Synthesis, characterization and DNA interaction of new copper(II) complexes of Schiff base-aroylhydrazones bearing naphthalene ring

Two new copper(II) complexes with the condensation products of methyl 2-naphthyl ketone with 4-hydroxybenzohydrazide, 4-hydroxy-N′-[(1Z)-1-(naphthalen-2-yl)ethylidene]benzohydrazide [HL1] and (Z)-ethyl 2-(4-(2-(1-(naphthalen-2-yl)ethylidene)hydrazinecarbonyl)phenoxy)acetate (HL2) were synthesized and characterized by elemental analysis, infrared spectra, UV–Vis electronic absorption spectra, magnetic susceptibility measurements, TGA, powder XRD and SEM–EDS. The binding properties of the copper(II) complexes with calf thymus DNA were studied by using the absorption titration method. DNA cleavage activities of the synthesized copper complexes were examined by using agarose gel electrophoresis. The effect of complex concentration on the DNA cleavage reactions in the absence and presence of H2O2 was also investigated. The experimental results suggest that the copper complexes bind significantly to calf thymus DNA by both groove binding and intercalation modes and cleavage effectively pBR322 DNA. The mechanistic studies demonstrate that a hydrogen peroxide-derived species and singlet oxygen (1O2) are the active oxidative species for DNA cleavage.

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► Two new Schiff base-hydrazone ligands and their mononuclear Cu(II) complexes have been synthesized and characterized.
► DNA binding and DNA cleavage activity of the copper complexes have been investigated.
► DNA binding studies reveals that the copper complexes bind to CT-DNA by both groove binding and intercalation modes.
► The copper complexes exhibit effective oxidative cleavage of pBR322 DNA.