Reaction Control of Photoinduced Electron Transfer in Porphyrin–Viologen Linked System by the Use of External Magnetic Fields

Effects of external magnetic fields on electron transfer reactions in porphyrin–viologen linked systems (ZnPCnV) were investigated by laser photolysis. Rates of reverse electron transfer in the photogenerated intramolecular ion radical pair, as originated from quenching of porphyrin triplet by viologen, were remarkably suppressed (by a factor of ten for n=8) at above 0.1 T. The lifetime of the charge separated state could be correspondingly extended by the use of external magnetic fields, which perturb electron spin relaxation process.