Two novel dinuclear ellipsoid Ni(II) and Co(II) complexes bridged by 4,5-bis(pyrazol-1-yl)phthalic acid: Synthesis, structural characterization and biological evaluation.

Two novel complexes, [Ni(L)(HO)]·4(HO) (1) and [Co(L)(HO)]·5(HO) (2) [HL = 4,5-bis(pyrazol-1-yl) phthalic acid] were synthesized and characterized by spectroscopy (IR, H NMR), and elemental analysis. The structures for the complexes were determined by X-ray crystallography providing the dinuclear ellipsoid Ni(II) and Co(II) complexes bridged by 4,5-bis(pyrazol-1-yl)phthalic acid ligands with same coordination modes. The interaction capacity of the complexes with FS-DNA (fish sperm DNA) has been investigated by UV and fluorescence spectroscopy. Gel electrophoresis assay demonstrated the ability of the complexes to cleave the pBR322 plasmid DNA. The cytotoxic activity of the complexes was tested against two different cancer cell lines, HeLa (human cervix epithelia carcinoma cells) and KB (human oral epithelial carcinoma cells), exhibiting significant cancer cell inhibitory rate. Furthermore, flow cytometry experiments and morphological apoptosis studies showed that the complexes induced apoptosis of KB tumor cell lines. The good visualization images supported with the experimental results of structure-activity relationship.