Synthesis of cadmium complexes of 4′-chloro-terpyridine: From discrete dimer to 1D chain polymer, crystal structure and antibacterial activity

Two new Cd(II) complexes with the ligand 4'-chloro-2,2':6',2 ''-terpyridine (Cltpy), [Cd(Cltpy)(N-3)(CH3COO)], 1, and [Cd(Cltpy)(NCS)(CH3COO)](n), 2, have been synthesized and characterized by CHN elemental analyses, H-1 NMR-, C-13 NMR-, IR spectroscopy and structurally analysed by X-ray single-crystal diffraction. The single crystal X-ray analyses show that the coordination number in these complexes is seven with three terpyridine (Cltpy) N-donor atoms, two acetate oxygens and two anionic bridged ligands. The crystal structure of 2 comprises a one-dimensional polymeric network bridged by NCS- anions. The antibacterial activities of Cltpy and its Cd(II) complexes are tested against different bacteria. Both complexes have shown good activity against all the tested bacteria. Against Klebsiella pneumonia and Staphylococcus aureus, antibacterial activity of complexes is higher than Cltpy ligand. The higher activity of complexes may be explained on the basis of chelation theory.