Diamino group-functionalized Zr-based metal-organic framework for fluorescence sensing of free chlorine in the aqueous phase and Knoevenagel condensation

Dalton Trans. 2022 May 3;51(17):6964-6975. doi: 10.1039/d2dt00194b.

Abstract

We developed a porous diamino group-functionalized Zr(IV) metal-organic framework (MOF). The synthesized MOF has a similar structure to DUT-52 (DUT = Dresden University of Technology), which has a face-centered cubic structure with an Fmm space group. The synthesized material (DUT-52-(NH2)2-1) was solvent exchanged with methanol (MeOH) and activated at 100 °C overnight. Both the as-synthesized and activated materials (DUT-52-(NH2)2-1') are thermally stable until 300 °C. The Brunauer-Emmett-Teller (BET) surface area of DUT-52-(NH2)2-1' was found to be 413 m2 g-1. DUT-52-(NH2)2-1' showed a significant quenching of fluorescence response after coming in contact with free chlorine (ClO-) in an aqueous medium. The selectivity of DUT-52-(NH2)2-1' towards ClO- was not significantly hampered in the presence of any competitive ion. The limit of detection (LOD) value was found to be 0.08 μM in phosphate-buffered saline (PBS, pH = 7.4). DUT-52-(NH2)2-1' is recyclable and very sensitive towards ClO-. Moreover, the paper strip method was developed for onsite identification of ClO-. Furthermore, the catalytic activity of DUT-52-(NH2)2-1' was tested in the Knoevenagel condensation between benzaldehyde and cyanoacetamide. The experimental results clearly indicate that DUT-52-(NH2)2-1' exhibits high activity with very high selectivity towards condensation products. The solid was reusable three times with no decay in its activity, as evidenced by powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FE-SEM) and fourier transform infrared (FT-IR).

MeSH terms

  • Chlorine
  • Halogens
  • Limit of Detection
  • Metal-Organic Frameworks* / chemistry
  • Spectroscopy, Fourier Transform Infrared
  • Water / chemistry

Substances

  • Halogens
  • Metal-Organic Frameworks
  • Water
  • Chlorine