First TPymT-Ln complexes (TPymT = 2,4,6-Tris(2-pyrimidyl)-1,3,5-triazine; Ln = Eu, Gd, Tb, Dy): Solvothermal synthesis, structure, magnetic and photoluminescent properties

Four novel mononuclear lanthanide complexes, [Ln(TPymT)(NO₃)₃(H₂O)₂] (Ln: Eu³⁺ (1), Gd³⁺ (2), Tb³⁺ (3) and Dy³⁺ (4)), have been solvothermally synthesized using multidentate 2,4,6-tris(2-pyrimidyl)-1,3,5-triazine (TPymT). Compounds 1–3 have been characterized by means of elemental analysis, FT-IR, and single-crystal/powder X-ray diffraction analysis. Compound 4 was structurally characterized. The Ln³⁺ ion in 1–4 is ten-coordinated, where TPymT serves as an N₃ donor in an isostructural series. The alternating-current magnetic studies showed frequency dependence below ca. 10 K for 3, as an indication of a single-ion magnet. The activation energy for the magnetization reorientation was estimated as U_eff/k_B = 95(9) K after applying a dc bias field 2000 Oe for 3. The photoluminescent studies clarified that 1 and 3 behaved as red and green light emitters with quantum yields as high as 17 and 39 %, respectively. The TD-DFT calculation supports the energy level scheme of ground and excited states of TPymT together with the reference compound 4′-phenyl-2,2’:6′,2″-terpyridine. The present work suggests a broad chance and motivation to apply TPymT to the field of 4f coordination chemistry.