Synthesis, crystallographic and spectroscopic studies, evaluation as antimicrobial and cytotoxic agents of a novel mixed-ligand nickel(II) complex

<p>A new mononuclear mixed-ligand complex of Ni(II) has been synthesized and structurally characterized by single-crystal X-ray diffraction as [Ni(4-Cl-pydc)(apym)(H₂O)₂], where 4-Cl-pydc and apym are 4-chloropyridine-26-dicarboxylate and 2-aminopyrimidine, respectively. Spectroscopic studies such as FT-IR, UV-vis, ¹H-NMR, and thermal analysis (TGA/DTA) were carried out. The fluorescence properties were studied in solvents with different dipole moments. Antimicrobial activities of 4-chloropyridine-26-dicarboxylic acid (<b>1</b>), 2-aminopyrimidine (<b>2</b>), complex (<b>3</b>), and nickel(II) nitrate hexahydrate (<b>4</b>) were investigated by disk diffusion and broth microdilution methods against three Gram-positive bacteria, <i>Staphylococcus aureus</i>, <i>Bacillus subtilis</i>, <i>Staphylococcus epidermidis</i> and three Gram-negative bacteria, <i>Escherichia coli</i>, <i>Pseudomonas aeruginosa</i>, <i>S. marcescens</i>; also antifungal effect was evaluated on <i>Aspergillus niger</i> and <i>Saccharomyces cerevisiae in vitro</i>. The highest antibacterial activity of complex was observed nearly equal to gentamicin as a standard drug toward <i>S. epidermids</i> with IZD of 18 mm. The <i>in vitro</i> antiproliferative activity of <b>1–4</b> on H1299 (a human non-small cell lung carcinoma), HepG2 (a human liver hepatocellular carcinoma), and β-TC3 (a mouse beta pancreatic) cell lines was evaluated by MTT (3-(45-dimethylthiazol-2-yl)-25-diphenyl-2H-tetrazolium bromide) assay and, effect of complex on depolarization of mitochondrial membrane (MMP) of all three cell lines was measured by rhodamine 123. The highest cytotoxic effect of complex was exhibited toward H1299 cell line with IC₅₀ value equal to 10 μM.</p