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

Task-specific Py-Zn@IPOP X with multiple active sites are developed and exhibit durable high-activity for cycloaddition of CO 2 to epoxides under additive-free conditions. [Display omitted] • Novel task-specific Py-Zn@IPOP X are constructed in green ionic liquid medium. • Py-Zn@IPOP I with multiple active sites can activate CO 2 and epoxide simultaneously. • Py-Zn@IPOP I realizes efficient CO 2 cycloaddition under additive-free conditions. • The developed catalyst is easily separated and exhibits durable high-activity. Based on the Schiff base reaction and post-modification strategy, novel nanocomposites of pyridine-zinc-based ionic porous organic polymers (Py-Zn@IPOP X , X = Br, I, Ac) were constructed and structurally characterized. Various Py-Zn@IPOP X were applied to the transformation of CO 2 and epoxides into cyclic carbonates, and their catalytic activities were studied and discussed in detail. The results showed that Py-Zn@IPOP I possesses Lewis acid-base bifunctional features, and also modified with superior nucleophilic active groups, which exerted an important synergistic effect on activation of CO 2 and epoxide, and ring-opening of epoxide. Under co-catalyst/solvent-free conditions, Py-Zn@IPOP I could afford 96 % PC yield and 99 % selectivity at 120 °C and 2.0 MPa CO 2 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 I 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 CO 2 activation and utilization. [ABSTRACT FROM AUTHOR]