Nonadditive CO2 Uptake of Type II Porous Liquids Based on Imine Cages.

Type II porous liquids can potentially exploit the fluidity of liquids and sorption properties of porous sorbents, yet CO₂ uptake in porous liquids is still poorly understood. Molecular simulations and experiments are used to examine CO₂ uptake by a prototypical porous liquid composed of porous organic cages (CC13) in 2'-hydroxyacetophenone (2'-HAP). The simulations are in reasonable agreement with experimental measurements of CO₂ solubility and provide unambiguous information on the partitioning of CO₂ within microenvironments in the liquid. Analysis of CO₂ dynamics is performed using these simulations, including assessing the self-diffusivity of CO₂ in both the neat solvent and porous liquid. This offers insights into the kinetics of CO₂ uptake and transport in type II porous liquids based on imine cages. Experiments with type II porous liquids formed by dissolving CC13 in three different size-excluded solvents show nonadditive CO₂ absorption relative to predictions based on ideal volume additivity. This nonadditive absorption behavior is also observed in simulations. Nonadditive CO₂ uptake is also demonstrated in type II porous liquids based on another imine-based porous cage, CC19.