DEACTIVATION OF PYRENE EXCIPLEXES IN WATER-IN-OIL MICROEMULSIONS PREPARED WITH BENZYLHEXADECYLDIMETHYLAMMONIUM CHLORIDE

The photophysical properties of exciplexes formed between pyrene and N ,N'-dimethylaniline (DMA) or p-dicyanobenzene (DCB) were studied in be nzene and benzylhexadecyldimethylammonium chloride-benzene-water micro emulsions. The fluorescence of the exciplexes in benzene solution was strongly quenched by the addition of benzylhexadecyldimethylammonium c hloride. Laser flash photolysis experiments were carried out in revers ed micellar solutions. The transient absorption spectra showed the pre sence of the pyrene triplet state in all cases. For the pyrene-DMA sys tem, the absorption of the pyrene radical anion was observed; however, the corresponding radical cation was not observed in the pyrene-DCB s ystem. These results are discussed in terms of hydrophobic and electro static effects at the surfactant-water interface of the microemulsion.