Interaction of mononuclear nickel(II) enantiomers, Δ- and Λ-bis(1,10-phenanthroline) (dipyrido[3,2-a:2′,3′-c]phenazine)nickel(II) chloride, with calf thymus DNA

Circular dichroism (CD) spectroscopy was used to investigate the interaction of Delta- and Lambda-enantiomers of a mononuclear Ni(II) complex, [Ni(phen)(2)(dppz)](2+) (where phen = 1,10-phenanthroline and dppz = dipyrido[3,2-a:2',3'-c]phenazine), with CT-DNA. The pure Ni(II) enantiomers were synthesized via a chiral precursor. The changes in the absorption and CD spectra upon binding provide detailed information about DNA binding of the enantiomers. The change in the CD spectra over time was used to calculate the racemization rates in the absence and presence of DNA. It was observed that the Delta-enantiomer racemizes slower than the Lambda-enantiomer in the presence of DNA. Competition between the Ru(II) enantiomers, Delta- and Lambda-[Ru(phen)(2)(dppz)](2+), and the Ni(II) enantiomers, Delta- and Lambda-[Ni(phen)(2)(dppz)](2+), was also studied via luminescence titration. (C) 2013 Elsevier B.V. All rights reserved.