Synthesis, Crystal Structures, Photoluminescence and Magnetic Properties of Lanthanide(III) Complexes Based on 2-(Thiophen-2-ylselanyl)acetic Acid Ligand

Six dinuclear lanthanide(III) complexes [Ln 2 (L) 6 (phen) 2 ] (Ln = Eu III ( 1 ), Tb III ( 2 ), Dy III ( 3 ), Ho III ( 4 ), Er III ( 5 ), Sm III ( 6 ), L = 2-(thiophen-2-ylselanyl)acetic acid, phen = 1,10-phenanthroline) have been synthesized and characterized by powder X-ray diffraction and single-crystal X-ray diffraction analysis. Single crystal X-ray diffraction analysis showed that complexes 1 – 6 are isostructural and crystallize in the triclinic space group P-1. The luminescent properties and lifetimes of complexes 1 – 3 have been studied, which show the characteristic emissions of Eu III ( 5 D 0 → 7 F 0-4 ), Tb III ( 5 D 4 → 7 F 6-3 ) and Dy III ( 4 F 9/2 → 6 H 15/2, 13/2, 11/2, 9/2 ), and the corresponding luminescent lifetimes are 1.24 ms, 6.25 μs and 4.26 μs, respectively. The magnetic properties of the complexes 3 and 4 were also measured and exhibited weak anti-ferromagnetic interactions between Ln III centers. Moreover, the complex 3 showed the properties of the potential single-molecule magnets with the energy barrier ( U/kB ) 47.50 K and the τ 0 9.73 × 10 –8 s. In view of this, the Dy III complex 3 displayed the behavior of the luminescent single-molecule magnets.