A Cationic Eu-Based Metal–Organic Framework and Its Mixed Matrix Membranes for Sensitive Detection of Nitroaromatic Explosives

Nitroaromatic explosives are hazardous substances, and their leakage poses severe threats to environmental safety, human health, and national security. Thus, the development of fluorescent probes capable of sensitive and rapid detection of nitroaromatic explosives is critically important. Although lanthanide-based metal-organic frameworks (Ln-MOFs) are widely investigated for this purpose, the development of ionic Ln-MOFs for nitroaromatic explosive detection remains significantly underdeveloped. Herein, we synthesized a novel cationic Eu(III)-MOF (NCULL) with a zwitterionic ligand, which is capable of rapid and highly sensitive detection of various nitroaromatic explosives in methanol, exhibiting an exceptionally low detection limit (LOD = 25.44 nM) for 2,4,6-trinitrophenol (TNP). To further expand the practical applications of NCULL, mixed-matrix membranes (MMMs) loaded with NCULL particles were fabricated. These MMMs not only achieved quantitative fluorescent detection of TNP in methanol solvent (LOD = 18.85 nM) but also could be regenerated by simple methanol washing. Furthermore, this study provides not only a prototype for the detection of various nitroaromatic compounds using cationic Ln-MOF but also offers a new example of efficient film-based detection in solutions.