Crystal structure studies and antimicrobial activities of transition metal complexes of pyridine-2,6-dicarboxylic acid and imidazole containing water clusters

<p>Two new copper(II) and chromium(III) complexes of tridentate 2,6-pyridinedicarboxylic acid (H<sub>2</sub>pydc) with imidazole (im), (Him)[Cu(Hpydc)(pydc)]∙H<sub>2</sub>pydc∙5H<sub>2</sub>O (<b>1</b>) and (Him)[Cr(pydc)<sub>2</sub>]∙H<sub>2</sub>pydc∙5H<sub>2</sub>O (<b>2</b>), have been prepared and characterized by elemental analysis, TGA measurements, FT-IR, and UV–Vis spectroscopy, powder and single crystal X-ray crystallography. Crystal structure analyses reveal that both copper(II) and chromium(III) ions are in a distorted octahedral environment. The optimized geometrical parameters were calculated using methods based on the density functional theory (DFT). These calculations agree closely with the X-ray structure. The antimicrobial activities of the ligand and the complexes were evaluated <i>in vitro</i> and compared with drugs in use. The results show that the complexes had stronger antibacterial activity than the corresponding ligand and the effectiveness was confirmed against <i>Bacillus subtilis</i> (gram positive) and <i>Klebsiella pneumoniae</i> (gram negative) for <b>1</b>, and <i>Escherichia coli</i> and <i>K. pneumoniae</i> (gram negative) for <b>2</b> by the well diffusion method.</p>