The Tunable Luminescence of Ruthenium(II) Complexes Containing Different Tetrazolate Ligands

Three luminescent mononuclear Ru-II compounds, [Ru-II(bpy)(2)(L-1)](BF4) (1), [Ru-II(bpy)(2)(L-2)](BF4) (2), and the neutral compound [Ru-II(bpy)(2)(L-3)] (3), were obtained, by treatment of [Ru-II(bpy)(2)Cl-2] with the tetrazolate (tz)-containing ligands L-1-L-3. All the compounds were well characterized by IR, UV/Vis, and H-1 NMR and their redox properties were also investigated by cyclic voltammogram. The crystal structure of 3 was determined by X-ray crystallography and it clearly shows that the Ru-II ion is octahedrally coordinated by two bpy ligands and a deprotonated L-3 ligand. After introduction of these tz ligands, 1-3 are more sensitive towards the change of micro-environment of solvents as compared with that of [Ru-II(bpy)(3)](2+). This effect is most obvious in 3, since it contains a 2(-) ligand L-3. The slight modification of diimine ligand make these complexes have potential applications as sensors.