Résumé
The synthesis of a new RuII complex [Ru(L1)(4,7-dpphen)]2+, bearing a tetradentate bis-1,10-phenanthroline ligand L1, is described. X-ray crystal structure analysis shows that the tetradentate ligand L1 coils around the metal and occupies both axial and two of the equatorial positions of the complex. 1H NMR studies clearly indicate that the complex has C2 symmetry in solution. The room temperature luminescence properties of [Ru(L1)(4,7-dpphen)]2+ have been studied, as have those of the related complex [Ru(L2)(4,4′-dmbp)]2+. For both complexes, the luminescence quantum yields and lifetimes are three to ten times higher than those of [Ru(bpy)3]2+. These unusual results are explained by the geometrical constraints imposed by the tetradentate ligands L1 and L2 in their respective complexes, resulting in an effective decoupling between the 3MLCT and 3MC excited states