Luminescent Properties of Ruthenium(II) Complexes with Sterically Expansive Ligands Bound to DNA Defects
A new family of ruthenium(II) complexes with sterically expansive ligands for targeting DNA defects was prepared, and their luminescent responses to base pair mismatches and/or abasic sites were investigated. Design of the complexes sought to combine the mismatch specificity of sterically expansive metalloinsertors, such as [Rh(bpy)_2(chrysi)]^(3+) (chrysi = chrysene-5,6-quinone diimine), and the light switch behavior of [Ru(bpy)_2(dppz)]^(2+) (dppz = dipyrido[3,2-ɑ:2′,3′c]phenazine). In one approach, complexes bearing analogues of chrysi incorporating hydrogen-bonding functionality similar to dppz were synthesized. While the complexes show luminescence only at low temperatures (77 K), competition experiments with [Ru(bpy)_2(dppz)]^(2+) at ambient temperatures reveal that the chrysi derivatives preferentially bind DNA mismatches. In another approach, various substituents were introduced onto the dppz ligand to increase its steric bulk for mismatch binding while maintaining planarity. Steady state luminescence and luminescence lifetime measurements reveal that these dppz derivative complexes behave as DNA "light switches" but that the selectivity in binding and luminescence with mismatched/abasic versus well-matched DNA is not high. In all cases, luminescence depends sensitively upon structural perturbations to the dppz ligand.
© 2012 American Chemical Society. Received: September 6, 2012. Published: October 31, 2012. We thank the NIH (GM33309 to J.K.B.) for their financial support, the Lindemann Trust for a postdoctoral fellowship to A.J.M., the Tobacco-Related Disease Research Program (TRDRP) for a postdoctoral fellowship to M.H.L., and a Dissertation Research Award to H.S. We also thank Dr. Eva Rüba for developing the synthesis of [Ru(bpy)2(chrysi)]2+ and Jessica Yeung for carrying out preliminary studies. We are grateful to the Beckman Institute Laser Resource Center (BILRC) at Caltech for facilities.
Published - ic3019524.pdf
Accepted Version - nihms419008.pdf
Supplemental Material - ic3019524_si_001.pdf