Iron complex and its use

Abstract

In this specification, the compound of formula (I) Disclosed are iron complexes containing JPEG2025520465000092.jpg36165 and salts thereof, and materials and devices containing one or more of the iron complexes of formula I or salts thereof. Also disclosed herein are methods of using the iron complexes of formula I or salts thereof, for example, methods for detecting ions such as phosphates, methods for removing ions such as phosphates from aqueous solutions or mixtures, and methods for treating hyperphosphatemia. The iron complexes disclosed herein are useful for detecting and sequestering ions (e.g., anions such as phosphates) and may be useful for treating hyperphosphatemia.

Description

Technical Field

[0001] Government Funding This invention was made with government support under Grant No. DK124333 awarded by the National Institutes of Health. The United States Government has certain rights in this invention.

[0002] Related Applications This application claims priority based on U.S. Provisional Application No. 63 / 353,332, filed on June 17, 2022. The entire content of the above-mentioned application is hereby incorporated by reference into this specification.

Background Art

[0003] Background of the Invention Phosphates are an important component of fertilizers required to maintain the world's food supply. Unfortunately, most of the phosphates used as fertilizers leach into surface waters, causing extensive eutrophication and harmful algal blooms. More than 65% of the estuaries and coastal waters in the United States are currently experiencing moderate to severe eutrophication, which has a significant impact on the ecosystems and industries that depend on those systems. 1、2 To address this problem, easy detection of phosphates in the μM range is needed, at least in part. 3、4 .

[0004] The current protocol of the U.S. Environmental Protection Agency (EPA) for measuring phosphate levels by the molybdenum blue method relies on the formation of phosphomolybdic acid keggin ions, followed by their reduction to obtain a blue mixed-valence complex. 5 The slow kinetics of these reactions make this multi-step protocol difficult. Additionally, the strongly acidic conditions required for the formation of keggin ions do not allow for a distinction between orthophosphate and other polyphosphates such as pyrophosphate, which may also be present at high concentrations in surface waters but have different effects on algal growth. 6Thus, recently, much attention has been paid to the development of molecular receptors and fluorescent probes for phosphates, but there is still a need for effective probes that can easily distinguish between phosphates and pyrophosphates. 7-12

[0005] Metal complexes are particularly suitable for the search for phosphates by luminescence. Anion recognition can be achieved either allosterically or directly through coordination. As in the case of heteroditopic ruthenium(II) bipyridyl complexes, allosteric recognition of phosphates is mainly achieved by directional hydrogen bond interactions. However, such probes do not function well in aqueous samples and are rarely selective for phosphates, including excessive pyrophosphates. 13-15 Since metal ions can overcome the high hydration enthalpy of phosphates, direct coordination of phosphates is more suitable for such applications. 7-11、16、17 Due to requirements regarding instability and hardness, current research is limited to copper, zinc, and lanthanide complexes, 18-23、7 some of which have significant selectivity and affinity for phosphates. Unfortunately, many of these probes are selective for phosphates over competing anions such as bicarbonate and chloride, but the selectivity for orthophosphates over polyphosphates such as pyrophosphates has not yet been established.

[0006] The presence of iron in the active sites of many phosphodiesterases and phosphatases suggests that iron can also be used in the design of phosphate receptors. 24-26 Furthermore, although iron is the most abundant transition metal, it has been little investigated in the design of molecular receptors, as is evident from the lack of iron complexes for anion recognition. 27-30 It is thought that no iron-based molecular receptors for any oxyanion that function at neutral pH and are more selective than interfering anions have been reported. 7Despite having a hardness suitable for hard anions, coordinatively unsaturated iron(III) complexes present several issues that are not yet fully mastered for such applications. In particular, iron(III) complexes with open coordination sites tend to form μ-oxo dimers, 31、32 which prevent or reduce further coordination of the targeted anion. 33 Therefore, the development of Fe III -based receptors for anions requires re-engineering the metal center to prevent such dimerization. In heme-based systems, the formation of μ-oxo dimers can be prevented by increasing the steric hindrance around the iron center using pylons 34、35 or via supramolecular assembly using cyclodextrin. 36 In non-heme iron-based systems, coordination at the open site by a weaker anion was thought to be sufficient to prevent dimerization. Considering the tendency of Fe III to quench fluorescence or organic dyes, 37 such metal-based receptors would also function as fluorescence probes if this weak anion also emits fluorescence.

[0007] In receptor design, other parameters need to be considered. First, the affinity of the receptor for anions is significantly affected by the total charge of the metal complex at the target pH. 21 Highly negatively charged complexes should be avoided. To prevent demetallation, Fe III complexes must also be thermodynamically stable enough. The bioinorganic chemistry of siderophores, natural products that are strong iron chelators, 38 suggests that both of these requirements can be met with tetra- or pentadentate ligands containing all oxygen donors such as 1,2-hydroxypyridinone (HOPO). For the corresponding molecular receptors Fe III -HOPO-fluo(1) and Fe III -HOPO-PhO-fluo(2) (Figure 1), the remaining one or two open coordination sites have a higher affinity for Fe IIIIt is protected by fluorescein, which is a weak ligand for iron(III). A hypothesis has been proposed that fluorescein coordinates strongly enough with iron(III) to prevent the formation of μ-oxo dimers, but is not too strong to allow substitution by phosphate. Accordingly, there is a continuing need for novel metal complexes (e.g., iron complexes) for detecting ions (e.g., anions such as phosphate) and removing ions (e.g., anions such as phosphate) from aqueous solutions or mixtures (e.g., wastewater), and for methods of treating hyperphosphatemia. SUMMARY OF THE INVENTION MEANS FOR SOLVING THE PROBLEM

[0008] The iron complexes disclosed herein are useful for detecting and sequestering ions (e.g., anions such as phosphate) and may be useful for treating hyperphosphatemia.

[0009] Accordingly, one embodiment provides an iron complex composition comprising Fe complexed with two pyridinone ligands, where the pyridinone ligands are covalently bonded to each other by a linker, each pyridinone is substituted with one hydroxy or -O II or Fe III and each pyridinone is optionally substituted with one or more (C1-C6) alkyls. -

[0010] One embodiment provides an iron complex comprising a compound of formula I CHEMICAL FORMULA or a salt thereof, wherein Fe is Fe II or Fe III and each CHEMICAL FORMULA moiety is independently a pyridinone substituted with one hydroxy or -O - and ​The pyridinone is optionally substituted with one or more (C1-C6) alkyl, each dashed bond is independently a single bond or a double bond, L is a linker, where the linker is -W a or -C(=O)(C1-C6)alkyl-X a optionally substituted with, and the -C(=O)(C1-C6)alkyl-X a is optionally substituted with -W b X is hydroxy or phenyl substituted with -O a W - is a linker group W a is a linker a group W b is a linker b group

[0011] One embodiment provides a mixture comprising two or more iron complexes, independently further comprising two compounds of formula I

Chemical formula

Chemical formula

[0012] One embodiment provides an iron complex comprising a compound of formula I

Chemical formula

Chemical formula

[0013] One embodiment provides an iron complex consisting essentially of a compound of Formula I described herein or a salt thereof.

[0014] One embodiment provides an iron complex of Formula I described herein or a salt thereof.

[0015] One embodiment provides a material or device comprising one or more (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more) iron complexes of Formula I described herein or a salt thereof.

[0016] One embodiment provides a material or device comprising a plurality of iron complexes of Formula I described herein or a salt thereof.

[0017] One embodiment provides a material or device comprising one or more (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more) iron complexes of Formula I described herein or a salt thereof, covalently attached to the material or device (e.g., via a linker a or linker b ).

[0018] One embodiment provides a material or device comprising a plurality of iron complexes of Formula I described herein or a salt thereof, covalently attached to the material or device (e.g., via a linker a or linker b ).

[0019] One embodiment provides a method for detecting an inorganic phosphate, comprising contacting the phosphate with an iron complex described herein.

[0020] One embodiment provides a method for removing an inorganic phosphate from an aqueous mixture or solution, comprising contacting the aqueous mixture or solution with an iron complex described herein.

[0021] One embodiment provides a method for treating hyperphosphatemia in a mammal in need of treatment for hyperphosphatemia, which comprises contacting blood of the mammal (e.g., a human such as a human patient) in need of treatment for hyperphosphatemia with an iron complex described herein. In one embodiment, the mammal has chronic kidney disease.

[0022] One embodiment provides a process and an intermediate disclosed herein that are useful for preparing an iron complex or a salt thereof that comprises a compound of formula I or a salt thereof.

Brief Description of the Drawings

[0023]

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Modes for Carrying Out the Invention

[0024] Unless otherwise indicated, the following definitions are used. That is, halo or halogen is fluoro, chloro, bromo or iodo. Alkyl and alkoxy, etc. indicate both straight-chain and branched-chain groups, but when referring to an individual radical such as propyl, only the straight-chain radical is included (branched-chain isomers such as isopropyl are specifically mentioned).

