Preparation, Crystal Structures and Luminescent Properties of Terbium and Europium Complexes with a New Amino-Alkenone Type Ligand

Solid complexes of terbium and europium nitrates with an amino-alkenone type ligand, 1-[2-(6-methylpyridin-2-ylamino)-5,6-dihydro-4H-pyran-3-yl]ethanone (L) have been prepared and characterized by elemental analysis, conductivity measurements, and IR spectra. The crystal and molecular structures of the complexes [TbL₂(NO₃)₃(H₂O)]·CHCl₃ (1) and [EuL₂(NO₃)₃(H₂O)]·CH₃CO₂C₂H₅ (2) have been determined by single crystal X-ray diffraction. And the coordination spheres of the complexes are similar. At the same time, the luminescent properties of the Tb³⁺ complex in solid state and in solvents were investigated at room temperature. Under the excitation of UV light, Tb(III) complex exhibited characteristic emissions but not for the Eu(III) complex. The lowest triplet state energy level of the ligand in the complex matches better to the resonance level of Tb(III) than Eu(III) ion.