Lewis Acid–Base Bifunctional Crystals with a Three-Dimensional Framework for Selective Coupling of CO2 and Epoxides under Mild and Solvent-Free Conditions

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• 作者：Xiangxiang Gao ; Mengshuai Liu ; Jianwen Lan ; Lin Liang ; Xiao ZhangJianmin Sun
• 刊名：Crystal Growth & Design
• 出版年：2017
• 出版时间：January 4, 2017
• 年：2017
• 卷：17
• 期：1
• 页码：51-57
• 全文大小：492K
• ISSN：1528-7505

文摘

Two Lewis acid–base bifunctional, isostructural metal–organic frameworks (MOFs), [Zn₃(Hbtc)₂(atz)₂]·CH₃CN·2CH₃OH (MOF-1) and [Co₃(Hbtc)₂(atz)₂]·H₂O·2DMF (MOF-2), containing NH₂ groups and four-coordinated metal sites were fabricated successfully, and the structures were thoroughly characterized by X-ray crystallography, powder X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, and N₂ adsorption/desorption techniques. Satisfactorily, the novel MOFs with a three-dimensional framework were highly efficient and stable heterogeneous catalysts for selective fixation of CO₂ to cyclic carbonates under mild conditions in the absence of solvent. The influences of various reaction parameters on catalytic performance were systematically investigated. Also the catalysts showed excellent versatility to epoxides with different substituents and could be easily recyclable with high activity. Additionally, the self-catalyzed mechanism as well as synergistic mechanism with tetrabutylammonium bromide (Bu₄NBr) for CO₂ conversion was proposed.