Electron transfer quenching of an excited amphiphilic Ru(bpy) 32+ derivative in langmuir-Blodgett films containing various ferrocene derivatives as electron donors

Abstract

Photoinduced electron transfer kinetics in Langmuir-Blodgett (LB) films was studied in connection with photoelectric conversion devices. Four kinds of amphiphilic ferrocene derivatives as electron donors with different standard redox potentials E 0 and with the same alkyl chain spacer were newly synthesized. By using nanosecond laser photolysis, the luminescence decay curves were recorded for a sensitizer Ru(bpy) 3 2+ derivative (where bpy is 2,2′-bipyridine) confined in one monolayer in heterogeneous LB films containing also one of the ferrocene derivatives as the other monolayer. The layer of ferrocene moieties in the heterostructures is located a fixed distance from the sensitizer layer. The comparison of the dependence of the electron transfer quenching rate on the standard free energy difference Δ G 0 of the reaction between the sensitizer and the donors for three different systems, i.e. the LB film, the micellar, and the solution systems, implies the presence of local electrical fields in these ionic LB films.