Designable Fluorescent Anthracene-Based Cd-Metal–Organic Frameworks for Sensing TNP, Fe3+, and Cr2O72–

Here, four new luminescent Cd(II)-metal–organic frameworks(MOFs) were solvothermally synthesized: [Cd₂(tatrz)_1.5(Hidc)₂H₂O]·3H₂O (CUST-981), [Cd(tatrz)(mip)]·2H₂O (CUST-982), [Cd(tatrz)_0.5(aip)]·2DMF (CUST-983), and [Cd(tatrz)(ntp)(H₂O)₂]·H₂O (CUST-984) (tatrz = 1-(9-(1H-1,2,4-triazol-1-yl)anthracen-10-yl)-1H-1,2,4-triazole, Hidc = imidazole-4,5-dicarboxylic acid, mip = 5-methylisophthalic acid, aip = 5-aminomethylisophthalic acid, ntp = 2-nitroterephthalic acid, CUST = Changchun University of Science and Technology). Using a semirigid anthracene-based ligand as the main ligand, the structures of the MOFs were finely tuned by carefully selecting bidentate, tridentate, and tetradentate auxiliary carboxylic acid ligands. The constructed MOFs exhibit unique two-dimensional (CUST-982 and CUST-984) and three-dimensional (CUST-981 and CUST-983) structures. CUST-981–984 possess good structural stability and thermal stability. Furthermore, CUST-981–984 all exhibit satisfactory sensitivity and selectivity for the detection of Fe³⁺, Cr₂O₇^2–, and TNP. CUST-983 displays the lowest detection limits of 0.132 and 0.481 μM for Fe³⁺ and Cr₂O₇^2–, respectively. CUST-984 shows the lowest detection limit for TNP, at 0.08 μM. The possible mechanisms of fluorescence quenching during the sensing process were systematically investigated using PXRD, UV–vis, and density functional theory. This work collectively provides a solid theoretical foundation for the applications of LMOFs in the field of contaminant detection.