Fluorescence and Laser Photolysis Studies on the Intramolecular Exciplex Systems in Micellar Solutions

The behavior of intramolecular exciplex systems consisting of pyrene and N,N-dimethylaniline was studied in cationic, anionic and neutral micellar solutions. These systems are favorable for the study of photoinduced CT interaction in micellar systems, since (i) a pair of donor-acceptor is always solubilized in the micelle and (ii) the complicated effect of the intermolecular interaction can be prevented. No exciplex emission was detected and relative quantum yields as well as lifetimes were measured on the monomer fluorescence. The results are interpreted by assuming two solubilized forms in the micelle-water interface. Efficient quenching occurs in the dodecyltrimethylammonium chloride solution irrespective of the length of the methylene chain, suggesting a different solubilization from the cases of other detergents. The efficient quenching is ascribed to the rapid ion-pair formation in the micelle-water interface, which was directly demonstrated by the ns laser photolysis method.