[0025] As used herein, the term “(C a -C b )alkyl” refers to a straight-chain or branched-chain alkyl radical having a to b carbon atoms where a and b are integers. Thus, for example, when a is 1 and b is 6, the term includes methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, n-pentyl and n-hexyl.

[0026] The term “alkoxy” refers to -O(alkyl), and the term “haloalkoxy” refers to alkoxy substituted with one or more (e.g., 1, 2, 3, or 4) halos.

[0027] The specific values listed below for radicals, substituents and ranges are for illustration only; they do not exclude other defined values or other values within the ranges defined for the radicals and substituents.

[0028] Specifically, (C1-C6)alkyl can be methyl, ethyl, propyl, isopropyl, butyl, iso-butyl, sec-butyl, pentyl, 3-pentyl or hexyl, (C1-C6)alkoxy can be methoxy, ethoxy, propoxy, isopropoxy, butoxy, iso-butoxy, sec-butoxy, pentoxy, 3-pentoxy or hexyloxy, (C3-C8)cycloalkyl can be cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl, and heteroaryl can be furyl, imidazolyl, triazolyl, triazinyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, pyrazolyl, pyrrolyl, pyrazinyl, tetrazolyl, pyridyl (or its N-oxide), thienyl, pyrimidinyl (or its N-oxide), indolyl, isoquinolyl (or its N-oxide) or quinolyl (or its N-oxide).

[0029] portion

Chemical formula

[0030] As used herein, "portion A" is a pyridinone (e.g., oxo(=O)-substituted pyridine) substituted with one hydroxy or -O - and the pyridinone is optionally substituted with one or more (C1-C6)alkyls. Generally, hydroxy is substituted on the carbon atom of the pyridinone, and -O - is substituted on the nitrogen atom of the pyridinone. It should be understood that the oxygen of the hydroxyl, the oxygen of the pyridinone, and the oxygen of the -O - group coordinate to the iron atom of the iron complex. Therefore, the hydrogen of the hydroxyl group is not specifically depicted in the compound of formula I and may or may not be present in the compound of formula I.

[0031] linker ("L") As used herein, linker "L" is a molecular moiety that joins two "moiety A" groups to each other. The linker functions to join two "moiety A" groups to each other such that the two "moiety A" groups may be variable as long as they can function as ligands of the iron metal complex as described herein. The linker can vary in length and atomic composition (e.g., C, H, N, O, S), and can be, for example, branched or unbranched or saturated or unsaturated, or combinations thereof.

[0032] In one embodiment, L is a linker containing 5 to 50 non-hydrogen atoms, where the non-hydrogen atoms are selected from C, N, S, and O, and the linker is -W a -Y or -C(=O)(C1-C6)alkyl-X a optionally substituted with, and -C(=O)(C1-C6)alkyl-X a is optionally substituted with -W b -Y.

[0033] In one embodiment, L is a linker containing 5 to 30 non-hydrogen atoms, where the non-hydrogen atoms are selected from C, N, S, and O, and the linker is -W a -Y or -C(=O)(C1-C6)alkyl-X a optionally substituted with, and -C(=O)(C1-C6)alkyl-X a is optionally substituted with -W b -Y.

[0034] In one embodiment, L is a linker containing 5 to 20 non-hydrogen atoms, where the non-hydrogen atoms are selected from C, N, S, and O, and the linker is -W a -Y or -C(=O)(C1-C6)alkyl-X a optionally substituted with, and -C(=O)(C1-C6)alkyl-X a is optionally substituted with -W b -Y.

[0035] In one embodiment, L is a linker containing 5 to 15 non-hydrogen atoms, where the non-hydrogen atoms are selected from C, N, S, and O, and the linker is -W a -Y or -C(=O)(C1-C6)alkyl-X a optionally substituted with, and -C(=O)(C1-C6)alkyl-X a is -W b optionally substituted with -Y.

[0036] In one embodiment, L is a linker containing 8 to 15 non-hydrogen atoms, where the non-hydrogen atoms are selected from C, N, S, and O, and the linker is -W a -Y or -C(=O)(C1-C6)alkyl-X a optionally substituted with, and -C(=O)(C1-C6)alkyl-X a is -W b optionally substituted with -Y.

[0037] In one embodiment, L is a linker containing 3 to 15 non-hydrogen atoms, where the non-hydrogen atoms are selected from C, N, S, and O, and the linker is -W a -Y or -C(=O)(C1-C6)alkyl-X a optionally substituted with, and -C(=O)(C1-C6)alkyl-X a is -W b optionally substituted with -Y.

[0038] In one embodiment, L is a linker containing 5 to 50 non-hydrogen atoms, where the non-hydrogen atoms are selected from halo, C, N, S, and O, and the linker is -W a -Y or -C(=O)(C1-C6)alkyl-X a optionally substituted with, and -C(=O)(C1-C6)alkyl-X a is -W b optionally substituted with -Y.

[0039] In one embodiment, L is a linker containing 5 to 30 non-hydrogen atoms, where the non-hydrogen atoms are selected from halo, C, N, S, and O, and the linker is -W a-Y or -C(=O)(C1-C6)alkyl-X a optionally substituted with, -C(=O)(C1-C6)alkyl-X a is -W b optionally substituted with -Y.

[0040] In one embodiment, L is a linker containing 5 to 20 non-hydrogen atoms, where the non-hydrogen atoms are selected from halo, C, N, S, and O, and the linker is -W a -Y or -C(=O)(C1-C6)alkyl-X a optionally substituted with, -C(=O)(C1-C6)alkyl-X a is -W b optionally substituted with -Y.

[0041] In one embodiment, L is a linker containing 5 to 15 non-hydrogen atoms, where the non-hydrogen atoms are selected from halo, C, N, S, and O, and the linker is -W a -Y or -C(=O)(C1-C6)alkyl-X a optionally substituted with, -C(=O)(C1-C6)alkyl-X a is -W b optionally substituted with -Y.

[0042] In one embodiment, L is a linker containing 8 to 15 non-hydrogen atoms, where the non-hydrogen atoms are selected from halo, C, N, S, and O, and the linker is -W a -Y or -C(=O)(C1-C6)alkyl-X a optionally substituted with, -C(=O)(C1-C6)alkyl-X a is -W b optionally substituted with -Y.

[0043] In one embodiment, L is a linker containing 3 to 15 (or 5 to 10) non-hydrogen atoms, where the non-hydrogen atoms are selected from halo, C, N, S, and O, and the linker is -W a -Y or -C(=O)(C1-C6)alkyl-X ais optionally replaced with -C(=O)(C1-C6)alkyl-X a is -W b is optionally substituted with -Y

[0044] In one embodiment, L is a linker comprising a branched or unbranched, saturated or unsaturated hydrocarbon chain having 3 to 15 carbon atoms, wherein one or more of said carbon atoms are optionally and independently replaced with -O-, -S-, -N(R a ), and the chain is optionally substituted with one or more (e.g., 1, 2, 3, 4, 5 or more) substituents independently selected from (C1-C4)alkyl, (C1-C6)alkoxy, oxo(=O), and halo, and each R a is independently H or (C1-C6)alkyl, and the linker is optionally substituted with -W a -Y or -C(=O)(C1-C6)alkyl-X a is optionally replaced with -C(=O)(C1-C6)alkyl-X a is -W b is optionally substituted with -Y

[0045] In one embodiment, L is a linker comprising a branched or unbranched, saturated or unsaturated hydrocarbon chain having 3 to 30 carbon atoms, wherein one or more of said carbon atoms are optionally and independently replaced with -O-, -S-, -N(R a ), and the chain is optionally substituted with one or more (e.g., 1, 2, 3, 4, 5 or more) substituents independently selected from (C1-C4)alkyl, (C1-C6)alkoxy, oxo(=O), and halo, and each R a is independently H or (C1-C6)alkyl, and the linker is optionally substituted with -W a -Y or -C(=O)(C1-C6)alkyl-X a is optionally replaced with -C(=O)(C1-C6)alkyl-X a is -W b is optionally substituted with -Y

[0046] In one embodiment, L is

Chemical formula

[0047] Linker a ("W a ") and linker b ("W b ") (or linker a subgroup and linker b subgroup) As used herein, linker a ("W a ") and linker b ("W b ") are molecular moieties that couple the iron complexes described herein (e.g., a compound of Formula I or a salt thereof) to another molecular entity such as a material (e.g., a polymer (e.g., a synthetic or natural polymer), a hydrogel, a membrane, a nanoparticle, or any other suitable material (e.g., a device)). The linker may be variable so long as it functions to couple the compound of Formula I to another molecular entity such that both the compound of Formula I (e.g., the iron complex) and the other molecular entity can function as described herein. The linker can vary in length and atomic composition (e.g., halo, C, H, N, O, S) and can be, for example, branched or unbranched or saturated or unsaturated, or combinations thereof.

