DNA interactions and biocidal activity of metal complexes of benzothiazole Schiff bases: synthesis, characterization and validation

Binary complexes of Cu(II), Ni(II) and Co(II) were synthesized using two novel Schiff bases $$\mathbf{L}_{1}$$ = 2-(-(benzothiazol-6-ylimino)methyl)-4-chlorophenol (BTEMCP), $$\mathbf{L}_{2}$$ = 2-(-(benzothiazol-6-ylimino)methyl)-4-nitrophenol. The Schiff bases and metal complexes were characterized by analytical and spectral methods like elemental analysis, Mass, $$^{1}\hbox {H}$$ -NMR, $$^{13}\hbox {C}$$ -NMR, UV-Vis, IR, ESR, SEM, EDX, XRD and magnetic susceptibility measurements. From the analytical data, square planar geometry has been proposed for all the metal complexes. The binding interaction between the metal complexes and DNA was investigated by means of electronic absorption, fluorescence spectroscopy and viscosity measurements. The DNA cleavage ability of the metal complexes was also evaluated by agarose gel electrophoresis method. These studies revealed that the complexes showed an intercalative mode of binding to CT DNA and also effectively cleaved the supercoiled pBR DNA. The synthesised compounds were evaluated for in vitro antibacterial activity against Gram positive and Gram negative bacteria, and found that the metal complexes showed more potent biocidal activity than the Schiff bases. SYNOPSIS Six mononuclear metal complexes of benzothiazole Schiff bases were synthesized and characterized. The DNA interaction studies showed that all the complexes bind with CT-DNA through an intercalative mode. Supercoiled pBR322 DNA was effectively cleaved by the complexes . All the metal complexes exhibited better antibacterial activity than the Schiff bases from which they were prepared.