Solvatomorphism Influence of Porous Organic Cage on C₂H₂/CO₂ Separation

Porous organic molecular (POM) materials can exhibit solvatomorphs via altering their crystallographic packing in the solid state, but investigating real gas mixture separation by porous materials with such a behavior is still very rare. Herein, we report that a lantern-shaped calix[4]resorcinarene-based porous organic cage (POC, namely, CPOC-101) can exhibit eight distinct solid-state solvatomorphs via crystallization in different solvents. This POC solvatomorphism has a significant influence on their gas sorption capacities as well as separation abilities. Specifically, the apparent Brunauer-Emmett-Teller (BET) surface area determined by nitrogen gas sorption at 77 K for CPOC-101α crystallized from toluene/chloroform is up to 406 m² g^-1, which is much higher than the rest of CPOC-101 solvatomorphs with BET values less than 40 m² g^-1. More interestingly, C₂H₂ and CO₂ adsorbed capacities, in addition to the C₂H₂/CO₂ separation ability at room temperature for CPOC-101α, are superior to those of CPOC-101β crystalized from nitrobenzene, the representative of POC solvatomorphs with low BET surface areas. These results indicate the possibility of adjusting gas sorption and separation properties of POC materials by controlling their solvatomorphs.