Synthesis, crystal structures and DNA-binding properties of Cd(II), Cu(II) and Ni(II) complexes with 2-(2-pyridyl)benzothiazole

Cd(II), Cu(II) and Ni(II) complexes (1–3) based on 2-(2-pyridyl)benzothiazole were synthesized. The formulas of these complexes are [Cd(NO3)2(bpt)](1), [Cu(bpt)Cl2C3H6NO](2) and [Ni(bpt)2Cl2][C4H10O](3), respectively. The crystal structures of complexes 1–3 have been determined by single-crystal X-ray diffraction analyses. The DNA binding property of complexes 1–3 was evaluated by absorption, fluorescence spectroscopy and viscosity measurements. UV studies of the interaction of the complexes with DNA have shown that they can bind to Calf thymus DNA (CT-DNA). The calculated binding constants of the complexes to DNA reveal tight binding to DNA. Results evaluated the binding affinity of complexes 1–3 to CT-DNA by UV and presented binding constants (Kb) of 4.522 × 102 M−1, 3.859 × 102 M−1 and 4.025 × 102 M−1, respectively. The complex 1 exhibits the highest binding constant. Evaluations of fluorescence showed that the complexes have strong interactions with CT-DNA. The complexes 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 complexes. The studies of the interaction of DNA-complexes have broad prospects for design anticancer drug.