Photoluminescence properties of dinuclear lanthanide complexes in visible and near-infrared region

Abstract Several dinuclear lanthanide complexes of Ln 2 (HTH) 6 TPPHZ (Ln=Eu, Sm, Er, Nd, Yb, Ho; TPPHZ=Tetrapyrido (3,2-a:2′,3′-c:3′,2″-h:2′″,3′″- j ) phenazine; HTH=4,5,5,6,6,6-heptafluroro-1-(2-thienyl)hexane-1,3-dione were synthesized and their photoluminescence properties were investigated. After ligand-mediated excitation, all the complexes showed the characteristic luminescence of the corresponding Ln(III) ions in the visible and NIR regions attributed to energy transfer from the ligands to the metal center. For Eu 2 (HTH) 6 TPPHZ complex, the quantum efficiency was calculated as 9.6% with the major 5 D 0 lifetime (477.86 μs) by the equation ϕ=τ obs /τ R , where τ obs was observed luminescence lifetime and τ R was radiative (or natural) lifetime (5 ms), and 14.9% with air-equilibrated aqueous [Ru(bpy) 3 ] (II) ·2Cl − solution as a standard sample (ϕ std =2.8%), in CH 2 Cl 2 solution at room temperature.