[0048] In certain embodiments, the material or device includes a membrane to which a ligand or an iron complex of a ligand is bound. In certain embodiments, the material or device includes a sensor or detector to which a ligand or an iron complex of a ligand is bound. In certain embodiments, the ligand can be chemically bound to the surface of the material or device (e.g., the surface of the membrane) via covalent and / or ionic bonds using various methods available to those skilled in the art. In certain embodiments, the ligand can include pendant functional groups (e.g., N, O, P, and / or S-containing groups) that can function as linkers for chemically binding the ligand to the surface of the material or device.

[0049] As used herein, linker a (“W a ”) and linker b (“W b ”) can also include one or more reactive groups (e.g., amine, hydroxy, thiol, ester, or amide; NR2, OH, SH, CO2R, CONR2, where each R is independently H or (C1-C6) alkyl). These linkers can function as precursors (e.g., intermediates) to which other molecular entities such as metals complexes and materials can covalently bind.

[0050] In one embodiment, each W a and W b independently includes from 2 to 50 non-hydrogen atoms, and the non-hydrogen atoms are selected from C, N, S, and O.

[0051] In one embodiment, each W a and W b independently includes from 2 to 50 non-hydrogen atoms, and the non-hydrogen atoms are selected from halo, C, N, S, and O.

[0052] In one embodiment, each W a and W b independently includes a branched or unbranched saturated or unsaturated hydrocarbon chain having from 1 to 20 carbon atoms, and one or more of the carbon atoms are optionally independently -O-, -S, -N(R a)- is replaced by, and the chain is optionally substituted with one or more (e.g., 1, 2, 3, 4, 5 or more) substituents independently selected from (C1-C4) alkyl, (C1-C6) alkoxy, hydroxy, and halo, each R a is independently H or (C1-C6) alkyl.

[0053] In one embodiment, each W a and W b independently includes a branched or unbranched saturated or unsaturated hydrocarbon chain having 1 to 20 carbon atoms, and one or more of the carbon atoms are optionally independently replaced by -O-, -S-, -N(R a )-, the chain is optionally substituted with one or more (e.g., 1, 2, 3, 4, 5 or more) substituents independently selected from oxo (C=O), (C1-C4) alkyl, (C1-C6) alkoxy, hydroxy, and halo, each R a is independently H or (C1-C6) alkyl.

[0054] In one embodiment, W a is

Chemical formula

Chemical formula

[0055] The term "polymer" includes any polymer (e.g., synthetic or natural polymer) suitable for linking to the metal complexes described herein. Examples include polyamides (including star polyamides), polyethylene glycol, polyethyleneamine, polysulfone, and polyethersulfone. The term "hydrogel" includes any hydrogel suitable for linking to the metal complexes described herein. Examples include cross-linked poly(N-isopropylacrylamide), cross-linked polyvinyl alcohol, PMA (polymethacrylate), PMMA (polymethylmethacrylate), PEMA (polyethylmethacrylate), and chitosan. The term "membrane" includes any membrane suitable for linking to the metal complexes described herein. The term "nanoparticle" includes any nanoparticle (e.g., metal-based, silica-based) suitable for linking to the metal complexes described herein. Examples include gold nanoparticles, iron oxide nanoparticles, and silica nanoparticles. The term "material" includes any material (e.g., solid material) suitable for linking to the metal complex. Examples include carbon, porous carbon, gold, carbon nanotubes, CuO nanowires, and WO3 nanowires.

[0056] Weak binding ligand As used herein, the term "weak binding ligand" is any ligand that can bind to the iron atom of an iron metal complex but can then be replaced by another ligand or ion (e.g., an anion such as phosphate). Weak binding ligands also include any ligand that can prevent the iron complex from forming an iron complex dimer (e.g., an iron complex containing two iron atoms).

[0057] The embodiments provided below or above are understood to be for the compounds of formula I and all of its sub-formulas (e.g., formula Ia, Ib, Ic, Id). It should be understood that two or more embodiments can be combined.

[0058] In one embodiment, Fe is Fe II is.

[0059] In one embodiment, Fe is Fe III .

[0060] In one embodiment, Fe is Fe II or Fe III mixture.

[0061] In one embodiment, each

Chemical formula

Chemical formula

[0062] In one embodiment, each

Chemical formula

Chemical formula

[0063] In one embodiment, each

Chemical formula

Chemical formula

[0064] In one embodiment, each

Chemical formula

Chemical formula

[0065] ​ In one embodiment, each

Chemical formula

Chemical formula

[0066] In one embodiment, each

Chemical formula

Chemical formula

[0067] In one embodiment, L is a linker containing 5 to 50 non-hydrogen atoms, where the non-hydrogen atoms are selected from C, N, S, and O, and the linker is -W a -Y or -C(=O)(C1-C6)alkyl-X a optionally substituted with, and -C(=O)(C1-C6)alkyl-X a is optionally substituted with -W b -Y.

[0068] In one embodiment, L is a linker containing 5 to 15 non-hydrogen atoms, where the non-hydrogen atoms are selected from C, N, S, and O, and the linker is -W a -Y or -C(=O)(C1-C6)alkyl-X a optionally substituted with, and -C(=O)(C1-C6)alkyl-X a is optionally substituted with -W b -Y.

[0069] In one embodiment, L is a linker containing a branched or unbranched, saturated or unsaturated hydrocarbon chain having 3 to 15 carbon atoms, where one or more of the carbon atoms are optionally independently -O-, -S, -N(R a)- is replaced by, and the chain is optionally substituted with one or more (e.g., 1, 2, 3, 4, 5 or more) substituents independently selected from (C1-C4) alkyl, (C1-C6) alkoxy, oxo (=O), and halo, each R a is independently H or (C1-C6) alkyl, and the linker is -W a -Y or -C(=O)(C1-C6) alkyl-X a optionally substituted with, and -C(=O)(C1-C6) alkyl-X a is -W b optionally substituted with -Y.

[0070] In one embodiment, L is

Chemical formula

[0071] In one embodiment, the compound of formula I is a compound of formula Ia,

Chemical formula

[0072] In one embodiment, R is H.

[0073] In one embodiment, R is -W a -Y.

[0074] In one embodiment, R is -C(=O)(C1-C6) alkyl-X aand wherein -C(=O)(C1-C6)alkyl-X a is -W b optionally substituted with -Y.

[0075] In one embodiment, L is a linker comprising 5 to 50 non-hydrogen atoms, wherein the non-hydrogen atoms are selected from C, N, S, and O, and the linker is -W a or -C(=O)(C1-C6)alkyl-X a optionally substituted with, and -C(=O)(C1-C6)alkyl-X a is -W b optionally substituted with.

[0076] In one embodiment, L is a linker comprising 5 to 15 non-hydrogen atoms, wherein the non-hydrogen atoms are selected from C, N, S, and O, and the linker is -W a or -C(=O)(C1-C6)alkyl-X a optionally substituted with, and -C(=O)(C1-C6)alkyl-X a is -W b optionally substituted with.

[0077] In one embodiment, L is a linker comprising a branched or unbranched, saturated or unsaturated hydrocarbon chain having 3 to 15 carbon atoms, wherein one or more of the carbon atoms are optionally independently replaced with -O-, -S-, -N(R a )-, and the chain is optionally substituted with one or more (e.g., 1, 2, 3, 4, 5 or more) substituents independently selected from (C1-C4)alkyl, (C1-C6)alkoxy, oxo(=O), and halo, and each R a is independently H or (C1-C6)alkyl, and the linker is -W a or -C(=O)(C1-C6)alkyl-X a optionally substituted with, and -C(=O)(C1-C6)alkyl-X a is -W b optionally substituted with.

[0078] In one embodiment, L is [Chemical formula] and L is -W a or -C(=O)(C1-C6)alkyl-X a optionally substituted with -C(=O)(C1-C6)alkyl-X a is -W b optionally substituted with.

[0079] One embodiment provides an iron complex or a salt thereof comprising a compound of formula Ia, [Chemical formula] wherein R is H, -W a or -C(=O)(C1-C6)alkyl-X a wherein -C(=O)(C1-C6)alkyl-X a is -W b optionally substituted with.

[0080] In one embodiment, R is -W a .

[0081] In one embodiment, R is -C(=O)(C1-C6)alkyl-X a wherein -C(=O)(C1-C6)alkyl-X a is -W b optionally substituted with.

[0082] One embodiment provides an iron complex or a salt thereof comprising a compound of formula Ib, [Chemical formula] wherein R 1 is H, -W b .

[0083] In one embodiment, each W a and W b independently contains 2 to 50 non-hydrogen atoms, and the non-hydrogen atoms are selected from C, N, S, and O.

