Cadmium MOF-Based Varied {Cd₂} Clusters as Multifunctional Fluorescence Sensors to Detect Fe³⁺, Cr₂O₇^2–, TNP, and NFT

Metal-organic frameworks (MOFs) have been widely used in the field of fluorescence sensing due to their highly ordered spatial structures, large porosity, and uniform pore sizes. Here, two new Cd- MOFs (JLJU-2 and JLJU-3), based on the ligand 4-(1H-1,2,4-triazol-1-yl)phenyl-4,2':6',4"-terpyridine (L) and two carboxylate ligands, were synthesized by the solvothermal method. JLJU-2 and JLJU-3 were characterized by single-crystal X-ray diffraction, powder X-ray diffraction, infrared spectroscopy, UV-visible spectroscopy, and thermogravimetric analysis. Respectively, JLJU-2 and JLJU-3 exhibit 2D and 3D structures using the L ligand and 2-aminoterephthalic acid (2-ATA)/nitroterephthalic acid (NTPA), adopted with different coordination modes. Furthermore, the porous crystal structures of JLJU-2 and JLJU-3 enable them to be well-suited for applications in the field of fluorescence sensing, in which JLJU-3 can detect Fe³⁺, Cr₂O₇^2-, TNP, and NFT with high selectivity and sensitivity. This work provides useful information for a versatile fluorescence sensing platform for the detection of environmental contaminants.