Imidazolium-Based Cationic Covalent Triazine Frameworks for Highly Efficient Cycloaddition of Carbon Dioxide

Covalent triazine frameworks (CTFs) have emerged as one class of outstanding porous materials due to their abundant nitrogen sites and highly thermal and chemical stability. However, most of the reported CTFs are neutral porous materials. Here, we report the synthesis of the well-designed cationic covalent triazine frameworks (CCTFs) via an ionothermal method from the imidazolium monomer 1,3-bis(4-cyanophenyl)imidazolium chloride. The imidazolium active sites and pore structure of CCTFs at different synthetic temperature were systematically investigated. The porous CCTFs with positively charged (imidazolium moieties) backbones could effectively adsorb and capture of CO2 through dipole-quadruple interactions. Furthermore, the positively charged imidazolium moieties and the spatially confined nucleophilic chloride anions works in concert on the substrate, leading to synergistically enhanced catalysis for the cycloaddition reaction of epoxide with CO2. These findings provide a new way to design and construct ionic porous materials for sustainable catalysis.