Photosensitisation of dioxygen-bridged cobalt(III) dinuclear complexes by the excited states of bipyridyl and phenanthroline complexes of ruthenium(II)

Abstract

Photosensitisation reactions of dioxygen-coordinated cobalt(III) dinuclear complexes have been studied using ruthenium(II) polypyridyl complexes as sensitisers. Quenching of the charge transfer excited states of ruthenium(II) polypyridyl complexes by the cobalt(III) oxo complexes is by a diffusion-controlled process. The quenching reaction was investigated by flash photolysis, and it was concluded that more than 90% of the quenching events proceed by an electron transfer pathway. Formation of minor quantities of cobalt(II) is attributed to energy transfer from the excited state of polypyridyl ruthenium(II) complex to the cobalt(II) oxo complex and the subsequent excited-state reaction of the acceptor complex.