"Orthogonal-Twisted-Arm" Ligands for The Construction of Metal-Organic Frameworks (MOFs): New Topology and Catalytic Reactivity

Extended tetratopic benzoic acid ligands with "orthogonal-twisted-arms" conformations were designed and synthesized for the construction of new MOF structures (OTA-MOF). Upon coordination with Cd²⁺ and Cu²⁺ cations, two well-defined new MOFs were prepared. X-ray single crystal structures were successfully obtained, demonstrating the formation of a new topology (4,4,4-c). The OTA2-MOF-Cu gave moderate stability in organic solvents and good gas sorption ability toward CO₂ . This new MOF showed superior catalytic reactivity toward the epoxide-CO₂ cycloaddition, giving >50 folds yield enhancement over the controlled reaction without MOF. It is expected that this new ligand design, porous structure, and excellent CO₂ catalytic reactivity will make OTA-MOF promising new materials for applications in catalysis and separation.