Interactions of Flexible Diamine-bridged Dinuclear Ruthenium(II)–2,2′-Bipyridine Complexes with Mononucleotides and DNA

A series of new flexible diamine-bridged dinuclear ruthenium(II) complexes [{RuCl(bpy)2}2(μ-BL)]2+ (bpy = 2,2′-bipyridine; BL = H2N(CH2)nNH2 (n = 4 ([1]2+), 8 ([2]2+), 12 ([3]2+))) were prepared. Time-course spectroscopic experiments revealed that these dinuclear ruthenium(II) complexes selectively bind to guanine residues in calf thymus (CT) DNA and the degree of binding of [2]2+ or [3]2+ to CT-DNA relative to [1]2+ is high.