Three-Dimensional Co(II)/Cd(II) Metal–Organic Frameworks: Luminescent Cd-MOF for Detection and Adsorption of 2,4,6-Trinitrophenol in the Aqueous Phase

Sensing and adsorption of hazardous and explosive nitroaromatic compounds using metal–organic frameworks (MOFs) have been a promising research field in the current scenario due to environmental concerns and homeland security. Here, we report two mixed ligand MOFs {[Co2(SDB)2(TIB)(H2O)](H2O)(1,4-dioxane)2}n (CP1) and {[Cd3(SDB)3(TIB)](H2O)2(1,4-dioxane)(G)x}n (CP2) (where SDB = 4,4′-sulfonyldibenzoate, TIB = 1,3,5-tris(imidazol-1-ylmethyl) benzene, and G = guest solvent molecules) synthesized by a hydrothermal method and the application of CP2 as an adsorbent and sensing material for 2,4,6-trinitrophenol (TNP). Both MOFs are characterized by various physicochemical techniques including single crystal X-ray analysis, and the crystal structures of CP1 and CP2 revealed that both MOFs are 3D frameworks composed of trimeric metal clusters linked by SDB ligand further coordinated through the imidazole nitrogen of the TIB moiety. Taking advantage of d10 transition metal present in the case of CP2, the recognition of nitroaromatics has been investigated engaging this fluorescent material. The photoluminescence property of CP2 revealed that significant and sensitive fluorescence quenching was observed toward TNP in the aqueous phase from different pools of NACs with a detection limit up to 35 ppb. Plausible accounts for the fluorescence quenching and CP2 as a column chromatographic filler for the adsorption of TNP from water have also been demonstrated.