Bimetallic docked covalent organic frameworks with high catalytic performance towards coupling/oxidation cascade reactions

Covalent organic frameworks (COFs) are an emerging class of crystalline porous polymers that make these materials suitable for use as excellent scaffold in heterogeneous catalysis. Here we synthesize a layered two-dimensional (2D) COF (TADP-COF) through the condensation reaction between four-branched 5,10,15,20-tetrakis(4-aminophenyl)porphyrin (TAPP) and linear 2,5-dihydroxyterephthalaldehyde (Dha) and 1,4-phthalaldehyde (PA) building blocks. Porphyrin units, imine and hydroxyl groups together with imines can provide wide coordination sites for metal docking. Using a programmed synthetic procedure, Cu(ii) ions first coordinated with the imine groups in conjunction with their adjacent hydroxyl groups, and porphyrin units and subsequently added Pd(ii) ions occupied the remaining imine sites in the space between adjacent COF layers. The bimetallic Pd(ii)/Cu(ii)@TADP-COF showed high catalytic activity in a one-pot coupling/oxidation cascade reaction in water. The high surface area, one-dimensional (1D) open channel structure and predesigned catalytic active sites of this material make it ideal candidate for use as heterogeneous catalyst in a wide range of catalytic reactions.

Automated summary

Covalent organic frameworks (COFs) are emerging crystalline porous polymers that serve as excellent scaffolds for heterogeneous catalysis. A layered two-dimensional (2D) COF (TADP-COF) was synthesized, providing wide coordination sites for metal docking and exhibiting high catalytic activity. This material, with its high surface area, one-dimensional open channel structure, and predesigned catalytic active sites, is an ideal candidate for use as a heterogeneous catalyst in various catalytic reactions.