Synthesis,crystal structure and DNA interaction studies of three coordination polymers with mixed ligand

Three coordination polymers Mn(Nip)(Pbim)] _n (1), Co(Nip)(Pbim)] _n (2) and Zn(Nip)(Pbim)] _n (3) 5-nitroisophthalate (Nip) and 2-(2-pyridyl)benzimidazole (Pbim)] were synthesised and characterised by elemental analysis, IR and single-crystal X-ray diffraction. Single-crystal X-ray diffraction analysis reveals that 1, 2 and 3 have 1-D ladder chain structures constructed from μ₃-bridge Nip ligands and metal atoms. All of these chain-like structures are finally packed into supramolecular networks through hydrogen bonds and π–π stacking interactions. Fluorescence spectral method has been used for the study on the interaction of film sperm DNA with complexes. The results show that the corresponding fluorescence spectrum appeared and the intensity was enhanced with the growth of the concentration of DNA. All of the results indicate that there exists strong interaction of the complexes with DNA.