An Ideal Detector Composed of Two-Dimensional Cd(II)-Triazole Frameworks for Nitro-Compound Explosives and Potassium Dichromate

The two‐dimensional (2D) metal–organic framework (MOF) [Cd(TPTZ)(H2O)2(HCOOH)(IPA)2]n (1; TPTZ={4‐[4‐(1H‐1,2,4‐triazol‐1‐yl)phenyl]phenyl}‐1H‐1,2,4‐triazole, IPA=isophthalic acid) has been constructed with the π‐electron‐rich aromatic ligand TPTZ, auxiliary ligand IPA, and the metal Cd2+ ion with a d10 configuration under solvothermal conditions. Complex 1 exhibits a strong ligand‐originated photoluminescence emission, which is selectively sensitive toward electron‐deficient nitroaromatic compounds, such as nitrobenzene (NB), 1,3‐dinitrobenzene (m‐DNB), and 1,4‐dinitrobenzene (p‐DNB), and nitro‐aliphatic compounds, such as nitromethane (NM) and tris(hydroxymethyl)nitromethane. This property makes complex 1 a potential fluorescence sensor for these chemicals. Single‐crystal X‐ray diffraction studies revealed that dinuclear cadmium building units were further bridged by TPTZ ligands to give a four‐connected uninodal net with the Schläfli symbol of [4.63.4.63.62.64]. Explosive findings: The luminescent emissions of a 2D CdII‐based metal–organic framework (MOF, see figure) with a C3‐symmetric multicarboxylate ligand can be quenched by trace amounts of nitro compounds and K2Cr2O7. The quenching mechanism is attributed to electron transfer from the excited‐state electron‐donating MOF framework to electron‐withdrawing nitroaromatic explosives and the highly dispersible nature of the MOF particles.