Chemically Stable Tetrazine‐Based Porous Organic Cages with Post‐Synthetic Modification via Inverse‐Electron‐Demand Diels–Alder Reactions for SF₆/N₂ and CO₂/N₂ Separation

Abstract

AbstractPorous 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 m2 g−1, and good chemically stability, surpassing most POCs formed through dynamic covalent chemistry. Its well‐defined, electron‐deficient cage cavity enable efficient SF6/N2 separation, showing the highest SF6 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 CO2/N2 selectivity.