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Synthesis, Cytotoxicity and Antibacterial Studies of Novel Symmetrically and Non‐Symmetrically p ‐Nitrobenzyl‐Substituted N‐Heterocyclic Carbene–Silver(I) Acetate Complexes
Author(s) -
Patil Siddappa,
Deally Anthony,
Gleeson Brendan,
Hackenberg Frauke,
MüllerBunz Helge,
Paradisi Francesca,
Tacke Matthias
Publication year - 2011
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.201000395
Subject(s) - imidazole , silver acetate , chemistry , carbene , benzimidazole , antibacterial activity , medicinal chemistry , yield (engineering) , antimicrobial , nuclear chemistry , organic chemistry , bacteria , materials science , catalysis , biology , metallurgy , genetics
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 IC 50 values ranging from 15 (+/–1) to 27 (+/–2) μM.