Ultrastable Imidazole‐linked Porous Organic Cages for Ammonia Capture and Detection

Here, we report the facile synthesis of imidazole‐linked porous organic cages (IPOCs) via an in‐situ cyclization reaction protocol. Specifically, three IPOCs with [2+4] lantern‐like structures and one with a [3+6] triangular prism structure were successfully prepared through condensation reactions between tetraformyl‐functionalized calix[4]arene and bis(o‐phenylenediamine) monomers in a single pot. Notably, these IPOCs exhibit high porosity, with Brunauer–Emmett–Teller (BET) specific surface areas reaching up to 1162 m2 g‐1. Moreover, they demonstrate excellent chemical stability in both strong acidic and alkaline solutions. Furthermore, IPOC‐2 and IPOC‐4 display a remarkable NH3 capturing capability, with uptakes of up to 11.5 mmol g‐1 at 1 bar and 298 K, surpassing most reported porous organic materials. Additionally, IPOC‐1 exhibits highly efficient fluorescent quenching sensing of aqueous NH3, with a detection limit as low as 3.35 × 10‐6 M. These findings strongly suggest the potential for widespread use of imidazole linkages in the development of robust functional porous organic cage materials for diverse applications.