Elemental analysis, infrared spectroscopy, and X-ray single crystal diffraction indicated that a novel metal-organic framework (Tb-MOF) designated as 0.5n[H2bpy]·[Tb(dpa)(H2O)2]n·4nH2O was synthesized successfully, (where H4dpa = 5-(3, 4-dicarboxy- phenoxy) isophenic acid, bpy = protonated 4,4'-bipyridine). Tb-MOF adopts a 3D network structure based on TbIII ions and the (dpa)4- ligand through µ4: η1, η2, η2, η2 binding modes. Various luminescent EuxTb1-x-MOFs were prepared by adjusting Tb3+ and Eu3+ concentrations. Fluorescence analysis revealed Tb-MOF's strong fluorescence and excellent sensing ability for pollutants like nitrobenzene (NB), ornidazole (ORN), and fluridine (Flu) in water. It is worth noting that the fluorescence quenching rate of Tb-MOF for nitrobenzene can reach 97.1 %, which is also one of the highest among Ln-MOFs. XPS, LUMO orbital energy levels, fluorescence lifetime, and UV absorption were employed to explore the fluorescence quenching mechanism. Tb-MOF demonstrates robust anti-counterfeiting properties and stability, particularly against Flu, and allows rapid in situ imaging of pesticide residues on vegetables. Moreover, leveraging the adjustable emission spectra of EuxTb1-x-MOF, a barcode system for anti-counterfeiting labels has been developed, showing the versatility of stable metal-organic frameworks in advanced technologies for anti-counterfeiting applications.
Keywords: 5-(3, 4-Dicarboxyphenoxy) isophthalic acid; Adjustable Ln-MOFs; Crystal structure; Fluorescence sensing; Information encryption.
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