The experimental and DFT studies of 1,3-dimethyl-2-[4-chloro-styryl]-benzimidazolium iodide

1,3-Dimethyl-2-[4-chloro-styryl]-benzimidazolium iodide (1) was synthesized and characterized by X-ray diffraction, 1H NMR, MS, IR, UV–vis spectra and elemental analysis. The crystals are monoclinic, space group P21/c, with a = 12.507(3) Å, b = 7.3259(19) Å, c = 36.705(9) Å, V = 3358.9(15) Å3, and Z = 4 (at 296(2) K). Crystal stacking scheme indicates the face-to-face π⋯π aromatic stacking interactions. Molecular geometries, frequencies, IR, 1H NMR and UV–vis were calculated at DFT/TD-DFT level using two hybrid exchange–correlation functionals, B3LYP and PBE1PBE. The stability of the molecule arising from hyperconjugative interaction and charge delocalization had been analyzed using natural bond orbital (NBO) analysis. These calculations on (1) provide deep insight into its electronic structure and properties.

► A styrylcyanine dye with benzimidazole nucleus was synthesized.
► The dye crystallizes in the P21/c space group with four molecules per unit cell.
► The hydrogen bonds and π⋯π aromatic stacking interactions exist in the crystal.
► The IR, 1H NMR and UV–vis obtained by DFT/TD-DFT are in good agreement with the experimental values.
► NBO analysis reveals the charge transfer within the molecule.