Excited state intramolecular proton transfer in 2-(2′-aminophenyl) benzimidazole in micelles

Abstract

The excited state intramolecular proton transfer in 2-(2′(-aminophenyl) benzimidazole (2-APBI) has been studied using absorption, fluorescence excitation spectra, steady state, and time resolved emission spectroscopy in anionic (sodium dodecyl sulphate, SDS), cationic (cetyltrimethylammonium bromide, CTAB) and non-ionic (Triton X-100, TX-100 and Tween-80) micelles. The spectral characteristics of the parent compound in these micelles are compared with those observed in different solvents to see the effect of these heterogeneous environments on the ground and excited singlet state spectral characteristics of 2-APBI. Observation of the tautomer emission has suggested that 2-APBI has been solubilized in these micelles. Double exponential decay of the normal emission in ionic micelles suggests the presence of rotamers I and IV, whereas the single exponential decay of the normal emission in TX-100 and Tween-80 suggests the existence of rotamer I and IV′, respectively in these micelles.