The sequential replacement of a bpy ligand (bpy=2,2'-bipyridine) by a dpb ligand (dpb =2,3-bis(2-pyridyl) benzoquinoxaline) in the series [Ru(bpy)(3-n)(dpb)(n)](2+) (n = 1-3) leads to a remarkable increase of the excited state lifetime, the O-1(2) quantum yield, and the binding affinity toward dsDNA, rendering both [Ru(bpy)(dpb)(2)](2+) and [Ru(dpb)(3)](2+) efficient DNA photocleavage activities upon red light irradiation (>= 600 nm).