基于[LnMo12]二十面体的三维稀土钼酸盐骨架的合成、结构及荧光性能

通过缓慢蒸发溶剂法合成了2例新的三维稀土钼酸盐：Ln (H₂O)₃]₃LnMo₁₂O₄₂]·xH₂O，其中Ln=Eu (1)、Tb (2)，x=7(1)，10.17(2)。这2种稀土钼酸盐中都含有新颖的二十面体LnMo₁₂O₄₂]构建单元，该单元通过与{LnO₉}多面体进一步连接形成三维网络。光致发光测试表明，化合物1和2显示出明显不同的发射特征，这与Eu³⁺和Tb³⁺离子的不同能级跃迁密切相关。化合物1表现出较强的红色发射(CIE色度坐标为(0.66，0.33))、高发光强度、较大的荧光量子产率(约60%)，对应于从⁵D0到⁷F_J (J=4、3、2、1、0)的跃迁；化合物2表现出浅绿色发射(CIE色度坐标为(0.34，0.60))，对应从⁵D₄到⁷F_J (J=6、5、4、3)的能级跃迁，其发光强度较弱和荧光量子产率较低(约20%)。有趣的是，一定量的Tb³⁺引入和大量溶剂分子的存在导致化合物2发生部分荧光猝灭，但对化合物1的荧光几乎没有影响。

Synthesis, crystal structure, and luminescence properties of three-dimensional rare earth molybdate framework based on [LnMo12] icosahedron

Two new 3D rare-earth molybdate frameworks, Ln(H₂O)₃]₃LnMo₁₂O₄₂]·xH₂O, where Ln=Eu (1), Tb (2); x= 7 (1), 10.17 (2), have been synthesized by slow evaporation. Both of these rare earth molybdate frameworks have a new rare-earth-centered icosahedron LnMo₁₂O42] building unit, which is further connected to adjacent ones by {LnO₉} polyhedra to form a 3D network. Photoluminescence tests reveal that 1 and 2 exhibited different emission properties, which are caused by the f-orbital energy levels of Eu³⁺ and Tb³⁺. 1 exhibited bright red emissions (CIE chromaticity coordinates: (0.66, 0.33)) corresponding to the transition from 5D₀ to ⁷F_J (J=4, 3, 2, 1, 0), with high luminescent emission intensity and high quantum yield (about 60%). 2 exhibited light green emissions (CIE chromaticity coordinates: (0.34, 0.60)) corresponding to the transition from 5D₀ to ⁷F_J(J=6, 5, 4, 3), with lower luminescent emission intensity and quantum yield (about 20%). Interestingly, the introduction of Tb and the presence of a large number of solvent molecules in compound 2, both lead to partial fluorescence quenching but have little effect on the fluorescence properties of 1.