Syntheses, Crystal Structures and DNA-binding Properties of Zn(II), Ni(II) and Co(II) Compounds Containing Thiazole Derivatives

Zn(II), Ni(II) and Co(II) compounds (1 similar to 3) based on 2-(2-pyridyl)benzothiazole (bpt) and terephthalic acid (PTA) were synthesized. The crystal structures of [Zn(bpt)(PTA)(2)] (1), [Ni(bpt)(PTA)(2)] (2), and [Co(bpt)(PTA)(2)] (3) have been determined by single-crystal X-ray diffraction analysis, which shows that all the three complexes belong to monoclinic system with space group P2(1)/c. Time-dependent density functional theory (TD-DFT) calculation is performed on a reference structure of compound 3. The excited electrons mainly localized at the pi* of ligand 2-(2-pyridyl)benzothiazole, which will be convenient for them to bind with the DNA reacting sites. Fluorescence spectroscopy, ultraviolet (UV) spectroscopy and viscosity were used to characterize the interaction of the compounds with Calf thymus DNA (CT-DNA). The results indicate that compounds 1 similar to 3 bind to CT-DNA and have a strong interaction with DNA. The compounds can probably bind to CT-DNA via a non-intercalative mode as concluded by studying the viscosity of a DNA solution in the presence of the compounds. This combination can effectively break DNA, which speculates that these three compounds may interact with the cancer cell DNA in this binding mode, thereby damaging the cancer cells.