Synthesis, crystal structure, and biological activity of 4′-chloro-2,2′: 6′,2"-terpyridine (Cltpy) as tridentate ligand in a Cd(II) complex

A new Cd(II) complex with 4'-chloro-2,20 : 6',2 ''-terpyridine (Cltpy), [Cd(Cltpy)(NO3)(2) (H2O)(0.45)(CH3OH)(0.55)], has been synthesized and characterized by CHN elemental analysis, 1 H-NMR, C-13-NMR, IR spectroscopy, and structurally analyzed by X-ray single-crystal diffraction. The single-crystal X-ray analyses show that the coordination number is seven with three terpyridine (Cltpy) N-donors, three oxygen atoms of two nitrates and one oxygen atom of methoxy/water. The antibacterial activities of Cltpy and its Cd(II) complex are tested against different bacteria. The free ligand has considerable activity against Staphylococcus aureus, Bacillus anthracis, and Pseudomonas aeruginosa (inhibition zones >= 20 mm), but has moderate activity against Escherichia coli and Streptococcus pyogenes (inhibition zones <= 15 mm). In comparison with free Cltpy ligand, its complex has more activity against Klebsiella pneumonia, S. aureus, and B. anthracis (inhibition zones >= 30 mm), but is inactive against P. aeruginosa and S. pyogenes. The quantitative assays gave minimal inhibitory concentration values in the range 6.25-100 mg mL(-1) that confirmed the above results. Against K. pneumonia and S. aureus, antibacterial activity of the complex is higher than Cltpy ligand.