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Title: Electron spin resonance and electron spin echo modulation studies of N,N,N',N'-tetramethylbenzidine photoionization in sodium dodecyl sulfate micelles: structural effects of alcohol addition

Journal Article · · J. Phys. Chem.; (United States)
DOI:https://doi.org/10.1021/j100292a026· OSTI ID:6629222

Electron spin echo modulation (ESEM) and electron spin resonance (ESR) spectra of the photogenerated N,N,N',N'-tetramethylbenzidine cation radical (TMB/sup +/) in frozen micellar solutions of sodium dodecyl sulfate containing 2-propanol, 1-propanol, 1-pentanol, 1-octanol, 2-propanol-d/sub 7/, and 1-octanol-d/sub 17/ in H/sub 2/O and D/sub 2/O have been studied as a function of the alcohol concentration from 0 to 200 mM. Modulation effects due to the TMB/sup +/ interactions with deuteriums in D/sub 2/O and in 2-propanol-d/sub 7/ or 1-octanol-d/sub 17/ give direct evidence that 2-propanol is mainly located at the micellar interface whereas the alkyl chain of 1-octanol is located deeper into the micelle. Alcohol addition leads to an increase of water penetration into the micellar interface in the order 1-propanol < 2-propanol approx.= 1-pentanol < 1-octanol. The initial efficiency of charge separation upon potoionization of TMB as a function of alcohol concentration correlates with the degree of water penetration into the micelle, but the maximum photoionization efficiency seems more related to the degree of water organization at the micellar surface due to specific perturbing effects on the micellar structure dependent on the alcohol structure.

Research Organization:
Univ. of Houston, TX
OSTI ID:
6629222
Journal Information:
J. Phys. Chem.; (United States), Vol. 91:8
Country of Publication:
United States
Language:
English