Synthesis, characterization and antimicrobial activity of copper(II) complexes with some S-alkyl derivatives of thiosalicylic acid. Crystal structure of the binuclear copper(II) complex with S-methyl derivative of thiosalicylic acid

The five new copper(II) complexes with some S-alkyl derivatives of thiosalicylic acid (alkyl = benzyl (L1), methyl (L2), ethyl (L3), propyl (L4), butyl (L5)) have been synthesized and characterized by microanalysis and infrared spectra. The spectroscopically predicted structure of the obtained binuclear copper(II) complex with S-methyl derivative of thiosalicylic acid was confirmed by X-ray analysis. Single crystals suitable for X-ray measurements were obtained by slow crystallization from a water solution. The compound crystallizes with two binuclear Cu(II) complex molecules in the asymmetric unit. Both molecules have typical paddle-wheel structure with apical positions occupied by water molecules. The independent molecules showed slight difference in configuration mainly reflected in the different orientation of the phenyl rings relating to their carboxylate groups. Antimicrobial activity of these complexes was tested by microdilution method and both minimal inhibitory and microbicidal concentration were determined. The intensity of the antimicrobial activity varied depending on the species of microorganism and the compound type. In general, the activity of the complexes was higher than or similar to the corresponding ligands. All the tested complexes demonstrated moderate or selective antibacterial activity and low antifungal activity. (C) 2014 Elsevier Ltd. All rights reserved.