On treatment of copper(II) acetate with aryl hydrazone ligands, four new solid derivatives of copper(II) were produced in appreciable yields. Various characterization techniques including infrared, UV–visible, NMR, electron paramagnetic resonance and mass spectroscopies, elemental analysis, scanning electron microscopy, powder X-ray diffraction and thermogravimetric analysis revealed a tetra-coordination in all the mononuclear crystalline complexes with high thermal stability. Further, significant interaction of these novel complexes with calf thymus DNA via intercalative mode of binding was revealed by electronic absorption spectroscopy. The chemical nuclease activity of the complexes on pBR322 DNA was investigated in the presence and absence of oxidizing agent (H2O2). A potent nuclease activity was observed only in the presence of H2O2. Further, antibacterial and antifungal studies of the new ligands and complexes revealed that the latter possessed comparatively better activity. Copyright © 2016 John Wiley & Sons, Ltd.