Photocaged metal / metalloid-alkoxy and siloxane polymer building blocks and applications thereof

Abstract

Methods of using photoremovable protecting groups (PPGs), and compositions made with or including PPGs, are described. PPGs may be used for 3D printing with or without preformed polymers, for surface patterning, for particle formation, for protecting silicon centers, or for functionalizing Cl / H-metal / metalloid systems, silanes, siloxanes, silesquioxanes, silica cages, or particles or other surfaces.

Description

64438-WO-PCT / IDN202 TITLE Photocaged Metal / Metalloid-Alkoxy and Siloxane Polymer Building Blocks and Applications Thereof Inventors: Joseph Coy Furgal, Mahmud Rashed, Ethan Chandler RELATED APPLICATIONS

[0001] This application claims priority to United States Provisional Application No.63 / 605,641 filed under 35 U.S.C. § 111(b) on December 4, 2023, the disclosure of which is incorporated herein by reference in its entirety. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

[0002] This invention was made with government support under grant number DMR-2137672 awarded by the National Science Foundation. The government has certain rights in this invention. BACKGROUND

[0003] Photoremovable protecting groups (PPGs) are chemical moieties that can be temporarily attached to a molecule to mark or protect a specific functional group or reactive site through a covalent linkage rendering the functional group or reactive site inert, and can be selectively removed using light, typically in the ultraviolet (UV) or visible range, restoring reactivity or function to the functional group or reactive site. (The term “photocage”, which is short for “photochemical caging group”, is used herein synonomously with PPG. The term “phototrigger” also refers to a PPG.) The use of light to trigger the removal of protecting groups provides a non-invasive and spatially controlled method, allowing for precise control over the release of the protected functional groups. A key advantage of PPGs is their ability to enable spatial and temporal control in a variety of applications, including photochemical synthesis, drug delivery, and biological studies.

[0004] PPGs offer protection and deprotection capabilities. For example, PPGs can be used to shield specific functional groups or reactive sites in a molecule, preventing undesired reactions during a chemical process. For deprotection, exposure to light of the appropriate wavelength triggers the cleavage of the PPG, leading to the removal of protection and revealing the reactive group. PPGs can be chosen or designed to be highly selective in their response to particular wavelengths of light, which allows for the controlled activation of specific protecting groups in a mixture of different functionalities. Some example applications that PPGs have been used for include organic synthesis, where the protection of certain functional groups is necessary to prevent unwanted reactions and PPGs enable the selective activation of these groups at specific points in the synthesis; biological studies, where PPGs can be employed to control the release of bioactive64438-WO-PCT / IDN202 compounds or to study cellular processes with high spatiotemporal precision; and drug delivery, where PPGs can be used to release therapeutic agents at specific sites in the body when exposed to light, minimizing off-target effects.

[0005] Many PPGs have been developed since the 1960’s for the effective protection and deprotection of alcohols. These have been crucial tools in the organic and biochemists’ toolbox, especially for modification in biological systems, which, like alkoxysilanes, can be highly environmentally sensitive. Example PPGs include o-nitrobenzyl, which is cleaved by UV light, coumarin-based groups, which are responsive to visible light, and spiroyan and spirooxazine derivatives, which undergo reversible photoisomerizations in response to light.

[0006] One of the most useful and longest serving PPG’s is o-nitrobenzyl alcohol. Its simple structure and general ease of attachment / removal have made it a workhorse, and it even reacts successfully with silanes. However, many known o-nitrobenzyl alcohol-based protection reactions have some disadvantages, in that they require high energy UV irradiation (300-350 nm) to be successful with efficient deprotection (i.e., at quantum efficiencies >50%). They can also be prone to producing reactive byproducts; however, their low costs and ease of implementation has generally favored their use over the challenges.

[0007] High energy wavelengths also have the potential to destroy many organic species. Therefore, other PPGs have been developed to overcome these limitations, including phenacyls, di-methylaminobenzyls, and BODIPYs, which are all much more reasonably recyclable after use, and with BODIPYs offering very highly tunable activation wavelengths from green to red / near IR activation. These derivatives have shown effective protection and deprotection on various carbon-based substances. However, they have not yet been used on silicon or other sol-gel active metals / metalloids.

[0008] There are a limited number of previous reports on alkoxysilane photo-protecting groups, notably from the 1980’s. These focused on the development of o-nitrobenzyloxy photo-caging of Rx- (alkoxy)y-silanes, where x=2-3 and y=1-2. Examples where y=3 were mentioned, but not synthesized. Though the initial motivation was to develop photo-curable siloxanes, most of the literature has examined their use as co-catalysts with tris(ethylacetoacetato)aluminum for epoxy resin polymerizations.

[0009] The methods by which PPG-R-alkoxysilanes are synthesized and photo-triggered are straightforward. Irradiation of the product using a medium-pressure mercury lamp have shown that the silanol is formed in an epoxy resin polymer formulation, though many details such as reaction efficiency and kinetics have not been described. For most of the examples in the literature, slightly electron withdrawing R-group substituents reportedly resulted in better photo-releasing efficiencies of the o-nitrobenzyl-alcohol (i.e., chloro or fluorophenyls), likely due to weakening of the Si-O bond. Others have shown that photo-decomposition of triphenyl(o-nitrobenzyloxy)silane (acetonitrile) irradiated by a 400 W mercury lamp (250-400 nm) took ~30 min to reach full conversion to silanol. It has also been found that photo-curable polydimethylsiloxanes from64438-WO-PCT / IDN202 dimethyl-di-(o-nitrobenzyloxy)silane were synthesizable with ~6,000 cSt viscosities after irradiation in the presence of a silanol condensing catalyst (di-butyltin-di-laurate, DBTDL), whereas dimethyl(methoxy)2silane showed no reactivity. These results show a lingering need in the art for the design of more versatile synthesis methods, and more efficient and better wavelength selective PPGs useful as alternatives to these systems. SUMMARY

[0010] Provided is a method of functionalizing a Cl-metal / metalloid system, the method comprising reacting a chlorine-containing silane or a chlorine-containing metal complex with an alcohol-containing photoremovable protecting group (PPG) compound and a catalyst in darkness to obtain a functionalized compound.

[0011] In certain embodiments, the catalyst comprises triethylamine. In certain embodiments, the catalyst comprises a non-amino base. In particular embodiments, the non-amino base comprises NaH.

[0012] In certain embodiments, the alcohol-containing PPG compound comprises an o- nitrobenzyloxy group.

[0013] In certain embodiments, the darkness is created by wrapping reaction vessels in foil, wherein the reaction vessels contain the chlorine-containing silane or chlorine-containing metal complex and the alcohol-containing PPG compound and catalyst.

[0014] In certain embodiments, the chlorine-containing silane comprises tetrachlorosilane, chlorotriethylsilane, 3-chloropropyl-methyl-dichlorosilane, chlorotriphenylsilane, dichlorodiethylsilane, trichloroethylsilane, trichlorophenylsilane, triethylchlorosilane, or chlorotriethylsilane. In certain embodiments, the chlorine-containing metal complex comprises titanium-tetrachloride. In certain embodiments, the chlorine-containing metal complex comprises zirconium-tetrachloride. In certain embodiments, the chlorine-containing metal complex comprises aluminum-trichloride.

[0015] In certain embodiments, the functionalized compound comprises tetrakis-2- nitrobenzyloxysilane, titanium-tetra-2-nitrobenzyloxide, 3-dimethylaminobenzyloxytriethylsilane, bis-2- nitrobenzyloxy-3-chloropropyl-methylsilane, 2-nitrobenzyloxytriethylsilane, 2- nitrobenzyloxytriphenylsilane, bis(2-nitrobenzyloxy)diethylsilane, bis(2-nitrobenzyloxy)diphenylsilane, bis(2-nitrobenzyloxy)methylphenylsilane, tris(2-nitrobenzyloxy)ethylsilane, tris(2- nitrobenzyloxy)phenylsilane, 3-dimethylaminobenzyloxytriethylsilane, 1-(3,4-dimethoxyphenyl)-2- hydroxyethan-1-one(phenacyl)-triethylsilane, 2,8-diiodo-1,3,5,5,7,9-hexamethyl-5H-4λ4,5λ4-dipyrrolo[1,2- c:2',1'-f][1,3,2]diazaborinin-10-yl)methanoxy(BODIPY)-triethylsilane, or 3- dimethylaminobenzyloxytriethylsilane.

[0016] Further provided is a method of functionalizing a silane, the method comprising reacting a Rx-silane with an alcohol- or alkoxy-containing photoremovable protecting group (PPG) compound in the64438-WO-PCT / IDN202 presence of a Lewis acid catalyst and in darkness to produce a functionalized silane, wherein R is an organic group, and x is from 1 to 3. In certain embodiments, R comprises an alkyl, a haloalkyl, an aryl, or a haloaryl. In certain embodiments, R comprises methyl, ethyl, propyl, chloropropyl, iodopropyl, chloromethyl, phenyl, or chlorobenzyl. In certain embodiments, the Rx-silane comprises triphenyl silane or diphenyl silane. In certain embodiments, the alcohol-containing PPG compound comprises 2-nitrobenzyl alcohol. In certain embodiments, the Lewis acid catalyst comprises tris(pentafluorophenyl)boron. In particular embodiments, alkoxy is methoxy or ethoxy. In certain embodiments, the darkness is created by wrapping reaction vessels in foil, wherein the reaction vessels contain the Rx-silane, the alcohol / alkoxy- containing PPG compound, and the Lewis acid catalyst.

[0017] Further provided is a method of protecting a silicon center against nucleophilic attack, the method comprising reacting an alkoxy-containing PPG compound with cyclohexanethiol and a base to produce a silane having a protected silicon center. In certain embodiments, the alkoxy-containing PPG compound comprises comprises bis-2-nitrobenzyloxy-3-chloropropyl-methylsilane. In certain embodiments, the base comprises NaH. In certain embodiments, the silane having a protected silicon center comprises bis-2-nitrobenzyloxy-cyclohexanethiopropyl-methylsilane.

[0018] Further provided is a method of functionalizing a siloxane, the method comprising reacting a siloxane containing a Si-H terminus or a pendant substitution with an alcohol / alkoxy containing a photoremovable protecting group (PPG) and a Lewis acid catalyst in darkness to obtain a functionalized siloxane. In certain embodiments, the Lewis acid catalyst comprises tris-pentafluorophenylboron. In certain embodiments, the PPG comprises an o-nitrobenzyloxy, a benzyl alkyl group substituted o- nitrobenzyloxy, a m-dialkylamino, a phenacyl, BODIPY, or a coumarin. In certain embodiments, the alcohol / alkoxy containing a PPG comprises 2-nitrobenzyl alcohol. In certain embodiments, the siloxane comprises hydrogen-terminated polydimethylsiloxane (H-PDMS), or H-PDMS containing pendant SiH substitutions. In certain embodiments, the siloxane comprises H-PDMS2-3cSt, H-PDMS100cSt, or H- PDMS20cSt-8-10-SiH. In certain embodiments, the functionalized siloxane comprises 2-nitrobenzyloxy terminated PDMS (ONB-PDMS), or 2-nitrobenzyloxy pendant / backbone PDMS (ONB-PDMSpendant).

[0019] Further provided is a method of functionalizing a silsesquioxane or silica cage containing Si- H corners, the method comprising reacting a silsesquioxane or a silica cage containing Si-H corners with an alcohol / alkoxy containing a photoremovable protecting group (PPG) and a Lewis acid catalyst in darkness to obtain a functionalized silsesquioxane or functionalized silica cage. In certain embodiments, the PPG comprises an o-nitrobenzyloxy, a benzyl alkyl group substituted o-nitrobenzyloxy, a m-dialkylamino, a phenacyl, BODIPY, or a coumarin. In certain embodiments, the Lewis acid catalyst comprises tris- pentafluorophenylboron. In certain embodiments, the silsesquioxane or silica cage comprises hydride terminated octakis(dimethylsiloxy)-Q-silica cage (H-Q8M8). In certain embodiments, the alcohol64438-WO-PCT / IDN202 containing a PPG comprises 2-nitrobenzyl alcohol.

[0020] Further provided is a method of functionalizing nanoparticles or microparticles, the method comprising reacting nanoparticles or microparticles containing Si-H groups with a photoremovable protecting group (PPG) compound containing an alcohol / alkoxy and a Lewis acid catalyst in darkness to obtain functionalized nanoparticles or functionalized microparticles. In certain embodiments, the PPG compound comprises an o-nitrobenzyloxy, a benzyl alkyl group substituted o-nitrobenzyloxy, a m- dialkylamino, a phenacyl, a BODIPY, or a coumarin. In certain embodiments, the Lewis acid catalyst comprises tris-pentafluorophenylboron.

[0021] Further provided is a method of functionalizing a surface, the method comprising reacting a surface containing Si-H groups with a photoremovable protecting group (PPG) compound containing an alcohol / alkoxy and a Lewis acid catalyst in darkness to obtain functionalized surface. In certain embodiments, the surface comprises silicon, metal, or glass.

[0022] Further provided is a method of patterning a surface, the method comprising adding a solution comprising a photoremovable protecting group (PPG) compound and dibutyltin (IV) dilaurate (DBTDL) or tris-pentafluorophenyl boron (BCF) to a surface, wherein the surface comprises hydroxyl or amine functionalization; masking portions of the surface to obtain a masked surface having unmasked portions; and exposing the masked surface to light to attach monomers from the PPG compound to the unmasked portions of the surface. In certain embodiments, no monomers are attached to unmasked portions of the surface. In certain embodiments, the silicon or glass is functionalized with OH groups, NHx groups or phenyl groups. In certain embodiments, the surface comprises silica, silicon, or glass.

