S. Patil, Anthony Deally, Brendan Gleeson
Mar 1, 2011
Citations
0
Influential Citations
57
Citations
Journal
Zeitschrift für anorganische und allgemeine Chemie
Abstract
From the reaction of 1H-imidazole (1a), 4,5-dichloro-1H-imidazole (1b), 1H-benzimidazole (1c), 1-methylimidazole (1d), 4,5-dichloro-1-methylimidazole (1e) and 1-methylbenzimidazole (1f) with p-nitrobenzyl bromide (2), symmetrically and non-symmetrically p-nitrobenzyl-substituted N-heterocyclic carbene (NHC) [(3a–f)] precursors were synthesised. These NHC-precursors were then reacted with silver(I) acetate to yield the NHC-silver acetate complexes [1,3-bis(4-nitrobenzyl)imidazol-2-ylidene]silver(I) acetate (4a), [4,5-dichloro-1,3-bis(4-nitrobenzyl)imidazol-2-ylidene]silver(I) acetate (4b), [1,3-bis(4-nitrobenzyl)benzimidazol-2-ylidene]silver(I) acetate (4c), [1-methyl-3-(4-nitrobenzyl)imidazole-2-ylidene] silver(I) acetate (4d), [4,5-dichloro-1-methyl-3-(4-nitrobenzyl)imidazole-2-ylidene] silver(I) acetate (4e) and [1-methyl-3-(4-nitrobenzyl)benzimidazole-2-ylidene] silver(I) acetate (4f), respectively. The two NHC–silver(I) acetate complexes 4a and 4e were characterised by single-crystal X-ray diffraction. All compounds studied in this work were preliminary screened for their antimicrobial activities in vitro against Gram-positive bacteria Staphylococcus aureus, and Gram-negative bacteria Escherichia coli using the qualitative Kirby–Bauer disk-diffusion method. All NHC–silver(I) acetate complexes exhibited medium to high antibacterial activity with areas of clearance ranging from 3 to 7 mm at the highest amount used, whereas the NHC-precursors showed significantly lower activity. In addition, NHC–silver(I) acetate complexes 4a–f had their preliminary cytotoxicity tests on the human renal-cancer cell line Caki-1 and showed medium to high cytotoxicity with IC50 values ranging from 15 (+/–1) to 27 (+/–2) μM.