Tuning the Excited State of Water-Soluble Ir-III-Based DNA Intercalators that are Isostructural with [Ru-II(NN)(2)(dppz)] Light-Switch Complexes

摘要

The synthesis of two new Ir(III)complexes which are effectively isostructural with well-established [Ru(NN)(2)(dppz)](2+) systems is reported (dppz=dipyridophenazine; NN=2,2-bipyridyl, or 1,10-phenanthroline). One of these Ir(III)complexes is tricationic and has a conventional N(6)coordination sphere. The second dicationic complex has a N(5)Ccoordination sphere, incorporating a cyclometalated analogue of the dppzligand. Both complexes show good water solubility. Experimental and computational studies show that the photoexcited states of the two complexes are very different from each other and also differ from their Ru(II)analogues. Both of the complexes bind to duplex DNA with affinities that are two orders of magnitude higher than previously reported Ir(dppz)-based systems and are comparable with Ru-II(dppz) analogues.