[0023] Further provided is a method of 3D printing, the method comprising mixing an alkoxysilane, siloxane, silsesquioxane, or cage silica containing a photoremovable protecting group (PPG) and a couping catalyst in a 3D printer; and operating the 3D printer in the presence of light to print a three-dimentionsal structure comprising a silicon-containing polymer. In certain embodiments, the PPG comprises an o- nitrobenzyloxy, a benzyl alkyl group substituted o-nitrobenzyloxy, a m-dialkylamino, a phenacyl, BODIPY, or a coumarin. In certain embodiments, the PPG comprises an ortho-nitrobenzyl alcohol / alkoxy, a meta- dialkylaminobenzyl alcohol / alkoxy, or a phenacyl derivative. In certain embodiments, the siloxane comprises polydimethylsiloxane. In certain embodiments, the silsesquioxane or cage-silica has mixed functionality of PPG and Si-H groups. In certain embodiments, the PPG comprises phenyl-(2- nitrobenzyloxy)3-silane. In certain embodiments, the coupling catalyst comprises dibutyltin (IV) dilaurate (DBTDL). In certain embodiments, the coupling catalyst comprises tris-pentafluorophenyl boron (BCF).

[0024] Further provided is a method of forming nanoparticles or microparticles, the method comprising irradiating a monomer comprising deprotecting a photoprotected monomer, wherein the photoprotected monomer comprises a photoremovable protecting group (PPG); and irradiating the64438-WO-PCT / IDN202 deprotected monomer with a laser to form nanoparticles or microparticles. In certain embodiments, the monomer comprises a silsesquioxane. In certain embodiments, the PPG comprises an o-nitrobenzyloxy, a benzyl alkyl group substituted o-nitrobenzyloxy, a m-dialkylamino, a phenacyl, BODIPY, or a coumarin.

[0025] Further provided is a use of dibutyltin (IV) dilaurate (DBTDL) as a coupling catalyst to induce coupling of species generated after photo-induced deprotection of a photoremovable protecting group (PPG).

[0026] In any method described herein the PPG may comprise a silicon atom directly bonded to an an o-nitrobenzyloxy group having Formula I: Formula I wherein R1, R2, R3, and R4,halogen atom, a nitro group, a cyano group, a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a substituted or unsubstituted aryl group, an aryloxy group, an acyloxy group having 1 to 5 carbon atoms, a hydroxy group, a mercapto group, an acetyl group, or an allyl group.

[0027] Further provided is a method of conducting 3D printing, the method comprising printing a siloxane monomer composition with light to form a three-dimensional article comprising a polymer formed from the siloxane monomer composition, wherein the siloxane monomer composition comprises a silicon compound having a silicon atom directly bonded to an o-nitrobenzyloxy group having Formula I: Formula I in R1, R2, R3where , and R4, are a a halogen atom, a nitro group, a cyano group, a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a substituted or unsubstituted aryl group, an aryloxy group, an acyloxy group having 1 to 5 carbon atoms, a hydroxy group, a mercapto group, an acetyl group, or an allyl group. In certain64438-WO-PCT / IDN202 embodiments, siloxane monomer composition further comprises a silanol-condensing catalyst. In certain embodiments, no preformed polymers are printed.

[0028] Further provided is a composition comprising titanium-tetra-2-nitrobenzyloxide.

[0029] Further provided is a composition comprising 3-dimethylaminobenzyloxytriethylsilane.

[0030] Further provided is a composition comprising bis-2-nitrobenzyloxy-3-chloropropyl- methylsilane.

[0031] Further provided is a composition comprising bis-2-nitrobenzyloxy-cyclohexanethiopropyl- methylsilane.

[0032] Further provided is a composition comprising 2-nitrobenzyloxytriethylsilane.

[0033] Further provided is a composition comprising 2-nitrobenzyloxytriphenylsilane.

[0034] Further provided is a composition comprising bis(2-nitrobenzyloxy)diethylsilane.

[0035] Further provided is a composition comprising bis(2-nitrobenzyloxy)diphenylsilane.

[0036] Further provided is a composition comprising bis(2-nitrobenzyloxy)methylphenylsilane.

[0037] Further provided is a composition comprising tris(2-nitrobenzyloxy)ethylsilane.

[0038] Further provided is a composition comprising tris(2-nitrobenzyloxy)phenylsilane.

[0039] Further provided is a composition comprising 3-dimethylaminobenzyloxytriethylsilane.

[0040] Further provided is a composition comprising 1-(3,4,-dimethoxyphenyl)-2-hydroxyethan-1- one(phenacyl)-triethylsilane.

[0041] Further provided is a composition comprising 2,8-diiodo-1,3,5,5,7,9-hexamethyl-5H-4λ4,5λ4- dipyrrolo[1,2-c:2',1'-f][1,3,2]diazaborinin-10-yl)methanoxy(BODIPY)-triethylsilane.

[0042] Further provided is a composition comprising 2-nitrobenzyloxytriphenylsilane.

[0043] Further provided is a composition comprising bis(2-nitrobenzyloxy)diphenylsilane.

[0044] Further provided is a composition comprising 3-dimethylaminobenzyloxytriethylsilane.

[0045] Further provided is a composition comprising 2-nitrobenzyloxy terminated polydimethylsiloxane having a viscosity of 27 centistokes.

[0046] Further provided is a composition comprising 2-nitrobenzyloxy terminated polydimethylsiloxane having a viscosity of 201 centistokes.

[0047] Further provided is a composition comprising 2-nitrobenzyloxy pendant polydimethylsiloxane.

[0048] Further provided is a composition comprising octakis(o-nitrobenzyloxy-dimethylsiloxy)-Q- silica cage (PPG-Q8M8).

[0049] Further provided is a composition comprising octakis(o-nitrobenzyloxy-dimethylsiloxy)-Q- silica cage with remaining Si-H functionality (Hx,PPGy-Q8M8) where x =1-7 and y=1-8 with or without tris- pentafluorophenyl boron.64438-WO-PCT / IDN202

[0050] Further provided is a method for fabricating a three-dimensional structure using two-photon polymerization, the method comprising providing a material composition that is sensitive to two-photon absorption, the material composition comprising a PPG-alkoxy-cage system or an o-nitrobenzyloxysilane; directing a pulsed laser beam onto the material composition within a predetermined focal region to induce removal of a photoremovable protecting group and form Si-O-Si bonds through simultaneous absorption of two photons configured to promote electrons in the material composition into an excited state through a half energy virtual state; scanning the pulsed laser beam in three dimensions according to a predefined pattern to form a desired three-dimensional structure of the material composition with removed photoremovable protecting groups and Si-O-Si bonds; and optionally, post-processing the three-dimensional structure to enhance one or more properties, wherein the post-processing step is selected from thermal treatment, chemical treatment, or surface modification. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

[0052] FIG.1: Reaction scheme for photocaging of silicon and other metal compounds by nucleophilic substitution or oxysilylation as described in Examples 1-4 and 6-18 herein.

[0053] FIG.2: Example alcohol photocage groups attachable to silicon and other metal compounds as described in Examples 1-4 and 6-22 herein.

[0054] FIG.3: Examples for photocaging siloxane polymers using oxysilylation catalysis with B(C6F5)3 as described in Examples 19-21 herein.

[0055] FIG.4: Example photocaged silsesquioxane and silica cage structures by oxysilylation as described in Example 22 herein.

[0056] FIG.5: Surface functionalization reaction methods using irradiation of phenyl-(2- nitrobenzyloxy)3-silane and condensation coupling to hydroxylated surfaces as demonstrated in Example 26 herein.

[0057] FIG.6: Surface functionalization of a masked silica TLC plate with fluorescent backing by irradiation of phenyl-(2-nitrobenzyloxy)3-silane and condensation coupling to hydroxylated surfaces as demonstrated in Example 26 herein.

[0058] FIG.7: Static contact angles of surface functionalization of a hydroxylated silicon and glass with phenyl-(2-nitrobenzyloxy)3-silane and condensation coupling demonstrated in Example 26 herein.

[0059] FIG.8: 3D printing study of a cross-linked siloxane rubber as demonstrated in Example 25 herein.64438-WO-PCT / IDN202

[0060] FIG.9: Demonstration of ethylsilsesquioxane particle formation by photolysis methods as described in Example 27 herein.

[0061] FIG.10: Non-limiting example scheme for the synthesis of 2-nitrobenzyloxy polymers.

[0062] FIG.11: Reaction scheme for the formation of H4-(2-nitrobenzyloxy)4-Q8M8in the presence of tris-pentafluorophenyl boron as a catalyst and subsequent UV Photopolymerization study of H4-(2- nitrobenzyloxy)4-Q8M8in the presence of tris-pentafluorophenyl boron as a catalyst.

[0063] FIG.12: Image of UV photopolymerization study of H4-(2-nitrobenzyloxy)4-Q8M8in the presence of tris-pentafluorophenyl boron as a catalyst. DETAILED DESCRIPTION

[0064] Throughout this disclosure, various publications, patents, and published patent specifications are referenced by an identifying citation. The disclosures of these publications, patents, and published patent specifications are hereby incorporated by reference into the present disclosure in their entirety to more fully describe the state of the art to which this invention pertains.

[0065] Provided herein are various methods of using PPG compounds (i.e., compounds containing at least one PPG), and compositions comprising PPG compounds. In accordance with the present disclosure, PPG compounds can be used in a wide variety of applications, and such PPG compounds may include, but are not limited to, photocurable silicon compounds which include a silicon atom directly bonded to an o- nitrobenzyloxy group having the following Formula I: Formula I 12 3 4wherein R , R , R , and R , halogen atom, a nitro group, a cyano group, a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a substituted or unsubstituted aryl group, an aryloxy group, an acyloxy group having 1 to 5 carbon atoms, a hydroxy group, a mercapto group, an acetyl group, or an allyl group.

[0066] Examples of the substitutents for the substituted alkyl group and the substituted aryl group represented respectively by R1, R2, R3, and R4in Formula I may include a carboxyl group, a thiocarboxyl group, a dithiocarboxyl group, an alkoxycarbonyl group having 1 to 5 carbon atoms, a cyano group, a formyl group, a carbonyl group, a hydroxyl group, a mercapto group, an alkoxy group having 1 to 5 carbon64438-WO-PCT / IDN202 atoms, a halogen atom, a nitro group, an allyl group, or a trifluoromethyl group.

[0067] Examples of the substituted or unsubstituted alkyl group having 1 to 5 carbon atoms represented respectively by R1, R2, R3, and R4may include a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, a sec-butyl group, a n-pentyl group, an isobutyl group, a t-butyl group, an isopentyl group, a neopentyl group, a t-pentyl group, a methoxymethyl group, a cyanomethyl group, a nitromethyl group, a chloromethyl group, a trifluoromethyl group, a 2-ethoxyethyl group, a 2- ethoxycarbonylethyl group, a 3-mercaptopropyl group, or a 2-nitropentyl group.

[0068] Examples of the alkoxy group having 1 to 5 carbon atoms may include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group, a sec-butoxy group, a t-butoxy group, a pentoxy group, an isopentoxy group, a neopentoxy group, or a t-pentoxy group.

[0069] Examples of the substituted or unsubstituted aryl group may include a phenyl group, an o- methylphenyl group, a m-methylphenyl group, a p-methylphenyl group, an o-methoxyphenyl group, a m- methoxyphenyl group, a p-methoxyphenyl group, an o-nitrophenyl group, a m-nitrophenyl group, a p- nitrophenyl group, an o-cyanophenyl group, a m-cyanophenyl group, a p-cyanophenyl group, an o- chlorophenyl group, a m-chlorophenyl group, a p-chlorophenyl group, an o-aminophenyl group, a m- aminophenyl group, or a p-aminophenyl group.

[0070] Examples of the aryloxy group may include a phenoxy group, an o-methylphenoxy group, a m-methylphenoxy group, a p-methylphenoxy group, an o-methoxyphenoxy group, a m-methoxyphenoxy group, a p-methoxyphenoxy group, an o-nitrophenoxy group, a m-nitrophenoxy group, a p-nitrophenoxy group, an o-cyanophenoxy group, a m-cyanophenoxy group, a p-cyanophenoxy group, an o-chlorophenoxy group, a m-chlorophenoxy group, a p-chlorophenoxy group, an o-aminophenoxy group, a m-aminophenoxy group, or a p-aminophenoxy group.

[0071] Examples of the acyloxy group having 1 to 5 carbon atoms may include a formyloxy group, an acetoxy group, a propionyloxy group, a butyloxy group, a valeryloxy group, an isovaleryloxy group, or a pivaloyloxy group.

[0072] On the other hand, examples of a group directly bonded to the silicon atom having the above- mentioned o-nitrobenzyloxy group may include a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group, an aryloxy group, a vinyl group, or an allyl group.

[0073] Of the above groups, examples of substituents for the alkyl group having 1 to 10 carbon atoms and the aryl group may include a carboxyl group, a thiocarboxyl group, a dithiocarboxyl group, an alkoxycarbonyl group having 1 to 5 carbon atoms, a cyano group, a formyl group, a carbonyl group, a hydroxyl group, a mercapto group, an alkoxyl group having 1 to 5 carbon atoms, a halogen atom, a nitro group, an allyl group, or a trifluoromethyl group.64438-WO-PCT / IDN202

[0074] Examples of the substituted or unsubstituted alkyl group having 1 to 10 carbon atoms may include a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, a sec-butyl group, a t-butyl group, a n-pentyl group, a neopentyl group, an isopentyl group, a t-pentyl group, a hexyl group, an isohexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, a methoxymethyl group, a cyanomethyl group, a nitromethyl group, a chloromethyl group, a 2-trifluoromethylethyl group, a 2-ethoxyethyl group, a 2-nitropentyl group, a 3-chlorohexyl group, or a 5-cyanoheptyl group.

[0075] Examples of the alkoxy group having 1 to 10 carbon atoms may include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group, a sec-butoxy group, a t-butoxy group, a pentyloxy group, an isopentyloxy group, a neopentyloxy group, a t-pentyloxy group, a hexyloxy group, a heptyloxy group, an octyloxy group, a nonyloxy group, or a decyloxy group.

[0076] Examples of the substituted or unsubstituted aryl group and the aryloxy group may include the same ones as exemplified for these groups represented by R1to R4.

