Multifunctional Lanthanide Metal-Organic Frameworks Are Used for Fluorescence Sensing of Bi³⁺, HPO₄^2-, Flu, and PNBA...

Using a nitrogen-containing tricarboxylic acid ligand (imidazole-1-yl) benzene-2,4,6-tricarboxylic acid (H₃ttc) and lanthanide metal elements (Dy, Eu, Nd, and Gd), four lanthanide metal organic frameworks (Ln-MOFs) with the same structure, namely, {[Dy₂ (Httc)₃]·1.5DMF}_n(1), {[Eu₂ (Httc)₃]·1.5DMF}_n(2), {[Nd₂ (Httc)₃]·1.5DMF}_n(3), and {[Gd₂ (Httc)₃]·1.5DMF}_n(4), were synthesized under solvothermal conditions. The characterization analysis showed that the four isomorphic Ln-MOFs were trigonal crystals of the R3̅c space group, with good phase purity and thermal stability. Fluorescence analysis showed that complex 1 can be an excellent fluorescence sensor for Bi³⁺, HPO₄^2-, and fluridine (Flu), while complex 2 can be an excellent fluorescence sensor for p-nitrobenzoic acid (PNBA). And their sensing mechanisms were discussed in detail. The fluorescent test paper and fluorescent seal were prepared by using the excellent luminescence properties of 1 and 2, and the pesticide on the surface of cherry tomato was detected. The applicability of these MOFs as fluorescence sensors was proved. Therefore, Ln-MOFs are expected to have unpredictable application prospects in the field of environmental detection.