Chiral anionic binuclear zinc complexes based on diaminocyclohexane ligand and their in vitro antiproliferative studies

Two novel binuclear chiral anionic Zn(II) complexes, [Zn2LCl3]− (C2H5)3N+ 1 and [Zn2L(CH3COO)3]− (C2H5)3N+ 2 counterbalanced by triethyl ammonium cation, have been synthesized from ligand, 2,2′-((1E,1′E)-((1R,2R)-cyclohexane-1,2-diylbis(azanylylidene))bis(methanylylidene))dipheno, H2L. The ligand, H2L and its complexes are characterized by elemental analyses, IR, 1H and 13C NMR, ESI-MS, electronic and thermal studies. Complex 1 has been additionally characterized by single crystal X-ray diffraction studies and confirmed a slightly distorted tetragonal pyramid coordination environment in which both zinc atoms are five coordinated by two imine nitrogen atoms, two oxygen atoms and one chloride ion located at the polyhedron apex. Ligand, H2L and its Zn(II) complexes have been subjected to antiproliferative studies against HCT p53 wild type as well as HCT p53 null cell lines, and the results suggest complexes to be an effective antiproliferative agent against these cancer cell lines in comparison to ligand, H2L. Furthermore, DNA fragmentation studies revealed that Zn(II) complexes induce significant p53 independent apoptosis in cancer cell lines.