Inverse and High CO₂/C₂H₂ Sorption Selectivity in Flexible Organic–Inorganic Ionic Crystals

Highly selective CO2 sorption and inverse CO2/C2H2 sorption selectivity (4.8 at 278 K, 100 kPa) were achieved with an organic–inorganic ionic crystal. The key for the high affinity toward CO2 is the combination of structural flexibility and strong binding sites (K+) characteristic of organic–inorganic ionic crystals.