title: Effect of micelles on the spectral characteristics of the prototropic species of 2-(2'-aminophenyl)benzimidazole.
abstract: The absorption and fluorescence spectra of 2-(2'-aminophenyl)benzimidazole (2-APBI) have been studied in anionic (sodium dodecylsulphate, SDS), cationic (cetyltrimethylammonium bromide, CTAB) and non-ionic micelles (Tween-80, TritonX-100) at different acid-base concentrations. Spectral characteristics of 2-APBI at various acid concentrations have established only one kind of monocation (MC) in Tween-80 and TritonX-100 (TX-100), whereas two kinds of MCs are present in SDS. Above study has further shown that there is a strong hydrogen bonding interaction between the polar polyoxyethylene groups of non-ionic micelles and the MCs of 2-APBI. This interaction is responsible for the stabilization of the MC III to MC III' which is more planar than either MC II or MC III, which is otherwise less stable in water. This is substantiated by the lifetime data, fluorescence excitation spectra and the pKa values of the monocation-neutral (MC-N) equilibrium.
authors.affiliation: Department of Chemistry, Indian Institute of Technology, Kanpur.
authors.forename: S
authors.initials: S
authors.lastname: Santra
authors.forename: S K
authors.initials: SK
authors.lastname: Dogra
mesh_terms: D001562:Benzimidazoles / Q000737:chemistry*; D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000737:chemistry; D003902:Detergents / Q000737:chemistry; D008823:Micelles; D015394:Molecular Structure; D017830:Octoxynol / Q000737:chemistry; D011136:Polysorbates / Q000737:chemistry; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D013050:Spectrometry, Fluorescence / Q000379:methods
chemical_list: C412329:2-(2'-aminophenyl)benzimidazole; D001562:Benzimidazoles; D002593:Cetrimonium Compounds; D003902:Detergents; D008823:Micelles; D011136:Polysorbates; D012967:Sodium Dodecyl Sulfate; D017830:Octoxynol; D000077286:Cetrimonium