Condensation and salt-induced decondensation of DNA upon incorporation of a V-shaped luminescent [Ru2(bpy)4(mbpibH2)]4 +

•V-shaped di-Ru(II) complex binds to DNA groove-surfaces with high binding affinity.•Luminescent di-Ru(II) complex can effectively induce condensation of DNA.•Herring sperm DNA is condensed into long chain particle clusters.•High salt concentration facilitates decondensation of DNA-based adducts.

This paper first reports on the condensation of DNA to a tightly packed state induced by a V-shaped di-ruthenium(II) complex [Ru2(bpy)4(mbpibH2)]Cl4 (bpy = 2,2′-bipyridine and mbpibH2 = 1,3-bis([1,10]phenanthroline[5,6-d]imidazol-2-yl)benzene), which binds to the groove of herring sperm DNA (hsDNA) with the binding constant of 2.0 × 107 M− 1 (0.05 M NaCl, pH 7.2). The di-Ru(II) complex is found to induce the condensation of both hsDNA to long chain-like particle clusters and originally circular plasmid pBR322 DNA to particulate structure under neutral conditions. More interestingly, the presence of NaCl has a significant impact on the condensation and decondensation of DNA upon incorporation of [Ru2(bpy)4(mbpibH2)]4 +, representing tunable luminescence characteristics by NaCl. High salt concentration facilitates the decondensation of DNA-[Ru2(bpy)4(mbpibH2)]4 + adducts. The results from this study offer an effective method to control the condensation and decondensation of DNA upon incorporation of luminescent concentrators.

Graphical abstractA V-shaped luminescent di-Ru(II) complex bound in DNA grooves can induce the formation of DNA-based adducts, which are released by varying NaCl concentration.Figure optionsDownload full-size imageDownload as PowerPoint slide