Synthesis and antimicrobial activity of bulky 3,5‐di‐ tert ‐butyl substituent‐containing silver–N‐heterocyclic carbene complexes

A series of novel benzimidazolium bromides containing bulky 3,5-di-tert-butyl group were synthesized in high yields as N-heterocyclic carbene (NHC) ligands. These NHC ligands were metallated with Ag2O under moderate conditions to give novel silver–NHC complexes. The structures of all compounds were characterized using 1H NMR, 13CNMR, infrared and elemental analysis techniques, which supported the proposed structures. The silver–NHC complexes were screened for their in vitro antimicrobial activities against the standard bacterial strains Enterococcus faecalis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa and the fungal strains Candida albicans and C. tropicalis. The results showed that most of the silver–NHC complexes inhibited the growth of all bacterial strains and fungal strains and were found to display effective antimicrobial activity against different microorganisms.