Structural elucidation, in vitro DNA binding and anticancer investigations of a new specific target dinuclear Zn(II) complex

Abstract

In this study, dinuclear bis(2,2′-bipyridine)-tris{[μ-pyrimidin-2-yl)sulfanyl]acetato}Zn(II) perchlorate complex was synthesized and characterized by FT-IR, ESI-MS, 1H NMR and single-crystal X-ray diffraction studies. The bis(2,2′-bipyridine)-tris{[μ-pyrimidin-2-yl)sulfanyl]acetato}Zn(II) perchlorate was crystallized in a monoclinic crystal system having a P 21/c space group. The single-crystal structure of bis(2,2′-bipyridine)-tris{[μ-pyrimidin-2-yl)sulfanyl]acetato}Zn(II) perchlorate reveals that Zn1 is five coordinated and has adopted distorted square pyramidal geometry while as Zn2 centre is six coordinated and has adopted distorted octahedral geometry, bridged by three carboxylate groups of (2-pyrimidylthio) acetic acid (PTAA). Hirshfeld surface analysis and density functional theory were determined by crystallographic computational tools to investigate the contribution of non-covalent interactions, reactivity and stability of bis(2,2′-bipyridine)-tris{[μ-pyrimidin-2-yl)sulfanyl]acetato}Zn(II) perchlorate. In vitro, ct-DNA binding studies of the complex were accomplished by applying various spectroscopic and analytical techniques. The results obtained suggested a groove or electrostatic mode of binding. The bis(2,2′-bipyridine)-tris{[μ-pyrimidin-2-yl)sulfanyl]acetato}Zn(II) perchlorate has caused significant double-stranded scission of pBR322 DNA through the hydrolytic pathway as observed by the gel electrophoretic experiment. Cytotoxicity of bis(2,2′-bipyridine)-tris{[μ-pyrimidin-2-yl)sulfanyl]acetato}Zn(II) perchlorate was evaluated against MCF-7, MDA-MB-231, Hop-62, AW13516 and SiHa human cancer cell lines, which revealed a moderate anticancer response. In addition, binding studies of the bis(2,2′-bipyridine)-tris{[μ-pyrimidin-2-yl)sulfanyl]acetato}Zn(II) perchlorate with BSA protein were performed by fluorescence spectroscopy. The synchronous fluorescence spectra suggested the efficient binding of complex towards tyrosine than tryptophan. The quenching mechanism of BSA by complex was found static in nature.