Synthesis, characterization and antimicrobial activity of palladium(II) complexes with some alkyl derivates of thiosalicylic acids: Crystal structure of the bis(S-benzyl-thiosalicylate)–palladium(II) complex, [Pd(S-bz-thiosal)2]

S-Alkyl (R = benzyl, methyl, ethyl, propyl and butyl) derivatives of thiosalicylic acid and the corresponding palladium(II) complexes were prepared and their structures were proposed on the basis of infrared, 1H and 13C NMR spectroscopy. The cis geometrical configurations of the isolated complexes were proposed on the basis of an X-ray structural study of the bis(S-benzyl-thiosalicylate)–palladium(II), [Pd(S-bz-thiosal)2] complex.Antimicrobial activity of the tested compounds was evaluated by determining the minimum inhibitory concentration (MIC) and minimum microbicidal concentration (MMC) in relation to 26 species of microorganisms. The tested ligands, with a few exceptions, show low antimicrobial activity. The palladium(II) complexes, [Pd(S-R-thiosal)2], have statistically significant higher activity than the corresponding ligands. The complexes [Pd(S-et-thiosal)2] and [Pd(S-pro-thiosal)2] displayed the strongest activity amongst the all tested compounds. The palladium(II) complexes show selective and moderate antibacterial activity and significant antifungal activity. The most sensitive were Aspergillus fumigatus and Aspergillus flavus.

Graphical abstractS-Alkyl (R = benzyl, methyl, ethyl, propyl and butyl) derivatives of thiosalicylic acid and the corresponding palladium(II) complexes were prepared and their antimicrobial activity was evaluated by determining the minimum inhibitory concentration and minimum microbicidal concentration in relation to 26 species of microorganisms. The cis geometrical configurations of the isolated complexes were confirmed on the basis of an X-ray structural study of the [Pd(S-bz-thiosal)2] complex.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Derivatives of thiosalicylic acid and the corresponding palladium(II) complexes have been prepared. ► Structures have been proposed based on infrared, 1H and 13C NMR spectroscopy and X-ray analysis. ► The antimicrobial activity was tested in relation to 26 species of microorganisms.