[0077] Two or more of the silicon atom to which the o-nitrobenzyloxy group is directly bonded may be linked to each other through oxygen atoms, alkylene groups such as methylene and ethylene, or aryl groups such as phenylene and so on.

[0078] Non-limiting examples of the PPG compound having a silicon atom to which an o- nitrobenzyloxy group is directly bonded include trimethyl(o-nitrobenzyloxy)silane, dimethyl(o- nitrobenzyloxy)phenylsilane, diphenylmethyl(o-nitrobenzyloxy)silane, triphenyl(o-nitrobenzyloxy)silane, triethyl(o-nitrobenzyloxy)silane, tri(2-chloroethyl)-o-nitrobenzyloxysilane, di(o- nitrobenzyloxy)diphenylsilane, di(o-nitrobenzyloxy)methylphenylsilane, diethyl-di(o-nitrobenzyloxy)silan, dimethyl-di(o-nitrobenzyloxy)silane, tri(o-nitrobenzyloxy)phenylsilane, tri(o-nitrobenzyloxy)methylsilane, di(p-methoxyphenyl)-di(o-nitrobenzyloxy)silane, di(p-chlorophenyl)-di(o-nitrobenzyloxy)silane, di(p- cyanophenyl)-di(o-nitrobenzyloxy)silane, tri(p-trifluoromethylphenyl)-o-nitrobenzyloxy-silane, di(o- nitrobenzyloxy)-p-methylphenylmethylsilane, triphenyl(2,6-dinitrobenzyloxy)silane, dimethyl(4-methoxy- 2-nitrobenzyloxy)phenylsilane, trimethyl(4,5-dimethoxy-2-nitrobenzyloxy)silane, dimethyl(4,5-dimethoxy- 2-nitrobenzyloxy)phenyl-silane, diphenylmethyl(4,5,6-trimethoxy-2-nitrobenzyloxy) silane, diphenylmethyl(3,4,5-trimethoxy-2-nitrobenzyloxy) silane, di(p-chloro-o- nitrobeyzloxy)methylphenylsilane, triphenyl(p-phenoxy-o-nitrobenzyloxy)silane, triethyl(3,4-dimethyl-2- nitrobenzyloxy)silane, di(4,5-dichloro-2-nitrobenzyloxy)dimehtylsilane, di(3,4-benzyloxy-2- nitrobenzyloxy)dimethylsilane, di(4,5-dimethoxy-2-nitrobenzyloxy)dimethylsilane, di(4-cyano-2- nitrobenzyloxy)dimethylsilane, di(4-ethoxy-2-nitrobenzyloxy)dimethylsilane, di(4-fluoro-2- nitrobenzyloxy)dimethylsilane, p-bis(o-nitrobenzyloxydimethylsilyl)benzene, 1,1,3,3,5,5-hexamethyl-1,5- di(2-nitrobenzyloxy)-siloxane, 1,1,3,3-tetraphenyl-1,3-di(2-nitrobenzyloxy)-siloxane, 1,1,3,3,5,5- hexaphenyl-1,5-di(2-nitrobenzyloxy)-siloxane, 1,3,5-trimethyl-1,3,5-triphenyl-1,5-di-(2-64438-WO-PCT / IDN202 nitrobenzyloxy)siloxane, (o-nitrobenzyloxy)vinyldiphenylsilane, (o- nitrobenzyloxy)vinylphenylmethylsilane, di(o-nitrobenzyloxy)vinylphenylsilane, di(o- nitrobenzyloxy)phenyl-t-butylsilane, di(3-methyl-2-nitrobenzyloxy)diphenylsilane, (5-methyl-2- nitrobenzyloxy)triphenylsilane, di(3-methoxy-2-nitrobenzyloxy)diphenylsilane, di(2-chloro-6- nitrobenzyloxy)diphenylsilane, (5-chloro-2-nitrobenzyloxy)triphenylsilane, di(2,4- dinitrobenzyloxy)diphenylsilane, (6-nitropiperonyloxy)triphenylsilane, diphenyl(3-methyl-4-methoxy-2- nitrobenzyloxy)-silane, (3,4-dimethoxy-2-nitrobenzyloxy)triphenylsilane.

[0079] Example PPG compounds including Formula I further include silicon compounds obtainable by the reaction of chlorinated silicon-containing silicone resin (for example, epoxy-modified silicone resin) with o-nitrobenzyl alcohol. An example of such a compound may include one having the above-mentioned o-nitrobenzyloxy groups at both ends of a molecular chain, whose principal chain comprises polysiloxane, polyoxyalkylene, or the like. To the principal chain, a side chain having a methyl group, a phenyl roup, or the like may further be linked. The chlorinated silicon-containing silicone may be obtained by hydrolysis of organochlorosilane or chlorination of silicone containing silicon hydride or silanol or alkoxysilanes. Usually, the silanol as formed undergoes condensation reaction immediately. If necessary, however, a condensing catalyst may be added to accelerate its condensation. The silanol-condensing catalyst is a compound which may activate a reaction of the following reaction scheme:. be used.

[0080] Examples of the silanol-condensing catalyst may include dibutyltin dilaurate, diacetylacetonate dichlorotin, lead octenoate, lead naphthenete, stannous naphthenate, stannic naphtenate, zinc octenoate, triphenylphosphine, BF3-monoethylamine, BF3-piperidine complex, trisacetylacetonatoiron, tris-pentafluorophenyl boron, etc. The above silanol-condensing catalyst may be added and mixed in an amount of from about 5 to about 0.01% by weight, or from about 2 to about 0.1% by weight, based on the silicon compound.64438-WO-PCT / IDN202

[0081] A photocurable silicon composition may also be prepared by mixing the silicon composition and the silanol-condensing catalyst in a conventional manner, and the resulting composition is useful as a PPG compound for the purposes described herein.

[0082] PPG compounds which include Formula I undergo a curing reaction by irradiation with light, particularly with ultraviolet light. Time for the light-irradiation may vary according to the composition, and cannot be unequivocally defined, but it may range from one minute to one hour or more; the same applies also to reaction temperature, which, however, may range from room temperature to 150 °C or even higher. As a light source, there may be employed a high-pressure mercury-vapor lamp, a carbon-arch lamp, an argon-glow discharge tube, or the like. The cured product obtained by the curing reaction is odorless and excellently heat-stable. It is further possible to obtain a cured product having desired mechanical properties by selecting optionally a substituent to be linked directly to the silicon atom of the silicon compound.

[0083] Silicon compounds having a PPG such as Formula I may liberate a silanol compound by irradiation with light, particularly with an ultraviolet ray, to undergo polymerization of the silanol compound, optionally in the presence of a silanol-condensing catalyst. Silicon compounds having Formula I are photocurable in a relatively short time without the use of any photosensitizer.

[0084] In general, the methods described herein may employ PPG compounds which may be any of the photocurable silicon compounds disclosed in U.S. Patent No.4,476,290, incorporated herein by reference. Such compounds can be made as described in U.S. Patent No.4,476,290. However, the PPG compounds having Formula I can also be made through alternative synthetic methods, and such alternative synthetic methods are encompassed within the scope of the present disclosure. Furthermore, the methods described herein may alternatively use PPG compounds other than those disclosed in U.S. Patent No. 4,476,290, as described in more detail below.

[0085] In one aspect of the present disclosure, it is possible to functionalize Cl-metal / metalloid systems with alcohol-containing PPGs such as, but not limited to, to o-nitrobenzyloxy (including benzyl alkyl group substituted), m-dialkylamino, phenacyls, BODIPYs, and coumarins [i.e., (chloro)n=1-4-(R)m=0-3- M, where M = silicon, aluminum, titanium, zirconium, boron, germanium, tin, gallium, lead, etc. excluding M = carbon], using a non-amino base catalyst for silicon, or any base such as alkylamines, hydrides, etc. for the others. Examples 1-4, 6-15, and 18 herein exemplify this. In this method, a chlorine-containing silane or a chlorine-containing metal complex is reacted with an alcohol-containing PPG compound and a catalyst in darkness to obtain a functionalized compound.

[0086] As described in Example 1 herein, tetrakis(2-nitrobenzyloxysilane), which can be abbreviated as TNBOS, can be prepared from reacting tetrachlorosilane with 2-nitrobenzyl alcohol in the presence of a triethylamine catalyst. The reaction utilizes dark conditions to prevent photoreactions, which can be accomplished by wrapping the reaction vessels in foil. TNBOS is a silane compound that contains four 2-64438-WO-PCT / IDN202 nitrobenzyloxy groups attached to a silicon atom, i.e., Si((OCH2PhNO2)2)4, where OCH2PhNO2represents the 2-nitrobenzyloxy group. TNBOS is a useful as a protecting group in organic synthesis. The 2- nitrobenzyloxy groups can be selectively removed with light, allowing for the controlled deprotection of specific functional groups. TNBOS is particularly useful in the protection and deprotection during the synthesis of complex organic molecules, especially in the context of multi-step syntheses.

[0087] As described in Example 2 herein, titanium-tetra-2-nitrobenzyloxide (Ti(ONO2)4) can be prepared by reacting titanium-tetrachloride (TiCl4) with 2-nitrobenzyl alcohol and triethylamine in the dark. Titanium-tetra-2-nitrobenzyloxide (Ti(ONO2)4) is useful as a protecting group in organic synthesis.

[0088] As described in Example 3 herein, 3-dimethylaminobenzyloxytriethylsilane can be prepared by reacting chlorotriethylsilane with 3-dimethylaminobenzyl alcohol and triethylamine in the dark. 3- Dimethylaminobenzyloxytriethylsilane is useful as a protecting group in organic synthesis.

[0089] As described in Example 4 herein, bis-2-nitrobenzyloxy-3-chloropropyl-methylsilane (C14H17ClNO4Si) can be prepared by reacting 3-chloropropyl-methyl-dichlorosilane with 2-nitrobenzyl alcohol and triethylamine in the dark. Bis-2-nitrobenzyloxy-3-chloropropyl-methylsilane (C14H17ClNO4Si) is useful as a protecting group in organic synthesis.

[0090] As described in Example 6 herein, 2-nitrobenzyloxytriethylsilane can be prepared by reacting chlorotriethylsilane with 2-nitrobenzyl alcohol and NaH in the dark. In this example, NaH is used as a non- amino catalyst. 2-Nitrobenzyloxytriethylsilane is useful in organic synthesis for various applications. The dual functionality of 2-nitrobenzyloxytriethylsilane, incorporating a protecting group and reductive group (i.e., the triethylsilane group can be used for reductive cleavage of various functional groups), makes it useful in the synthesis of organic compounds with specific structural requirements. The compound’s reactivity and selectivity are advantageous in designing and executing multi-step synthetic routes for the production of complex molecules in organic chemistry research and industrial applications.

[0091] As described in Example 7 herein, 2-nitrobenzyloxytriphenylsilane can be prepared by reacting chlorotriphenylsilane with 2-nitrobenzyl alcohol and NaH. 2-Nitrobenzyloxytriphenylsilane is useful as a reagent in organic synthesis, particularly in processes that involve protecting groups, nucleophilic substitutions, or transformations of functional groups.

[0092] As described in Example 8 herein, bis(2-nitrobenzyloxy)diethylsilane can be prepared by reacting dichlorodiethylsilane with 2-nitrobenzyl alcohol and NaH in the dark. Bis(2- nitrobenzyloxy)diethylsilane is useful in organic synthesis, particularly in processes that involve protecting groups and functional group transformations. Bis(2-nitrobenzyloxy)diethylsilane also has both protecting group functionality and reductive functionality because of the 2-nitrobenzyloxy group and the diethylsilane group, respectively.

[0093] As described in Example 9 herein, bis(2-nitrobenzyloxy)diphenylsilane can be prepared by64438-WO-PCT / IDN202 reacting dichlorodiethylsilane with 2-nitrobenzyl alcohol and NaH in the dark. Bis(2- nitrobenzyloxy)diphenylsilane is useful in organic synthesis, again because of its dual functionality from having both a protecting group (the 2-nitrobenzyloxy) and a reductive group (the diphenylsilane).

[0094] As described in Example 10 herein, bis(2-nitrobenzyloxy)methylphenylsilane can be prepared by reacting dichlorodiethylsilane with 2-nitrobenzyl alcohol and NaH in the dark. Bis(2- nitrobenzyloxy)methylphenylsilane is useful in organic synthesis not only because of its ability to serve as a protecting group but also because it can serve as a source of hydrogen in catalytic reactions due to its methylphenylsilane moiety.

[0095] As described in Example 11 herein, tris(2-nitrobenzyloxy)ethylsilane can be prepared by reacting trichloroethylsilane with 2-nitrobenzyl alcohol and NaH in the dark. Tris(2- nitrobenzyloxy)ethylsilane is useful as a protecting group in organic synthesis.

[0096] As described in Example 12 herein, tris(2-nitrobenzyloxy)phenylsilane can be prepared by reacting trichlorophenylsilane with 2-nitrobenzyl alcohol and NaH in the dark. Tris(2- nitrobenzyloxy)phenylsilane is useful in organic synthesis because of its protecting group functionality (from the 2-nitrobenzyloxy group) and its reductive group functionality (from the phenylsilane group).

[0097] As described in Example 13 herein, 3-dimethylaminobenzyloxytriethylsilane can be prepared by reacting chlorotriethylsilane with 3-dimethylaminobenzyl alcohol and sodium hydride in the dark. 3- Dimethylaminobenzyloxytriethylsilane is useful in organic synthesis because of its protecting group functionality (from the 2-nitrobenzyloxy group) and its reductive group functionality (from the triethylsilane group).

[0098] As described in Example 14 herein, 1-(3,4-dimethoxyphenyl)-2-hydroxyethan-1- one(phenacyl)-triethylsilane can be prepared by reacting triethylchlorosilane with 1-(3,4-dimethoxyphenyl)- 2-hydroxyethan-1-one and triethylamine in the dark. 1-(3,4-Dimethoxyphenyl)-2-hydroxyethan-1- one(phenacyl)-triethylsilane is useful in organic synthesis because of its protecting group functionality and reductive group functionality from the triethylsilane group.

