Multifunctional Lanthanide Metal-Organic Frameworks Are Used for Fluorescence Sensing of Bi3+, HPO42-, Flu, and PNBA and Application

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+, HPO42-, 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.

Preferential Enrichment of Enantiomer from Amino Acid Schiff Bases by Coordination Interaction and Crystallization

In this paper, preferential enrichment (PE) is described for three pairs of novel amino acid Schiff base Cu(II)/Cu(I) complexes. Single crystal X-ray diffraction indicated that 1-S/R are one-dimensional coordination polymers (CPs) with helical structures, and 2-S/R and 3-S/R are one-dimensional CPs with auxiliary ligands. By tuning the pH, the solvent and second ligands, the 1-S/R, 3-S/R underwent polymorphic transitions, resulting in enantioselective liberation of excess enantiomers into solution, until the deposited crystals were slightly enriched with the opposite enantiomer, thereby successfully exhibiting PE. However, under the effects of Cu(II), the solvent and low pH, 2-S/R did not exhibit PE and resulted in enrichment of racemic compounds, which was attributed to amino acid Schiff base chiral complex mechanisms of PE. The three pairs of Cu complex structures were characterized by UV-vis, MS and X-ray photoelectron spectroscopy (XPS). All chiral properties were studied by circular dichroism (CD) in the solid and liquid.