INTERACTION OF ORGANOMETALLIC CATIONIC COMPLEX-IONS CONTAINING TERPYRIDINE LIGANDS WITH NUCLEIC-ACIDS - AN INVESTIGATION ON AGGREGATIVE PHENOMENA

Organometallic cationic complex ions of the type [Pt(R-terpy)R']Cl (R= H, Ph; R' =Me, Ph) are soluble and stable in aqueous solution, where t hey self-aggregate to form large supramolecular assemblies. The intera ction of these aggregates with calf thymus DNA was investigated by UV- Vis and circular dichroism spectroscopy, resonance light scattering te chnique, thermal denaturation and gel electrophoresis mobility assays. Comparative studies were carried out on the complex [Pt(terpy)Me]Cl u sing poly(S'-A) and poly(vinylsulfonate). At high r(f), ([complex] / [ DNA]) ratios the complexes form extended aggregates on the surface of the polyanions, but at lower r(f),ratios evidence was obtained for int ercalation, at least in the case of the less hindered complex [Pt(terp y)Me] Cl. The relevance of steric effects on the binding process is di scussed. (C) 1998 Elsevier Science S.A. All rights reserved.