Synthesis, spectral characterization and DNA binding properties of dinuclear copper(II) complexes with pyridinehydrazones

Dinuclear copper(II) complexes of functionalized heterocyclic hydrazones, viz. 2-acetylpyridine acetoylhydrazone (APAH), 2-acetylpyridine benzoylhydrazone (APBH), 2-benzoylpyridine acetoylhydrazone (BPAH), 2-benzoylpyridine benzoylhydrazone (BPBH) have been synthesized and characterized on the basis of elemental analysis, molar conductivity measurements, magnetic susceptibility, electronic, infrared and electron spin resonance spectral data. Electrolytic nature of complexes is investigated by conductivity studies. IR spectral data suggest that the ligands act as neutral trifunctional NNO-donor system. Electronic spectral data suggest octahedral geometry for the complexes. Electrochemical behavior of metal complexes is investigated by using cyclic voltammetry. The complexes undergo quasi-reversible one electron reduction. Absorption titration studies revealed that these complexes are avid binder to calf-thymus DNA. The electronic absorption titrations suggest that the complexes bind DNA through intercalation involving a strong pi-stacking interaction between the aromatic chromophore and base pairs of DNA.