Ultrafine copper oxide nanoparticles immobilized on poly (4-vinylpyridine)-grafted UiO-66-NH2 as heterogeneous catalyst for oxidative homocoupling of terminal alkynes

Terminal alkyne homocoupling is an effective route to synthesize 1,3-diynes, which are crucial components of many fine chemicals and natural products. However, the reaction often faces challenges of catalyst recovery and typically necessitates the introduction of basic additives, which limits its practical applicability. Here, we have developed a green and efficient Cu₂O@UiO-66-g-P4VP nanocatalyst that exhibits outstanding activity for homocoupling terminal alkynes under mild, base- or ligand-free conditions. The characterization results indicate that the nitrogen atoms in P4VP interfere with the electronic structure of Cu in Cu₂O nanoparticles, causing the N electrons to shift onto Cu. Density functional theory (DFT) calculations suggest that this catalytic system facilitates the activation of oxygen on the copper surface, promoting the coupling reaction. This work provides a feasible strategy for the rational fabrication of MOF-supported polybase and Cu₂O nanocrystals as heterogeneous nanocatalysts in the oxidative homocoupling of alkynes.