Proton coupled electron transfer reaction of phenols with excited state ruthenium(II) – polypyridyl complexes

Abstract

Abstract The reaction of phenols with the excited state, *[Ru(bpy) 3 ] 2+ ( E 0 = 0.76 V) and *[Ru(H 2 dcbpy) 3 ] 2+ , (dcbpy = 4,4′‐dicarboxy‐2,2′‐bipyridine) ( E 0 = 1.55 V vs . SCE) complexes in CH 3 CN has been studied by luminescence quenching technique and the quenching is dynamic. The formation of phenoxyl radical as a transient is confirmed by its characteristic absorption at 400 nm. The k q value is highly sensitive to the change of pH of the medium and Δ G 0 of the reaction. Based on the treatment of k q data in terms of energetics of the reaction and pH of the medium, proton coupled electron transfer (PCET) mechanism has been proposed for the reaction. Copyright © 2010 John Wiley & Sons, Ltd.