[0084] In one embodiment, each W a and W b independently includes a branched or unbranched saturated or unsaturated hydrocarbon chain having 1 to 20 carbon atoms, and one or more of the carbon atoms are optionally independently replaced by -O-, -S, -N(R a ), and the chain is optionally substituted with one or more (e.g., 1, 2, 3, 4, 5 or more) substituents independently selected from oxo (C=O), (C1-C4) alkyl, (C1-C6) alkoxy, hydroxy, and halo, and each R a is independently H or (C1-C6) alkyl.

[0085] In one embodiment, each W a and W b independently includes a branched or unbranched saturated or unsaturated hydrocarbon chain having 1 to 20 carbon atoms, and one or more of the carbon atoms are optionally independently replaced by -O-, -S, or -N(R a ), and the chain is optionally substituted with one or more (e.g., 1, 2, 3, 4, 5 or more) substituents independently selected from oxo (C=O), (C1-C4) alkyl, (C1-C6) alkoxy, hydroxy, and halo, and each R a is independently H or (C1-C6) alkyl, and the chain is substituted with one or more reactive groups.

[0086] In one embodiment, each W a and W b independently includes a branched or unbranched saturated or unsaturated hydrocarbon chain having 1 to 10 carbon atoms, and one or more of the carbon atoms are optionally independently replaced by -O-, -S, or -N(R a ), and the chain is optionally substituted with one or more (e.g., 1, 2, 3, 4, 5 or more) substituents independently selected from oxo (C=O), (C1-C4) alkyl, (C1-C6) alkoxy, hydroxy, and halo, and each R a is independently H or (C1-C6) alkyl, and the chain is substituted with one or more reactive groups.

[0087] In one embodiment, each reactive group is independently an amine, a thiol, a hydroxy, an amide or an ester.

[0088] In one embodiment, W a is

Chemical formula

Chemical formula

[0089] In one embodiment, the compound of formula I is a compound of formula Ib,

Chemical formula

[0090] In one embodiment, each W a and W b independently contains 2 to 50 non-hydrogen atoms, and the non-hydrogen atoms are selected from C, N, S, and O.

[0091] In one embodiment, each W a and W b independently contains a branched or unbranched saturated or unsaturated hydrocarbon chain having 1 to 20 carbon atoms, and one or more of the carbon atoms are optionally independently replaced by -O-, -S, -N(R a ), and the chain is optionally substituted with one or more (e.g., 1, 2, 3, 4, 5 or more) substituents independently selected from (C1-C4) alkyl, (C1-C6) alkoxy, hydroxy, and halo, and each R ais independently H or (C1-C6) alkyl.

[0092] In one embodiment, W a is

Chemical formula

Chemical formula

[0093] In one embodiment, W a is

Chemical formula

Chemical formula

[0094] In one embodiment, W a is

Chemical formula

Chemical formula

[0095] In one embodiment, L is

Chemical formula

[0096] In one embodiment, the compound of formula I is a compound of formula Ia’

Chemical formula

[0097] In one embodiment, the compound of formula I is a compound of formula Ib’

Chemical formula

[0098] In one embodiment, the compound of formula I is as follows:

Chemical formula

Chemical formula

[0099] In one embodiment, the compound of formula I is as follows:

Chemical formula

[0100] One embodiment provides a material or device comprising one or more iron complexes or salts thereof described herein. In one embodiment, the material or device is a linker W a or W bis bound to one or more iron complexes or salts thereof.

[0101] One embodiment provides a material or device comprising one or more iron complexes

Chemical formula

[0102] In one embodiment, W a is

Chemical formula

Chemical formula

[0103] One embodiment provides a ligand of Formula II or a salt thereof,

Chemical formula

Chemical formula

[0104] One embodiment provides a ligand of formula II,

Chemical formula

Chemical formula

[0105] One embodiment provides a ligand of formula II, wherein A, L, X a , W a , W bAnd Y are as defined in any of the embodiments or claims provided herein.

[0106] One embodiment provides a compound described herein that does not contain iron atoms

Chemical formula

[0107] One embodiment provides an iron complex comprising a compound of formula Ic

Chemical formula

[0108] One embodiment provides an iron complex comprising a compound of formula Id

Chemical formula

[0109] One embodiment provides an iron complex as described herein, further comprising a weak binding ligand. In one embodiment, the weak binding ligand is fluorescein

[0110] One embodiment provides a method for detecting inorganic phosphate, comprising contacting the phosphate with an iron complex as described herein. In one embodiment, the phosphate is selectively detected in the presence of other anions. In one embodiment, the anion is selected from the group consisting of carbonate, nitrate, sulfate, halide, arsenate and pyrophosphate. In one embodiment, the phosphate contacts the iron complex as a liquid sample at a nearly neutral pH. In one embodiment, the liquid sample is obtained from an aqueous environment. In one embodiment, the liquid sample is an eutrophic sample. In one embodiment, the phosphate is detected by fluorescence sensing by an indicator displacement assay

[0111] One embodiment provides a method for removing inorganic phosphate from an aqueous mixture or aqueous solution, which includes contacting the aqueous mixture or aqueous solution with an iron complex described herein. One embodiment provides a method for sequestering or removing inorganic phosphate from an aqueous mixture or aqueous solution, which includes contacting the aqueous mixture or aqueous solution with an iron complex described herein. One embodiment provides a method for removing inorganic phosphate from an aqueous mixture or aqueous solution, which includes contacting the aqueous mixture or aqueous solution with an iron complex described herein under conditions such that the phosphate binds to the iron complex and is partially or completely removed from the aqueous mixture or aqueous solution. One embodiment provides a method for sequestering or removing inorganic phosphate from an aqueous mixture or aqueous solution, which includes contacting the aqueous mixture or aqueous solution with an iron complex described herein under conditions such that the phosphate binds to the iron complex and is partially or completely removed from the aqueous mixture or aqueous solution.

[0112] The present invention will be described by the following non-limiting examples.

Examples

[0113] Example 1. Experimental section Unless otherwise specified, all chemicals were purchased from commercial suppliers and used without further purification. The heavy solvents were obtained from Cambridge Isotope Laboratories (Tewskbury, MA, USA). Distilled water was obtained from a Millipore Simplicity UV system (resistivity 18×10 6It was further purified by (Ω). All organic extracts were dried over anhydrous MgSO4 (plural available). NaF, NaCl, NaBr, NaI, Na2SO4, NaNO3, NaHCO3, NaOAc, Na4P2O7, and Na2HAsO4·7H2O were used for the anion screening test. Flash chromatography was carried out on Merck Silica Gel. The silica gel in 37% HCl (aqueous solution) was heated at 50 °C for 6 hours, and it was further washed with deionized water until the pH of the filtrate became neutral, and it was dried at 100 °C under reduced pressure to prepare a modified silica gel. The collected silica gel was then suspended in toluene together with 1% (v / v) hexadecyltrimethoxysilane. After stirring the mixture at 100 °C for 6 hours, the mixture was filtered, rinsed with toluene and ethyl acetate, and dried at 100 °C under reduced pressure. 1 1H NMR spectra and 13 13C NMR spectra were recorded at room temperature in the LeClaire-Dow Instrumentation Laboratory of the Department of Chemistry, University of Minnesota, on a Bruker Advance III 400 at 400 MHz and 100 MHz, respectively, or on a Bruker Advance III AV 500 at 500 MHz and 125 MHz, respectively. The peaks of the residual solvents were used as internal references. 1 The 1H NMR data were recorded as follows: chemical shift (δ, ppm), multiplicity (s = singlet, d = doublet, t = triplet, q = quartet, br = broad, m = multiplet), coupling constant (Hz), integration. 13The 13C NMR data were recorded as follows: chemical shift (δ, ppm). Low-resolution (LR) and high-resolution (HR) electrospray ionization time-of-flight mass spectrometry (ESI / TOF-MS) were recorded on a Bruker BioTOF I in the LeClair-Dow Instrumentation Laboratory of the Department of Chemistry, University of Minnesota. The UV-visible spectra were recorded on a Varian Cary 100 Bio spectrophotometer. The data were collected over the range of 200 - 800 nm. The luminescence data were acquired on a Varian Cary Eclipse fluorescence spectrophotometer using a quartz cell with a path length of 1 cm and a cell volume of 400 μL. The sample solutions were equilibrated for 5 minutes prior to the measurement of their luminescence spectra, and in initial studies, this time was demonstrated to be sufficient to achieve thermodynamic equilibrium (Figures 17 and 18). All fluorescence titration data were acquired at room temperature (T = 25 °C). Each data point was measured three times from three separately prepared samples. For fluorescence titrations or anion selectivity tests, 5 mM anions were prepared in water and the pH was adjusted to 7 using 0.1 N HCl or 0.1 N NaOH. Wet ethanol indicates that the water content in ethanol is 10 (v / v)% or less. The luminescence data were processed with Scilab 6.0.2 and QtiPlot 0.9.8.9 software. All pH measurements were performed using a Thermo Scientific Ag / AgCl refillable probe and a Thermo Orion 3 Benchtop pH meter. High-performance liquid chromatography (HPLC) data were collected on a Varian Prostar model 210 combined with an Agilent FORBAX Eclipse XDB-C18 column and a Varian ProStar 335 diode array detector. Unless otherwise specified, HPLC measurements were performed at a flow rate of 1.0 mL min -1 and were carried out under the following elution conditions: from 0 - 10 minutes, 15% CH3CN / 85% water, followed by a linear gradient from 10 - 23 minutes to 85% CH3CN / 15% water, and from 23 - 45 minutes, 85% CH3CN / 15% water.

