Tuning the porosity of ionic covalent triazine frameworks using auxiliary monomers for highly efficient CO2 and I2 capture

A series of ionic covalent triazine frameworks (CTFs) bearing charged groups were designed and prepared through ZnCl2-catalyzed cyclotrimerization of 1,3-bis(4-cyanophenyl)imidazolium chloride and tricyanobenzene as an auxiliary monomer. Pore properties of the ionic CTFs could be controlled by varying the proportion of monomer. The resulting ionic CTFs had high BET specific surface areas up to 1105 m2/g, high pore volumes up to 0.65 cm3/g, and high physicochemical stability. Among the four ionic CTFs, tCTF-Cl-3 exhibited the highest CO2 adsorption of 72.7 cm3/g and highest I2 capture capacity of 370 wt%. The incorporation of ionic functional groups, the existence of homogenous charge distribution, and the permanent porosity improved the capturing ability and affinity of the ionic CTFs for CO2 and I2. This methodology, based on the fine tuning of monomer ratio, can be utilized to obtain new insights into the preparation of functional ionic porous materials.