Ultrasonic exfoliation of a Cd-based metal–organic framework into ultrathin nanosheet for visible-light-initiated trifluoromethylation and sequential oxidation–cyclisation reaction

Abstract

Herein, we successfully obtained a two-dimensional (2D) Cd(II) metal–organic framework with [Cd2(ADPA)(H2O)2(NMP)2]n (XAIU-5, NMP = N-methylpyrrolidone) by using Cd(NO3)2·4H2O and 5,5'-(anthracene-9,10-diyl)diisophthalic acid (H4ADPA). Single-crystal X-ray diffraction revealed its staggered ABAB-layered arrangement, with interpenetration between layers forming a 2D + 2D → three-dimensional (3D) supramolecular architecture. XAIU-5 demonstrated remarkable photocatalytic activity for trifluoromethylation reaction and sequential oxidation-cyclization reaction under visible light irradiation. Moreover, each Cd(II) center in the adjacent bimetallic motif is ligated by one water and one N-methyl-2-pyrrolidone molecule that are readily displaced during the reaction, thereby furnishing vacant active sites for the substrate molecules. Ultrasonic exfoliation of XAIU-5 yielded single-layer structured nanosheets (XAIU-5-NS) with enhanced photocatalytic activity, attributed to exposed straticulate Cd(II) active sites and reduced charge-transfer resistance, which facilitated efficient electron-hole separation and substrate activation. This work not only presents a sustainable strategy for synthesizing trifluoromethyl drugs, thiazole, oxazole and imidazole products under visible light, but also underscores the critical role of catalyst nanosheets in optimizing photo-redox performance.