Synthesis and photoluminescent properties of five homodinuclear lanthanide (Ln3+ = Eu3+, Sm3+, Er3+, Yb3+, Pr3+) complexes

A series of homodinuclear lanthanide complexes Ln(2)(HTH)(6)Bpm (where Ln=Eu, Sm, Er, Yb, Pr; HTH = 4,4,5,5,6,6,6-heptafluroro-1-(2-thienyl)hexane-1,3-dione; Bpm = 2,2'-bipyrimidine) were synthesized and the photoluminescence properties of these complexes are described. After ligand-mediated excitation of the complexes, they all show the characteristic luminescence of the corresponding Ln(3+) ions in the visible and NIR regions attributed to efficient energy transfer from the ligands to the metal centres. For the Eu-2(HTH)(6)Bpm complex a lifetime of 738.8 mu s (100%, chi(2) = 1.362) is found in solid and two life-times of 455.4 mu s (12.88%) and 618.5 mu s (87.12%) (chi(2) = 1.652) are found in CH2Cl2 solution, respectively. Its quantum efficiency in air-equilibrated CH2Cl2 solution is found to be 28.4%, by using air-equilibrated aqueous [Ru(bpy)(3)](2+)center dot 2Cl(-) solution as reference sample (phi(std) = 2.8%). (C) 2009 Elsevier B.V. All rights reserved.