Coupled electron-proton transfer in interactions of triplet C-60 with hydrogen-bonded phenols: Effects of solvation, deuteration, and redox potentials

Biczók, László and Gupta, N. and Linschitz, H. (1997) Coupled electron-proton transfer in interactions of triplet C-60 with hydrogen-bonded phenols: Effects of solvation, deuteration, and redox potentials. JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 119 (51). pp. 12601-12609. ISSN 0002-7863

Text 1215215.pdf Restricted to Repository staff only Download (552kB) | Request a copy

Abstract

The quenching of triplet C60 by phenols is greatly enhanced by addition of pyridines, which also lower the phenol voltammetric oxidation potentials. Flash photolysis shows that the products of this quenching reaction are the C60 ¥- anion radical, neutral phenoxy (or naphthoxy) radicals, and protonated pyridines. Analysis of the second-order kinetics gives quenching rate constants and values of formation constants of hydrogen-bonded phenolpyridine pairs. The latter agree with those derived from absorption spectra over a wide range of phenols, pyridines, and solvents. Significant deuterium kinetic isotope effects are observed, indicating the importance of both proton transfer and hydrogen bonding in enhancing the rate. Quenching rates and radical yields both increase with solvent polarity. It is concluded that this quenching process involves interaction between 3C60 and a hydrogen-bonded phenolpyridine complex, in which electron transfer from the phenol to 3C60 is concerted with proton transfer from phenol to hydrogen-bonded pyridine.

Actions (login required)

Edit Item