Photoredox behavior and chiral discrimination of DNA bound M(diimine)(3)(n+) complexes (M = Ru2+, Cr3+)

An overview is given of the rapidly developing field of bioinorganic chemis try involving the interaction of Ru(diimine)(3)(2+) complexes with double-s tranded DNA. This contribution focusses on the photoredox behavior of these DNA bound systems and the presence of chiral discrimination in the binding process. Cr(diimine)(3)(3+) complexes are attractive new candidates for su ch studies in view of their long-lived room temperature luminescence and st rong excited state oxidizing power. For these Cr(III) systems we observe st rong quenching of the emission signal in the presence of B-DNA, and provide evidence that this quenching is associated with a photoredox process invol ving guanine base oxidation. We also demonstrate the value of capillary ele ctrophoresis (CE) as a technique for assessing the relative binding constan ts and the stereoselectivities of transition metal interactions with DNA. I n addition, we explore the use of CE as an alternative approach to help res olve literature disagreements between different Ru(phen)(3)(2+)/DNA binding models. (C) 2001 Elsevier Science B.V. All rights reserved.