Benzimidazolium Salts Bearing 2-methyl-1,4-benzodioxane Group: Synthesis, Characterization, Computational Studies, In vitro Antioxidant and Antimicrobial Activity

This study contains the synthesis of the 1-(2-methyl-1,4-benzodioxane)benzimidazole and 2-methyl-1,4-benzodioxane substituted benzimidazolium salts. The benzimidazolium salts were synthesized from the reaction of the 1-(2-methyl-1,4-benzodioxane)benzimidazole and various aryl chlorides. All compounds were characterized using 1H NMR, 13C NMR, FTIR spectroscopy, and elemental analysis techniques. The antioxidant properties of benzimidazolium salts were examined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging and hydrogen peroxide scavenging ability assays. The compounds showed a moderate inhibitory effect on DPPH radical (The percent inhibition = 29.53-39.75). Also, the compounds exhibited significant H2O2 radical scavenging activity. Antimicrobial activities of the compounds were examined against nine bacterial strains and Candida albicans. All compounds displayed marked antimicrobial activity against tested microorganisms, particularly against Pseudomonas aeruginosa, Listeria monocytogenes, and C. albicans. From the computational perspective, benzimidazolium salts were also optimized at B3LYP / DMol3// DFT level using the Discovery Studio 2020 program. HOMO–LUMO analysis and molecular electrostatic potential surface (MESP) were exerted to examine the effects of benzimidazolium salts' electronic and structural properties.