Enhancement of luminescence performance of rare-earth complexes by tuning the synergistic effect of Sm (III) and Eu (III)

The study of rare-earth ion organic complex materials is an overlapping field of inorganic and organic luminescence research. It has important theoretical significance and has been widely used in temperature sensing and biomedical applications, among others. In this work, a series of samarium and europium binuclear rare-earth organic complexes Eu_1-xSm_x(BA)₃phen (x = 0.2,0.5,0.8) were synthesized by using benzoic acid (BA) and phenanthroline (Phen) as the first and second ligands. The possible molecular structure of the newly synthesized complex was also speculated. The results of UV/Vis spectra show that the series of rare-earth organic complexes can effectively absorb ultraviolet light and visible light, and the absorption peaks mainly come from the organic ligands BA and Phen. The results of fluorescence spectroscopy (FS) show that the incorporation of Sm³⁺ has a fluorescence enhancement effect on Eu³⁺. When the molar fraction of Sm³⁺ is 50%, the Eu_0.5Sm_0.5(BA)₃phen complex exhibits a sheet shape and the luminescence intensity reaches the maximum. Thermogravimetric analysis showed that the rare-earth complexes had good thermal stability. In addition, it can emit bright fluorescence under ultraviolet light irradiation. This work uses the antenna effect to elucidate the energy transfer mechanism in the dinuclear rare-earth complexes and the synergistic enhancement of the fluorescence properties of the two rare-earth ions, which provides some theoretical basis for the study of rare-earth complexes.

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