Study of the interaction between novel ruthenium(II)-polypyridyl complexes and calf thymus DNA

Four new complexes L2RuL'2+, where L = 2,2'-bipyridine (bpy) and 1,10-phenanthroline (phen), L' are Schiff bases or phenylhydrazones derived from 4,5-diazafluoren-9-one (AFO), were prepared. They were characterized by elemental analyses, absorption, IR, and emission spectra. The binding of these complexes to calf thymus DNA has been investigated by absorption, circular dichroism spectroscopy, and viscosity measurement. The experimental results show that the complexes bind to calf thymus DNA by three kinds of binding modes, respectively-electrostatic mode, nonintercalative binding mode, and intercalative binding mode.