Structural investigation into the threading intercalation of a chiral dinuclear ruthenium(II) polypyridyl complex through a B‑DNA oligonucleotide

Fairbanks, Simon D.;Robertson, Craig C.;Keene, F. Richard;Thomas, Jim A.;Williamson, Mike P.

Abstract

Herein we report the separation of the three stereoisomers of the DNA light-switch compound [{Ru(bpy)2}2(tpphz)]4+ (tpphz = tetrapyrido[3,2-a:2',3'-c:3",2"-h:2‴,3‴-j]phenazine) by column chromatography and the characterization of each stereoisomer by X-ray crystallography. The interaction of these compounds with a DNA octanucleotide d(GCATATCG).d(CGATATGC) has been studied using NMR techniques. Selective deuteration of the bipyridyl rings was needed to provide sufficient spectral resolution to characterize structures. NMR-derived structures for these complexes show a threading intercalation binding mode with slow and chirality-dependent rates. This represents the first solution structure of an intercalated bis-ruthenium ligand. Intriguingly, we find that the binding site selectivity is dependent on the nature of the stereoisomer employed, with Λ RuII centers showing a better intercalation fit.

Journal

Journal of the American Chemical Society

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141

ISBN/ISSN

1520-5126

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American Chemical Society

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DOI

10.1021/jacs.8b12280