Synthesis, characterization and biological evaluation of Bis-benzimidazolium salts and their silver(I)-N-heterocyclic carbene complexes

Abstract

Azolium salts are stable sources of N-heterocyclic carbenes (NHCs), an emerging class of ligands. Due to prominent properties, they have versatile applications. In the current study, new bis-benzimidazolium salts and their silver complexes were synthesized and confirmed through spectroscopic analysis. Compounds were characterized using FT-IR, 1H NMR, and 13C NMR spectroscopies. Biological potentials of these compounds were investigated for antibacterial activity against both the gram-positive (Staphylococcus Aureus) and gram-negative (Escherichia Coli) strains. The salts L1 and L2 showed zone inhibition of 17 ± 1 and 13.33 ± 0.58 mm for S. Aureus and 8.83 ± 0.76 and 8.83 ± 0.58 mm for E. Coli, respectively. The respective silver complexes C1 and C2 showed better zone of inhibitions for both the strains, i.e., 18.67 ± 0.58 and 19.83 ± 0.29 mm for S. Aureus and 12.5 ± 0.5 and 14.33 ± 0.58 mm for E. Coli, respectively. The salts showed a good trend in scavenging concerning the increasing concentration and presented the IC50 values in the range of 3.51 and 15.36 μg/mL, respectively, which showed that these compounds are good antioxidant agents. The Hemolytic potential of compounds were checked and L2 was found least toxic with 7.37 ± 0.11 value.