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

Conformations, vibrational spectra and force field of 1-methyl-2-(2′-pyridyl)benzimidazole: experimental data and density functional theory investigation in comparison with 2-(2′-pyridyl)benzimidazole

“…The significant influence of solvent on the geometry was observed for the pivotal (central) C-C bond in 2PBI-C molecule [14], and the same result is obtained for Me2PBI-C conformation, where the length of pivotal bond is increased (by *0.02-0.03 Å ) in both solvents in comparison with isolated molecules. The influence of methyl group on geometry of Me2PBI in comparison with 2PBI is practically negligible except the slight elongation (*0.01-0.015 Å ) of skeleton bonds adjusted to CH 3 group and C1-N2 imidazole bond near pivotal C-C bond of Me2PBI-A, and also shortening two other bonds of imidazole group.…”

“…On a base of calculated potential energy distribution in local symmetry coordinates, the interpretation of experimental IR and Raman spectra has been proposed (Table S2). The comparison of scaled frequencies with experimental data and results of similar calculations of 2PBI [14] confirms the possibility of using scaling procedure in Cartesian coordinates for the correction of harmonic calculations.…”

“…Appearance of a broadband in the 3400-3450 cm -1 region in IR spectrum of Me2PBI could be explained by possible influence of water molecules associated with Me2PBI [14]. One of the main differences between experimental IR spectra of 2PBI and Me2PBI is an occurrence of very broad complicated shape band in the 2500-3200 cm -1 region in IR spectrum of 2PBI, which is absent in the Me2PBI IR spectrum.…”

“…The hybrid density functionals used in our investigation have demonstrated very good performance for a prediction of molecular structure and vibrational spectra of similar organic molecules [12,[14][15][16]. Experimental 2-(2 0 -Pyridyl)benzimidazole (2PBI) and 1-methyl 2-(2 0 -pyridyl)benzimidazole (Me2PBI) have been synthesized in the Laboratory of Bioactive Organic Compounds (Department of Chemistry, Lomonosov Moscow State University) and had a purity about 98 %.…”

“…The structure of solid 2PBI has been determined by the X-ray diffraction [13]. Recently, the effect of microhydration on the structure and vibrational spectra of 2PBI and 1-methyl-2-(2 0 -pyridyl)benzimidazole (Me2PBI) has been investigated at B3LYP/6-31?G(d,p) level of theory [14].…”