Dipyridophenazine complexes of cobalt(III) and nickel(II): DNA-binding and photocleavage studies

Thermal denaturation, absorption titration and differential-pulse voltammetric studies indicate that (Co(phen)2DPPZ)3+ and (Ni(phen)2DPPZ)2+, where phen = 1,10-phenanthroline and DPPZ = dipyrido(3,2-a:2',3'-c)phenazine, bind DNA. Substitution by different metal ions changes the properties and the DNA interactions of the complexes. The cobalt(III) complex effectively cleaves supercoiled pBR 322 DNA in the presence of light while the nickel(II) complex fails to do so.