Photoluminescence quenching/recovery kinetics of [Ru(bpy)2(tatp)]2+ and [Ru(bpy)2(dmtatp)]2+ intercalated within DNA by copper(II) ions and EDTA.

The quenching and recovery kinetics of photoluminescence of [Ru(bpy)(2)(tatp)](2+) (Ru1) and [Ru(bpy)(2)(dmtatp)](2+) (Ru2) intercalated within DNA (where bpy=2,2'-bipyridine, tatp=1,4,8,9-tetra-aza-triphenylene and dmtatp=2,3-dimethyl-1,4,8,9-tetra-aza-triphenylene) have been investigated by steady-state and time-resolved methods performed at various temperatures (293-333K). Two complexes Ru1 and Ru2 show a single-exponential luminescence decay with τ(Ru1)=246.0 ns and τ(Ru2)=513.5 ns, whose luminescence upon intercalating into DNA exhibits very consistent bi-exponential decay changes. The addition of Cu(2+) ions is found to dynamically quench the luminescence of both DNA-bound Ru(II) complexes, involving a spontaneous exothermic process. The sequential addition of EDTA can partially recover the luminescence quenched by Cu(2+), however depending on methyl substituents of the intercalative ligand. The chemical conversion and luminescence control mechanism of the two DNA-bound Ru(II) complexes is discussed in detail. The present results should be of value for better understanding chemical modulation of DNA-bound Ru(II) complexes as luminescence probes.