Crystallographic Studies and Theoretical Comparison of Some New Benzimidazole Derivatives and Their Antifungal Study

ABSTRACT In view of rising demand and the importance of antifungal drugs, we have synthesized some new benzimidazole derivatives by reacting 4,5‐dimethyl benzene‐1,2‐diamine and substituted aromatic aldehydes in a comparatively eco‐friendly method using polyethylene glycol(PEG)‐ethanol medium. The structures of the synthesized benzimidazoles were confirmed by spectroscopic methods, viz. UV–vis, FTIR, 1 H NMR, HRMS, and crystallographic studies. A theoretical study has also been carried out by performing DFT and molecular docking to back the experimental values. The result of the antifungal study showed that the benzimidazole 5‐(5,6‐dimethyl‐1H‐benzo[d]imidazole‐2‐methoxyphenol, which is derived from 4,5‐dimethyl benzene‐1,2‐diamine and o‐vanillin, has appreciable antifungal activity in comparison to benzimidazoles derived from other aldehydes like 5‐bromoindole‐3‐carboxyaldehyde and syringaldehyde against the pathogen S. Cerevisiae than the pathogen C. Tropicalis. The reactivity of antifungal behaviour against pathogens is also in accordance with the lowest to highest HOMO‐LUMO energy gap of the mentioned benzimidazoles.