Crystal structures and antimicrobial and cytotoxic activities of zinc(II), nickel(II) and copper(II) complexes of N-(piperidylthiocarbonyl) benzamide

A new zinc(II) complex of N-(piperidylthiocarbonyl)benzamide, [ZnL2], has been synthesized and characterized using elemental analysis, Fourier transform infrared and H-1 NMR spectroscopies. X-ray diffraction indicates that [ZnL2] presents a tetrahedral structure within an O2S2 donor set, which is different from analogous square planar [NiL2] and [CuL2] available in the literature. The antimicrobial activities of [ZnL2], [NiL2] and [CuL2] were evaluated against fungi and bacteria. The results show that [ZnL2] is the best for control of the studied fungi and bacteria, and its antimicrobial activity is close to that exhibited by commercial products. The relationship between the structures and antimicrobial activities of the complexes was further investigated using density functional theory calculations. It is elucidated that the increase of the polarity of carbonyl and thiocarbonyl groups determines antifungal and antibacterial activities. Moreover, the cytotoxicity of the complexes was tested against human cancer cells (hepatocellular carcinoma (SK-Hep-1) and breast carcinoma (MCF-7)). The [CuL2] complex is found to be the most cytotoxic. Copyright (c) 2015 John Wiley & Sons, Ltd.