Oriented construction of the Mixed-metal organic framework with triazine hexacarboxylic acid and fluorescence detection: Fe3+, Cr2O72- and TNP

Metal-organic frameworks composed of two metals in the structure are called mixed-metal metal organic frameworks (MM-MOFs). In this work, we constructed three MM-MOFs, namely [Zn3Eu2(TTHA)2(H2O)6]·6H2O (1), [Zn3Sm2(TTHA)2(H2O)6]·2H2O (2) and [ZnDy(HTTHA)(H2O)4]·2H2O (3) by the reaction of H6TTHA ligand (H6TTHA = 1, 3, 5-triazine-2, 4, 6-triamine hexaacetic acid), Ln(NO3)3·6H2O (Ln = Eu, Sm, Dy) and Zn(NO3)2·6H2O under hydrothermal conditions. The complexes 1–2 were a 3D microporous structure and complex 3 formed a 3D network structure. Furthermore, complex 1 exhibited excellent fluorescence properties. We explored the fluorescence sensing abilities of complex 1 for metal ions, anions, and organic nitro compounds. The experimental results showed that complex 1 could sensitively and efficiently detect Fe3+, Cr2O72- ions and 2,4,6-trinitrophenol (TNP). It was worth noting that complex 1 showed prominent sensitivity for TNP, the detection limit was as low as 1.14 μM.