Novel benzimidazol-2-ylidene carbene precursors and their silver(I) complexes: Potential antimicrobial agents.

Novel benzimidazolium salts were synthesized as N-heterocyclic carbene (NHC) precursors, these NHC precursors were metallated with Ag2O in dichloromethane at room temperature to give novel silver(I)-NHC complexes. Structures of these benzimidazolium salts and silver(I)-NHC complexes were characterized on the basis of elemental analysis, (1)H NMR, (13)C NMR, IR and LC-MS spectroscopic techniques. A series of benzimidazolium salts and silver(I)-NHC complexes were tested against standard bacterial strains: Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and the fungal strains: Candida albicans and Candida tropicalis. The results showed that benzimidazolium salts inhibited the growth of all bacteria and fungi strains and all silver(I)-NHC complexes performed good activities against different microorganisms.