Photoreaction of [Ru(hat)2phen]2+ with guanosine-5'-monophosphate and DNA: formation of new types of photoadducts.

[Ru(hat)2phen]2+ (HAT=1,4,5,8,9,12-hexaazatriphenylene, phen=1,10-phenanthroline) interacts with a good affinity with polynucleotides and DNA by intercalation, despite the presence of a second voluminous ancillary HAT ligand. It photoreacts with guanosine-5'-monophosphate (GMP). From HPLC, ESMS and NMR analyses, it can be concluded that this complex forms photoadducts with GMP. In contrast to the photoadducts isolated with Ru-TAP complexes (TAP=1,4,5,8-tetraazaphenanthrene), the photoadducts with [Ru(hat)2phen]2+ contain a covalent link between the oxygen atom of the guanine unit and a HAT ligand. Formation of oxidised photoadducts and compounds resulting from the addition of two GMP entities to the complex are also detected as side products. In the presence of oligo- and polynucleotides, [Ru(hat)2phen]2+ yields photoadducts when guanine bases are present.