All-in-one ionic covalent triazine frameworks with integrated Salen(Al) sites for synergistic CO2 fixation into cyclic carbonates

The conversion of carbon dioxide (CO 2 ) into valuable chemicals represents a promising strategy for mitigating greenhouse gas emissions while simultaneously producing industrially important products. Herein, we report the design and synthesis of a novel “all-in-one” heterogeneous catalyst (Im/Salen(Al)-CTF) constructed by integrating imidazolium-based ionic liquid (IL) moieties and aluminum salen (salen(Al)) complexes into a covalent triazine framework (CTF) via ionothermal trimerization. The resulting material features a microporous structure with a Brunauer-Emmett-Teller (BET) surface area of 81.0 m 2 g −1 , excellent CO 2 adsorption capacity (41.7 cm 3 g −1 at 273 K and 1 bar), and remarkable CO 2 /N 2 selectivity (51.5). The synergistic effect between electrophilic Lewis acidic Al 3+ sites and nucleophilic Cl − anions, combined with the CO 2 -philic triazine/imidazolium units, enables Im/Salen(Al)-CTF to catalyze the cycloaddition of CO 2 with epoxides under solvent-free and co-catalyst-free conditions. Epichlorohydrin conversion reached 99% with 98% selectivity toward the corresponding cyclic carbonate at 100 °C and 1.0 MPa CO 2 within 16 h. Moreover, Im/Salen(Al)-CTF exhibited good substrate adaptability, excellent recyclability over six consecutive runs without significant loss of activity, and promising performance even with simulated flue gas (15% CO 2 /85% N 2 ). This work provides a promising strategy for developing multifunctional polymeric materials for integrated CO 2 capture and conversion.