Synergistic effects of multiple functionalities in a modified triazine-based organic polymer for enhanced CO2 cycloaddition with epoxides

Organic porous polymers with triazine rings are a promising porous material for catalyzing CO 2 conversion into high-value products. However, the lack of active sites limits their potential. In this work, triazine-based porous organic polymer PAN-PD was synthesized by using melamine and 4-pyridinealdehyde, followed by quaternization with 2-bromoethanol to synthesize PAN-PD-BrOH with triazine ring Lewis basic N sites, double hydrogen bond donor groups (–NH-/–OH), and nucleophilic anions (Br - ). PAN-PD-BrOH catalyzed the CO 2 cycloaddition to produce chloroallyl carbonate with a yield of 96 % under the conditions of 100°C, 8 h, and 0.5 MPa. It demonstrates well universality and stability, with the ability to be recycled 5 times without obvious loss of activity. Experiments and density functional theory calculations have elucidated the reaction pathways and mechanisms of Br - synergistically catalyzing CO 2 cycloaddition with different hydrogen bond donor groups (–NH/–OH). In addition, the triazine ring N sites in the catalyst synergistically cooperated with hydrogen bond donor groups to reduce the energy barrier of the ring-opening step in the CO 2 cycloaddition, thereby accelerating the rate-determining step of epoxide ring-opening.