2655-65-4Relevant articles and documents
Transient Spontaneous Raman Study of Photoionization Kinetics at the Hydrocarbon/Water Interface in Micellar Solutions
Beck, S. M.,Brus, L. E.
, p. 1106 - 1111 (1983)
Transient spontaneous Raman spectroscopy (416 nm) has been used to observe the kinetics of TMB+ and TMB2+ ions following photoionization of tetramethylbenzidine (TMB) in aqueous micellar solutions.The ground-state TMB pKa values are shifted by micellar solubilization in the directions predicted by calculated surface pH values.In SDS micelles, the TMB+ ion initially produced is stabilized by negative surface groups.No time evolution of the TMB+ Raman spectrum occures, and bimolecular ion reactions are not observed.However, in CTAB micelles, TMB+ is destabilized by positive surface groups.The TMB+ Raman spectrum evolves on the 10-6-s time scale, suggesting that the ion has moved into the Stern layer and is assymmetrically solvated.On the 10-4-s time scale, TMB2+ appears from disproportionation of two TMB+ ions.Positive spectral identifications are facilitated by comparison with spectra obtained by chemical oxidation in various enviroments.
Electron Spin Resonance and Electron Spin-echo Modulation Studies of 5-Doxylstearic Acid and N,N,N',N'-Tetramethylbenzidine Photoionization in Sodium Dodecylsulphate Micelles. Effects of 15-Crown-5 and 18-Crown-6 Ether addition
Baglioni, Piero,Kevan, Larry
, p. 467 - 472 (2007/10/02)
Electron spin-echo modulation (e.s.e.m.) and electron spin resonance (e.s.r.) spectra of the photogenerated N,N,N',N'-tetramethylbenzidine (TMB) cation radical and 5-doxylstearic acid (5-DSA) in frozen micellar solutions of sodium dodecylsulphate containing 15-crown-5 and 18-crown-6 ethers in D2O and H2O have been studied as a function of the crown ether concentrations.Modulation effects due to 5-DSA interactions with water deuteriums give direct evidence that both crown ethers are mainly located at the micellar interface and that their interaction causes a decrease of hydration of the micellar interface.Modulation effects from TMB+ interaction with water deuteriums indicate that the TMB molecule moves toward the interfacial region when the sodium cation is complexed by the crown ether to decrease the local ionic strength in the interfacial region.The efficiency of charge separation upon TMB photoionization increases ca. 10percent with crown ether addition, and correlates with the increased TMB+-water interactions.The sodium cation complexation by the crown ether to change the charge distribution and ionic strength at the micellar interface seems to cause the interfacial hydration changes that promote the photoionization efficiency.
Photochemical Behaviour of N,N,N',N'-Tetramethylbenzidine and its Protonated Forms in Sodium Dodecyl Sulphate Anionic Micelles under 337 nm Laser Irradiation
Arce, Rafael,Kevan, Larry
, p. 1669 - 1676 (2007/10/02)
Continuous 337 nm laser excitation of N,N,N',N'-tetramethylbenzidine (TMB) in 0.1 mol dm-3 sodium dodecyl sulphate micelles produces monophotonic ionization of the molecule.A study of the photoionization process has resulted in the following new results: (1) the radical-cation quantum yield decreases with adsorbed light because of its spectral overlap with TMB and its simultaneous photodestruction during irradiation, (2) partial regeneration of the TMB absorption band after radical-cation decay suggests that a principal mode of radical decay is through a disproportionation reaction, (3) the photoionization yield is affected by the degree of protonation of TMB, increasing with increasing bulk pH, and (4) diprotonated TMB, TMBH22+, photodecomposes into TMB2+.
