A dual-walled cage MOF as an efficient heterogeneous catalyst for the conversion of CO₂ under mild and co-catalyst free conditions

A novel 3D → 3D interpenetrated Zn-polyhedral MOF [Zn₆(TATAB)₄(DABCO)₃(H₂O)₃]·12DMF·9H₂O (1) (H₃TATAB = 4,4′,4′′-s-triazine-1,3,5-triyl-tri-p-aminobenzoic acid, DABCO = 1,4-diazabicyclo[2.2.2]octane) based on a dual-walled icosahedral cage has been assembled by incorporating zinc paddlewheel units with nitrogen-rich tritopic carboxylate ligands. Owing to the high density of Lewis acid active sites and affinity to CO₂ of the cage, this material exhibits an excellent catalytic efficiency in the cycloaddition of propylene oxide with CO₂ into propylene carbonate under mild conditions (100 °C and ambient CO₂ pressure) with a high yield of 99% over 16 h. Moreover, the catalytic reaction is environmentally friendly without any need for co-catalysts and solvents.