Ru(II) complexes and light: molecular tools for biomolecules

Ruthenium(II) (Ru(II)) complexes are the focus of numerous research works with various applications mainly due to their attractive photophysical and photochemical properties. In biological research areas, in particular, they are developed as efficient photoprobes or photosensors of biological molecules. More interestingly specific Ru(II) complexes bearing pi-deficient ligands such as TAP = 1,4,5,8-tetraazaphenanthrene, bpz = 2,2'-bipyrazyl or HAT = 1,4,5,8,9,12-hexaazatriphenylene exhibit interesting photoreactivity with biomolecules (DNA, polypeptides). The photoreactions are initiated by a photo-electron transfer from the biomolecule to the excited metal complex. A back electron transfer (BET) succeeds this primary process. However in competition with this BET, a DNA photocleavage and/or formation of adducts of the complex with guanine units of DNA or with tryptophan (Trp) residues of polypeptides can take place. In this review we highlight the studies of these photo-adducts carried out by our laboratories, and connected to some applications. Copyright (c) 2008 John Wiley & Sons, Ltd.