Silver(I) N-heterocyclic carbene complexes: Synthesis, characterization and antibacterial activity

Five new silver complexes having bidentate N-heterocyclic carbene ligands were synthesized and characterized by elemental analysis, IR, NMR and mass spectroscopic methods. Four of the ligands used are neutral, having an alcohol group on alkyl substituent of one of the two nitrogen atoms of the heterocycle [NHC–OH], the fifth, having a ligand alkoxide, is mono-anionic [NHC–O]. A study on the rate of hydrolysis of complexes synthesized, showed that they are stable to hydrolysis even after 24 h. Probably, the pincer effect of both [NHC–OH] and [NHC–O] ligands stabilizes these compounds. All the synthesized complexes do not show cytotoxicity, but they have a significant antibacterial activity. They were tested on Escherichia coli and Bacillus subtilis and data obtained demonstrate that the synthesized Ag-complexes are very promising candidates to be used as antimicrobial compounds.