and 60-62, excluding dependency form claim 59, wherein the compound of Formula (Iaa) is further reacted with a targeting moiety to provide the conjugate of Formula (I') as defined in claim 1.

69. The method of claim 68, wherein the targeting moiety is a nanoparticle, an immunoglobulin, a nucleic acid, a protein, an oligopeptide, a polypeptide, an antibody, a fragment of an antigenic polypeptide, or a repebody.

70. The method of claim 69, wherein the targeting moiety is an antibody selected from an intact polyclonal antibody, an intact monoclonal antibody, an antibody fragment, a single chain Fv (scFv) mutant, a multispecific antibody, a bispecific antibody, a chimeric antibody, a humanized antibody, a human antibody, a fusion protein comprising an antigenic determinant portion of an antibody, and other modified immunoglobulin molecules comprising antigen recognition sites.

71. The method of claim 69, wherein the targeting moiety is an antibody selected from Muromonab-CD3, Abciximab, Rituximab, Daclizumab, Palivizumab, Infliximab, Trastuzumab (herceptin), Etanercept, Basiliximab, Gemtuzumab ozogamicin, Alemtuzumab, Ibritumomab tiuxetan, Adalimumab, Alefacept, Omalizumab, Efalizumab, Tositumomab-I<com:Sup>131< / com:Sup>, Cetuximab, Bevacizumab, Natalizumab, Ranibizumab, Panitumumab, Eculizumab, Rilonacept, Certolizumab pegol, Romiplostim, AMG-531, CNTO-148, CNTO-1275, ABT-874, LEA-29Y, Belimumab, TACI-Ig, Second generation anti-CD20, ACZ-885, Tocilizumab, Atlizumab, Mepolizumab, Pertuzumab, Humax CD20, Tremelimumab (CP-675 206), Ticilimumab, MDX-010, IDEC-114, Inotuzumab ozogamycin, HuMax EGFR, Aflibercept, HuMax-CD4, Ala-Ala, ChAglyCD3, TRX4, Catumaxomab, IGN101, MT-201, Pregovomab, CH-14.18, WX-G250, AMG-162, AAB-001, Motavizumab, MEDI-524, Efumgumab, Aurograb, Raxibacumab, Third generation anti-CD20, LY2469298, and Veltuzumab.