Chemically Stable Tetrazine-Based Porous Organic Cages with Post-Synthetic Modification via Inverse-Electron-Demand Diels-Alder Reactions for SF/N and CO/N Separation.

Porous organic cages (POCs) have emerged as promising porous materials for a wide range of applications. However, their development is often limited by insufficient chemical stability and challenges in systematically functionalization. Herein, we reported the design and synthesis of a tetrazine-based POC (TC1) featuring rigid tetrahedral structure, prepared via a one-pot nucleophilic aromatic substitution reaction. TC1 exhibits high porosity, with a BET surface area at 1157 m g, and good chemically stability, surpassing most POCs formed through dynamic covalent chemistry. Its well-defined, electron-deficient cage cavity enable efficient SF/N separation, showing the highest SF adsorption capacity and selectivity among all reported porous molecular materials to data, as confirmed by dynamic breakthrough experiments. Post-synthetic modification of TC1 via inverse electron-demand Diels-Alder (iEDDA) reactions yielded two functionalized cages (TC2 and TC3), which maintain good porosity and display further enhanced chemical stability over a broad pH range (-1 to 15). Furthermore, cage-based networked materials (TC1-P1 and TC1-P2) were successfully constructed through the iEDDA polymerization using TC1 as building unit, resulting in tunable porous frameworks with improved CO/N selectivity.