Photoinduced electron transfer reactions of ruthenium(II) complexes containing 2,2′-bipyridine-4,4′-dicarboxylic acid with phenols: Steric and charge effects

Abstract

Luminescent mixed-ligand ruthenium(II) complexes of type RuL n X 3− n (L = 2,2′-bipyridine, X = 2,2′-bipyridine-4,4′-dicarboxylic acid, n = 0,1,2,3) have been synthesized and their photophysical and electrochemical properties are investigated. The emission lifetime measured for RuL n X 3− n reveals that the lifetime increases as the ligand L is replaced by X. The luminescence quenching of *RuL n X 3− n with several substituted phenolate ions in aqueous medium is efficient and the change of quenching rate data with the change of structure of ligand of RuL n X 3− n and phenolate ion is explained in terms of exergonicity of the reaction, electron transfer distance and charge effect. The semiclassical theory of electron transfer has been successfully applied to this photoredox system.