Using Visible Light to Tune Boronic Acid–ester Equilibria

We report a series of azobenzene boronic acids that can be used to control diol binding via photochemical isomerization. When the boronic acid is ortho to the azo group, the thermodynamically-favored E isomer binds weakly with diols to form boronic esters. Isomerization of the E azobenzene to its Z isomer enhances diol binding, and the extent of this enhancement is affected by the azobenzene structure. 2,6-Dimethoxy azobenzene boronic acids show over 20-fold enhancement in binding upon E–Z isomerization, which can be triggered with red light. Competition experiments and computational studies suggest that the changes in binding affinity originate from stabilization of the E boronic acids and destabilization of the E boronic esters. We demonstrate a correlation between diol binding and photostationary state: different wavelengths of irradiation yield different quantities of bound diol. Higher binding constants for the Z isomer relative to the E isomer was observed with all diols investigated, including cyclic diols, nitrocatechol, biologically relevant drugs, and polyols. This photoswitch was employed to “catch and release” a fluorescently tagged diol in buffered water. By tethering this photoswitch to a poly(ethylene glycol) star polymer, we can tune the stiffness of covalent adaptable hydrogels using different wavelengths of visible light. This work establishes photoswitchable equilibria as a tool for the reversible ligation of molecular and macromolecular species.

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Using Visible Light to Tune Boronic Acid–ester Equilibria

10.26434/chemrxiv.12756023.v2 ◽

2020 ◽

Author(s):

Joseph Accardo ◽

Emily McClure ◽

Martin Mosquera ◽

Julia Kalow

Keyword(s):

Visible Light ◽

Boronic Acid ◽

Red Light ◽

Binding Constants ◽

Boronic Acids ◽

Star Polymer ◽

Light Competition ◽

Biologically Relevant ◽

Boronic Esters ◽

Poly Ethylene

We report a series of azobenzene boronic acids that reversibly control the extent of diol binding via photochemical isomerization. When the boronic acid is ortho to the azo group, the thermodynamically-favored E isomer binds weakly with diols to form boronic esters. Isomerization of the E azobenzene to its Z isomer enhances diol binding, and the magnitude of this enhancement is affected by the azobenzene structure. 2,6-Dimethoxy azobenzene boronic acids show over 20-fold enhancement in binding upon E–Z isomerization, which can be triggered with red light. Competition experiments and computational studies suggest that the changes in binding affinity originate from stabilization of the E boronic acids and destabilization of the E boronic esters. We demonstrate a correlation between diol binding and photostationary state: different wavelengths of irradiation yield different quantities of bound diol. Higher binding constants for the Z isomer relative to the E isomer was observed with all diols investigated, including cyclic diols, nitrocatechol, biologically relevant compounds, and polyols. This photoswitch was employed to “catch and release” a fluorescently tagged diol in buffered water. By tethering this photoswitch to a poly(ethylene glycol) star polymer, we can tune the stiffness of covalent adaptable hydrogels using different wavelengths of visible light. This work establishes photoswitchable equilibria as a tool for the reversible ligation of molecular and macromolecular species.

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Visible-light-mediated photoredox minisci C–H alkylation with alkyl boronic acids using molecular oxygen as an oxidant

Chemical Communications ◽

10.1039/d0cc05946c ◽

2020 ◽

Vol 56 (83) ◽

pp. 12652-12655 ◽

Cited By ~ 1

Author(s):

Jianyang Dong ◽

Fuyang Yue ◽

Hongjian Song ◽

Yuxiu Liu ◽

Qingmin Wang

Keyword(s):

Visible Light ◽

Molecular Oxygen ◽

Boronic Acid ◽

Room Temperature ◽

Boronic Acids ◽

Acid Activation ◽

Alkylation Reactions

Direct visible-light-mediated Minisci C–H alkylation reactions of N-heteroarenes with alkyl boronic acids at room temperature with molecular oxygen as an oxidant and boronic acid activation reagent were reported.

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Chemoselective oxidation of aryl organoboron systems enabled by boronic acid-selective phase transfer

Chemical Science ◽

10.1039/c6sc04014d ◽

2017 ◽

Vol 8 (2) ◽

pp. 1551-1559 ◽

Cited By ~ 28

Author(s):

John J. Molloy ◽

Thomas A. Clohessy ◽

Craig Irving ◽

Niall A. Anderson ◽

Guy C. Lloyd-Jones ◽

...

Keyword(s):

Boronic Acid ◽

Phase Transfer ◽

Boronic Acids ◽

Boronic Esters

Chemoselective boronate formation and phase transfer allows chemoselective Brown oxidation of boronic acids in the presence of boronic esters.

