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 [Ln2(L)6(phen)2] (Ln = EuIII (1), TbIII (2), DyIII (3), HoIII (4), ErIII (5), SmIII (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 EuIII (5D0 → 7F0-4), TbIII (5D4 → 7F6-3) and DyIII (4F9/2 → 6H15/2, 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 LnIII 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 τ0 9.73 × 10–8 s. In view of this, the DyIII complex 3 displayed the behavior of the luminescent single-molecule magnets.