Photo-induced electron-transfer reaction of naphthalocyanine

Abstract

Quenching of fluorescence emission of a series of siloxanes (R₃SiO)₂ SiNc by a variety of quenchers ranging from acceptors to donors was studied in dichloromethane solution. The relationship between fluorescence quenching rates and half-wave potentials of the quenchers suggests that quenching results from the photoinduced electron-transfer reaction of substrates (R₃SiO)₂SiNc with quenchers. The results indicate that (R₃SiO)₂SiNc acts as an electron-donating sensitizer for acceptors and as an electron-accepting sensitizer for donors. The small values of the Coulombic attraction (ω_p) obtained from our experiments indicate that the radical-ion pair consisting of (R₃SiO)₂SiNc and a quencher can dissociate easily even in dichloromethane, because (R₃SiO)₂SiNc is an extremely large molecule.