Synthesis and antimicrobial studies of 1-methyl-2-dimethylaminoethyl-substituted benzimidazolium salts and N-heterocyclic carbene-silver complexes

The synthesis and antimicrobial studies of 1-methyl-2-dimethylaminoethyl-substituted carbene precursors and silver complexes are reported. The carbene precursors (1a-d) have been prepared from 1-methyl-2-dimethylaminoethyl-substituted benzimidazole and various alkyl halides. The silver-NHC complexes (2a-d) were synthesized from the benzimidazolium salts and Ag2O in dichloromethane at room temperature. The new compounds were characterized by H-1 NMR, C-13 NMR, FT-IR, and elemental analyses. The new carbene precursors and Ag-complexes were tested for their in vitro antimicrobial activity against a variety of Gram-positive and Gram-negative bacteria, as well as for their antifungal activities against Candida albicans and Candida tropicalis.