Color-tunable and white-light emitting lanthanide complexes based on (CexEuyTb1−x−y)2(BDC)3(H2O)4

Ce³⁺, Eu³⁺ and Tb³⁺ complexes were synthesized through facile and mild approaches with terephthalic acid (H₂BDC) as the ligand. Their chemical compositions were determined as (Ce_xEu_yTb_1−x−y)₂(BDC)₃(H₂O)₄ by elemental analysis (EA), Fourier transform infrared (FTIR) spectra and X-ray diffraction (XRD) measurements. Fluorescent properties of the as-synthesized complexes were investigated by changing the molar ratio of Ce³⁺, Tb³⁺ and Eu³⁺ ions, and the optimized ratio of 3.0:2.0:0.15 for Ce³⁺:Tb³⁺:Eu³⁺ in the complex was determined for white-light emission. Tuning on the emitting color was realized by adjusting the ratio among lanthanide ions, indicating the energy transfer process inside the complex. It was found that Tb³⁺ could sensitize the fluorescence of Eu³⁺ while its own fluorescence was quenched by the latter ion, and concentration quenching of Ce³⁺ was also observed. Fairly good thermal stability and oxidation resistance of the as-synthesized complexes were also demonstrated.