Engineering Supramolecular Binding Sites in a Chemically Stable Metal-Organic Framework for Simultaneous High C 2 H 2 Storage and Separation.

Developing porous materials to overcome the trade-off between adsorption capacity and selectivity for C 2 H 2 /CO 2 separation remains a challenge. Herein, we report a stable HKUST-1-like MOF (ZJU-50a), featuring large cages decorated with high density of supramolecular binding sites to achieve both high C 2 H 2 storage and selectivity. ZJU-50a exhibits one of the highest C 2 H 2 storage capacity (192 cm 3  g -1 ) and concurrently high C 2 H 2 /CO 2 selectivity (12) at 298 K and 1 bar. Single-crystal X-ray diffraction studies on gas-loaded ZJU-50a crystal unveil that the incorporated supramolecular binding sites can selectively take up C 2 H 2 molecule but not CO 2 to result in both high C 2 H 2 storage and selectivity. Breakthrough experiments validated its separation performance for C 2 H 2 /CO 2 mixtures, providing a high C 2 H 2 recovery capacity of 84.2 L kg -1 with 99.5 % purity. This study suggests a novel strategy of engineering supramolecular binding sites into MOFs to overcome the trade-off for this separation.