Synthesis of a Pyridine-Zinc-Based Porous Organic Polymer for the Co-catalyst-Free Cycloaddition of Epoxides

The synthesis of solid catalysts for the co-catalyst-free cycloaddition of CO2 has attracted much attention. Herein, we report a hierarchical porous organic polymer, Py-Zn@MA, that is able to catalyze the cycloaddition reaction of epoxides and CO2 without using any additives or co-catalyst to afford turnover frequency (TOF) values as high as 250 and 97 h(-1) at 130 degrees C by using pure and diluted CO2 (simulating flue gas), respectively. These results are superior to those obtained from previously reported heterogeneous co-catalystfree systems. The high activity of Py-Zn@MA is mainly attributed to its bifunctional nature with ZnBr2 and pyridine activating the epoxide in a cooperative way. Notably, Py-Zn@MA can be easily prepared on a large scale without using any catalyst and the chemicals are cost effective. Moreover, PyZn@MA shows good substrate universality for the cycloaddition reactions of epoxides. Our designed porous organic polymer Py-Zn@MA material has the potential to serve as an efficient catalyst for the direct conversion of flue gas with epoxides into value-added cyclic carbonates.