Decay kinetics of N,N,N',N'-tetramethylbenzidine photocations in frozen micellar solution of cetyltrimethylammonium bromide.
After UV irradiation of rapidly frozen solutions of N,N,N',N'-tetramethylbenzidine (TMB) in dilute aqueous micellar cetyltrimethylammonium bromide at 80 K, the ESR signal corresponding to the TMB+ cation was detected indicating photoionization. This signal was monitored as a function of time at various temperatures between 80 K and 260 K. On a timescale of a few days the signal decayed to a plateau value that was stable for months. Two distinct second-order processes for the decay from the initial to the plateau value were observed: one prevailing at low temperatures with an activation energy of 0.6 kJ/mol, and one prevailing at T > 220 K with an activation energy of 13 kJ/mol. By means of spin probe investigations the latter process was shown to be connected with a local softening of the region adjacent to the micellar surface.
Wolff
T
T
Technische Universität Dresden, Institut für Physikalische Chemie, Germany.
Weber
S
S
Böhm
B
B
Schütz
A
A
D001560:Benzidines / Q000737:chemistry*; D002412:Cations; D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000737:chemistry*; D003902:Detergents; D005615:Freezing; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008823:Micelles; D010777:Photochemistry; D012996:Solutions; D013113:Spin Labels
D001560:Benzidines; D002412:Cations; D002593:Cetrimonium Compounds; D003902:Detergents; D008823:Micelles; D012996:Solutions; D013113:Spin Labels; C020515:N,N,N',N'-tetramethylbenzidine; D000077286:Cetrimonium