Dinuclear silver(I)-N-heterocyclic carbene complexes of N-allyl substituted (benz)imidazol-2-ylidenes with pyridine spacers: synthesis, crystal structures, nuclease and antibacterial studies

The synthesis, structures and antibacterial studies of silver complexes of N-heterocyclic carbene (NHC) ligands are reported. The NHC precursors, 2,6-bis(3-allylimidazol-1-ylmethyl) pyridine hexafluorophosphate (1) and 2,6-bis(3-allylbenzimidazol-1-ylmethyl)pyridine dibromide (2) were treated with Ag2O to yield 2,6-bis(3-allylimidazol-1-ylmethyl)pyridine disilver bis(hexafluorophosphate) (3) and 2,6-bis(3-allylbenzimidazolium-1-ylmethyl)pyridine disilver bis(hexafluorophosphate) (4). All four compounds were characterized by physico-chemical and spectroscopic techniques and by single-crystal X-ray diffraction. The compounds were screened for their antibacterial activities against Staphylococcus aureus (ATCC 12600) as a Gram-positive and Escherichia coli (ATCC 11303) as a Gram-negative bacteria. Compounds 1 and 2 showed no inhibition while 3 and 4 inhibited the growth of these bacteria. The nuclease activities of the compounds were evaluated by gel electrophoresis, and the results indicate that complexes 3 and 4 can degrade both DNA and RNA.