Copper(II) complexes of 14-membered hexaaza macrocyclic ligands L-1 and L-2 have been synthesized and characterized by spectral, electrochemical and X-ray crystallographic techniques. The crystal structure of the complexes [Cu(L-1)(ClO4)(2)] and [Cu(L-2)(ClO4)(2)] shows a distorted octahedral geometry and the two perchlorate ions are weakly coordinated to the metal ion in the axial position. The interaction of copper(II) complexes [Cu(L-1)(ClO4)(2)] and [Cu(L-2)(ClO4)(2)] with plasmid DNA has been explored by absorption and emission spectral as well as electrochemical studies. From the experimental results, the DNA binding constants of [Cu(L-1)(ClO4)(2)] and [Cu(L-2)(ClO4)(2)] are found to be 3.7 x 10(3) M-1 and 8.0 x 10(3) M-1, respectively. Both the complexes cleave pUC 18 DNA oxidatively in the presence of hydrogen peroxide. (C) 2012 Elsevier B. V. All rights reserved.