A facile route to bimetallic ruthenium dipyridophenazine complexes

Using achiral coordinatively unsaturated metal complex building-blocks, the two step synthesis of a bimetallic complex containing independent [Ru(II)dppz] units tethered together by a linking 4,4'dipyridyl-1,5-pentane ligand is reported. Photophysical studies on this prototype system indicate that the characteristic luminescence of the [Ru(II)dppz] moieties is perturbed by self-quenching processes. Preliminary binding studies on the complex with natural and synthetic duplex DNA is reported. Luminescence and calorimetric titrations reveal that the complex does not show enhanced binding affinity with respect to analogous monometallic complexes. This result is interpreted by a consideration of the length and rigidity of the linker employed in the complex.