Synthesis, characterization and DNA interaction of hexaaza macrotricyclic copper(II) complexes

Copper(II) complexes of 14-membered hexaaza macrocyclic ligands L1 and L2 have been synthesized and characterized by spectral, electrochemical and X-ray crystallographic techniques. The crystal structure of the complexes [Cu(L1)(ClO4)2] and [Cu(L2)(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(L1)(ClO4)2] and [Cu(L2)(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(L1)(ClO4)2] and [Cu(L2)(ClO4)2] are found to be 3.7 × 103 M−1 and 8.0 × 103 M−1, respectively. Both the complexes cleave pUC 18 DNA oxidatively in the presence of hydrogen peroxide.