[0114] Synthesis 4-Nitrophenyl 1-(benzyloxy)-6-oxo-1,6-dihydropyridine-2-carboxylate (3). The p-nitrophenyl activated ester was prepared by referring to a similar procedure for the preparation of the podant's N-hydroxysuccinimidyl ester (F. Guerard, M. Beyler, Y.-S. Lee, R. Tripier, J.-F. Gestin, M. W. Brechbiel, Dalton Trans. 2017, 46, 4749-4758). HOPO(Bn)-OH (1000 mg, 4.080 mmol) was suspended in anhydrous methylene chloride (10 mL) under an N2 atmosphere, followed by the addition of oxalyl chloride (400 μL, 4.90 mmol), and 1 drop of DMF was added dropwise. After stirring the reaction mixture at room temperature for 1 h, the solvent, HCl, and excess oxalyl chloride were removed under high vacuum using a liquid N2 trap. Under an N2 atmosphere, the residue was dissolved in 10 mL of anhydrous methylene chloride. After adding p-nitrophenol (568 mg, 4.08 mmol) to the solution, the mixture was cooled in an ice bath, and NEt3 (900 μL, 6.10 mmol) was slowly injected into the mixture. The mixture was then warmed to room temperature over 6 h, and then washed with 10% citric acid solution and 10% sodium bicarbonate solution, dried over anhydrous MgSO4 (plural available), and concentrated under vacuum to obtain a viscous liquid. This crude product was purified by silica flash chromatography eluting with 60% EtOAc / 20% Hex to obtain white solid 3 (1.363 g, 91%). 1 1H NMR (400 MHz, CDCl3): δ 8.29 (d, J = 9 Hz, 2H), 7.49 (d, J = 6 Hz, 2H), 7.41 - 7.26 (m, 6H), 6.94 (d, J = 9 Hz, 1H), 6.79 (d, J = 7 Hz, 1H), 5.42 (s, 2H). 13 13C NMR (100 MHz, CDCl3): δ 158.6, 157.2, 154.4, 145.8, 137.1, 136.9, 133.3, 130.2, 129.4, 128.6, 127.6, 125.3, 122.2, 109.4, 78.8. ESI-HRMS: m / z = 389.0755 ([M+Na] + ), (calculated 389.0744).

[0115] N,N’-(Azanediylbis(ethane-2,1-diyl))bis(1-(benzyloxy)-6-oxo-1,6-dihydropyridine-2-carboxamide) (4). The p-nitrophenol activated ester 3 (808 mg, 2.207 mmol) was dissolved in 20 mL of methylene chloride, followed by the slow injection of diethylenetriamine (119 μL, 1.10 mmol) and NEt3 (300. μL, 2.21 mmol). The reaction mixture was stirred at room temperature for 1 hour. The mixture was washed with 20 mL of 1N NaOH solution, dried over anhydrous MgSO4 (plural available), and concentrated under vacuum to obtain a viscous liquid. This crude product was purified by silica flash chromatography eluting with 12% MeOH / 88% CH2Cl2 to give the foaming liquid 4 (1.045 g, 85%). 1 1H NMR (400 MHz, CDCl3): δ 7.59 (br, 2H), 7.35 - 7.22 (m, 10H), 7.14 (dd, J1 = 9 Hz, J2 = 7 Hz, 2H), 6.36 (d, J = 9 Hz, 2H), 6.21 (d, J = 7 Hz, 2H), 5.18 (s, 4H), 3.14 (d, J = 10 Hz, 4H), 2.51 - 2.48 (m, 4H), 1.62 (br, 1H). 13 13C NMR (100 MHz, CDCl3): δ 160.4, 158.3, 143.0, 138.3, 133.3, 129.6, 129.0, 128.3, 123.0, 105.6, 78.9, 47.1, 39.3. ESI-HRMS: m / z = 580.2156 ([M+Na] + ), (calculated value 580.2167).

[0116] N,N’-(Azanediylbis(ethane-2,1-diyl))bis(1-hydroxy-6-oxo-1,6-dihydropyridine-2-carboxamide) HBr (5). Protected ligand 4 (200 mg, 0.359 mmol) was dissolved in 1 mL of glacial acetic acid, and 1 mL of 30% HBr was added to the reaction mixture. After 6 hours, acetic acid and HBr were removed under high vacuum to obtain a foamy liquid. This crude product was purified by modified silica flash chromatography eluting with a gradient from 0% MeOH / 100% H2O to 5% MeOH / 95% H2O to give white foamy liquid 5 (150 mg, 91%). 1 1H NMR (400 MHz, CF3COOD): δ 7.80 (t, J = 8 Hz, 2H), 7.52 (d, J = 8 Hz, 2H), 7.30 (d, J = 9 Hz, 2H), 4.00 (br, 4H), 3.65 (br, 4H). 13 13C NMR (100 MHz, CF3COOD): δ 165.4, 160.1, 141.4, 138.0, 121.9, 118.6, 51.6, 40.0. ESI-HRMS: m / z = 378.1310 ([M−Br] + ), (calculated 378.1408).

[0117] Fe III -HOPO-fluo (1). Ligand 5 (5.0 mg, 0.011 mmol) and fluorescein (3.6 mg, 0.011 mmol) were suspended in anhydrous EtOH (10 mL), followed by injection of 1N NaOH (22 μL, 0.022 mmol). Then, 0.1N ethanolic FeBr3 (110 μL, 0.011 mmol) was added to the reaction mixture. The purity and identity of the in situ formed Fe III -HOPO-fluo were characterized by HPLC and ESI-HRMS. The solution was used without further purification. ESI-HRMS: m / z = 763.1138 ([M−Br] + ), (calculated 763.1208).

[0118] 3-(2-(Benzyloxy)phenyl)propanoic acid (6). The benzyl-protected side arm 6 was prepared according to the reported procedure [2]Synthesized according to the procedure and characterized by NMR and ESI-HRMS. 1 H NMR (400 MHz, CDCl3): δ 11.05 (br, 1H), 7.46 - 7.32 (m, 5H), 7.26 - 7.19 (m, 2H), 6.94 - 6.90 (m, 2H), 5.12 (s, 2H), 3.04 (t, J = 8 Hz, 2H), 2.72 (t, J = 8 Hz, 2H). 13 C NMR (100 MHz, CDCl3): δ 179.6, 156.5, 137.2, 130.1, 128.8, 128.6, 127.8, 127.7, 127.0, 120.8, 111.6, 69.8, 34.0, 25.9. ESI-HRMS: m / z = 279.1009 ([M+Na] + ), (calculated value 279.0992).

