离子液体催化二氧化碳（CO2）的环加成反应早已成为研究的热点，然而在无有机溶剂、无助催化剂或者无负载的情况下，单一组分的离子液体还难于在常温常压下催化该反应。我们首次合成了一系列吡唑类离子液体，发现它们可以高效催化CO2的环加成反应。与之前的研究相比，催化条件仅略有改善。最近研究发现在同一个离子液体中增加阴阳离子中心的个数才有望大幅提升催化性能。本课题拟采用实验和理论相结合的方法，合成一系列结构新颖的类胍盐离子液体，同一个离子液体中具有2对或者多对阴阳离子中心；研究它们催化CO2环加成反应的性能；并且采用量子化学的方法阐明反应机理，从分子尺度揭示控制催化性能的关键因素，为进一步改进离子液体的催化性能提供依据。该项目的完成不仅可以发现一类结构新颖的离子液体，使用单一组分的离子液体就能够在常温常压下催化CO2的环加成反应，还可以探索新的微观反应机理，为设计更加高效的离子液体催化剂提供新思路。

Although the cycloaddition of carbon dioxide (CO2) catalyzed by the ionic liquids have been extensively investigated, it could not be completed at room temperature under atmospheric pressure catalyzed by single-component ionic liquid without co-catalyst, organic solvent, and/or be loaded on other materials. A series of pyrazolium ionic liquids have been firstly reported by us. Moreover, they would catalyze the coupling reaction of CO2 and epoxides efficiently with the reasonable product yields. As compared with other single-component ionic liquids reported in previous literature, the reaction temperature or CO2 initial pressure is slightly decreased along with other refined properties. However, there are still problems required to be resolved. It testified that the catalytic conditions would be greatly improved if there are one more positive and negative ionic centers in single ionic liquid. In this project, a series of ionic liquids similar to guanidinium salt would be firstly synthesized, which have the novel structures. After confirmation of their structures, the catalytic properties towards the cycloaddition of CO2 would be explored. Next, the mechanism of corresponding reaction is investigated by quantum chemical methods to elucidate the critical item in the catalysis from the microscopic scale, which would provide helpful clue to develop ionic liquids with the better catalytic performance. Our ultimate goals are to develop the novel ionic liquids, to efficiently catalyze the cycloaddition of CO2 under mild conditions, and to explore the new mechanism for coupling reaction of CO2 and epoxides.