Excited-state intramolecular proton transfer of 2-(2′-hydroxyphenyl)benzimidazole in cyclodextrins and binary solvent mixtures
The excited-state intramolecular proton transfer (ESIPT) of 2-(2′-hydroxyphenyl)benzimidazole (HBI) has been studied using absorbance, steady-state, and time-resolved emission spectroscopies in cyclodextrins (β-, γ-, and 2,6-di-O-methyl-β-cyclodextrins) and in binary aqueous solvent mixtures. The spectral characteristics of HBI in cyclodextrins and binary solvent mixtures (dioxane:water, MeOH:water, and solutions of cyclohexane containing MeOH and trifluoroethanol) are compared to further study the effects of various microenvironments on the ground and excited-state properties of the molecule. The intermolecular interactions of HBI with cyclodextrins and various solvents appear to weaken intramolecular hydrogen bonding in HBI and facilitate the formation of strong intermolecular hydrogen bonds with the various cyclodextrins and solvent molecules. The acquired data are used to suggest the formation of a zwitterionic structure of HBI in cyclodextrins.
Publication Source (Journal or Book title)
Journal of Physical Chemistry A
Roberts, E., Dey, J., & Warner, I. (1997). Excited-state intramolecular proton transfer of 2-(2′-hydroxyphenyl)benzimidazole in cyclodextrins and binary solvent mixtures. Journal of Physical Chemistry A, 101 (29), 5296-5301. https://doi.org/10.1021/jp971232w