Interaction of Ruthenium(II)-dipyridophenazine Complexes with CT-DNA: Effects of the Polythioether Ancillary Ligands (original) (raw)

The complexes [Ru ([9]aneS3)(dppz)Cl]Cl 1 and [Ru(II2]aneS4)(dppz)]Ci_ 2 ([9]aneS3=l,4,7 trithiaciclononane and [12]aneS4=l,4,7,10-tetrathiaciclododecane) were synthesised and fully characterised. These complexes belong to a small family of dipyridophenazine complexes with non-polypyridyl ancillary ligands. Interaction studies of these complexes with CT-DNA (UV/Vis titrations, steady-state emission and thermal denaturation) revealed their high affinity for DNA. Intercalation constants determined by UV/Vis titrations are of the same order of magnitude (106) as other dppz metallointercalators, namely [Ru(II)(bpy)2dppz]2+. Differences between and 2 were identified by steady-state emission and thermal denaturation studies. Emission results are in accordance with structural data, which indicate how geometric distortions and different donor and/or acceptor ligand abilities affect luminescence. The possibility of noncovalent interactions between ancillary ligands and nucleobases by van der Waals contacts and H-bridges is discussed. Furthermore, complex undergoes aquation under intra-cellular conditions and an equilibrium with the aquated form I' is attained. This behaviour may increase the diversity of available interaction modes.