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Laboratoire d'Electrochimie Moleculaire, LEM, Paris

UMR CNRS - Université Paris Diderot - Paris France

Master Frontiers in Chemistry | UFR de Chimie - Université Paris Diderot - Paris 7 CNRS - Institut de chimie Université de Paris Master Chimie Sorbonne Paris Cité UFR de Chimie - Université Paris Diderot - Paris 7 CNRS - Institut de chimie
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Université Paris Diderot
Université de Paris CNRS, Centre National de la Recherche Scientifique

Le LEM - Publications: Abstracts

Publication 750

J. Am. Chem. Soc., 136 (25), 8907-8910, 2014



Proton-coupled electron transfer in azobenzene-hydrazobenzene couples with pending acid-base functions. Hydrogen-bonding and structural effects.

Jean-Michel Savéant and Cédric Tard

Université Paris Diderot, Sorbonne Paris Cité, Laboratoire d’Electrochimie Moléculaire, Unité Mixte de Recherche Université - CNRS N° 7591, Bâtiment Lavoisier, 15 rue Jean de Baïf, 75205 Paris Cedex 13, France

Electron transfer in azobenzene derivatives bearing two carboxylic acid groups is coupled with intramolecular proton transfer in a stepwise manner in the title 2e– + 2H+ redox couple. The presence of the pendant acid–base functions pushes the redox chemistry of the azo/hydrazo couple toward positive potentials by as much as 0.75 V. This is essentially the result of H-bonding of one of the nitrogen atoms by the neighboring carboxylic group and H-bonding of one carboxylate by the neighboring protonated nitrogen atom. The two electron-transfer reactions, particularly the second one, are accompanied by strong structural changes, which results in the occurrence of a square scheme mechanism in which electron transfer and structural change are not concerted. These are typical phenomena that are likely to be encountered when attempting to boost proton-coupled electron-transfer stoichiometric or catalytic processes by installing pendant acid–base functionalities in the close vicinity of the reacting center.

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