[0119] 1-(Benzyloxy)-N-(2-(N-(2-(1-(benzyloxy)-6-oxo-1,6-dihydropyridine-2-carboxamido)ethyl)-3-(2-(benzyloxy)phenyl)propanamido)ethyl)-6-oxo-1,6-dihydropyridine-2-carboxamide (7). Protected arm 6 (316 mg, 1.23 mmol) was suspended in anhydrous methylene chloride (10 mL) under N2 atmosphere, followed by injection of oxalyl chloride (0.1 mL, 1.4 mmol), and 1 drop of DMF was added dropwise. After stirring the reaction mixture at room temperature for 1 h, the solvent, HCl, and excess oxalyl chloride were removed by high vacuum using a liquid N2 trap. Under N2 atmosphere, the residue was dissolved in 10 mL of anhydrous methylene chloride and cooled in an ice bath. The protected ligand 4 (687 mg, 1.23 mmol) was dissolved in anhydrous methylene chloride (5 mL) and slowly injected into the cooled reaction mixture. Then, NEt3 (344 μL, 2.47 mmol) was injected into the mixture. The mixture was then warmed to room temperature for 1 h, then washed with 10% citric acid solution, dried over anhydrous MgSO4 (multiple), and concentrated under vacuum to obtain a viscous liquid. This crude product was purified by silica flash chromatography eluting with 4% MeOH / 96% CH2Cl2 to give white foamy liquid 7 (805 mg, 82%). 11H NMR (400 MHz, CDCl3): δ 7.48 - 7.46 (m, 2H), 7.41 - 7.36 (m, 5H), 7.34 - 7.27 (m, 9H), 7.25 - 7.21 (m, 2H), 7.13 - 7.09 (m, 2H), 6.94 (br, 1H), 6.89 - 6.82 (m, 3H), 6.68 (dd, J1 = 1 Hz, J2 = 8 Hz, 2H), 6.24 (t, J = 2 Hz, 1H), 6.23 (t, J = 2 Hz, 1H), 5.32 (s, 2H), 5.24 (s, 2H), 5.02 (s, 2H), 3.31 (br, 4H), 3.06 (br, 4H), 2.88 (t, J = 7 Hz, 2H), 2.48 (t, J = 8 Hz, 2H). 13 13C NMR (100 MHz, CDCl3): δ 174.3, 160.7, 160.6, 158.5, 158.4, 156.5, 142.8, 142.2, 138.0, 137.9, 137.0, 133.5, 133.1, 130.3, 130.1, 129.5, 129.1, 128.60, 128.55, 128.50, 128.0, 127.7, 127.3, 124.1, 120.8, 111.6, 105.9, 105.2, 79.3, 79.0, 69.9, 47.40, 45.7, 39.3, 38.7, 32.8, 26.9. ESI - HRMS: m / z = 818.3181 ([M + Na] + ), (calcd 818.3160).

[0120] 1 - Hydroxy - N-(2-(N-(2-(1 - hydroxy - 6 - oxo - 1,6 - dihydropyridine - 2 - carboxamido)ethyl)-3-(2 - hydroxyphenyl)propanamido)ethyl)-6 - oxo - 1,6 - dihydropyridine - 2 - carboxamide (8). Protected ligand 7 (450 mg, 0.566 mmol) was dissolved in 1 mL of glacial acetic acid and 1 mL of 30% HBr was added to the reaction mixture. After 6 h, acetic acid and HBr were removed under high vacuum to give a foamy liquid. The crude product was purified by modified silica flash chromatography eluting with a gradient from 0% MeOH / 100% H2O to 5% MeOH / 95% H2O to give white foamy liquid 8 (270 mg, 91%). 11H NMR (500 MHz, CD3OD): δ 7.48 - 7.42 (m, 2H), 7.04 (d, J = 7 Hz, 1H), 6.97 (dd, J1 = 1 Hz, J2 = 8 Hz, 2H), 6.75 - 6.68 (m, 4H), 6.61 (dd, J1 = 1 Hz, J2 = 7 Hz, 1H), 6.56 (dd, J1 = 1 Hz, J2 = 7 Hz, 1H), 3.65 - 3.61 (m, 4H), 3.56 - 3.54 (m, 4H), 2.88 (t, J = 7 Hz, 2H), 2.75 (t, J = 8 Hz, 2H). 13 13C NMR (125 MHz, CD3OD): δ 176.5, 162.8, 162.7, 160.2, 160.1, 156.5, 142.0, 141.7, 139.0, 138.8, 131.5, 128.7, 120.94, 120.85, 116.4, 108.7, 108.5, 48.3, 46.3, 39.4, 39.0, 34.7, 27.6. ESI - HRMS: m / z = 524.1775 ([M - H] - ), (calculated value 524.1776).

[0121] Fe III -HOPO-PhO-fluo(2). Ligand 8 (5.0 mg, 9.5 μmol) and fluorescein (3.6 mg, 9.5 μmol) were suspended in anhydrous EtOH (10 mL), and then 1N NaOH (29 μL, 29 μmol) was injected. Subsequently, 0.1N ethanolic FeBr3 (95 μL, 9.5 μmol) was added to the reaction mixture. The Fe III -HOPO-PhO-fluo formed in situ was characterized by HPLC and ESI - HRMS. The solution was used without further purification. ESI - HRMS: m / z = 911.1830 ([M + 3H] + ), (calculated value 911.1733).

[0122] Data fitting Fe III -complex + Pi data fitting used the following equation:

Equation

Number

Number

Table S1

[0123] Discussion Receptor Fe III -HOPO - fluo and Fe III -HOPO - PhO - fluo were synthesized according to Schemes 1 and 2, respectively. The p - nitrophenol activated ester of benzyl - protected HOPO podand 3, synthesized previously according to the prior examples in the literature, selectively acylates the primary amino group of the triamine skeleton to obtain the protected ligand 4. Deprotection under strongly acidic conditions gives the final ligand 5. This is further metallated with Fe 39 in the presence of fluorescein to obtain the final receptor Fe III -HOPO - fluo. III

[0124] Scheme 1 Synthesis of Fe III -HOPO - PhO - fluor a ​​[Chemistry]

[0125] Scheme 2 Fe III -HOPO-fluor a Synthesis [Chemistry]

[0126] Fe III -HOPO-PhO-fluo uses a pentadentate ligand in which the phenolate moiety occupies another coordination site at the Fe III center. The benzyl-protected phenol podand 6, previously synthesized according to the literature report 40 , was activated with oxalyl chloride, enabling coupling to the central secondary amine of 4, thereby yielding the protected ligand 7. Deprotection under strongly acidic conditions gave the final ligand 8. This was further metallated with Fe III in the presence of fluorescein to give the final receptor Fe III -HOPO-PhO-fluo2.

[0127] In both syntheses, the formation and purity of the ternary complexes 1 and 2 were confirmed by HPLC and ESI-MS (Figs. 5, 7, 8, and 10). The μ-oxo diiron dimer was not detected, and it was confirmed that the coordination of the fluorescein ligand is sufficient to protect the Fe III center and prevent the formation of the dimetal species. In contrast, in the absence of fluorescein, the μ-oxo diiron dimer was the dominant species observed by MS. The significant line broadening (Figs. 6 and 9) observed by 1H NMR of the ternary complexes in solution, typical of paramagnetic Fe(III) species, further supported the coordination of fluorescein to the receptors 1 and 2. The Fe 1 ·fluorescein complexes were both stable as solids and in ethanol for several weeks. Both could tolerate up to 10 vol% water adjusted to pH 7 without significant dissociation of fluorescein (<1%) in ethanol. III The Fe·fluorescein complexes were both stable as solids and in ethanol for several weeks. Both could tolerate up to 10 vol% water adjusted to pH 7 without significant dissociation of fluorescein (<1%) in ethanol.

[0128] Direct coordination of phosphate to the iron center of the receptor with replacement of the fluorescein moiety upon addition of the oxoanion was first confirmed from attenuated total reflection infrared (ATR-IR) spectroscopy of the precipitate obtained from Fe III -HOPO-fluo + Pi and Fe III -HOPO-PhO-fluo + Pi. The iron complex Fe III -HOPO-Pi shows characteristic ν(Fe-O) vibrations at 571 and 461 cm -1 and ν(P-O) bands at 1088, 1067, 968 cm -1 and a δ(O-P-O) band at (541) cm -1 (Figure 2A). 41-44 Each of these bands was also observed for the Fe III -HOPO-PhO-Pi adduct (Figure 11). These observations are consistent with the formation of the postulated ternary complex.

[0129] Fe III The formation of the L·Pi ternary complex was also supported by NMR spectroscopy. The III P NMR spectrum of Fe 31 -HOPO-Pi is almost featureless (Figure 12), an observation that results from shortening of the transverse relaxation time T2 of the III P nuclei by the strong paramagnetic Fe 31 . As is evident in Figure 2B, referring to an external standard of H3PO4, in the titration monitored by NMR, the 31 P signal of phosphate gradually downfields from 1.61 to 4.72 ppm upon successive addition of Fe III -HOPO-fluo (1). This shift is accompanied by a significant broadening of the line corresponding to a decrease in T2 of the phosphorus nucleus from 0.11 s (without Fe III -HOPO-fluo) to 1.95 ms (1 equivalent of Fe III -HOPO-fluo). Both of these observations are due to coordination of orthophosphate to the strong paramagnetic Fe III center. 45、46 Notably, 31The presence of a single peak in P also suggests the existence of a rapid equilibrium between bound and free phosphate. Using a pentadentate ligand, Fe III -HOPO-PhO-fluo(2) shows behavior similar to the coordination of phosphate to the Fe 31 center, as confirmed by both ATR-IR and III P NMR spectra (Figures 11 and 12, respectively). Unfortunately, further attempts to characterize the ternary phosphate complexes by mass spectrometry were unsuccessful due to their low solubility and known ability to suppress the ionization of phosphate. 47、48

[0130] The indicator displacement assay (IDA) was evaluated by both UV-visible and fluorescence spectroscopy. Upon the gradual addition of 1 equivalent of orthophosphate, a 20-fold turn-on fluorescence was observed (Figure 3A). Fluorescence titrations of both receptors (Figures 3 and 19) best fit a 1:1 binding model from which the equilibrium constants were derived (Table 1). This 1:1 stoichiometry was determined by first evaluating the goodness of fit of the titration and then confirmed by Job's plot (Figures 15 for Fe III -HOPO-fluo and Figure 16 for Fe III -HOPO-PhO-fluo, respectively). Interestingly, the use of the tetradentate ligand in Fe III -HOPO-fluo does not seem to favor the coordination of two phosphate anions to the metal center. The two receptors show similar turn-on responses (20-fold at 1 equivalent) and similar equilibrium constants for phosphate: 8.8 × 10 III M 5 for Fe -1 -HOPO-fluo and 1.1 × 10 III M 6 for Fe -1This similarity in both the turn-on response and the apparent equilibrium constant may be attributed to the equivalent core structures of both receptors. Interestingly, the additional two phenolate podands in 2 do not seem to affect the displacement of the fluorescein moiety by phosphate. Similar effects are expected for the possible coordinating solvent molecules.

