From Discrete Molecular Cages to a Network of Cages Exhibiting Enhanced CO₂ Adsorption Capacity

We have adopted the concept of “cage to frameworks” to successfully produce a Na–N connected coordination networked cage Na-NC1 by using a [3+6] porous imine-linked organic cage NC1 (Nanjing Cage 1) as the precursor. It is found that Na-NC1 exhibits hierarchical porosity (inherent permanent voids and interconnected channel) and gas sorption measurements reveal a significantly enhanced CO₂ uptake (1093 cm³ g⁻¹ at 23 bar and 273 K) than that of NC1 (162 cm³ g⁻¹ under the same conditions). In addition, Na-NC1 exhibits very low CO₂ adsorption enthalpy making it a good candidate for porous materials with both high CO₂ storage and low adsorption enthalpy.