Novel Schiff base metal complexes: synthesis, characterization, DNA binding, DNA cleavage and molecular docking studies

A novel Schiff base, 3-(((1H-1,2,4-triazol-3-yl)imino)methyl)-4H-chromen-4-one (L) was synthesized and used as ligand for the synthesis of Co(II), Ni(II), Cu(II), Zn(II) and Pd(II) complexes. The structural characterization of the ligand and its metal complexes was determined by using various physicochemical and spectroscopic methods. The IR data show that the Schiff base ligand acts as a bidentate donor coordinating through the oxygen atom of the chromone and nitrogen atom of the imine group. Based on all spectral data, tetrahedral geometry has been proposed for all the metal complexes except Cu(II) and Pd(II) complexes. However, square-planar geometry has been proposed for Cu(II) and Pd(II) complexes. DNA binding interaction of the ligand and its metal complexes was investigated by using UV–visible absorption, fluorescence and molecular docking studies. The binding constants were in the order of 104 M−1 suggesting good binding affinity towards CT-DNA. The DNA cleavage activity of the synthesized compounds was investigated by using agarose gel electrophoresis. In vitro antimicrobial activity of the synthesized compounds were screened against two gram-positive bacteria (Bacillus subtilis, Staphylococcus aureu) and two gram-negative bacteria (Escherichia coli, Proteus vulgaris) and one fungi strain Candida albicans using disc diffusion method. Antioxidant activity was carried out by DPPH radical scavenging method. In vitro anti-proliferative activity of the ligand and its metal complexes was also carried on the HEK-293, HeLa, IMR-32 and MCF-7 cancer cell lines using MTT assay.