[0099] As described in Example 15 herein, 2,8-diiodo-1,3,5,5,7,9-hexamethyl-5H-4λ4,5λ4- dipyrrolo[1,2-c:2',1'-f][1,3,2]diazaborinin-10-yl)methanoxy(BODIPY)-triethylsilane can be prepared by reacting triethylchlorosilane with 2,8-diiodo-1,3,5,5,7,9-hexamethyl-5H-4λ4,5λ4-dipyrrolo[1,2-c:2',1'- f][1,3,2]diazaborinin-10-yl)methanol and triethylamine in the dark. BODIPY-triethylsilane is useful as a protecting group for organic synthesis.

[0100] As described in Example 18 herein, 3-dimethylaminobenzyloxytriethylsilane can be prepared by reacting chlorotriethylsilane with 3-dimethylaminobenzyl alcohol and sodium hydride in the dark. 3- Dimethylaminobenzyloxytriethylsilane is useful in organic synthesis because of its protecting group functionality (from the 3-dimethylaminobenzyloxy group) and reductive group functionality (from the64438-WO-PCT / IDN202 triethylsilane group).

[0101] In another aspect of the present disclosure, it is possible to functionalize Rx-silanes, where x = 1-3, with alcohol- or alkoxy-containing PPG compounds such as, but not limited to, o-nitrobenzyloxy compounds (including benzyl alkyl group substituted compounds), m-dialkylamino compounds, phenacyls, BODIPYs, and coumarins, using oxysilylation (Piers-Rubinsztajn) methods such as, but not limited to, a Lewis Acid catalyst such as tris-pentafluorophenylboron in 0.01-10 mol%, and R groups including, but not limited to, methyl, ethyl, propyl, chloropropyl, iodopropyl, chloromethyl, phenyl, chlorobenzyl, etc. Examples 16-17 herein exemplify this. A Rx-silane can be reacted with an alcohol / alkoxy-containing PPG compound in the presence of a Lewis acid catalyst and in the dark to produce a functionalized silane. In this method, the reaction can be quenched at completion by adding neutral alumina.

[0102] As described in Example 16 herein, 2-nitrobenzyloxytriphenylsilane can be prepared by reacting tris(pentafluorophenyl)boron, triphenylsilane, and 2-nitrobenzyl alcohol in the dark. 2- Nitrobenzyloxytriphenylsilane is useful for organic synthesis because of its protecting group functionality (from the 2-nitrobenzyloxy group) and reductive group functionality (from the triphenylsilane group).

[0103] As described in Example 17 herein, bis(2-nitrobenzyloxy)diphenylsilane can be prepared by reacting tris(pentafluorophenyl)boron with diphenylsilane and 2-nitrobenzyl alcohol in the dark. Bis(2- nitrobenzyloxy)diphenylsilane is useful for organic synthesis because of its protecting group functionality (from the 2-nitrobenzyloxy group) and reductive group functionality (from the diphenylsilane group).

[0104] In another aspect of the present disclosure, silicon centers can be protected against nucleophilic attack by bulky alkoxy photocage groups attached to silicon, allowing for substitution on R- groups. An alkoxy-containing PPG compound can be reacted with cyclohexanethiol and a base to produce a silane having a protected silicon center. Example 5 herein exemplifies this. As described in Example 5 herein, bis-2-nitrobenzyloxy-cyclohexanethiopropyl-methylsilane can be prepared by reacting bis-2- nitrobenzyloxy-3-chloropropyl-methylsilane with cyclohexanethiol and NaH. Bis-2-nitrobenzyloxy- cyclohexanethiopropyl-methylsilane is useful as a protecting group in organic synthesis.

[0105] In another aspect of the present disclosure, described is the functionalization of siloxanes containing a Si-H terminus and backbone / pendant substitutions, with alcohol- or alkoxy- (e.g., methoxy or ethoxy) containing PPGs such as, but not limited to, o-nitrobenzyloxy (including benzyl alkyl group substituted), m-dialkylamino, phenacyls, BODIPYs, and coumarins using oxysilylation (Piers-Rubinsztajn) methods such as with, but not limited to, a Lewis Acid catalyst such as tris-pentafluorophenylboron in 0.01- 10 mol%. Examples 19-21 herein exemplify this.

[0106] As described in Example 19 herein, 2-nitrobenzyloxy terminated polydimethylsiloxane (ONB-PDMS27cSt) can be prepared by reacting tris(pentafluorphenyl)boron, H-PDMS2-3cSt, and 2- nitrobenzyl alcohol in the dark. As described in Example 20 herein, ONB-PDMS201cStcan be prepared by64438-WO-PCT / IDN202 reacting tris(pentafluorphenyl)boron, H-PDMS100cSt, and 2-nitrobenzyl alcohol in the dark. As described in Example 21 herein, ONB-PDMSpendantcan be prepared by reacting tris(pentafluorphenyl)boron, H- PDMS20cSt-8-10-SiH, and 2-nitrobenzyl alcohol in the dark. ONB-PDMS is a polymeric material where the ends of the PDMS chains are modified with 2-nitrobenzyloxy groups, which allows for the introduction of specific functional groups to the polymer. The subscript terms “2-3cSt”, “201cSt”, and “100cSt” refer to the viscosity of the PDMS, specified in centistokes (cSt). Centistokes is a unit of kinematic viscosity commonly used for describing the viscosity of silicone oils such as PDMS. Thus, for example, H- PDMS100cSt is hydrogen-terminated PDMS with a viscosity of 100 centistokes. ONB-PDMS201cSt is 2- nitrobenzyloxy terminated PDMS with a viscosity of 201 centistokes. The term “H-PDMS20cSt-8-10-SiH” refers to hydrogen-terminated PDMS having a viscosity of 20 centistokes, chains with a length distribution of from 8 to 10 repeating units, and the presence of SiH groups. The term ONB-PDMSpendant refers to PDMS which has 2-nitrobenzyloxy groups extending from the main chain of the polymer.

[0107] In another aspect of the present disclosure, described herein is the functionalization of silsesquioxanes and silica cages containing Si-H corners with alcohol or alkoxy containing photo-protecting groups / photocages such as, but not limited to, o-nitrobenzyloxy (including benzyl alkyl group substituted), m-dialkylamino, phenacyls, BODIPYs, and coumarins using oxysilylation (Piers-Rubinsztajn) methods such as with, but not limited to, a Lewis Acid catalyst such as tris-pentafluorophenylboron in 0.01-10 mol%. Example 22 herein exemplifies this.

[0108] As described in Example 22 herein, octakis(o-nitrobenzyloxy-dimethylsiloxy)-Q-silica cage (H-Q8M8) can be prepared by reacting hydride terminated octakis(dimethylsiloxy)-Q-silica cage (H-Q8M8) with 2-nitrobenzyl alcohol and tri(pentafluorophenyl)boron. Octakis(o-nitrobenzyloxy-dimethylsiloxy)-Q- silica cage (H-Q8M8) is useful for organic synthesis or controlled release applications due to the presence of the o-nitrobenzyloxy groups.

[0109] In another aspect of the present disclosure, nano- and microparticles containing Si-H groups can be functionalized with alcohol or alkoxy containing PPGs such as, but not limited to, o-nitrobenzyloxy (including benzyl alkyl group substituted), m-dialkylaminos, phenacyls, BODIPYs, and coumarins using oxysilylation (Piers-Rubinsztajn) methods such as with, but not limited to, a Lewis Acid catalyst such as tris-pentafluorophenylboron in 0.01-10 mol%. Nanoparticles or microparticles comprising Si-H groups can be reacted with an alcohol / alkoxy-containing PPG compound and a Lewis acid catalyst in the dark to obtain functionalized nanoparticles or microparticles.

[0110] In another aspect of the present disclosure, surfaces containing Si-H groups can be functionalized with alcohol / alkoxy-containing PPG compounds such as, but not limited to, o- nitrobenzyloxy (including benzyl alkyl group substituted), m-dialkylaminos, phenacyls, BODIPYs, and coumarins using oxysilylation (Piers-Rubinsztajn) methods such as with, but not limited to, a Lewis Acid64438-WO-PCT / IDN202 catalyst such as tris-pentafluorophenylboron in 0.01-10 mol%. Any surface comprising Si-H groups can be reacted with an alcohol / alkoxy-containing PPG compound and a Lewis acid catalyst in the dark to obtain a functionalized surface. The surface may be, for example, silicon, metal, or glass.

[0111] As described in Examples 23-24 herein, 2-nitrobenzyloxy-polysiloxanes can be photopolymerized with a 250-400 nm, 450 W lamp with 100 mw / cm2output. The presence of tin, such as in dibutyltin (IV) dilaurate (DBTDL), can facilitate photodeprotection reactions. Photodeprotection of 2- nitrobenzyloxy-polysiloxane can be accomplished with the addition of H2O and DBTDL prior to the photopolymerization. For cross-linked siloxane formation each 2-nitrobenzyloxy-polysiloxane is mixed with phenyl-(2-nitrobenzyloxy)3-silane or used alone for linear siloxane formation. Upon removal of solvent, solid particles can be separated from the polymer products.

[0112] DBTDL may also be used as a coupling catalyst to induce coupling of species generated after photo-induced deprotection. Examples 23-27 herein exemplify this. As described in Example 25 herein, DBTDL can be used in 3D printing to aid in coupling of Si-OH groups. As described in Example 26 herein, DBTDL can be used to aid in surface patterning of a silica plate. As described in Example 27 herein, DBTDL can be used to aid in ethyl-silsesquioxane particle formation.

[0113] In another aspect of the present disclosure, PPG compounds can be used as cross-linkers in photo-induced polymerization processes. Examples 24, 25, and 27 herein exemplify this. This can be utilized to conduct 3D printing or surface patterning as described in more detail below.

[0114] In another aspect of the present disclosure, hydroxylated surfaces may be functionalized with (R)-metal oxides by a process using a PPG compound by photomasking and light irradiation to impart specific patterns through covalent attachment. This surface patterning is exemplified in Example 26 herein. A solution comprising a PPG compound and a coupling catalyst (such as DBTDL) can be added to a surface, where the surface includes a hydroxyl functionalization, and parts of the surface can then be masked with a suitable photomask to prevent photoreactions in the masked portion of the surface. It is possible to functionalize silicon, metal, glass, or other substrates. Any surface which can be hydroxylated can be masked. The masked surface can be irradiated with light sufficient to cause attachment of monomers from the PPG compound to the unmasked portions of the surface. As described in Example 26 herein, spatio-temporal control of monomer attachments to the surface can be accomplished with, as a non-limiting example, 1 hour irradiation at 100 mw / cm2output with a 250-400 nm, 450 W lamp. FIGS.5-6 show an illustratin and photograph of this on TLC plates, respectively, and FIG.7 shows the results of this on silicon and glass examples.

[0115] In another aspect of the present disclosure, direct laser polymerization of photo-caged monomers can lead to the formation of nano / microparticles with specific sizes and shapes. A monomer comprising a PPG can be deprotected and irradiated with a laser to form nanoparticles or microparticles.64438-WO-PCT / IDN202 The monomer may be, for example, a silsesquioxane. The PPG can be any of a o-nitrobenzyloxy, a benzyl alkyl group substituted o-nitrobenzyloxy, a m-dialkylamino, a phenacyl, BODIPY, or a coumarin.

[0116] In another aspect of the present disclosure, photoinduced 3D printing methods can be used with PPG comounds to directly generate Si-O bonds in-situ to form printed material structures. Example 25 herein exemplifies this. As described in Example 25 herein, a PPG compound can be added to a 3D printer along with a siloxane, and a coupling catalyst (such as DBTDL, to aid in coupling the Si-OH groups), and the printer can print a deprotected siloxane rubber in the presence of light, avoiding the need to use preformed polymers as starting materials. FIG.8 shows the results of the example 3D printing described in Example 25.

[0117] Present technology in siloxane 3D printing is limited by the need to use preformed polymers which can limit the functionality on said materials. These polymers are typically extruded through a nozzle onto a surface or photocured to join polymers together in a bath type system. The methodology described herein allows for writing Si-O bonds directly using photochemical methods without the need for preformed polymers. Small photoresponsive alkoxysilane monomers can be activated using light and form polymers in-situ, eliminating the need to preform polymers with functional groups capable of reacting in the 3D printing system. Furthermore, the system allows for sequence defined printed materials with alternating and block capabilities which are not currently possible through traditional siloxane 3D printing methods.

[0118] Light is printing the monomers in situ. Light is printing the monomers, not curing the monomers. Si-O bonds can be made merely by shining light on the monomers. There is no need for a preformed polymer, although a preformed polymer may help with the color of the printed article because a preformed polymer may have no end groups. In some cases, the 3D printing method produces a product which is substantially black. If rinsed out, the printed article may be yellow. However, different PPGs in the monomer may lead to a different color in the printed article. Byproducts of the 3D printing include phenyl ring radical species (generally black in color) that cannot be reused, though other materials may be used to remake the starting material.

[0119] Conventional methods of siloxane 3D printing use pre-formed silicone polymers which are then linked. This means that the polymers must be put together with the right functionality before the printing process can occur. The 3D printing method described herein, however, uses the direct formation of Si-O bonds without first needing to make pre-formed silicone polymers, with light being used to build up these polymers on demand. This bypasses a current step necessary in siloxane-silicone 3D printing in which polymers, often of limited functionality, are needed to be made first.

[0120] Photoactive alkoxysilanes can be 3D printed to enable direct-write 3D printing of advanced materials by photochemical methods. Photoprotecting groups containing silicon-based monomers can be used in making on-demand polymers. This provides extensive control over 3D printing and other iterative64438-WO-PCT / IDN202 Si-O bond formation processes without the need for preformed polymeric siloxanes as a base material, and instead offers in-situ polymer formation with sequence definition using multi-color bath, inkjet, or other printing techniques using light. The methodology can be applied to standard photochemical 3D printers, inkjet-based systems, and two-photon type printing systems.

