Silver complexes of ligands derived from adamantylamines: Water-soluble silver-donating compounds with antibacterial properties.

Two new silver(I) complexes, namely [Ag(qyAm)2](CF3SO3) (1) and [Ag(qyTAm)2](CF3SO3) (2), (qyAm=2-(quinonyl)iminoadamantane, qyTAm=2-(quinonyl)iminotriazaadamantane) have been synthesized and characterized by elemental analyses, 1H NMR, IR, electronic absorption spectroscopy, and X-ray diffraction. The coordination geometry of the silver center in both complexes is distorted tetrahedral where their respective qyAm and qyTAm ligand bind in a bidentate fashion using the imine and quinoline nitrogen atoms. Complex 2 is soluble in water and exhibits strong antimicrobial actions on both Gram-negative (E. coli, and P. aeruginosa) and Gram-positive (S. aureus) bacteria. The minimal inhibitory concentration (MIC) values for complex 2 (4, 4, and 8 μg for E. coli, P. aeruginosa, and S. aureus, respectively) are comparable to MIC values of silver nitrate and silver sulfadiazine.