Pulse radiolytic investigation on the reactivity of hydrated electron towards acceptors bound to cationic micelles. 3,3'-dimethylbiphenyl and hexadecylpyridinium chloride as electron scavengers

Abstract

The decay of hydrated electron (e - aq) has been studied by pulse radiolysis in cationic micellar solutions of hexadecyltrimethylammonium bromide (HTAB) containing 3,3'-dimethylbiphenyl (DMBP) and hexadecylpyridinium chloride (HPC). The pseudo-first order equation of dispersive kinetics has been used for accurate description of the data. The results are compared with those obtained earlier for N,N,N',N'-tetramethylbenzidine as e - aqscavenger. There is discussed the mechanism including trapping of e - aq in positive micellar field, its migration between aggregates and intramicellar electron transfer. It is concluded that, contrary to what was suggested earlier, reactivity of e - aq in cationic micellar solution does depend on the kind of micelle bound acceptor. This may be related to different solubilization loci of the scavengers in micelles and/or to the different scavenging effectiveness. The present data indicate that DMBP molecule is located rather in the head group region than inside HTAB aggregates.