[0121] Iterative control and formation of Si-O bonds is not generally achieved by typical siloxane chemistries. Typically, siloxanes (i.e., silicones) are generated by using acid or base catalysis which results in poor control over the polymerization occurring to make base materials, and also for 3D printing applications limits the materials which can be used to those which can be pre-polymerized and then cured on demand using light or heat, or extruded by melting through a nozzle. Thus, the 3D printing described herein is surprising advantageous.

[0122] The 3D printing method described herein allows for making siloxanes with unique functionalization through the use of PPGs. These PPGs are placed on various silanes with near limitless functional groups. These systems may contain 1-4 PPGs and 1-3 R-organic groups (FIG.1). The PPGs on these systems may contain, but are not limited to containing, ortho-nitrobenzyl alcohols, meta- dialkylaminobenzyl alcohols, any phenacyl derivatives, and the like. Various wavelengths of light or laser systems in the presence of a coupling catalyst such as dibutylindilaurate can be used to then deprotect the photoprotected alkoxysilanes and result in polymerization. The use of two different protecting groups (reacting with different wavelengths of light) on the same system allows for iterative alternative copolymerization with control not observed by conventional methods. Both the monocolor and multicolor protected systems are useful as 3D printing or additive manufacturing starting materials, which can be built up in specific locations to form 3D objects on demand. Furthermore, two different monomers can be added that respond to two different wavelengths, which enables soft and hard regions within the same printed material to be achieved. This is something not currently achievable in siloxane 3D printing methods. The monomers can also be used in an inkjet printing style system where the monomers are printed onto a surface and cured using a light pen in a layer-by-layer process. The use of these monomers in interative and additive manufacturing processes is a major advance in the field of siloxane chemistry.

[0123] In another aspect of the present disclosure, two-photon polymerization (TPP) of the aforementioned photo-caged monomers / materials can lead to micro / nanostructured glasses for optics and electronics applications after pyrolysis.

[0124] Tiny silica glass structures are highly transparent, and have excellent thermal, mechanical, and mechanical resistance needed for high performance applications such as quantum computing. Well defined structures of nano / micro glasses are used for applications in micro-optics, photonics, electromechanical systems (MEMS), and microfluidic devices. Typical manufacturing relies on intricate top-down assembly processes involving 2D processes with masking+lithography, chemical vapor deposition, thermal oxidation,64438-WO-PCT / IDN202 and controlled etching, making detailed features highly difficult to realize. 3D printing / molding techniques have been developed to overcome many of these processes but most rely on melting (>1100 ºC) and controlled glass particle sintering techniques.

[0125] Two-photon laser 3D free-form glass printing (TPP) techniques have been developed to overcome many of the challenges with high temperature systems. Two-photon absorption uses pulsed laser systems (~600 nm+) and a combination of two distinct lower energy photons to promote electrons in molecules into the excited state through a half energy virtual state. This allows for ultra-small focal points that depend on the diffraction limit of the optics and (<1 mm) and the laser pulses themselves (<1 ns), which allows for direct polymerization of features at excellent resolution. TPP examples have included silica particle-loaded systems in a polymerizable binder matrix, which allow for low temperature printing but require high temperatures to remove the printed plastics and gain Si-O-Si bond condensing (>1100 ºC under vacuum). The use of silsesquioxane (POSS) structures is also possible as a more direct method to conduct TPP and gain low temperature sintering since most of the requisite Si-O bonds are pre-formed. An example of this entails methacrylate functionalized POSS (viscous liquids), which are polymerized on their side chains (radical photoinitiators used), and then fused at temperatures as low as 650 ºC. While this is a step in the right direction, there are still considerable challenges with feature shrinkage (42+% linear) when they are fused due to long alkyl chains between Si components still needing to be removed in the process. To solve shrinkage issues and further lower fusion temperatures, direct Si-O bond formation reactions upon TPP irradiation is highly beneficial. The PPG-alkoxy-cage systems, siloxanes, and silanes described herein are highly beneficial to this process. TPP can be used to remove the protecting groups in-situ, followed by direct Si-O-Si coupling reactions. Since no organic bridges are present in the system, final shrinkage of the free-form glasses are minimal, and the temperature needed for cleanup / fusion of the organic byproducts is just over 400 ºC (by TGA for o-nitrobenzyl), far less than the 650 ºC low temperature methods. Experiments with o- nitrobenzyloxysilanes at higher concentrations show the Si-O-Si bonds form readily without catalyst, but it is understood that use of a catalyst is possible and encompassed within the scope of the present disclosure. The design and mechanism for PPG group removal may involve a small amount of easily removed solvent present (alcohol / water), but this is not an obstacle in the TPP process. PPG systems with adequate two-photon cross- sections (i.e., BODIPY) give the desired reactivity in this process and those with the greatest fluidity (liquid like) are highly advantageous over solids. The high modifiability of R-groups on PPG structures, PEG, alkyl, or siloxane groups can be added to impart liquid-like properties as needed. The BODY-PPG-silica cage systems are excellent materials for this process, especially those in the green absorbing region, which can be two-photon-activated by 1000 nm laser systems. This leads to low shrinkage and low temperature processing, since most of the Si-O bonds are already formed and only peripheral bonds are needed for the polymerization process. Advantageously, this results in no organic bridges which need to be burned off, only non-attached64438-WO-PCT / IDN202 PPGs and methyl groups from siloxanes.

[0126] Other alterations are possible. The number of PPG groups that are present can be tailored to alter reactivity. For example, leaving Si-H groups attached to a silica cage structure can reduce the number of PPGs needed to give the same level of reactivity (Si-OH [O-] + Si-H -> Si-O-Si), lessening byproduct impact. Multifunctional cages with non-reactive organics present on corners can lead to selective porosity upon the fusion process, giving modifiability to optical and electronic properties. Lastly, the use of the metal / metalloid- PPG-alkoxide systems in combinations can induce doping within the nano / microglass structures.

[0127] In accordance with the present disclosure, routes to the functionalization of silicon-based materials such as phenacyls, di-methylaminobenzyls, and BODIPYs have been developed due to their nucleophilicity as alcohols giving relatively simple incorporation. Furthermore, reasonable byproducts that have reduced interference with silanol coupling result from the functionalization. These derivatives can also be incorporated into pre-formed siloxane polymers / cages to improve reactivities and reduce byproduct formation.

[0128] In any of the methods described herein, multiple PPGs may be present and selectively removed at specific wavelengths. Examples 24-25 herein demonstrate this. Furthermore, the PPGs can be removed by UV, visible, or near-IR light stimulus neat or in solvents such as THF, acetonitrile, chloroform, cyclopentylmethylether, alcohols, etc., with or without the presence of water. In sum, PPGs are highly versatile and useful in a wide variety of applications, including for the preparation of various compositions useful in organic synthesis for protection or reduction functions.

[0129] EXAMPLES

[0130] Example 1

[0131] Tetrakis-2-nitrobenzyloxysilane

[0132] Tetrachlorosilane (3.7 mmol, 1 eq.) was dissolved in dry THF and added dropwise to a mixture of 2-nitrobenzyl alcohol (19.4 mmol, 4.4 eq.) and triethylamine (19.4 mmol, 4.4 eq.) in THF under nitrogen at 0 °C in the dark (wrapped in foil) and were mixed for 3 h at which time it was allowed to warm up to room temperature. The sample was filtered through filter paper to remove formed salts and then the solvent was removed under high vacuum. The product was purified with silica gel chromatography (hexane / dichloromethane, 1:1) resulting in a yellowish solid at 64.1% yield. The sample was stored in a freezer.1H NMR (500 MHz, CDCl3) δ 8.09-8.11 (d, 4 H), 7.96-7.98 (d, 4 H), 7.67-7.70 (t, 4 H), 7.40-7.44 (t, 4 H), 5.13 (s, 8 H);13C NMR (125MHz, CDCl3) δ 146.46, 138.33, 133.78, 127.94, 127.37, 124.48, 61.76;29Si NMR (59.6 MHz, CDCl3) δ 22.08; HRMS (ESI / QTOF) m / z [M + H]+calculated for C28H24N4O12Si 636.1160, found 636.1168.

[0133] Example 2

[0134] Titanium-tetra-2-nitrobenzyloxide64438-WO-PCT / IDN202

[0135] Titanium-tetrachloride (3.7 mmol, 1 eq.) was dissolved in dry THF and added dropwise to a mixture of 2-nitrobenzyl alcohol (19.4 mmol, 4.4 eq.) and triethylamine (19.4 mmol, 4.4 eq.) in THF under nitrogen at 0 °C in the dark (wrapped in foil) and were mixed for 3 h at which time it was allowed to warm up to room temperature. The sample was filtered through filter paper to remove formed salts and then the solvent was removed under high vacuum, resulting in a yellowish solid at 46.4% yield. The sample was stored in the freezer.1H NMR (500 MHz, CDCl3) δ 8.10 (d, 4 H), 7.65 (t, 4 H), 7.48-7.50 (m, 8 H), 5.13 (s, 8 H);13C NMR (125MHz, CDCl3) δ 145.7, 134.6, 132.6, 130.5, 128.3, 123.1, 63.1; HRMS (ESI / QTOF) m / z [M + H]+calculated for C28H24N4O12Ti 656.0870, found 656.0880.

[0136] Example 3

[0137] 3-dimethylaminobenzyloxytriethylsilane

[0138] To a solution of chlorotriethylsilane (1 mmol, 1 eq.) was dissolved in 30 ml of dry THF and added dropwise to a mixture of 3-dimethylaminobenzyl alcohol (1.2 mmol, 1.2 eq.) and triethylamine (2 mmol, 2 eq.) in THF at reflux 69 °C for 7 h in the dark (wrapped in foil), followed by continuous stirring at room temperature overnight. The solution was filtered to remove the undissolved salts. The solvent was removed under a high vacuum. Product isolated in 60% yield.1H NMR (300 MHz, CDCl3) δ 7.13 (t, 1H), 6.74 (d, 1 H), 6.64 (d, 2 H), 4.44 (s, 2 H), 2.89 (s, 6 H), 0.91 (m, 9 H), 0.47 (m, 6 H).

[0139] Example 4

[0140] Bis-2-Nitrobenzyloxy-3-chloropropyl-methylsilane

[0141] To a solution of 3-chloropropyl-methyl-dichlorosilane (1 mmol, 1 eq.) was dissolved in 30 ml of dry THF and added dropwise to a mixture of 2-nitrobenzyl alcohol (1.2 mmol, 1.2 eq.) and triethylamine (1.2 mmol, 1.2 eq.) THF under nitrogen at 0 °C in the dark (wrapped in foil) and were mixed for 3 h at which time it was allowed to warm up to room temperature. The solution was filtered to remove the undissolved salts. The solvent was removed under a high vacuum. Product isolated in 63% yield.1H NMR (300 MHz, CDCl3) δ 8.09-8.11 (d, 1 H), 7.96-7.98 (d, 1 H), 7.67-7.70 (t, 1 H), 7.40-7.44 (t, 1 H), 5.13 (s, 1 H), 2.56 (t, 2H), 1.98 (t, 2H), 0.95 (t, 2H), 0.34 (s, 3H).

[0142] Example 5

[0143] Bis-2-Nitrobenzyloxy-cyclohexanethiopropyl-methylsilane

[0144] Bis-2-nitrobenzyloxy-3-chloropropyl-methylsilane (0.4 mmol, 1 eq.) and NaH (0.4 mmol, 1 eq.) were dissolved in 10 ml of dry THF with a magnetic stir bar at 0 °C. To this solution was added cyclohexanethiol (0.5 mmol, 1.25 eq.). The solution was stirred for 24 h and then filtered to remove the undissolved salts. The solvent was removed under a high vacuum. Product isolated in 22% yield.1H NMR (300 MHz, CDCl3) δ 8.09-8.11 (d, 1 H), 7.96-7.98 (d, 1 H), 7.67-7.70 (t, 1 H), 7.40-7.44 (t, 1 H), 5.13 (s, 1 H), 2.77 (s, 1H, 2.57 (t, 2H), 1.97 (t, 4H), 1.76 (s, 1H), 1.58, (d, 1H), 1.51 (d, 1H), 1.30 (m, 4H), 0.95 (t, 2H), 0.34 (s, 3H).64438-WO-PCT / IDN202

[0145] Example 6

[0146] 2-Nitrobenzyloxytriethylsilane

[0147] Chlorotriethylsilane (3.7 mmol, 1 eq.) was dissolved in 30 ml of dry THF and added dropwise to a mixture of 2-nitrobenzyl alcohol (4.4 mmol, 1.2 eq.), and NaH (4.4 mmol, 1.2 eq.) in 20 ml of dry THF under nitrogen at 0 °C in the dark (wrapped in foil) and were mixed for 3 h at which time it was allowed to slowly warm up to room temperature. The sample was filtered through filter paper to remove formed salts and then the solvent was removed under high vacuum. The product was purified with silica gel chromatography (hexane / dichloromethane, 1:1) resulting in a yellow / golden oil at 90.4% yield.1H NMR (500 MHz, CDCl3) δ 8.09-8.11 (d, 1 H), 7.96-7.98 (d, 1 H), 7.67-7.70 (t, 1 H), 7.40-7.44 (t, 1 H), 5.13 (s, 1 H), 1.00-1.04 (t, 9 H), 0.70-0.74 (q, 6 H);13C NMR (125MHz, CDCl3) δ 146.46, 138.33, 133.78, 127.94, 127.37, 124.48, 61.76, 6.74, 4.41;29Si NMR (59.6 MHz, CDCl3) δ 22.08; HRMS (ESI / QTOF) m / z [M + H]+calculated for C13H21NO3Si 267.1291, found 267.1298.

