LIGHT-INITIATED ELECTRON-TRANSFER IN FUNCTIONAL SURFACTANT ASSEMBLIES .1. MICELLES WITH TRANSITION-METAL COUNTERIONS

The photoinduced reduction of cupric ions by organic donors (D) was studied in functional surfactant assemblies in which the Cu2+ ions constitute the counterion atmosphere of the micelle. The donors employed were N-methylphenothiazine (MPTH) and N, N-dimethyl-5, 1 1-dihydroindolo[3, 2-b]carbazole (DI). Laser photolysis, steady-state illumination, and fluorescence techniques were used to investigate the photoredox processes. The transfer of an electron from the excited donor inside the micelle to the counterion occurs so rapidly that it cannot be resolved kinetically by nanosecond laser techniques. In the case of DI, the reactive excited state was found to be the first excited singlet state whose lifetime in the Cu2+ micelles is 1.2 X 10-9 s. The cuprous ion formed in the photoredox process escapes from the micelle into the bulk solution before back transfer of electrons to D+ can occur. There it may be used for a second redox reaction with a negative ion or a zwitterion. In such a system, the back reaction between reduced acceptor ion and oxidized donor is prevented by the micellar surface potential allowing for storage of light energy. The dynamics of excited-state interaction with micellar counterions was investigated also in aggregates with Co2+ and Ni2+ counterion atmospheres, respectively. © 1979, American Chemical Society. All rights reserved.