Ruthenium arene complexes with chalcone ligands incorporating pyridyl and anthryl units: Synthesis, aqueous stability and interaction with quadruplex DNA

Abstract

Twelve ruthenium(II) arene complexes incorporating chalcone ligands with pyridyl and anthryl units, as well as chlorido or oxalato ancillary ligands, have been synthesized and structurally characterized by 1H NMR spectroscopy, ESI mass spectrometry and elemental analysis. Compared to the oxalato compounds, the chlorido complexes were less stable and more susceptible to aquation in solution; the dissociation was suppressed in the presence of chloride ions. All six of the chlorido complexes and three of the oxalato complexes were able to bind to quadruplex DNA, exhibiting greater selectivity for HTelo over c-myc. The cationic species 3f, in which the chalcone chelates to the metal center, was found to bind to HTelo most strongly. These results indicate that the ancillary ligand, the location of the N-donor atom in the pyridyl ring, the position of the α,β-unsaturated ketone relative to the pyridyl and anthryl entities in the chalcone moiety, as well as the presence of the metal center all play significant roles in improving the binding of such complexes to quadruplex DNA.