Record-Breaking H₂S Capture and ppm-Level Sensing with a Chemically Stable Porous Organic Cage

The first experimental investigation of a porous organic cage (POC) for the challenging task of H₂S capture is reported. The N-containing cage molecular material, a tertiary amine POC (6FT-RCC3), demonstrates the highest H₂S (hydrogen sulfide) capture (record capacity) for a porous material at room temperature and atmospheric pressure (20.6 mmol H₂S g^-1; 25 H₂S molecules per cage) combined with excellent reversibility for at least five adsorption-desorption cycles. In situ FTIR spectroscopy, solid-state ¹³C, and ¹⁵N CP MAS NMR spectroscopy experiments are applied to investigate the adsorption mechanism, identifying relatively weak interactions via hydrogen bonding. In addition, the fluorescence performances of this POC material are evaluated for the detection and sensing of H₂S, where a clear H₂S selectivity is observed over other gases. Remarkably, the limit of detection (LOD) is calculated to be 0.13 mm (≈4.43 ppm) in a tetrahydrofuran (THF) solution of H₂S.