Luminescence properties of a di-ruthenium(II) complex with an intramolecular hydrogen bond modulated by DNA and copper(II) ion

Abstract

Modulation of the luminescence properties of a di-ruthenium(II) complex [(bpy) 2 Ru(BL)Ru(bpy) 2 ] 4? (bpy = 2,2 0 -bipyridine, BL = 2-hydroxyl-5-methyl-1,3-bis([1,10]phenanthroline-[5,6-d]imidazol-2-yl)benzene) by DNA and/or Cu 2? ion has been investigated. It is found that the ruthenium(II) complex can coordinate to the Cu 2? ion in both the absence and presence of DNA. Binding to DNA is through electrostatic interactions and the intramolecular hydrogen bond in the complex is located outside of the DNA. The binding constant is 1.6 9 10 4 M -1 . Moreover, it is demonstrated that DNA has the ability to enhance the luminescence intensities of both the di-ruthenium(II) complex and the tri-metallic system generated by chelating with Cu 2? . Conversely, Cu 2? ion can quench the luminescence of both the free ruthenium(II) complex and the DNA-bound ruthenium(II) complex.

Recent advances in 1,10-phenanthroline ligands for chemosensing of cations and anions

“…On the contrary, addition of Cu 2+ ions to the 14a-ctDNA system caused only negligible changes in the luminescence or absorption spectrum, which pointed to the fact that the middle phen chelating unit of 14a was located deeply in between the hydrophobic DNA base pairs, making access of Cu 2+ ions difficult. 43 The complexes 14b, 14c, 16a and 16b also gave luminescence changes with Cu 2+ ions and ctDNA; [44][45][46][47] however, 15a-ctDNA and 15b-ctDNA were selective towards Co 2+ and Ag + , respectively. 48,49 The decreased emission intensity can be revived in both cases by adding EDTA (ethylenediamine tetraacetic acid) owing to a strong chelation of metal ions with EDTA.…”

Chemical modulation of the luminescence of a DNA-bound diruthenium(II) complex by copper(II) ion and EDTA

“…In our previous study on the modulation of DNA-binding behavior of mono-and di-ruthenium complexes by the coordination of intermolecular hydrogen bonded Cu 2? ion [21,22], two DNA-binding modes were suggested in relationship to the structure of the ligands, indicating that the intramolecular hydrogen bond was located inside and outside the DNA, respectively.…”