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Water photo-oxidation sensitized by zinc(II) meso- tetrakis(N-methyl-4-pyridyl)porphine

1991; Elsevier BV; Volume: 56; Issue: 2-3 Linguagem: Inglês

10.1016/1010-6030(91)80028-g

1873-2666

Oleg V. Gerasimov, Sergei V. Lymar, Valentin N. Parmon,

Photosynthetic Processes and Mechanisms

Abstract The irradiation (λ>520 nm) of a weakly acidic solution containing zinc(II) meso -tetrakis( N - methyl-4-pyridyl)porphine (ZnTMPyP 4+ ), Fe(bpy) 2+ 3 (bpy≡2,2′-bipyridine) and S 2 O 8 2− leads to the formation of the strong one-electron oxidant Fe(bpy) 3 3+ with a quantum yield of about 0.2. The reaction mechanism established by means of flash and steady state photolysis includes photochemical generation of zinc porphyrin radical cation ZnTMPyP ·5+ , which rapidly oxidizes Fe(bpy) 3 3+ and ZnTMPyP 4+ . After the accumulation of Fe(bpy) 3 3+ in the presence of Co 2+ (oxygen evolution catalyst precursor) an oxygen formation reaction was initiated by means of the addition of KOH (to pH 12) to the solution. O 2 was detected in the gas phase by gas chromatography.