Porous Organic Cages for Gas Chromatography Separations
Porous Organic Cages for Gas Chromatography Separations
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DOI：
10.1021/acs.chemmater.5b01112
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发表时间：
2015-05-12
影响因子：
8.6
通讯作者：
Cooper, Andrew I.
中科院分区：
文献类型：
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作者：
Kewley, Adam;Stephenson, Andrew;Cooper, Andrew I.
混合物的分析或制备分离是化学的核心过程。例如，通过催化异构化大规模生产己烷异构体的混合物，然后分离出最有价值的异构体。 1 同样，许多化学分析依赖于通过色谱法分离复杂混合物。改进的色谱固定相和新的分离介质正在不断开发，但某些混合物仍然难以分离。这通常是因为组分仅通过尺寸或分子形状的微小变化来区分。目前，聚硅氧烷是气相色谱 (GC) 柱中最常见的固定相。然而，对于更复杂的分离，通常优选环糊精。环糊精本质上是手性分子，有不同尺寸且易于衍生化。环糊精气相色谱柱经过多年优化，无论在几何分离还是手性分离中，都能实现非常高效的分离和清晰的色谱峰。 2− 4 最近，人们一直在寻找环糊精的替代品，其中一种策略是使用多孔材料。微孔材料适合基于形状的分离，因为它们的孔径为分子量级（< 2 nm）。因此，诸如沸石、5 金属有机骨架（MOF）、6 和多孔有机骨架（POF）7 等材料都已被研究作为分子分离的固定相。最近人们对 MOF 8 和沸石的手性分离特别感兴趣。 9 然而，骨架材料的不溶性使其难以在某些色谱柱形式中使用。对于窄孔色谱柱尤其如此，例如气相色谱中使用的色谱柱，在其中引入这些不溶性骨架的颗粒可能在技术上具有挑战性。相比之下，多孔有机笼 10-12 (POC) 是离散分子，将永久孔隙结构与溶液可加工性相结合。例如，CC3（方案 1）是一种 POC，之前已证明可以对芳香族化合物 13 进行形状分类并分离氪/氙混合物和手性醇。 14 在这里，我们展示CC3也可以使用
The analytical or preparative separation of mixtures is a central process in chemistry. For example, mixtures of hexane isomers are produced on a large scale via catalytic isomerization and then separated to isolate the most valuable isomers. 1 Likewise, many chemical analyses rely on the separation of complex mixtures by chromatography. Improved chromatographic stationary phases and new separation media are continually being developed, but some mixtures remain challenging to separate. This is usually because the components are differentiated only by small changes in size or molecular shape.Currently, polysiloxanes are the most common stationary phases in gas chromatography (GC) columns. However, for more complex separations, cyclodextrins are often preferred. Cyclodextrins are intrinsically chiral molecules that are available in different sizes and easily derivatized. Cyclodextrin GC columns have been optimized over a number of years to give very efficient separations and sharp chromatographic peaks, both in geometrical or in chiral separations. 2− 4 Recently, there has been a search for alternatives to cyclodextrins, and one strategy has been to use porous materials. Microporous materials are suited for shape-based separations because their pore sizes are of the order of molecules (< 2 nm). Hence, materials such as zeolites, 5 metal-organic frameworks (MOFs), 6 and porous organic frameworks (POFs) 7 have all been investigated as stationary phases for molecular separations. There has been particular interest recently in chiral separations, both for MOFs 8 and also for zeolites. 9 However, the insolubility of framework materials can render them difficult to use in some column formats. This is particularly true for narrow-bore columns, such as those used in GC, where it may be technically challenging to introduce particles of these insoluble frameworks. By contrast, porous organic cages 10− 12 (POCs) are discrete molecules that combine a permanent pore structure with solution processability. For example, CC3 (Scheme 1) is a POC that was shown previously to shape-sort aromatic compounds 13 and to separate both krypton/xenon mixtures and chiral alcohols. 14 Here, we show that CC3 can also be used