Spectroscopic, computational and electrochemical studies on 2-(4-nitrophenyl)-1H-benzo[d]imidazole and its interaction with cationic surfactant cetyltrimethylammonium bromide

Abstract

2-(4-Nitrophenyl)-1H-benzo[d]imidazole (4-NBI) was prepared and characterized by experimental and computational methods. Electrochemical reduction of the compound was studied in dimethyl sulphoxide media which showed that the nitro group of the molecule undergoes quasireversible three-step reduction producing –NH2 while the imidazole nitrogen bonded to hydrogen undergoes an irreversible one-electron reduction. The electronic spectra were studied by TDDFT computational method and compared with the experimental results which corroborated each other excellently. The interaction of 4-NBI with the cationic surfactant cetyltrimethylammonium bromide (CTAB) was investigated in aqueous solution at physiological pH (7.4) by UV–Vis spectroscopy. By using different nonlinear fitting methods binding parameters were evaluated for 4-NBI – CTAB micelles interaction. The results showed that the electrostatic interaction plays a major role over hydrophobic interaction in the binding of 4-NBI to CTAB micelles. The electrostatic interaction has also an important role in the distribution of 4-NBI between CTAB micelle–water phases. Gibbs free energy for the binding and distribution of 4-NBI between the bulk aqueous medium and surfactant micelles was calculated.