A binuclear chloride bridged Cu(II) and a mononuclear Ni(II) complex: Synthesis, crystal structure, photo catalytic and biological studies

In the present paper, one new binuclear chloride bridged Cu(II) complex [Cl2Cu-(mu-Cl)-Cu(L)Cl-2] (1) and one mononuclear Ni(II) complex [Ni(L ')(2)](ClO4)(2) (2) where L = N-1-(pyridine-2-ylmethylene)-N-2-(2-(pyridine-2-ylmethyleneamino)ethyl)ethane-1,2-diamine derived from pyridine-2-aldehyde and diethylenetriamine, L' = Piperidine-2-yl-N-(pyridine-2-ylmethylene)methanamine derived from pyridine-2-aldehyde and 2-aminomethylpiperidine have been synthesized and characterized by single crystal X-ray diffraction studies. The crystal structure of the binuclear Cu(II) complex (1) shows that the two square pyramidal Cu(II) moieties are joined through a single chloride (mu-Cl) bridge and the coordination environment around the two copper atoms are same, whereas the nickel ion in complex (2) has an octahedral geometry. The antibacterial study for metal salts, ligands and complexes were performed using Staphylococcus aureus. The result shows that among the complexes, complex (2) exhibits better antibacterial properties than complex (1). Optical band gaps of 3.3 and 3.1 eV for complexes 1 and 2 respectively reveal that both the complexes have some semiconducting properties. Photo catalytic activity and H2O2 sensing activity for both the complexes were also determined. The photo catalytic test was performed against Rhodamine B (RB), Methylene Blue (MB), Malachite Green (MG) and Bromocressol Green (BG) in presence of sunlight. Results of photo catalytic and H2O2 sensing tests have revealed that both the complexes have degradation ability against each dye but complex 1 have only H2O2 sensing properties. DNA binding ability of the complexes was done by absorption titration, ethidium bromide displacement and viscosity measurement studies. Furthermore, molecular docking studies for complex 2 were also performed with B-DNA model sequence. It has been shown that complex 2 interacts with DNA through partial intercalation as well as minor-groove binding. The cell viable activity of the ligand, copper and nickel complexes were measured in vitro against the Hela cell and it shows that the metal complexes are biocompatible in nature. So the utility of this study is that the complexes under investigation can effectively be used as pharmaceutical components in several antibacterial drugs as they are biocompatible in nature and can also be used in waste dye degradation or separation process from water or to detect H2O2 widely used in food, cosmetic, pharmaceutical and paper industries.