[0131] Two Fe, generally estimated to be three times the standard deviation of the measurement III The detection limits (LOD) (3σ) of phosphate by the receptors are 3.5 μM for Fe III -HOPO-fluo(1) and 4.1 μM for Fe III -HOPO-PhO-fluo(2) (Table S1). Although not as sensitive as the previous Eu III probes, these iron receptors have sufficient sensitivity to detect the problematic phosphate levels in eutrophic samples (2 - 10 μM). 21、22 49、50 49、50

Table 1

[0132] The selectivity of the two iron receptors for phosphate, which is higher than that of the competing anions commonly found in environmental samples, was also evaluated by fluorescence spectroscopy. As shown by the white bars in Figure 4, the fluorescence intensities of both probes are not affected by the addition of 1 equivalent of common competing anions including halides, sulfates, and nitrates. Subsequently, the addition of 1 equivalent of phosphate restores the emission of the indicator (Figure 4, gray bars), further indicating that these competing anions do not interfere with the detection of phosphate. Interestingly, Fe III -HOPO-fluo is more selective for bicarbonate and acetate than Fe III -HOPO-PhO-fluo. Thus, it does not seem that the more sterically hindered recognition sites lead to higher selectivity for the targeted anion.

[0133] Uniquely and importantly, Fe III-HOPO-fluo(1) and Fe III Both -HOPO-PhO-fluo(2) and -HOPO-fluo(1) are selective for phosphate over pyrophosphate. While numerous probes selective for pyrophosphate over phosphate have been described in the literature, 39-41 complexes 1 and 2 are thought to be unique in that they have the opposite selectivity for phosphate over pyrophosphate. This selectivity may be due to the preferred bidentate binding mode of pyrophosphate and may be due to steric hindrance at the coordination site. 51、52 Since there is only one replaceable fluorescein, bidentate binding is not preferred. Arsenate, a somewhat softer anion, also does not displace fluorescein despite being structurally similar to phosphate. This is an unusual selectivity given that most metal probes for phosphate also respond to arsenate. 7 Thus, these fluorescent iron(III) probes offer a unique ability to rapidly monitor the levels of phosphate, the most important phosphorus species causing nutrient pollution in surface waters.

[0134] Summary Herein, non-heme iron(III) complexes containing Fe III -HOPO-fluo and Fe III -HOPO-PhO-fluo are described for the selective recognition of inorganic phosphate. This is demonstrated by an indicator displacement assay. The open coordination site is sufficiently protected by weakly coordinating fluorescein to prevent dimerization in aerated solutions. Coordination of inorganic phosphate in combination with substitution of the fluorescein moiety increases the emission of the fluorescein moiety by 20-fold. Uniquely, these probes are distinguished from other receptors that function by direct metal coordination in that they are highly selective for phosphate over pyrophosphate. They are also more selective than common competing endogenous anions such as carbonate, nitrate, sulfate, halides, and unusually arsenate. Each of Fe III -HOPO-fluo and Fe IIIThe detection limits of the iron(III) receptors, which are 3.5 and 4.1 μM for -HOPO-PhO-fluo, enable the detection of phosphate typical of eutrophic water samples. Based on this, two iron(III) probes enable the rapid and easy detection of phosphate in eutrophic samples. These are thought to be the first examples using non-heme Fe III -based molecular receptors. Thus, these results provide the use of inorganic phosphate probes containing iron, an economically abundant element on Earth.

[0135] References of the document (1)National Oceanic and Atmospheric Administration. What is eutrophication? https: / / oceanservice.noaa.gov / facts / eutrophication.html(accessed Nov 9,2020). (2)Bricker,S.B.Effects of Nutrient Enrichment in the Nation’s Estuaries:A Decade of Change:National Estuarine Eutrophication Assessment Update;NOAA Coastal Ocean Program decision analysis series;no.26;328;Silver Spring,MD,2007. (3)5.6 Phosphorus|Monitoring&Assessment|US EPA https: / / archive.epa.gov / water / archive / web / html / vms56.html(accessed Nov 23,2020). (4)Boyd,C.E.Water Quality:An Introduction,3rd ed.;Springer International Publishing,2020. (5)Rice, E.W.; Baird, R.B.; Eaton, A.D. Standard Methods for the Examination of Water and Wastewater, 23rd ed.; American Public Health Association, American Water Works Association, Water Environment Federation, 2017. (6)Sundareshwar, P.V.; Morris, J.T.; Pellechia, P.J.; Cohen, H.J.; Porter, D.E.; Jones, B.C. 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Biometals 2018, 31(6), 1091-1099

[0136] Any publication, patent, and patent application are hereby incorporated by reference as if individually incorporated by reference. The present invention has been described with reference to various specific and preferred embodiments and techniques. However, it should be understood that many variations and modifications may be made while remaining within the spirit and scope of the present invention.

Claims

1. An iron complex containing a compound of Formula I 【Chemical 54】 or a salt thereof. (Wherein, Fe is Fe ＩＩ Or Fe ＩＩＩ and Each 【Chemical Formula 55】 The moiety is independently a pyridinone substituted with one hydroxy or -O － and wherein the pyridinone is optionally substituted with one or more (C １ -C ６ ) alkyl; Each dashed bond is independently a single bond or a double bond, L is a linker, and the linker is -W ａ or -C(=O)(C １ -C ６ alkyl-X ａ optionally substituted with, and said -C(=O)(C １ -C ６ alkyl-X ａ optionally substituted with -W ｂ and X ａ is phenyl substituted with hydroxy or -O － and W ａ is a linker ａ group, and W ｂ is a linker ｂ group. )

2. The iron complex according to Claim 1, containing a compound of Formula I 【Chemical 56】 or a salt thereof. (wherein Fe is Fe ＩＩ or Fe ＩＩＩ and) Each 【Chemical 57】 The moiety is independently a pyridinone substituted with one hydroxy or -O － and wherein the pyridinone is optionally substituted with one or more (C １ -C ６ ) alkyl, Each dashed bond is independently a single bond or a double bond, L is a linker, and the linker is -W ａ -Y or -C(=O)(C １ -C ６ )alkyl-X ａ optionally substituted with, and the -C(=O)(C １ -C ６ )alkyl-X ａ is optionally substituted with -W ｂ -Y, X ａ is phenyl substituted with hydroxy or -O － and W ａ is a linker ａ group and W ｂ is a linker ｂ group, and Y is a polymer, hydrogel, membrane, nanoparticle, or material. )

3. the linker ａ group and the linker ｂ group is further optionally substituted with Y, wherein Y is a polymer, hydrogel, membrane, nanoparticle, or material, the iron complex according to claim 1.

4. Each 【Chemical Formula 58】 Each moiety is independently 【Chemical Formula 59】 selected from the group consisting of Each R ａ is independently (C １ -C ６ ) alkyl, the iron complex according to claim 1.

5. Each 【Chemical Formula 60】 Each moiety 【Chemical Formula 61】 is the iron complex according to Claim 1.

6. Each 【Chemical 62】 Each moiety 【Chemical Formula 63】 is the iron complex according to Claim 1.

7. Each 【Chemical Formula 64】 Each moiety 【Chemical Formula 65】 is the iron complex according to Claim 1.

8. Each 【Chemical Formula 66】 Each moiety 【Chemical 67】 is the iron complex according to Claim 1.

9. Each 【Chemical Formula 68】 Each moiety 【Chemical Formula 69】 is the iron complex according to Claim 1.

10. L is a linker containing 5 to 50 non-hydrogen atoms, the non-hydrogen atoms being selected from halo, C, N, S, and O, and the linker being -W ａ or -C(=O)(C １ -C ６ )alkyl-X ａ optionally substituted with, and the -C(=O)(C １ -C ６ )alkyl-X ａ being optionally substituted with -W ｂ The iron complex according to any one of claims 1 to 9.

