Cu/Cu2O Nanoparticles Supported on a Phenol–Pyridyl COF as a Heterogeneous Catalyst for the Synthesis of Unsymmetrical Diynes via Glaser–Hay Coupling

Covalent organic frameworks (COFs) are a new class of porous crystalline polymers with a modular construct that favors functionalization. COF pores can be used to grow nanoparticles (nPs) with dramatic size reduction, stabilize them as dispersions, and provide excellent nP access. Embedding substrate binding sites in COFs can generate host–guest synergy, leading to enhanced catalytic activity. In this report, Cu/Cu2O nPs (2–3 nm) are grown on a COF, which is built by linking a phenolic trialdehyde and a triamine through Schiff bonds. Their micropores restrict the nP to exceptionally small sizes (∼2–3 nm), and the pore walls decorated with strategically positioned hydrogen-bonding phenolic groups anchor the substrates via hydrogen-bonding, whereas the basic pyridyl sites serve as cationic species to stabilize the [CuclusterCl2]2– type reactive intermediates. This composite catalyst shows high activity for Glaser–Hay heterocoupling reactions, an essential 1,3-diyne yielding reaction with widespread applicab...