With fossil energy resources increasingly drying up and gradually causing serious environmental impacts, pursuing a tandem and green synthetic route for a complex and high-value-added compound by using low-cost raw materials has attracted considerable attention. In this regard, the selective and efficient conversion of light olefins with CO2 into high-value-added organic cyclic carbonates (OCCs) is of great significance owing to their high atom economy and absence of the isolation of intermediates. To fulfill this expectation, a multifunctional catalytic system with controllable spatial arrangement of varied catalytic sites and stable texture, in particular, within a single catalyst, is generally needed. Here, by using a stepwise electrostatic interaction strategy, imidazolium-based ILs and Au nanoparticles (NPs) were stepwise immobilized into a sulfonic group grafted MOF to construct a multifunctional single catalyst with a highly ordered arrangement of catalytic sites. The Au NPs and imidazolium cation are separately responsible for the selective epoxidation and cycloaddition reaction. The mesoporous cage within the MOF enriches the substrate molecules and provides a confined catalytic room for the tandem catalysis. More importantly, the highly ordered arrangement of the varied active sites and strong electrostatic attraction interaction result in the intimate contact and effective mass transfer between the catalytic sites, which allow for the highly efficient (>74% yield) and stable (repeatedly usage for at least 8 times) catalytic transformation. The stepwise electrostatic interaction strategy herein provides an absolutely new approach in fabricating the controllable multifunctional catalysts, especially for tandem catalysis.

中文翻译：

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在单一催化剂上串联合成环状碳酸酯时，分子水平上多功能位点的空间有序排列。

随着化石能源资源日益枯竭并逐渐造成严重的环境影响，通过使用低成本原材料寻求复杂而高附加值化合物的串联和绿色合成路线已引起了广泛的关注。在这方面，由于轻烯烃与CO 2的选择性和有效转化为高附加值的有机环状碳酸酯（OCC），由于它们的高原子经济性和没有中间体的分离而具有重要意义。为了满足该期望，通常需要具有变化的催化位点和稳定的质地的可控的空间布置的多功能催化体系，特别是在单个催化剂内。在这里，通过使用逐步静电相互作用策略，将基于咪唑鎓的ILs和Au纳米颗粒（NPs）逐步固定到接枝磺酸基的MOF上，以构建催化位点排列高度有序的多功能单一催化剂。Au NP和咪唑鎓阳离子分别负责选择性环氧化和环加成反应。MOF中的中孔笼使底物分子富集，并为串联催化提供了密闭的催化空间。更重要的是，各种活性位点的高度有序排列和强烈的静电吸引相互作用导致了催化位点之间的紧密接触和有效的质量转移，从而实现了高效（> 74％的收率）和稳定的（重复用于至少8次）催化转化。