Electron Spin Resonance and Electron Spin Echo Modulation Studies of N,N,N',N'-Tetramethylbenzidine Photoionization in Frozen Micellar Solutions: Structural Effect of 1-Butanol Addition to Sodium and Tetramethylammonium Dodecylsulfate and Dodecyltrimethylammonium Chloride Micelles

Article abstract of DOI:10.1021/ja00309a007

The electron spin echo modulation (ESEM) and electron spin resonance (ESR) spectra of the photogenerated N,N,N',N'-tetramethylbenzidine cation radical (TMB⁺) in frozen micellar solutions of sodium and tetramethylammonium dodecylsulfate (SDS and TMADS, respectively) as well as dodecyltrimethylammonium chloride (DTAC) have been studied as a function of 1-butanol (1-BuOH) concentration from 0 to 200 mM.A 5-doxylstearic acid spin probe has also been used in the ESEM experiments.The efficiency of TMB photoionization has been determined from ESR data, while ESEM analysis has given information about micelle hydration and aqueous interactions of TMB⁺.The variations observed with 1-BuOH addition depend on the micellar charge and the nature of the counterion in dodecylsulfate micelles.The main findings are that (1) hydration of TMADS micelles decreases from 0 to 200 mM 1-BuOH, while hydration of SDS and DTAC micelles increases somewhat from 0 to 100 mM and remains constant from 100 to 200 mM 1-BuOH, and (2) the efficiency of charge separation upon photoionization of TMB can be increased by alcohol addition in SDS micelles but not in TMADS and DTAC micelles.The results are interpreted primarily in terms of the effect of added alcohol on the surfactant headgroup density.