Thermal and photoinduced electron-transfer catalysis of high-valent metal-oxo porphyrins in oxidation of substrates

In this manuscript, we have overviewed thermal and photoinduced electron transfer catalysis of high-valent metal-oxo porphyrins in oxidation of various substrates. The high-valent iron-oxo porphyrin in cytochrome P450 (P450) is produced by photoinduced electron transfer from electron donors, such as triethanolamine (TEOA), to the excited state of a photosensitizer such as eosin Y, followed by the reduction of the heme domain of P450 by the resulting radical anion of the photosensitizer and the subsequent reaction of the reduced heme with dioxygen (O₂). Various substrates were oxidized by O₂ in this visible light-driven electron-transfer catalytic reaction with several P450s from bacteria and humans. A manganese(V)-oxo corrorazine was produced by photoinduced electron transfer from the excited state of manganese(III) corrorazine to O₂, followed by hydrogen abstraction from toluene derivatives, catalyzing the oxidation of toluene derivatives with O₂ in the presence of an acid via photoinduced electron transfer catalysis. High-valent manganese-oxo porphyrins are also produced by photoinduced electron transfer from the excited state of [Ru(bpy)₃]²⁺ (bpy = 2,2′-bipyridine) to electron acceptors, followed by electron transfer oxidation of manganese(III) porphyrins with [Ru(bpy)₃]³⁺, catalyzing oxidation of various substrates with O₂. Finally photoinduced electron-transfer catalysis of cobalt porphyrins is discussed for the photocatalytic water oxidation with persulfate.