Pore-wall functionalization of covalent organic framework palladium catalysts boosts the multicomponent reaction of CO2

Abstract

Although supported metal nanoparticles (NPs) have demonstrated great potential in heterogeneous catalysis, the regulation of their interaction with the support framework remains a significant challenge. Herein, we employed a pore-wall functionalization strategy to construct four covalent organic frameworks (COFs) with distinct chemical microenvironments. Palladium nanoparticles were incorporated into the frameworks (Pd@TA, Pd@TA-4F, Pd@TA-OCH₃, and Pd@TA-OHex), and the materials were applied in the multicomponent reaction of carbon dioxide. Impressively, modifications in the pore-wall microenvironment exhibited a regular modulating effect on the catalytic performance of the Pd NPs. Among them, Pd@TA-OCH₃, which combines electron-donating effects and low steric hindrance, demonstrated the best catalytic performance. Furthermore, due to the altered surface microenvironment, Pd@TA-OCH₃ exhibited optimal enrichment and adsorption (k = 0.32 h⁻¹) behavior toward the substrates. In-depth catalytic and adsorption experiments, along with DFT calculations, confirmed the structure–activity relationship between the microenvironments of the COFs and their catalytic performance.