Synthesis and DNA binding studies of cobalt (III) mixed-polypyridyl complex

The complex of Co(phen)(2)dppz(3+) (where phen is o-phenanthroline, and dppz is dipyrido [3,2-a:2',3'-c] phenazine) has been synthesized. This complex was characterized by elemental analysis, molar conductivity, IR and H-1 NMR spectroscopy. The interaction of the complex with calf thymus DNA has been studied using absorption and emission spectroscopy, DNA melting techniques, cyclic voltammetric, viscosity, and electrophoresis measurements. The compound shows absorption hypochromicity, fluorescence enhancement, DNA melting temperature, and the specific viscosity increased when binding to calf thymus DNA. CV measurement shows that the shifts in oxidation-reduction potential and change in peak current with addition of DNA. The complex is also shown to be more efficient photosensitisers for single strand breaks in plasmid DNA. (C) 1997 Elsevier Science Inc.