[0148] Example 7

[0149] 2-Nitrobenzyloxytriphenylsilane

[0150] Chlorotriphenylsilane (2.4 mmol, 1 eq.), was dissolved in 30 ml of dry THF and added dropwise to a mixture of 2-nitrobenzyl alcohol (2.9 mmol, 1.2 eq.), and NaH (2.9 mmol, 1.2 eq.) in 20 ml of dry THF under nitrogen at 0 °C in the dark (wrapped in foil) and were mixed for 3 h at which time it was allowed to slowly warm up to room temperature. The sample was filtered through filter paper to remove formed salts and then the solvent was removed under high vacuum. The product was purified with silica gel chromatography (hexane / dichloromethane 1:1) resulting in white crystals at 95.6% yield.1H NMR (500 MHz, CDCl3) δ 8.11-8.15 (m, 2 H), 7.68-7.73 (m, 7 H), 7.46-7.51 (m, 3 H), 7.42-7.45 (m, 7 H), 5.34 (s, 1 H);13C NMR (125MHz, CDCl3) δ 146.45, 137.54, 135.39, 133.94, 133.42, 130.36, 128.13, 128.08, 127.57, 124.62, 62.81;29Si NMR (59.6 MHz, CDCl3) δ -10.53; HRMS (ESI / QTOF) m / z [M + H]+calculated for C25H21NO3Si 411.1291, found 411.1292.

[0151] Example 8

[0152] Bis(2-nitrobenzyloxy)diethylsilane

[0153] The compound was obtained from dissolving dichlorodiethylsilane (2.56 mmol, 1 eq.) in 30 ml of dry THF and added dropwise to a mixture of 2-nitrobenzyl alcohol (5.63 mmol, 2.2 eq.), and NaH (5.63 mmol, 2.2 eq.) in 20 ml of dry THF under nitrogen at 0 °C in the dark (wrapped in foil) and were mixed for 3 h at which time it was allowed to slowly warm up to room temperature. The sample was filtered through filter paper to remove formed salts and then the solvent was removed under high vacuum. The product was purified with silica gel chromatography (hexane / dichloromethane 1:1) resulting in a white powder at 86.2% yield.1H NMR (500 MHz, CDCl3) δ 8.03-8.05 (d, 2 H), 7.89-7.91 (d, 2 H), 7.63-7.67 (t, 2 H), 7.38-7.41 (t, 2 H), 5.20 (s, 4 H), 1.08-1.11 (t, 6 H), 0.82-0.87 (q, 4 H);13C NMR (125MHz, CDCl3) δ64438-WO-PCT / IDN202 146.37, 137.36, 133.88, 127.74, 127.65, 124.55, 61.63, 6.47, 3.84;29Si NMR (59.6 MHz, CDCl3) δ -1.99; HRMS (ESI / QTOF) m / z [M + H]+calculated for C18H22N2O6Si 390.1247, found 390.1254.

[0154] Example 9

[0155] Bis(2-nitrobenzyloxy)diphenylsilane

[0156] The compound was obtained from mixing dichlorodiethylsilane (2.05 mmol, 1 eq) in 30 ml of dry THF and added dropwise to a mixture of 2-nitrobenzyl alcohol (4.51 mmol, 2.2 eq.), and NaH (4.51 mmol, 2.2 eq.) in 20 ml of dry THF under nitrogen at 0 °C in the dark (wrapped in foil) and were mixed for 3 h at which time it was allowed to slowly warm up to room temperature. The sample was filtered through filter paper to remove formed salts and then the solvent was removed under high vacuum. The product was purified by recrystallization using a combination of dichloromethane (DCM) and methanol (MeOH), which yielded the product as a white solid in 80.5%.1H NMR (500 MHz, CDCl3) δ 8.07-8.08 (d, 2 H), 8.02-8.04 (d, 2 H), 7.78-7.79 (t, 2 H), 7.76-7.77 (d, 2 H), 7.67-7.71 (t, 2 H), 7.52-7.54 (t, 1 H), 7.51 (s, 1 H), 7.46-7.47 (t, 1 H), 7.42-7.46 (m, 5 H), 5.31 (s, 4 H);13C NMR (125MHz, CDCl3) δ 146.51, 136.84, 134.83, 133.92, 131.24, 130.98, 128.26, 127.94, 127.79, 124.65, 62.25;29Si NMR (59.6 MHz, CDCl3) δ -29.03; HRMS (ESI / QTOF) m / z [M + H]+calculated for C26H22N2O6Si 486.1247, found 486.1253.

[0157] Example 10

[0158] Bis(2-nitrobenzyloxy)methylphenylsilane

[0159] The compound was obtained from mixing dichlorodiethylsilane (2.35 mmol, 1 eq) in 30 ml of dry THF and added dropwise to a mixture of 2-nitrobenzyl alcohol (7.52 mmol, 3.2 eq), and NaH (7.52 mmol, 3.2 eq) in 20 ml of dry THF under nitrogen at 0 °C in the dark (wrapped in foil) and were mixed for 3 h at which time it was allowed to slowly warm up to room temperature. The sample was filtered through filter paper to remove formed salts and then the solvent was removed under high vacuum. The product was purified by recrystallization using a combination of DCM and MeOH, which gave the product as a white powder in 93.6% yield.1H NMR (500 MHz, CDCl3) δ 8.07-8.09 (d, 2 H), 7.95-7.97 (d, 2 H), 7.739-7.74 (t, 1 H), 7.726-7.729 (d, 1 H), 7.42-7.53 (m, 5 H), 5.26-5.27 (d, 4 H), 0.59 (s, 3 H);13C NMR (125MHz, CDCl3) δ 146.52, 136.97, 133.93, 132.97, 130.76, 128.26, 127.96, 127.76, 124.64, 61.97, -4.45;29Si NMR (59.6 MHz, CDCl3) δ -14.06; HRMS (ESI / QTOF) m / z [M + H]+calculated for C21H20N2O6Si 424.4840, found 424.1095.

[0160] Example 11

[0161] Tris(2-nitrobenzyloxy)ethylsilane

[0162] To a solution of trichloroethylsilane (1.94 mmol, 1 eq) dissolved in 30 mL of dry THF was added dropwise to a mixture of 2-nitrobenzyl alcohol (6.21mmol, 3.2 eq) with NaH (6.21 mmol, 3.2 eq) in dry THF (20 ml), under nitrogen at 0 °C in the dark (wrapped in foil) and were mixed for 3 h at which time it was allowed to slowly warm up to room temperature. The sample was filtered through filter paper to64438-WO-PCT / IDN202 remove formed salts and then the solvent was removed under high vacuum. The product was purified by recrystallization using a combination of DCM and MeOH, which gives the product as a white crystal in 89.0% yield.1H NMR (500 MHz, CDCl3) δ 8.09-8.12 (d, 3 H) 7.87-7.89 (d, 3 H), 7.66-7.71 (t, 3 H), 7.43- 7.48 (t, 3 H), 5.31 (s, 6 H), 1.13-1.18 (t, 3 H), 0.91-0.99 (q, 2 H);13C NMR (125MHz, CDCl3) δ 146.47, 136.58, 133.96, 127.91, 127.76, 124.70, 61.96, 6.40, 1.96;29Si NMR (59.6 MHz, CDCl3) δ -42.11; HRMS (ESI / QTOF) m / z [M + H]+calculated for C23H23N3O9Si 513.5340, found 513.1215.

[0163] Example 12

[0164] Tris(2-nitrobenzyloxy)phenylsilane

[0165] To a solution of trichlorophenylsilane (1.78 mmol, 1 eq) dissolved in 30 mL of dry THF was added dropwise to a mixture of 2-nitrobenzyl alcohol (6.23 mmol, 3.2 eq) with NaH (6.23 mmol, 3.2 eq) in dry THF (20 ml), under nitrogen at 0 °C in the dark (wrapped in foil) and were mixed for 3 h at which time it was allowed to slowly warm up to room temperature. The sample was filtered through filter paper to remove formed salts and then the solvent was removed under high vacuum. The product was purified by recrystallization using a combination of DCM and MeOH, which yielded the product as a white crystal in 94.09%.1H NMR (500 MHz, CDCl3) δ 8.09-8.11 (d, 3 H), 7.93-7.95 (d, 3 H), 7.77-7.79 (d, 2 H), 7.67-7.70 (t, 3 H), 7.54-7.57 (t, 1 H), 7.44-7.49 (m, 5 H), 5.39 (s, 6 H);13C NMR (125MHz, CDCl3) δ 146.43, 136.36, 134.70, 134.04, 131.53, 128.50, 127.98, 127.82, 124.75, 62.53;29Si NMR (59.6 MHz, CDCl3) δ -56.11; HRMS (ESI / QTOF) m / z [M + H]+calculated for C27H23N3O9Si 561.5780, found 561.1202.

[0166] Example 13

[0167] 3-Dimethylaminobenzyloxytriethylsilane

[0168] To a solution of chlorotriethylsilane (0.2 ml, 1 mmol, 1 eq.) was dissolved in 30 ml of dry THF and added dropwise to a mixture of 3-dimethylaminobenzyl alcohol (170 mml, 1.2 mmol, 1.2 eq.) with sodium hydride (2.8 mg, 1.2 mmol, 1.2 eq.) in dry THF under 5 °C for 2 h in the dark (wrapped in foil), followed by continuous stirring at room temperature overnight. The solution was filtered to remove the undissolved materials. The solvent was removed under a high vacuum. Product was isolated in 24% yield.1H NMR (300 MHz, CDCl3) δ 7.12 (t, 1H), 6.73 (d, 1 H), 6.64 (d, 2 H), 4.43 (s, 2 H), 2.88 (s, 6 H), 0.91 (m, 9 H), 0.47 (m, 6 H);13C NMR (125MHz, CDCl3) δ 150.5, 143.6, 128.9, 115.1, 111.5, 111.1, 64.1, 40.5, 7.0, 6.12.

[0169] Example 14

[0170] 1-(3,4-Dimethoxyphenyl)-2-hydroxyethan-1-one(phenacyl)-triethylsilane

[0171] Triethylchlorosilane (1 mmol, 1 eq.) was dissolved in 30 ml of dry THF and added dropwise to a mixture of 1-(3,4-dimethoxyphenyl)-2-hydroxyethan-1-one (1.2 mmol, 1.2 eq.) and triethylamine (1.2 mmol, 1.2 eq.) in THF under nitrogen at 0 °C in the dark (wrapped in foil) and were mixed for 3 h at which time it was allowed to warm up to room temperature. The solution was filtered to remove the undissolved64438-WO-PCT / IDN202 salts. The solvent was removed under a high vacuum. Product isolated in 59% yield.1H NMR (300 MHz, CDCl3) δ 7.59 (d, 1 H), 7.40 (s, 1 H), 7.09 (d, 1 H), 4.79 (s, 2H), 3.83 (s, 6H);13C NMR (125MHz, CDCl3) δ 197.8, 153.8, 149.7, 127.5, 122.1, 111.7, 110.1, 67.756.1.

[0172] Example 15

[0173] 2,8-diiodo-1,3,5,5,7,9-hexamethyl-5H-4λ4,5λ4-dipyrrolo[1,2-c:2',1'-f][1,3,2]diazaborinin-10-to a mixture of 2,8-diiodo-1,3,5,5,7,9-hexamethyl-5H-4λ4,5λ4-dipyrrolo[1,2-c:2',1'-f][1,3,2]diazaborinin-10- yl)methanol (1.2 mmol, 1.2 eq.) and triethylamine (1.2 mmol, 1.2 eq.) in THF under nitrogen at 0 °C in the dark (wrapped in foil) and were mixed for 3 h at which time it was allowed to warm up to room temperature. The solution was filtered to remove the undissolved salts. The solvent was removed under a high vacuum. Product isolated in 48% yield.1H NMR (300 MHz, CDCl3) δ 4.61 (s, 2 H), 2.52 (s, 6 H), 2.31 (s, 6 H), 0.22 (s, 6H);13C NMR (125MHz, CDCl3) δ 174.7, 146.9, 138.7, 133.2, 129.5, 126.5, 106.5, 69.6, 59.0, 30.2, 14.8, 14.6, 14.5, 13.2, 6.3.

[0175] Example 16

[0176] 2-Nitrobenzyloxytriphenylsilane

[0177] Tris(pentafluorophenyl)boron (B(C6F5)3, BCF, 0.2 mol %), triphenylsilane (1 ml, 2 mmol, 1 eq), and 2-nitrobenzyl alcohol (2.2 mmol, 1.2 eq) were added to toluene in the dark (wrapped in foil), followed by sonicating for 3 h in a 50 °C water bath. After the reaction, the mixture was quenched by addition of neutral alumina (~ 1g). The mixture was filtered through filter paper to remove salts and then the solvent was removed under high vacuum. The sample was filtered through filter paper to remove formed salts and then the solvent was removed under high vacuum. The product was purified with silica gel chromatography (hexane / dichloromethane 1:1) resulting in white crystals at 95.6% yield (0.95 g).1H NMR (500 MHz, CDCl3) δ 8.11-8.15 (m, 2 H), 7.68-7.73 (m, 7 H), 7.46-7.51 (m, 3 H), 7.42-7.45 (m, 7 H), 5.34 (s, 1 H);13C NMR (125MHz, CDCl3) δ 146.45, 137.54, 135.39, 133.94, 133.42, 130.36, 128.13, 128.08, 127.57, 124.62, 62.81;29Si NMR (59.6 MHz, CDCl3) δ -10.53; HRMS (ESI / QTOF) m / z [M + H]+calculated for C25H21NO3Si 411.1291, found 411.1290.

