Photoinduced electron transfer between ruthenium complexes and nucleotides or DNA

The quenching of the luminescence of Ru(TAP)(3)(2+), Ru(HAT)(2)(bpy)(2+) (TAP = 1,4,5,8-tetraazaphenanthrene; HAT = 1,4,5,8,9,12-hexaazatriphenylene; bpy = 2,2'-bipyridyl) and related oxidising complexes by DNA, polynucleotides, and purine nucleotides occurs by reductive electron transfer. Laser flash photolysis provides evidence for the formation of the reduced metal complex and the deprotonated nucleotide radical cation. This photo-oxidation leads to DNA strand-breaks and to the formation of covalent adducts with GMP or DNA. The adducts with Ru(TAP)(3)(2+) or Ru(HAT)(2)(bpy)(2+) are formed via a covalent bond between the C atom beta to the coordinating N in the TAP or HAT ligand and the N2 of guanine.