Photoionization of phenothiazinyl- and (carbazolylalkyl)trimethylammonium bromides in frozen AOT reversed micellar solutions studied by electron spin echo modulation and electron spin resonance

Abstract

Electron spin echo (ESE) modulation and electron spin resonance of photoionized N-({omega}-phenothiazin-10-alkyl)-N,N,N-trimethylammonium bromide (PC{sub n}TAB) and N-({omega}-(3,6-didodecyl)carbazol-9-ylalkyl)-N,N,N-trimethylammonium bromide (CzC{sub n}TAB) (where alkyl = C{sub 4}H{sub 9}, C{sub 12}H{sub 25}, and C{sub 4}H{sub 9}, C{sub 8}H{sub 17}, C{sub 12}H{sub 25}) have been studied as a function of the size of the water pool of sodium bis(2-ethyl-1-hexyl)sulfosuccinate (AOT) reverse micellar solutions in D{sub 2}O and isooctane. Deuterium modulation effects measured by ESE spectroscopy from the photogenerate carbazole or phenothiazine cation radical show that the heterocyclic moiety experiences strong water interactions and is located near the AOT-water interface of the reverse micelle and that the alkyl chain is bent. Thus, both the location of the phenothiazine or carbazole group near the micellar interface and the degree of water disorder near the interface affect optimization of the photo efficiency for charge separation.