NIR-FT Raman spectroscopy of the stereoisomers of a dinuclear Ru-HAT complex, photoprobe of denatured DNA

Abstract

The 3 stereoisomers of the dinuclear complex [Ru(bpy)2]2HAT4+, the racemic Δ-Δ and Λ-Λ and the meso Δ-Λ forms, have been recently isolated and characterized. It has been shown that the racemic and the meso forms exhibit different luminescence lifetimes of the excited MLCT state (metal to ligand charge transfer). It has been demonstrated that each of the three stereoisomers gives rise to a photoelectron transfer with the GMP (GMP) and this, very interestingly, with a different rate. Furthermore, in the presence of denatured DNA, there is also a stereospecific behavior of the dinuclear species. These features underline the interest of using the stereoisomers as specific DNA photoprobes. Because of the close similarity of their UV-visible absorption spectra, only the emission lifetimes and NMR spectroscopy have allowed the distinction between the diastereoisomers. The preliminary results of a near IR-Fourier transform Raman study of minute quantities of the sep. stereoisomers of the dinuclear Ru-HAT complex are hereby reported. [on SciFinder(R)]