Quantum-chemical modeling of the effect of microhydration and media on the vibrational spectra of 2-(2′-pyridyl)-benzimidazole and its 1-methylsubstituted analogue

Abstract

Quantum-chemical calculations of the optimized structures, harmonic force fields, and frequencies of 1 : 1 and 1 : 2 complexes of 2-(2′-pyridyl)-benzimidazole and 1-methyl-2-pyridine-2-yl-1H-benzimidazole are performed by means of DFT (B3LYP/6-31+G**). The shifts in the frequencies of the vibrational spectra of the investigated complexes are considered with allowance for the conformational structure and effect of the medium. Analytical bands (spectral marks) are proposed that can be used to identify complexes of 2-(2′-pyridyl)-benzimidazole and 1-methyl-2-pyridine-2-yl-1H-benzimidazole with water. It is concluded that considering the environment within a model of a polarized continuum allows the forecasting of possible shifts in the frequencies in the vibrational spectra of the studied compounds in aqueous media and DMF.