Synthesis, characterization, and antibacterial activity of novel Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) complexes with vitamin K 3-thiosemicarbazone

Abstract

Vitamin K 3-thiosemicarbazone (C 12H 11N 3NaO 4S 2·5H 2O, abbreviated as VT), a new Schiff base derivative, has been synthesized. Its crystal structure, determined by X-ray diffraction, is triclinic, space group P 1 ̄ . We have also prepared five novel complexes of VT with transition metals: [M(VT) 22H 2O]· nH 2O, ( n=1 and 2 for M=Cu(II) and Zn(II), respectively) and [M′(HVT) 2Cl 2]· mH 2O, ( m=4, 5, and 7 for M′=Co(II), Mn(II), and Ni(II), respectively). These compounds were characterized by IR and UV–Vis spectroscopy, molar conductivity, thermal analyses, complexometric titration, and elemental analysis. In all the complexes, the VT ligand coordinates through sulfur and oxygen atoms, and the geometry around metal atom is best described as octahedral. In vitro tests of antibacterial activity showed that VT and its complexes with Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) all had strong inhibitory actions against G(+) Staphylococcus aureus, G(+) Hay bacillus, and G(−) Escherichia coli.