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Boronic acid ester with dopamine as a tool for bioconjugation and for visualization of cell apoptosis

Chemical Communications ◽

10.1039/c3cc49100e ◽

2014 ◽

Vol 50 (48) ◽

pp. 6390-6393 ◽

Cited By ~ 17

Author(s):

Wei Scarano ◽

Hongxu Lu ◽

Martina H. Stenzel

Keyword(s):

Cell Apoptosis ◽

Boronic Acid ◽

Acid Ester ◽

Physiological Condition ◽

Boronic Acids ◽

Acidic Ph ◽

Ph Values ◽

Boronic Ester ◽

Boronic Esters

Boronic esters between 1,2-benzodiols and boronic acids are an efficient way for bioconjugation. The ester is stable at physiological condition, but it cleaves very slowly at acidic pH values found in the endosomes and lysosomes. During apoptosis, the boronic ester is cleaved, most likely due to the influx of Ca2+ ions and the oxidation of 1,2-benzodiols.

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A Boronic Acid-Based Fluorescence Hydrogel for Monosaccharide Detection

10.26434/chemrxiv.7176989 ◽

2018 ◽

Author(s):

Suying Xu ◽

Adam Sedgwick ◽

Souad Elfecky ◽

Wenbo Chen ◽

Ashley Jones ◽

...

Keyword(s):

Fluorescent Probe ◽

Boronic Acid ◽

Binding Constants ◽

Strong Fluorescence ◽

Fluorescence Response ◽

Turn On ◽

Fluorescence Turn On ◽

Hydrogel System

A boronic acid-based anthracene fluorescent probe was functionalised with an acrylamide unit to incorporate into a hydrogel system for monosaccharide detection. In solution, the fluorescent probe displayed a strong fluorescence turn-on response upon exposure to fructose, and an expected trend in apparent binding constants, as judged by a fluorescence response where D-fructose > D-galactose > D-mannose > D-glucose. The hydrogel incorporating the boronic acid monomer demonstrated the ability to detect monosaccharides by fluorescence with the same overall trend as the monomer in solution with the addition of fructose resulting in a 10-fold enhancement (≤ 0.25 M).

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Metal‐Free and Heterogeneous Photocatalytic Reduction of 4‐Nitroaniline by a Poly(Ethylene Glycol)‐Supported Eosin Dye under Visible‐Light Exposure

ChemCatChem ◽

10.1002/cctc.201900040 ◽

2019 ◽

Vol 11 (14) ◽

pp. 3307-3317

Author(s):

Andreea L. Chibac ◽

Violeta Melinte ◽

Vlasta Brezová ◽

Estelle Renard ◽

Arnaud Brosseau ◽

...

Keyword(s):

Ethylene Glycol ◽

Visible Light ◽

Light Exposure ◽

Photocatalytic Reduction ◽

Poly Ethylene Glycol ◽

Metal Free ◽

Poly Ethylene

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The Merger of CF3SO2Na and Palladium Catalysis to Enable Decarboxylative Cross-Coupling for the Synthesis of Aromatic Ketones under Room Temperature

Organic Chemistry Frontiers ◽

10.1039/d1qo00438g ◽

2021 ◽

Author(s):

Pan Xie ◽

Cheng Xue ◽

Cancan Wang ◽

Dongdong Du ◽

Sanshan Shi

Keyword(s):

Visible Light ◽

Room Temperature ◽

Palladium Catalysis ◽

Cross Coupling ◽

Boronic Acids ◽

Aromatic Ketones ◽

Aryl Ketones ◽

Oxocarboxylic Acids

A CF3SO2Na/Pd(OAc)2 co-catalyzed strategy is developed to produce aryl ketones via visible-light-induced decarboxylative cross-coupling of α-oxocarboxylic acids and aryl boronic acids. This process was perfomed under air at room temperature,...

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Photocatalytic Activity and Characterization of Carbon-Modified Titania for Visible-Light-Active Photodegradation of Nitrogen Oxides

International Journal of Photoenergy ◽

10.1155/2012/548647 ◽

2012 ◽

Vol 2012 ◽

pp. 1-13 ◽

Cited By ~ 6

Author(s):

Chun-Hung Huang ◽

Yu-Ming Lin ◽

I-Kai Wang ◽

Chun-Mei Lu

Keyword(s):

Visible Light ◽

Carbon Number ◽

Red Light ◽

Matrix Material ◽

Carbon Sources ◽

Impregnation Method ◽

Light Spectrum ◽

Precursor Molecule ◽

Visible Light Active ◽

Carbonate Species

A variety of carbon-modified titania powders were prepared by impregnation method using a commercial available titania powder, Hombikat UV100, as matrix material while a range of alcohols from propanol to hexanol were used as precursors of carbon sources. Rising the carbon number of alcoholic precursor molecule, the modified titania showed increasing visible activities ofNOxphotodegradation. The catalyst modified with cyclohexanol exhibited the best activities of 62%, 62%, 59%, and 54% for the totalNOxremoval under UV, blue, green, and red light irradiation, respectively. The high activity with long wavelength irradiation suggested a good capability of photocatalysis in full visible light spectrum. Analysis of UV-visible spectrum indicated that carbon modification promoted visible light absorption and red shift in band gap. XPS spectroscopic analysis identified the existence of carbonate species (C=O), which increased with the increasing carbon number of precursor molecule. Photoluminescence spectra demonstrated that the carbonate species suppressed the recombination rate of electron-hole pair. As a result, a mechanism of visible-light-active photocatalyst was proposed according to the formation of carbonate species on carbon-modified TiO2.

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