Synthesis, spectral studies and solvatochromism of some novel benzimidazole derivatives – ESIPT process

Some novel benzimidazole derivatives were synthesized and characterized by 1H, 13C NMR mass and elemental analysis. XRD analysis was carried out for 1-(4-methylbenzyl)-2-p-tolyl-1H-benzo[d]imidazole. The solvent effect on the absorption and fluorescence bands has been analyzed. The energetic analysis of the potential energy surface (PES), HOMO and LUMO levels [DFT/B3LYP/6-31G(d,p)] evidenced the existence of excited state intramolecular proton transfer (ESIPT) in hydroxy benzimidazole derivative.

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► Absorption and emission spectral studies have been carried out.
► HOMO–LUMO – probable charge transfer taking place.
► Formation of the keto-isomer due to ESIPT.
► Competition of intra and intermolecular hydrogen bonding.