Synthesis, Structure, Magnetic and Photoluminescent Properties of Lanthanide(III) Complexes with a Ligand Based on 1,10-Phenanthroline and (+)−3-Carene

Abstract

Ionic complexes of the composition [LnL₂(NO₃)₂]₂[Ln(NO₃)₅]3Me₂CO (Ln = Sm (1), Eu (2), Tb (3), Dy (4)) with an optically active ligand L containing 1,10-phenanthroline and (+)−3-carene moieties are synthesized. According to the X-ray crystallographic data, the crystal structure of compound 2 is composed of complex [EuL₂(NO₃)₂]⁺ cations (N₆O₄ polyhedron) and complex [Eu(NO₃)₅]²⁻ anions (O₁₀ polyhedron), and also Me₂CO molecules. The L and NO₃ ligands perform both tridentate and bidentate chelating functions respectively. Complexes 1–4 are isostructural and crystallize in the non-centrosymmetric space group P1; their magnetic properties are studied in the temperature range 2–300 K. The μ_eff values for 1–4 at 300 K are 3.14 μ_B, 6.08 μ_B, 16.76 μ_B, and 18.30 μ_B respectively and are typical of Ln³⁺ ions. For complex 3 significant anisotropy results in a nonlinear field dependence of the magnetization at 2 K. Complexes 1–4 exhibit metal-centered orange (Sm³⁺), red (Eu³⁺), green (Tb³⁺), and yellow (Dy³⁺) luminescence in the solid state at room temperature. Luminescence quantum yield decreases for solid samples in the order 2 > 1 > 3 ≈ 4.