[0178] Example 17

[0179] Bis(2-nitrobenzyloxy)diphenylsilane

[0180] Tris(pentafluorophenyl)boron (B(C6F5)3, BCF, 0.2 mol %), diphenylsilane (1 ml, 2 mmol, 1 eq), and 2-nitrobenzyl alcohol (4.2 mmol, 2.2 eq) were added to toluene in the dark (wrapped in foil), followed by sonicating for 3 h in a 50 °C water bath. After the reaction, the mixture was quenched by addition of neutral alumina (~ 1g). The mixture was filtered through filter paper to remove salts and then the solvent was removed under high vacuum. The sample was filtered through filter paper to remove64438-WO-PCT / IDN202 formed salts and then the solvent was removed under high vacuum. The product was purified by recrystallization using a combination of dichloromethane (DCM) and methanol (MeOH), which yielded the product as a white solid in 84% yield. Stored in freezer.1H NMR (500 MHz, CDCl3) δ 8.07-8.08 (d, 2 H), 8.02-8.04 (d, 2 H), 7.78-7.79 (t, 2 H), 7.76-7.77 (d, 2 H), 7.67-7.71 (t, 2 H), 7.52-7.54 (t, 1 H), 7.51 (s, 1 H), 7.46-7.47 (t, 1 H), 7.42-7.46 (m, 5 H), 5.31 (s, 4 H);13C NMR (125 MHz, CDCl3) δ 146.51, 136.84, 134.83, 133.92, 131.24, 130.98, 128.26, 127.94, 127.79, 124.65, 62.25;29Si NMR (59.6 MHz, CDCl3) δ -29.03; HRMS (ESI / QTOF) m / z [M + H]+calculated for C26H22N2O6Si 486.1247, found 486.1249.

[0181] Example 18

[0182] 3-dimethylaminobenzyloxytriethylsilane

[0183] To a solution of chlorotriethylsilane (0.2 ml, 1 mmol, 1 eq.) was dissolved in 30 ml of dry THF and added dropwise to a mixture of 3-dimethylaminobenzyl alcohol (170 mml, 1.2 mmol, 1.2 eq.) with sodium hydride (2.8 mg, 1.2 mmol, 1.2 eq.) in dry THF under 5 °C for 2 h in the dark (wrapped in foil), followed by continuous stirring at room temperature overnight. The solution was filtered to remove the undissolved materials. The solvent was removed under a high vacuum. Product was isolated in 24% yield.1H NMR (300 MHz, CDCl3) δ 7.12 (t, 1H), 6.73 (d, 1 H), 6.64 (d, 2 H), 4.43 (s, 2 H), 2.88 (s, 6 H), 0.91 (m, 9 H), 0.47 (m, 6 H);13C NMR (125 MHz, CDCl3) δ 150.5, 143.6, 128.9, 115.1, 111.5, 111.1, 64.1, 40.5, 7.0, 6.12.

[0184] Example 19

[0185] 2-Nitrobenzyloxy terminated polydimethylsiloxane (ONB-PDMS27cSt)

[0186] Tris(pentafluorophenyl)boron (B(C6F5)3, BCF, 0.2 mol %), H-PDMS2-3cSt (2 mmol, 1 eq), and 2-nitrobenzyl alcohol (2.2 mmol, 2.2 eq) were added to toluene in the dark (wrapped in foil), followed by sonicating for 3 h in a 50 °C water bath. After, the reaction mixture was quenched by addition of neutral alumina (~ 1g). The mixture was filtered through filter paper to remove salts and then the solvent was removed under high vacuum. The products of each reaction were purified with silica gel chromatography (hexane / dichloromethane, 1:1). The products were stored in a freezer. The purified product resulted in a colorless oil at 88.6% yield (0.89 mL).1H NMR (500 MHz, CDCl3) δ 8.06-8.12 (d, 2 H), 7.86-7.93 (d, 2 H), 7.62-7.68 (t, 2 H), 7.39-7.44 (t, 2 H), 5.17 (s, 4 H), 0.19-0.21 (m, 12 H), 0.05-0.1 (m, 64 H);13C NMR (125MHz, CDCl3) δ 147.59, 138.97, 134.88, 129.20, 128, 55, 125.65, 62.29, 2.14, 1.09;29Si NMR (59.6 MHz, CDCl3) δ -11.75, -22.65.

[0187] Example 20

[0188] 2-Nitrobenzyloxy terminated polydimethylsiloxane (ONB-PDMS201cSt)

[0189] Tris(pentafluorophenyl)boron (B(C6F5)3, BCF, 0.2 mol %), H-PDMS100cSt (1 mmol, 1 eq), and 2-nitrobenzyl alcohol (2.2 mmol, 2.2 eq) were added to toluene in the dark (wrapped in foil), followed by sonicating for 3 h in a 50 °C water bath. Afterwards, the reaction mixture was quenched by addition of64438-WO-PCT / IDN202 neutral alumina (~ 1g). The mixture was filtered through filter paper to remove salts and then the solvent was removed under high vacuum. The products of each reaction were purified with silica gel chromatography (hexane / dichloromethane, 1:1). The purified product resulted in a colorless oil at 92% yield (4.27 ml). The product was stored in a freezer.1H NMR (500 MHz, CDCl3) δ 8.10-8.12 (d, 2 H), 7.92-7.93 (d, 2 H), 7.65-7.68 (t, 2 H), 7.40-7.43 (t, 2 H), 5.17 (s, 4 H), 0.2 (s, 12 H), 0.06-0.08 (m, 594 H);13C NMR (125MHz, CDCl3) δ 147.60, 139.00, 134.88, 129.20, 128.55, 125.66, 62.30, 2.13, 1.08;29Si NMR (59.6 MHz, CDCl3) δ -11.01, -21.69.

[0190] Example 21

[0191] 2-Nitrobenzyloxy pendant / backbone polydimethylsiloxane (ONB-PDMSpendant) Tris(pentafluorophenyl)boron (B(C6F5)3, 0.6 mol %), H-PDMS20cSt-8-10-SiH (1 mmol, 1 eq), and 2-nitrobenzyl alcohol (11 mmol, 11 eq) were added to toluene in the dark (wrapped in foil), followed by sonicating for 3 h in a 50 °C water bath. Afterwards, the reaction mixture was quenched by addition of neutral alumina (~ 1g). The mixture was filtered through filter paper to remove salts and then the solvent was removed under high vacuum. The products of each reaction were purified with silica gel chromatography (hexane / dichloromethane, 1:1). The purified product resulted in a yellow tinted sticky solid at 34% yield. The product was stored in a freezer.1H NMR (500 MHz, CDCl3) δ 8.10-8.12 (d, ~9 H), 7.92-7.93 (d, ~9 H), 7.65-7.68 (t, ~9 H), 7.40-7.43 (t, ~9 H), 5.17 (s, 18 H), 0.2 (s, ~78 H), 0.06-0.08 (m, 594 H);13C NMR (125MHz, CDCl3) δ 147.60, 139.00, 134.88, 129.20, 128.55, 125.66, 62.30, 2.13, 1.08;29Si NMR (59.6 MHz, CDCl3) δ -11.03, -21.80.

[0192] Example 22

[0193] Octakis(o-nitrobenzyloxy-dimethylsiloxy)-Q-silica cage (H-Q8M8)

[0194] To a solution of tris(pentafluorophenyl)boron (B(C6F5)3, BCF, 0.8 mg, 1.6 µmol, 0.2 mol %) was dissolved in toluene and added to a mixture of hydride terminated octakis(dimethylsiloxy)-Q-silica cage (H-Q8M8, 1 g, 0.9 mmol, 1 eq) with 2-nitrobenzyl alcohol (1.2 g, 8 mmol, mol, 1.2 eq) in toluene in the dark (wrapped in foil), followed by sonicating for 3 h in a 50 °C water bath. Afterwards, the reaction mixture was quenched by addition of neutral alumina (~ 1g). The mixture was filtered through filter paper to remove salts and then the solvent was removed under high vacuum. Product was insoluble after concentration (43% yield) but verified by thermal gravimetric analysis. Expected ceramic yield 43.2%, actual CY 44.1%.

[0195] Example 23

[0196] Photoreactions general

[0197] Photoreactions were conducted with a broad spectrum 450 W medium-pressure mercury lamp (250-400 nm lamp, 100 mw / cm2output measured at sample) in a blackout cabinet. To prevent the degradation of silanes from the heat produced from the lamp, a cooling tube which connected to a water64438-WO-PCT / IDN202 circulating chiller was used, as was an air circulation system exchanging air between inside and outside the cabinet. Samples were in NMR tubes and / or quartz cuvettes as needed. The distance between the light source and the samples was 20 cm.

[0198] Example 24

[0199] Procedure of photopolymerizing 2-nitrobenzyloxy-polysiloxane’s

[0200] The photodeprotection of 2-nitrobenzyloxy-polysiloxane’s was aided by the addition of H2O (~3 eq.) and 10 mol % of DBTDL. For cross-linked siloxane formation, each 2-nitrobenzyloxy- polysiloxane (~4 ml) was mixed with phenyl-(2-nitrobenzyloxy)3-silane (0.4 g) in 4 ml of THF (0.19 M). 2-nitrobenzyloxy-polysiloxane (4 ml) alone was used for linear siloxane formation. The THF was removed from the samples by high vacuum, and then the mixtures were filtered after adding hexane. The remaining solid particles were separated from the polymers using a centrifuge, and then the polymers were decanted into other vials for further testing.

[0201] Example 25

[0202] 3D Printing

[0203] To a Phrozen DLP 3D printer was added 15 g of 2-nitrobenzyloxy-end capped 201 cSt polydimethylsiloxane and 2 g of solid phenyl-(2-nitrobenzyloxy)3-silane. The solid was mixed into the liquid siloxane, water (1 eq.), 5 mL isopropanol, and then 0.5 mL of di-butyl-tin-dilaurate (DBTL) was added to aid in coupling of the Si-OH groups. A simple square structure was designed and supports were automatically added in the software. The siloxane rubber structure (1 cm x 1 cm) was printed at a rate of 25 µm per hour to ensure the fullest deprotection, for a total thickness of 3 mm. The resulting print was removed from the build plate, trimmed, and then swollen and rinsed to remove photo-cage byproduct. (FIG.8.)

[0204] Example 26

[0205] Surface Patterning

[0206] A mixture of 100 mg of tris(2-nitrobenzyloxy)phenylsilane, 0.2 mL DBTL, 3 eq. of water, and 2 mL of solution were prepared and added over a surface of a silica thin layer chromatography (TLC) plate (3 cm x 2 cm) with fluorescent backing, OH functionalized silicon, or OH functionalized glass in a small evaporating dish. A mask was added to a TLC plate to demonstrate spatio-temporal control of the surface attachment of the monomer. The mixture was then covered with a quartz glass plate and irradiated 1 hour at ~100 mw / cm2by a medium-pressure mercury lamp. The samples were then rinsed with THF to remove excess reagents. FIGS.5-7 show TLC, silicon, and glass examples.

[0207] Example 27

[0208] Ethyl-Silsesquioxane Particle Formation

[0209] The photodeprotection of phenyl-(2-nitrobenzyloxy)3-silane (1 mmol) was aided by the64438-WO-PCT / IDN202 addition of H2O (~3 eq.), 10 mol % of DBTDL, and 4 ml of THF. The mixture was irradiated 24 hours to ensure full removal and silsesquioxane particle formation (FIG.9). The sample resulted in a dark brown tar which was then subsequently washed by hexane and acetone to remove photo-byproducts. It was then vacuum dried resulting in 67 mg of ethylsilsesquioxane white powder.

[0210] Example 28

[0211] Synthesis of H4-(2-nitrobenzyloxy)4-Q8M8using Piers-Rubinsztajn method

[0212] Tris(pentafluorophenyl)boron (B(C6F5)3, 0.6 mol %), Q8M8H (1 mmol, 1 eq), and 2- nitrobenzyl alcohol (0.5 mmol, 0.5 eq) were added to dichloromethane with a magnetic stir bar in the dark (wrapped in foil), followed by stirring for 3 h at room temperature. The reaction mixture with catalyst left behind was left to dry / concentrate under ambient conditions for 12 h, resulting in an off-white solid (FIG. 11).1H NMR and FTIR confirmed 2-nitrobenzyloxy attachment and remaining Si-H groups.1H NMR (∂ppm CDCl3): 0.25 (m (br), 48 H), 4.67 (m (br), 4H), 5.09 (m (br), 8H), 7.36 (m (br), 4H), 7.58 (m (br), 4H), 7.81 (m (br), 4H), 8.02 (m (br), 4H). FTIR (cm-1): 1050 (Si-O), 1100 (Si-O), 1500 (Si-C), 2150 (Si-H), 2900 (C-H).

[0213] Example 29

[0214] Glass polymerization method using a partially PPG functionalized Q-silica cage

[0215] H4-(2-nitrobenzyloxy)4-Q8M8 in the presence of tris-pentafluorophenyl boron (B(C6F5)3) as a catalyst left from synthesis was dissolved in minimum THF and 2-drops of water added. PPG functionalized Q-silica cage is stable in the presence of B(C6F5)3 at this stage. A UV-365 nm LED was then used to polymerize this mixture directly, where the PPG group is removed and B(C6F5)3 conducted the self polymerization of Si-OH to Si-H groups using the Piers-Rubinsztajn method to give a solid insoluble hard glass-like polymer with slight yellow coloration from the removal of PPG groups (FIGS.11 and 12). FTIR (cm-1): 1050 (Si-O), 1100 (Si-O), 1500 (Si-C), 2900 (C-H). The polymer was then pyrolized / sintered at 600 °C to form a glass structure.

[0216] Certain embodiments of the compositions and methods disclosed herein are defined in the above examples. It should be understood that these examples, while indicating particular embodiments of the invention, are given by way of illustration only. From the above discussion and these examples, one skilled in the art can ascertain the essential characteristics of this disclosure, and without departing from the spirit and scope thereof, can make various changes and modifications to adapt the compositions and methods described herein to various usages and conditions. Various changes may be made and equivalents may be substituted for elements thereof without departing from the essential scope of the disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the essential scope thereof.

Claims

64438-WO-PCT / IDN202 CLAIMS What is claimed is:

1. A method of functionalizing a Cl-metal / metalloid system, the method comprising: reacting a chlorine-containing silane or a chlorine-containing metal complex with an alcohol- containing photoremovable protecting group (PPG) compound and a catalyst in darkness to obtain a functionalized compound.

2. The method of claim 1, wherein the catalyst comprises triethylamine.

3. The method of claim 1, wherein the catalyst comprises a non-amino base.

4. The method of claim 3, wherein the non-amino base comprises NaH.

5. The method of claim 1, wherein the alcohol-containing PPG compound comprises an o- nitrobenzyloxy group.

6. The method of claim 1, wherein the darkness is created by wrapping reaction vessels in foil, wherein the reaction vessels contain the chlorine-containing silane or chlorine-containing metal complex and the alcohol-containing PPG compound and catalyst.

