A treatise on benzimidazole based Schiff base metal(II) complexes accentuating their biological efficacy: Spectroscopic evaluation of DNA interactions, DNA cleavage and antimicrobial screening

•Synthesis of new and efficient benzimidazole based DNA targeting complexes•Synthesis of efficient metallointercalators•Excellent DNA exploiting ability of Cu(II) complexes•Efficient antimicrobial agents against various pathogens

Two novel imidazole derived Schiff bases, (Z)-1-(1H-benzo[d]imidazol-2-yl)-N-benzylidenemethanamine (L1) and 1-(1H-benzo[d]imidazol-2-yl)-N-(4-nitrobenzylidene) methanamine, and a series of their transition metal complexes of the types [M(L1)2]Cl2 and [M(L2)2]Cl2 where, M = Cu(II), Ni(II), Co(II) and Zn(II) have been designed and synthesized. These compounds were characterized by various spectral and physicochemical data. UV–Vis, magnetic susceptibility and molar conductivity data indicate that all the complexes adopt square planar geometry. The EPR spectral data of the Cu(II) complexes have provided supportive evidence to the conclusion derived on the basis of electronic absorption and magnetic moment values. Moreover, the interaction of complexes with DNA via intercalation has been explored by absorption, fluorescence spectroscopy, cyclic voltammetry, viscosity and circular dichroism. Agarose gel electrophoresis technique reveals that the complexes are good metallonucleases. All the compounds have relatively high antibacterial and antifungal potencies. Among the metal complexes, Cu(II) complexes exhibit higher efficacy against all the pathogens.

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