Ionic Conjugated Microporous Polymers for Cycloaddition of Carbon Dioxide to Epoxides

Along the development of ionic porous organic polymers, simple and efficient synthetic methods are actively pursued. Herein, the Debus-Radziszewski reaction is applied to synthesize ionic conjugated microporous polymers (iCMPs) in one step. A series of imidazolium-linked iCMP-X (X = 1, 2, 3) are developed for CO2 sorption and in situ conversion with epoxide into cyclic carbonates. The as-synthesized iCMPs are characterized in detail by scanning electron microscope, solid-state nuclear magnetic resonance, X-ray photoelectron spectroscopy, X-ray diffraction analysis, N2/CO2 sorption, and more. Among all synthesized iCMPs, iCMP-1 possesses the highest specific surface area and in turn the strongest CO2 sorption capacity. Moreover, through a simple anion ion exchange reaction with halide, iCMP-1 is transformed to iCMP-1@Cl that embodies significant catalytic capability for converting CO2 into cyclic carbonates. A facile synthetic route is developed for imidazole-based ionic conjugated microporous polymers (iCMPs) via the Debus-Radziszewski reaction, featuring mild preparation conditions. Among the iCMPs, the iCMP-1@Cl exhibits the most remarkable catalytic performance and cyclic stability in the cycloaddition reaction between epichlorohydrin and CO2, without the use of solvents, metals, or co-catalysts.image