7. The method of claim 1, wherein the chlorine-containing silane comprises tetrachlorosilane, chlorotriethylsilane, 3-chloropropyl-methyl-dichlorosilane, chlorotriphenylsilane, dichlorodiethylsilane, trichloroethylsilane, trichlorophenylsilane, triethylchlorosilane, or chlorotriethylsilane.

8. The method of claim 1, wherein the chlorine-containing metal complex comprises titanium-tetrachloride, zirconium-tetrachloride, or aluminum-trichloride.

9. The method of claim 1, wherein the functionalized compound comprises tetrakis-2- nitrobenzyloxysilane, titanium-tetra-2-nitrobenzyloxide, 3-dimethylaminobenzyloxytriethylsilane, bis-2- nitrobenzyloxy-3-chloropropyl-methylsilane, 2-nitrobenzyloxytriethylsilane, 2- nitrobenzyloxytriphenylsilane, bis(2-nitrobenzyloxy)diethylsilane, bis(2-nitrobenzyloxy)diphenylsilane, bis(2-nitrobenzyloxy)methylphenylsilane, tris(2-nitrobenzyloxy)ethylsilane, tris(2- nitrobenzyloxy)phenylsilane, 3-dimethylaminobenzyloxytriethylsilane, 1-(3,4-dimethoxyphenyl)-2-64438-WO-PCT / IDN202 hydroxyethan-1-one(phenacyl)-triethylsilane, 2,8-diiodo-1,3,5,5,7,9-hexamethyl-5H-4λ4,5λ4- dipyrrolo[1,2-c:2',1'-f][1,3,2]diazaborinin-10-yl)methanoxy(BODIPY)-triethylsilane, or 3- dimethylaminobenzyloxytriethylsilane.

10. A method of functionalizing a silane, the method comprising: reacting a Rx-silane with an alcohol- or alkoxy-containing photoremovable protecting group (PPG) compound in the presence of a Lewis acid catalyst and in darkness to produce a functionalized silane; wherein: R is an organic group, and x is from 1 to 3.

11. The method of claim 10, wherein R comprises an alkyl, a haloalkyl, an aryl, or a haloaryl.

12. The method of claim 10, wherein R comprises methyl, ethyl, propyl, chloropropyl, iodopropyl, chloromethyl, phenyl, or chlorobenzyl.

13. The method of claim 10, wherein the Rx-silane comprises triphenyl silane or diphenyl silane.

14. The method of claim 10, wherein the alcohol / alkoxy-containing PPG compound comprises 2-nitrobenzyl alcohol.

15. The method of claim 10, wherein the Lewis acid catalyst comprises tris(pentafluorophenyl)boron.

16. The method of claim 15, wherein the alkoxy is methoxy or ethoxy.

17. The method of claim 10, wherein the darkness is created by wrapping reaction vessels in foil, wherein the reaction vessels contain the Rx-silane, the alcohol-containing PPG compound, and the Lewis acid catalyst.

18. A method of protecting a silicon center against nucleophilic attack, the method comprising reacting an alkoxy-containing PPG compound with cyclohexanethiol and a base to produce a silane having a protected silicon center.64438-WO-PCT / IDN202 19. The method of claim 18, wherein the alkoxy-containing PPG compound comprises comprises bis-2-nitrobenzyloxy-3-chloropropyl-methylsilane.

20. The method of claim 18, wherein the base comprises NaH.

21. The method of claim 18, wherein the silane having a protected silicon center comprises bis-2-nitrobenzyloxy-cyclohexanethiopropyl-methylsilane.

22. A method of functionalizing a siloxane, the method comprising: reacting a siloxane containing a Si-H terminus or a pendant substitution with an alcohol or alkoxy containing a photoremovable protecting group (PPG) and a Lewis acid catalyst in darkness to obtain a functionalized siloxane.

23. The method of claim 22, wherein the Lewis acid catalyst comprises tris- pentafluorophenylboron.

24. The method of claim 22, wherein the PPG comprises an o-nitrobenzyloxy, a benzyl alkyl group substituted o-nitrobenzyloxy, a m-dialkylamino, a phenacyl, BODIPY, or a coumarin.

25. The method of claim 22, wherein the alcohol or alkoxy containing a PPG comprises 2- nitrobenzyl alcohol.

26. The method of claim 22, wherein the siloxane comprises hydrogen-terminated polydimethylsiloxane (H-PDMS), or H-PDMS containing pendant SiH substitutions.

27. The method of claim 22, wherein the siloxane comprises H-PDMS2-3cSt, H-PDMS100cSt,or H-PDMS20cSt-8-10-SiH.

28. The method of claim 22, wherein the functionalized siloxane comprises 2-nitrobenzyloxy terminated PDMS (ONB-PDMS), or 2-nitrobenzyloxy pendant / backbone PDMS (ONB-PDMSpendant).

29. A method of functionalizing a silsesquioxane or silica cage containing Si-H corners, the method comprising:64438-WO-PCT / IDN202 reacting a silsesquioxane or a silica cage containing Si-H corners with an alcohol or alkoxy containing a photoremovable protecting group (PPG) and a Lewis acid catalyst in darkness to obtain a functionalized silsesquioxane or functionalized silica cage.

30. The method of claim 29, wherein the PPG comprises an o-nitrobenzyloxy, a benzyl alkyl group substituted o-nitrobenzyloxy, a m-dialkylamino, a phenacyl, BODIPY, or a coumarin.

31. The method of claim 29, wherein the Lewis acid catalyst comprises tris- pentafluorophenylboron.

32. The method of claim 29, wherein the silsesquioxane or silica cage comprises hydride terminated octakis(dimethylsiloxy)-Q-silica cage (H-Q8M8).

33. The method of claim 29, wherein the alcohol or alkoxy containing a PPG comprises 2- nitrobenzyl alcohol.

34. A method of functionalizing nanoparticles or microparticles, the method comprising reacting nanoparticles or microparticles containing Si-H groups with a photoremovable protecting group (PPG) compound containing an alcohol and a Lewis acid catalyst in darkness to obtain functionalized nanoparticles or functionalized microparticles.

35. The method of claim 34, wherein the PPG compound comprises an o-nitrobenzyloxy, a benzyl alkyl group substituted o-nitrobenzyloxy, a m-dialkylamino, a phenacyl, a BODIPY, or a coumarin.

36. The method of claim 34, wherein the Lewis acid catalyst comprises tris- pentafluorophenylboron.

37. A method of functionalizing a surface, the method comprising reacting a surface containing Si-H groups with a photoremovable protecting group (PPG) compound containing an alcohol and a Lewis acid catalyst in darkness to obtain functionalized surface.

38. The method of claim 37, wherein the surface comprises silicon, metal, or glass.

39. A method of patterning a surface, the method comprising:64438-WO-PCT / IDN202 adding a solution comprising a photoremovable protecting group (PPG) compound and dibutyltin (IV) dilaurate (DBTDL) or tris-pentafluorophenyl boron (BCF) to a surface, wherein the surface comprises hydroxyl or amine functionalization; masking portions of the surface to obtain a masked surface having unmasked portions; and exposing the masked surface to light to attach monomers from the PPG compound to the unmasked portions of the surface.

40. The method of claim 39, wherein no monomers are attached to unmasked portions of the surface.

41. The method of claim 39, wherein the silicon or glass is functionalized with OH groups, NHx groups, or phenyl groups.

42. The method of claim 39, wherein the surface comprises silica, silicon, or glass.

43. A method of 3D printing, the method comprising: mixing an alkoxysilane, a siloxane, a silsesquioxane, or a cage silica containing a photoremovable protecting group (PPG) and a couping catalyst in a 3D printer; and operating the 3D printer in the presence of light to print a three-dimentionsal structure comprising a silicon-containing polymer.

44. The method of claim 43, wherein the PPG comprises an o-nitrobenzyloxy, a benzyl alkyl group substituted o-nitrobenzyloxy, a m-dialkylamino, a phenacyl, BODIPY, or a coumarin.

45. The method of claim 43, wherein the PPG comprises an ortho-nitrobenzyl alcohol, a meta-dialkylaminobenzyl alcohol, or a phenacyl derivative.

46. The method of claim 43, wherein the siloxane comprises polydimethylsiloxane.

47. The method of claim 43, wherein the silsesquioxane or cage silica has mixed functionality of PPG and Si-H groups.

48. The method of claim 43, wherein the PPG comprises phenyl-(2-nitrobenzyloxy)3-silane.

49. The method of claim 43, wherein the coupling catalyst comprises dibutyltin (IV)64438-WO-PCT / IDN202 dilaurate (DBTDL).

50. The method of claim 43, wherein the coupling catalyst comprises tris-pentafluorophenyl boron (BCF).

51. A method of forming nanoparticles or microparticles, the method comprising irradiating a monomer comprising: deprotecting a photoprotected monomer, wherein the photoprotected monomer comprises a photoremovable protecting group (PPG); and irradiating the deprotected monomer with a laser to form nanoparticles or microparticles.

52. The method of claim 51, wherein the monomer comprises a silsesquioxane.

53. The method of claim 51, wherein the PPG comprises an o-nitrobenzyloxy, a benzyl alkyl group substituted o-nitrobenzyloxy, a m-dialkylamino, a phenacyl, BODIPY, or a coumarin.

54. Use of dibutyltin (IV) dilaurate (DBTDL) as a coupling catalyst to induce coupling of species generated after photo-induced deprotection of a photoremovable protecting group (PPG).

55. The method of any preceding claim, wherein the PPG comprises a silicon atom directly bonded to an o-nitrobenzyloxy group having Formula I: Formula I; 12wherein R , R , atom, a halogen atom, a nitro group, a cyano group, a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a substituted or unsubstituted aryl group, an aryloxy group, an acyloxy group having 1 to 5 carbon atoms, a hydroxy group, a mercapto group, an acetyl group, or an allyl group.

56. A method of conducting 3D printing, the method comprising printing a siloxane monomer composition with light to form a three-dimensional article comprising a polymer formed from64438-WO-PCT / IDN202 the siloxane monomer composition, wherein the siloxane monomer composition comprises a silicon compound having a silicon atom directly bonded to an o-nitrobenzyloxy group having Formula I: Formula I; wherein R1, R2,atom, a halogen atom, a nitro group, a cyano group, a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a substituted or unsubstituted aryl group, an aryloxy group, an acyloxy group having 1 to 5 carbon atoms, a hydroxy group, a mercapto group, an acetyl group, or an allyl group.

57. The method of claim 56, wherein siloxane monomer composition further comprises a silanol-condensing catalyst.

58. The method of claim 56, wherein no preformed polymers are printed.

59. A composition comprising titanium-tetra-2-nitrobenzyloxide.

60. A composition comprising 3-dimethylaminobenzyloxytriethylsilane.

61. A composition ncomprising bis-2-nitrobenzyloxy-3-chloropropyl-methylsilane.

62. A composition comprising bis-2-nitrobenzyloxy-cyclohexanethiopropyl-methylsilane.

63. A composition comprising 2-nitrobenzyloxytriethylsilane.

64. A composition comprising 2-nitrobenzyloxytriphenylsilane.

65. A composition comprising bis(2-nitrobenzyloxy)diethylsilane.

66. A composition comprising bis(2-nitrobenzyloxy)diphenylsilane.

67. A composition comprising bis(2-nitrobenzyloxy)methylphenylsilane.64438-WO-PCT / IDN202 68. A composition ncomprising tris(2-nitrobenzyloxy)ethylsilane.

69. A composition comprising tris(2-nitrobenzyloxy)phenylsilane.

70. A composition comprising 3-dimethylaminobenzyloxytriethylsilane.

71. A composition comprising 1-(3,4,-dimethoxyphenyl)-2-hydroxyethan-1-one(phenacyl)- triethylsilane.

72. A composition comprising 2,8-diiodo-1,3,5,5,7,9-hexamethyl-5H-4λ4,5λ4-dipyrrolo[1,2- c:2',1'-f][1,3,2]diazaborinin-10-yl)methanoxy(BODIPY)-triethylsilane.

73. A composition comprising 2-nitrobenzyloxytriphenylsilane.

74. A composition comprising bis(2-nitrobenzyloxy)diphenylsilane.

75. A composition comprising 3-dimethylaminobenzyloxytriethylsilane.

76. A composition comprising 2-nitrobenzyloxy terminated polydimethylsiloxane having a viscosity of 27 centistokes.

77. A composition comprising 2-nitrobenzyloxy terminated polydimethylsiloxane having a viscosity of 201 centistokes.

78. A composition comprising 2-nitrobenzyloxy pendant polydimethylsiloxane.

79. A composition comprising octakis(o-nitrobenzyloxy-dimethylsiloxy)-Q-silica cage (PPG- Q8M8).

80. A composition comprising octakis(o-nitrobenzyloxy-dimethylsiloxy)-Q-silica cage with remaining Si-H functionality (Hx,PPGy-Q8M8), wherein x is from 1 to 7 and y is from 1 to 8, with or without tris-pentafluorophenyl boron.

81. A method for fabricating a three-dimensional structure using two-photon polymerization, the method comprising: providing a material composition that is sensitive to two-photon absorption, the material64438-WO-PCT / IDN202 composition comprising a PPG-alkoxy-cage system or an o-nitrobenzyloxysilane; directing a pulsed laser beam onto the material composition within a predetermined focal region to induce removal of a photoremovable protecting group and form Si-O-Si bonds through simultaneous absorption of two photons configured to promote electrons in the material composition into an excited state through a half energy virtual state; scanning the pulsed laser beam in three dimensions according to a predefined pattern to form a desired three-dimensional structure of the material composition with removed photoremovable protecting groups and Si-O-Si bonds; and optionally, post-processing the three-dimensional structure to enhance one or more properties, wherein the post-processing step is selected from thermal treatment, chemical treatment, or surface modification.

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