Thread insertion of a bis(dipyridophenazine) diruthenium complex into the DNA double helix by the extrusion of at base pairs and cross-linking of DNA duplexes

Abstract

The crystal structure of the Δ,Δ enantiomer of the binuclear >light-switch> ruthenium complex [μ-(11,11′-bidppz)(1,10- phenanthroline)4 Ru2]4+ bound to the oligonucleotide d(CGTACG) shows that one dppz moiety of the dumbbell-like compound inserts into the DNA stack through the extrusion of an AT base pair. The second dppz moiety recruits a neighboring DNA molecule, and the complex thus cross-links two adjacent duplexes by bridging their major grooves. Pinned together by molecular rivets: The crystal structure of the complex between double-stranded DNA and the binuclear complex [μ-(11,11′-bidppz)(1,10- phenanthroline)4 Ru2]4+ (1, shown in blue; bidppz=bis(dipyridophenazine)), showed that one half of the bidppz ligand inserts into a DNA duplex, and the other half stacks onto the blunt end of a nearby DNA duplex. Two molecules of 1 with the same binding mode effectively cross-link two DNA duplexes. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.