Porous organic cages for efficient gas selective separation and iodine capture

The enantiomeric porous organic cages, (R)/(S)-BTPOC, have been devised and prepared by means of dynamic covalent chemistry, using imine bond formation between bithiophene-based tetraaldehyde and cyclohexanediamine building blocks. These two cage molecules with porous interiors, stable aromatic backbones, and multiple electron-rich building units have been fully characterized by spectroscopy and single crystal X-ray diffraction studies. Self-assembly of BTPOC molecules provided porous crystalline materials with high CO2 adsorption of 265 cm(3 )g(-1)- under 760 mmHg and 196 K according to the physical gas sorption analysis. The guest-free cage shows distinct CO2, CH4, and N-2 adsorption behaviors. Moreover, BTPOC is able to accommodate a large amount of I-2 with a high uptake value of 3.21 g g(-1), superior to almost all the porous molecular crystals reported thus far. This stable material has also excellent recyclability, keeping above 85% capacity when being activated for the fourth cycles. Mechanism investigations reveal the close association of the good adsorption ability with the abundant porosity, pi-conjugated network structure, and high imine bonds content. The present work shows the great application potentialities of these microporous POCs.

Automated summary

The enantiomeric porous organic cages, (R)/(S)-BTPOC, prepared via dynamic covalent chemistry, exhibit high CO2 and I-2 adsorption capacities, excellent recyclability, and adsorption ability closely associated with porosity, pi-conjugated network structure, and imine bonds content. This study demonstrates the great application potential of these microporous POCs.