Synthesis, physico-chemical investigations and biological screening of metal (II) complexes with Schiff base derived from naphthofuran-2-carbohydrazide and citral

A series of Co(II), Ni(II), Cu(II), Cd(II), Zn(II) and Hg(II) complexes of the type CuLCl2. 2H2O and ML2Cl2 [M = Co(II), Ni(II), Cd(II), Zn(II) and Hg(II)], respectively, where L = Schiff's base derived from condensation of citral and naphthofuran-2-carbohydrazide have been synthesized. The proposed structures of the obtained complexes have been established from elemental analyses, IR, Electronic, Mass, 1H NMR, ESR spectral data, magnetic and thermal studies. From the above spectral studies it is concluded that the ligand acts as a bidentate coordinating through azomethine nitrogen and amide oxygen. The measured low molar conductance values in DMF indicate that the complexes are non-electrolytic in nature. The electron transfer mechanism of the Cu(II) complex is investigated by the aid of cyclic voltammetry. The free ligand and its metal complexes have been screened for their antioxidant activity by the DPPH method and in vitro antibacterial (Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa) and antifungal (Aspergillus niger, Aspergillus flavus, Cladosporium oxysporum and Candida albicans) activities by the minimum inhibitory concentration (MIC) method. The DNA cleavage studies of all the complexes were studied by agarose gel electrophoresis method. The results indicate that the biological activity increases on complexation.