Rational design of Lewis acid-base bifunctional nanopolymers with high performance on CO2/epoxide cycloaddition without a cocatalyst

Based on the Schiff base reaction and post-modification strategy, novel nanocomposites of pyridine-zinc-based ionic porous organic polymers (Py-Zn@IPOPx, X = Br, I, Ac) were constructed and structurally characterized. Various Py-Zn@IPOPx were applied to the transformation of CO2 and epoxides into cyclic carbonates, and their catalytic activities were studied and discussed in detail. The results showed that Py-Zn@IPOP] possesses Lewis acid-base bifunctional features, and also modified with superior nucleophilic active groups, which exerted an important synergistic effect on activation of CO2 and epoxide, and ring-opening of epoxide. Under co-catalyst/ solvent-free conditions, Py-Zn@IPOP] could afford 96 % PC yield and 99 % selectivity at 120 degrees C and 2.0 MPa CO2 pressure for 6 h, and turnover frequency (TOF) was high to 230 h(-1). Moreover, the reusability and versatility of the catalyst were examined, and the catalytic mechanism was speculated according to the obtained results. Compared with previously reported porous polymer catalysts, Py-Zn@IPOP ] requires much greener and milder reaction conditions while avoids the use of a co-catalyst, displaying bright prospects for the design and synthesis of ionic porous organic polymers for CO2 activation and utilization.