Functionally enhanced polyether-bridged amidopyridinium dicationic ionic liquids for highly efficient and sustainable fixation of CO2 to cyclic carbonates

Task-specific ionic liquids integrated with multi-active sites display promising potential for use in the cycloaddition reaction of CO 2 and epoxides. Utilizing the functional enhancement strategy, we successfully synthesized a novel range of polyether-bridged amidopyridinium dicationic ionic liquids (PE-PyDILs) via efficient bisamidation and biquaternization reactions. Under relatively mild reaction conditions, PE-PyDILs can catalyze the coupling of CO 2 with various epoxides to produce cyclic carbonates in quantitative yields, demonstrating an enhanced effectiveness and a longer service life compared to previous DILs. At a very low loading of 0.01 mol%, the TON value is as high as 7700. The excellent catalytic performance can be attributed to the intramolecular cooperative activation of epoxides with two amidopyridinium cations bridged by polyether , as supported by the spectroscopic analysis and kinetic studies. This mechanism led to a reduction in activation energy and improved the efficiency of the cycloaddition reaction.