Effect of substituent of terpyridines on the DNA-interaction of polypyridyl ruthenium(II) complexes

An octahedral complexes of ruthenium with 2,9-dimethyl-1,10-phenanthroline (dmphen) and substituted terpyridine have been synthesized. The RuII complexes have been characterized by elemental analyses, thermogravimetric analyses, magnetic moment measurements, FT-IR, electronic, 1H NMR and FAB mass spectra. The binding strength and mode of interaction of the complexes with Herring Sperm DNA has been investigated using absorption titration and viscosity measurement studies. Results suggest that the substituent on terpyridine ligand affects the binding mode and binding ability of the complexes. Effect of time and ionic strength on DNA cleavage ability of complex has also been studied by gel electrophoresis. Results suggest that more than 200 mM concentration of NaCl decreases the cleavage ability of complex.

Graphical abstractChange in substituent on ancillary ligand affects the binding mode and binding ability of complexes.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The Kb values were found in the range 3.71 × 103 to 9.21 x 104 M−1. ► Complex with electron withdrawing group shows higher DNA binding affinity. ► Complex with electron donating group shows lower DNA binding affinity. ► Presence of NaCl higher than 200 mM decreases the DNA cleavage ability of complex.