11. L is a linker containing 5 to 15 non-hydrogen atoms, the non-hydrogen atoms are selected from halo, C, N, S, and O, and the linker is -W ａ or -C(=O)(C １ -C ６ )alkyl-X ａ optionally substituted with, and the -C(=O)(C １ -C ６ )alkyl-X ａ is optionally substituted with -W ｂ The iron complex according to any one of claims 1 to 9.

12. L is a linker comprising a branched or unbranched, saturated or unsaturated hydrocarbon chain having 3 to 15 carbon atoms, one or more of said carbon atoms being optionally and independently replaced by -O-, -S-, -N(R ａ ), the chain being optionally substituted by one or more (e.g., 1, 2, 3, 4, 5 or more) substituents independently selected from (C １ -C ４ )alkyl, (C １ -C ６ )alkoxy, oxo(=O), and halo, each R ａ being independently H or (C １ -C ６ )alkyl, the linker being optionally substituted by -W ａ or -C(=O)(C １ -C ６ )alkyl-X ａ , said -C(=O)(C １ -C ６ )alkyl-X ａ being optionally substituted by -W ｂ , the iron complex according to any one of claims 1 to 9.

13. L is 【Chemical Formula 70】 and L is -W ａ or -C(=O)(C １ -C ６ )alkyl-X ａ optionally substituted, and the -C(=O)(C １ -C ６ )alkyl-X ａ is optionally substituted with -W ｂ and n is 0 or 1. The iron complex according to any one of claims 1 to 9

14. The iron complex according to Claim 1, containing a compound of Formula Ia' 【Chemical 71】 or a salt thereof. (wherein n is 0 or 1, and R is H, -W ａ , or -C(=O)(C １ -C ６ )alkyl-X ａ and the -C(=O)(C １ -C ６ )alkyl-X ａ is optionally substituted with -W ｂ ).)

15. The iron complex according to Claim 14, wherein R is H.

16. R is -W ａ The iron complex according to claim 14, wherein R is -W

17. R is -C(=O)(C １ -C ６ )alkyl-X ａ and the -C(=O)(C １ -C ６ )alkyl-X ａ is optionally substituted with -W ｂ The iron complex according to claim 14.

18. The iron complex according to Claim 1, containing a compound of Formula Ib' 【Chemical Formula 72】 or a salt thereof. (wherein n is 0 or 1, and R １ is H or -W ｂ .)

19. Each W ａ and W ｂ independently contains 2 to 50 non-hydrogen atoms, and the non-hydrogen atoms are selected from halo, C, N, S, and O. The iron complex according to any one of claims 1 to 14 or 16 to 18.

20. Each W ａ and W ｂ independently contains a branched or unbranched saturated or unsaturated hydrocarbon chain having 1 to 20 carbon atoms, and one or more of said carbon atoms are optionally independently replaced by -O-, -S-, -N(R ａ ), and said chain is optionally substituted by one or more (e.g., 1, 2, 3, 4, 5 or more) substituents independently selected from oxo (C=O), (C １ -C ４ )alkyl, (C １ -C ６ )alkoxy, hydroxy, and halo, and each R ａ is independently H or (C １ -C ６ )alkyl, the iron complex according to any one of claims 1 to 14 or 16 to 18.

21. Each W ａ and W ｂ independently contains a branched or unbranched saturated or unsaturated hydrocarbon chain having 1 to 20 carbon atoms, and one or more of said carbon atoms are optionally independently replaced by -O-, -S, or -N(R ａ ), and the chain is optionally substituted with one or more (e.g., 1, 2, 3, 4, 5 or more) substituents independently selected from oxo (C=O), (C １ -C ４ )alkyl, (C １ -C ６ )alkoxy, hydroxy, and halo, each R ａ is independently H or (C １ -C ６ )alkyl, and the chain is substituted with one or more reactive groups, the iron complex according to any one of claims 1 to 14 or 16 to 18.

22. Each W ａ and W ｂ independently includes a branched or unbranched saturated or unsaturated hydrocarbon chain having 1 to 10 carbon atoms, and one or more of said carbon atoms are optionally independently replaced by -O-, -S, or -N(R ａ ), and the chain is optionally substituted with one or more (e.g., 1, 2, 3, 4, 5 or more) substituents independently selected from oxo (C=O), (C １ -C ４ )alkyl, (C １ -C ６ )alkoxy, hydroxy, and halo, each R ａ is independently H or (C １ -C ６ )alkyl, and the chain is substituted with one or more reactive groups. The iron complex according to any one of claims 1 to 14 or 16 to 18.

23. The iron complex according to Claim 21 or 22, wherein each reactive group is independently an amine, thiol, hydroxy, amide, or ester.

24. W ａ is 【Chemical 73】 and W ｂ is 【Chemical 74】 being R is H or (C １ -C ６ ) alkyl, and n is 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, the iron complex according to any one of Claims 1 to 14 or 16 to 18.

25. The compound of Formula I is: 【Chemical 75】 or a salt thereof, the iron complex according to Claim 1.

26. A material or device containing one or more iron complexes according to any one of Claims 1 to 25 or a salt thereof.

27. The material or device, linker W ａ or W ｂ bonded thereto, the material or device according to claim 26.

28. 【Fig. 76】 The material or device according to Claim 26 or 27, containing one or more iron complexes or a salt thereof selected from

29. W ａ is 【Chemical 77】 and W ｂ is 【Chemical 78】 being, and n is 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, the iron complex or a salt thereof according to any one of Claims 26 to 28.

30. The compound of Formula I is 【Chemical 79】 or a salt thereof, the iron complex or a salt thereof according to Claim 2.

31. The compound of Formula I is 【Chemical Formula 80】 or a salt thereof, the iron complex according to Claim 1.

32. The iron complex according to any one of Claims 1 to 31, further containing a weak binding ligand.

33. The iron complex according to claim 32, wherein the weak binding ligand is fluorescein.

34. A method for detecting the phosphate, comprising contacting an inorganic phosphate with the iron complex according to any one of claims 1 to 33.

35. The method according to claim 34, wherein the phosphate is selectively detected in the presence of other anions.

36. The method according to claim 35, wherein the other anion is selected from the group consisting of carbonate, nitrate, sulfate, halide, arsenate, and pyrophosphate.

37. The method according to any one of claims 34 to 36, wherein the phosphate contacts the iron complex as a liquid sample at a substantially neutral pH.

38. The method according to claim 37, wherein the liquid sample is a sample obtained from a water area.

39. The method according to claim 37 or 38, wherein the liquid sample is a eutrophic sample.

40. The method according to any one of claims 34 to 39, wherein the phosphate is detected by fluorescence sensing by an indicator displacement assay.

41. A method for removing an inorganic phosphate from the aqueous mixture or aqueous solution, comprising contacting the aqueous mixture or aqueous solution with the iron complex according to any one of claims 1 to 33.

42. The method according to claim 41, wherein the aqueous mixture or aqueous solution is wastewater.

43. A method for treating hyperphosphatemia in a mammal in need of treatment for hyperphosphatemia, comprising contacting blood of the mammal in need of treatment for hyperphosphatemia with the iron complex according to any one of claims 1 to 33.

44. The method according to claim 43, wherein the mammal has chronic kidney disease.

45. The ligand of formula II. 【Chemical Formula 81】 (wherein each 【Chemical 82】 The moiety is independently a pyridinone substituted with one hydroxy or -O － and wherein the pyridinone is optionally substituted with one or more (C １ -C ６ ), L is a linker, and the linker is -W ａ -Y or -C(=O)(C １ -C ６ )alkyl-X ａ optionally substituted with, and the -C(=O)(C １ -C ６ )alkyl-X ａ is optionally substituted with -W ｂ -Y, X ａ is phenyl substituted with hydroxy or -O － and W ａ is a linker ａ group, and W ｂ is a linker ｂ group, and Y is a polymer, hydrogel, membrane, nanoparticle, or material.)

46. The ligand of formula II. 【Chemical 83】 (each 【Chemical 84】 The moiety is independently a pyridinone substituted with one hydroxy or -O － and wherein the pyridinone is optionally substituted with one or more (C １ -C ６ ) alkyl; L is a linker, and the linker is -W ａ or -C(=O)(C １ -C ６ )alkyl-X ａ optionally substituted with, and the -C(=O)(C １ -C ６ )alkyl-X ａ is optionally substituted with -W ｂ and X ａ is phenyl substituted with hydroxy or -O － and W ａ is a linker ａ group and W ｂ is a linker ｂ group.)

47. A, L, X ａ , W ａ , W ｂ and Y are as defined in any one of claims 1 to 33, the ligand according to claim 45 or 46.

48. Iron (Fe (Fe ＩＩ or Fe ＩＩＩ is absent)), is absent, a compound of formula I or a salt thereof according to any one of claims 1 to 33.

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