Relationship between binding affinity for calf-thymus DNA of [Pt(2,2′-bpy)(n-Rpy) 2 ] 2+ (n= 2,4) and basicity of coordinated pyridine

The binding affinity for DNA of the complexes [Pt(2,2′-bpy)(n-Rpy)2]2+(n= 2,4) systematically increases on increasing pKa of the coordinated pyridine, with the exception of the 2-methyl-substituted derivative.