Silver(I) and gold(I) complexes with penicillamine: Synthesis, spectroscopic characterization and biological studies

Two new metal complexes of penicillamine (Pen), with molecular formulas [Ag(C5H10O2NS)]center dot H2O and [Au(C5H10O2NS)], were synthesized by the reaction of the ligand with, respectively, silver nitrate and potassium dicyanoaurate(I) salts in aqueous solutions. Analytical characterizations of the complexes were based on elemental (C, H, N and S), thermal (TG-DTA) and electrospray ionization mass spectrometry (ESI-MS) analyses. Solid-state C-13 nuclear magnetic resonance (SSNMR) and infrared (IR) spectroscopic measurements indicate coordination of Pen to Ag(l) or Au(I) through the sulfur atom. Studies based on density functional theory (OFT) confirmed that Pen acts as an S-donor ligand to Au(I) or Ag(I). Thermal decompositions of the silver(I) and gold(I) complexes start at temperatures near 50 degrees C, leading to the formation of Ag-0 and Au-0 at 700 degrees C and 500 degrees C, respectively. Both complexes are just slightly soluble in common solvents such as water, methanol, ethanol, acetonitrile, hexane and dimethylsulfoxide. An antibiogram assay was performed by the disc diffusion method. The AgPen complex showed antibacterial activities against Escherichia coli and Pseudomonas aeruginosa bacterial strains. (C) 2012 Elsevier Ltd. All rights reserved.