%0 Journal Article
%T Novel Nonsymmetrically p-Benzyl-Substituted (Benz)imidazole N-Heterocyclic Carbene-Silver(I) Acetate Complexes: Synthesis and Biological Evaluation
%A Frauke Hackenberg
%A Anthony Deally
%A Grainne Lally
%A Sina Malenke
%A Helge M邦ller-Bunz
%A Francesca Paradisi
%A Siddappa Patil
%A Daniela Quaglia
%A Matthias Tacke
%J International Journal of Inorganic Chemistry
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/121540
%X Nonsymmetrically substituted N-heterocyclic carbene (NHC) precursors 1a每d and 3a每d were synthesised by first reacting 1H-(benz)imidazole with p-cyanobenzyl bromide to give 4-(1H-imidazole-1-ylmethyl)benzonitrile (1) and 4-(1H-benzimidazole-1-ylmethyl)benzonitrile (3) and afterwards introducing benzyl bromide, 1-(bromomethyl)-4-methylbenzene, 1-(bromomethyl)-4-methoxybenzene, and methyl 4-(bromomethyl)benzoate. The NHC-silver(I) acetate complexes (1-benzyl-3-(4-cyanobenzyl)-2,3-dihydro-1H-imidazole-2-ylidene) silver(I) acetate (2a), (1-(4-cyanobenzyl)-3-(4-methylbenzyl)-2,3-dihydro-1H-imidazole-2-ylidene) silver(I) acetate (2b), (1-(4-cyanobenzyl)-3-[4-(methoxycarbonyl)benzyl]-2,3-dihydro-1H-imidazole-2-ylidene) silver(I) acetate (2c), (1-benzyl-3-(4-cyanobenzyl)-2,3-dihydro-1H-benzimidazole-2-ylidene) silver(I) acetate (4a), (1-(4-cyanobenzyl)-3-(4-methylbenzyl)-2,3-dihydro-1H-benzimidazole-2-ylidene) silver(I) acetate (4b), (1-(4-cyanobenzyl)-3-(4-methoxybenzyl)-2,3-dihydro-1H-benzimidazole-2-ylidene) silver(I) acetate (4c), and (1-(4-cyanobenzyl)-3-[4-(methoxycarbonyl)benzyl]-2,3-dihydro-1H-benzimidazole-2-ylidene) silver(I) acetate (4d) were yielded by reacting these NHC precursors with silver(I) acetate. The silver(I) acetate complex 4b was characterised by single crystal X-ray diffraction. Preliminary in vitro antibacterial studies against the Gram-positive bacteria Staphylococcus aureus and the Gram-negative bacteria Escherichia coli, using the Kirby-Bauer disc diffusion method, were carried out on the seven NHC-silver(I) acetate complexes 2a每c and 4a每d. Also the IC50 values of these seven complexes were determined by an MTT-based assay against the human renal cancer cell line Caki-1. The complexes 2a每c and 4a每c revealed the following IC50 values, respectively, 25 (㊣1), 15 (㊣2), 5.4 (㊣0.8), 16 (㊣2), 7.1 (㊣1), 20 (㊣4), and 14 (㊣1)ˋ米M. 1. Introduction N-Heterocyclic carbenes (NHCs) are versatile ligands in silver complexes exhibiting antimicrobial activity, in particular for the possible treatment of pulmonary infections accompanying cystic fibrosis (CF) and chronic lung infections [1每3] and maybe in the treatment of cancer [4]. Youngs＊ research group have reported antimicrobial activity of NHC-silver complexes derived from 1H-imidazole, 4,5-dichloro-1H-imidazole and xanthines against a panel of highly resistant pathogens recovered from the respiratory tract of cystic fibrosis (CF) patients [1, 3, 5]. Another important contribution by the Ghosh research group led to the synthesis and antimicrobial evaluation of NHC-silver complexes derived from
%U http://www.hindawi.com/journals/ijic/2012/121540/