Fluorine-Functionalized 2D Dysprosium(III)–Organic Framework for Highly Catalyzing the CO2-Epoxide Cycloaddition

Abstract

Two-dimensional metal−organic frameworks (2D MOFs) have aroused great interest in the material realm due to their unique topological structure and excellent physicochemical properties. Herein, the exquisite combination of scarcely reported dinuclear [Dy₂(COO)₆(DMF)₄] units and meticulously designed H₄FPDC ligands under the acidic solvothermal conditions led to a highly robust 2D rare-earth-cluster based framework of {[Dy(HFPDC)(DMF)₂]·3DMF·2H₂O}_n (NUC-139) (H₄FPDC = 4,4′-(4-(4-fluorophenyl)pyridine-2,6-diyl)diisophthalic acid). After removing the lattice and associated DMF molecules, the activated host framework of NUC-139a not only has higher-order in-plane nanoscale pores of ca. 10.5 ×11.8 ×14.8 ų, but also is functionalized by the multifarious symbiotic acid-base active sites including Lewis acidic Dy³⁺ ions, strong electron-affinity fluorine atoms, uncoordinated carboxyl groups and free pyridine moieties on upper and lower surfaces. Catalytic tests exhibited that, under mild conditions, the cycloaddition of CO₂ with a series of epoxides could be catalyzed by activated NUC-139a with high yield and selectivity. In addition, kinetic studies have demonstrated the positive effects of various active ingredients on efficient catalysis under milder conditions. In a word, this work offers a brand structure-oriented organic connector, which can propagate metal ions into functionalized 2D nanoporous materials, thereby providing more options for the research of functional materials.