Proton coupled electron transfer reaction of phenols with excited state ruthenium(II) - Polypyridyl complexes

摘要

The reaction of phenols with the excited state,*[Ru(bpy) _3]~(2+) (E_0=0.76 V) and*[Ru(H _2dcbpy)_3]~(2+), (dcbpy=4,4′-dicarboxy-2, 2′-bipyridine) (E_0=1.55 V vs. SCE) complexes in CH _3CN 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 ΔG~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.