Proton transfer reactions in apolar aprotic solvents

Abstract

Proton transfer reactions are advantageously investigated in low‐dielectric‐constant apolar aprotic solvents where specific solute–solvent interactions are greatly minimized, if not eliminated, and proton transfer occurs directly. An intriguing feature of these reactions is their general acid/base‐catalyzed kinetics with a timescale over microseconds to minutes. Proton‐coupled electron transfer (PCET), a great promise in the development of renewable energy sources, is an emerging application of the reactions. This article is an updated review of the post‐1980 developments in understanding the mechanism of proton transfer reactions, quantitative structure–reactivity relationships, acid/base‐catalyzed molecular rearrangements, reverse trends between acidity parameters and 13C δco (a measure of electron population at the carboxyl carbon) in aromatic carboxylic acids, coupling of proton transfer with electron transfer, and PCET reactions in suitably designed model systems in apolar aprotic solvents for renewable energy devices. Copyright © 2015 John Wiley & Sons, Ltd.

Theoretical investigation on the excited state intramolecular proton coupled charge transfer phenomenon for a novel fluorophore

“…Compounds that undergo excited state intramolecular proton transfer (ESIPT), discovered first by Weller, have attracted attention due to their applications in green fluorescent protein, bioimaging, organic light‐emitting diodes, fluorescent chemosensors, and photophysical studies . In general, the molecules with the ESIPT properties exist in the enol form at the ground state, stabilized by a heterocyclic ring, which consists of the intramolecular hydrogen bond (IMHB) between a hydroxyl group and a neighboring proton acceptor.…”

Proton transfer mediated recognition of amines by ionizable macrocyclic receptors

“…Ionizable macrocycles have been extensively investigated by the group of Bartsch, who published several papers on the use of carboxyl calix [4]arenes, 35 crown ethers 14 (especially lariat ethers 36 ) and calix [4]crowns 37 as metal ion extractants. They synthesized a huge number of ionophores over the years, exploring the influence of the number and the tri-dimensional arrangement of the carboxylate moieties on the extraction efficiency and selectivity of singly charged and multi charged ions.…”

“…10. a) Calix [4]arene-crown 312H and b) the solid-state structure of its complex with (R)-phenylglycinol. 47 Following the track set by this seminal paper, a homooxacalix [3]arene receptor (32H) was reported, bearing a dye-functionalized phenol moiety able to ionize and induce a change of colour once the proton is released.…”

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Proton transfer rate‐equilibria in apolar aprotic solvents: a historical perspective

“…In a close succession, Zeegers‐Huyskens and Huyskens authored in 1980 a book chapter reviewing studies on the formation of proton transfer and ion transfer complexes in inert solvents using dipole moment and infrared (IR) and other spectral measurements . Recently, a comprehensive review on the post‐1980 era developments in studies on various aspects of proton transfer reactions in apolar aprotic solvents has been published . On the other hand, reviews published in pre‐1980 era dealt, however, with one or another aspect of proton transfer processes in such media.…”