Hydrogen evolution using photoinduced electron transfer in water soluble bisviologen-linked cationic zinc porphyrin

Water soluble bisviologen-linked cationic zinc porphyrin (ZnP(C4VAC4VB)(4)) and butylviologen-linked zinc porphyrin (ZnP(C4VC4)(4)) were synthesized and characterized. The intramolecular electron transfer rate constants from the zinc porphyrin moiety to viologens were measured by fluorescence lifetime and laser flash photolysis. In the case of ZnP(C4VC4)(4), the photoexcited singlet state and the triplet state of thr porphyrin were quenched by the bonded butylviologen. For ZnP(C4VAC4VB)(4), on the other hand, only the photoexcited singlet state of the porphyrin was quenched by the bonded viologens. These compounds were applied to photoinduced hydrogen evolution in the system containing nicotinamide adenine dinucleotide phosphate (reduced form NADPH), ZnP(C4VAC4VB)(4) or ZnP(C4VC4)(4) and hydrogenase under steady state irradiation. (C) 1999 Elsevier Science B.V. All rights reserved.