A Bifunctional Three-Dimensional Zn(II) Metal-Organic Framework with Strong Luminescence and Adsorption Cr(VI) Properties.

The mixed ligand 3-amino-1,2,4-triazole (Hatz) and terephthalic acid (Hpta) reacted with Zn(NO)·6HO to synthesize a three-dimensional binuclear Zn(II) metal-organic framework: {[Zn·(atz)·(pta)]·3HO} (). This has two different types of pores (4.5 × 4.5 Å, 5.7 × 5.7 Å). The crystalline could be prepared into nanomaterials () with particles of approximately 100 nm by a cell fragmentation apparatus. Compared with the solid-state luminescence of Hatz and Hpta, it was found that exhibited strong luminescence performance and significant red-shift phenomenon. Due to the decrease in electronegativity and rigidity of ligands, as well as the effect of ligand metal charge transfer (LMCT), the fluorescence lifetime and quantum yield of were 2.7241 ns and 3.02%, respectively. The maximum experimental adsorption capacity of could reach 125.52 mg/g, which was superior to the majority of MOF adsorbents under the optimal adsorption conditions (25 °C, pH = 7, and the adsorbent concentration is 0.2000 g/L). The thermodynamic analysis of adsorption showed that the adsorption of Cr(VI) by was a spontaneous (△ < 0) and exothermic (△ < 0) process. It could be found that was a bifunctional material with potential applications by comprehensive analysis of the fluorescence and adsorption Cr(VI) performance.