Assembly of Two Isostructural Metal-organic Frameworks Based on Hetero-N,O Donor Ligand for Detecting Nitro Explosives

Two isostructural metal-organic frameworks,NO₃] M₃(H₂O)₃O(TBA)₃]·2DMF·6H₂O(1 and 2)M=In and Fe, H₂TBA=4-(1H-tetrazol-5-yl)-benzoic acid], have been successfully synthesized. Compounds 1 and 2 have three-dimensional structures bridged via the typical 6-connected tri-nuclear cluster units M₃O(COO)₆ and linear linker H₂TBA. The whole 3D framework possesses a 6-connected acs topology. Notably, by the fluorescence technique, compound 1 can detect nitro explosives through fluorescence quenching effect, especially for 2,4,6-trinitrophenol(TNP, K_sv=3.64×10⁴ L/mol). Furthermore, the fluorescence spectrum red shifts as the number of-NO₂ group increases. Based on the aforementioned consideration, compound 1 can be considered as a potential luminescent probe for the detection of TNP.