Porous organic molecular cages as a new type of porous materials have attracted a tremendous attention for their potential applications in recent years. Here we report the use of a homochiral porous organic cage (POC) (CC3-R) diluted with a polysiloxane (OV-1701) as a stationary phase for high-resolution gas chromatography (GC) with excellent enantioselectivity. A large number of optical isomers have been resolved without derivatization, including chiral alcohols, diols, amines, alcohol amines, esters, ketones, ethers, halohydrocarbons, organic acids, amino acid methyl esters, and sulfoxides. Compared with commercial β-DEX 120 and Chirasil-L-Val columns, the CC3-R coated capillary column offered more preeminent enantioselectivity. In addition, CC3-R also exhibits good selectivity for the separation of isomers, linear alkanes, alcohols, and aromatic hydrocarbons. The excellent resolution ability, repeatability, and thermal stability make CC3-R a promising candidate as a novel stationary phase for GC. The study described herein first proves useful commercially. This work also indicates that porous organic molecular materials will become more attractive in separation science.

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Chiral metal–organic frameworks (MOFs) have aroused great attention in the chiral separation field based on their excellent characteristics, including abundant topological structures, large surface area, adjustable pore/channel sizes, multiple active sites, and good chemical stability. However, the irregular morphology and nonuniformity of the synthesized MOF particles cause low column efficiency and high column backpressure for MOF-packed columns, which significantly affects their separation performance. Herein, we prepared a homochiral d-his-ZIF-8@SiO2 composite by growing of d-his-ZIF-8 on the carboxylic-functionalized SiO2 microspheres via a simple one-pot synthesis approach. The d-his-ZIF-8@SiO2 core–shell microspheres with uniform particles and narrow size distribution were applied as the chiral stationary phase (CSP) for enantioseparations in HPLC. Various racemates were separated on the d-his-ZIF-8@SiO2-packed columns with n-hexane/isopropanol as the mobile phase. Eighteen racemates including alcohol, phenol, amine, ketone, and organic acid were well resolved on the homochiral d-his-ZIF-8@SiO2 CSP. The d-his-ZIF-8@SiO2 core–shell microspheres’ CSP possesses an excellent chiral resolution ability toward various racemic compounds with good reproducibility and stability. Hence, the fabrication of chiral MOF@SiO2 core–shell microspheres is an effective strategy to improve the application of homochiral MOFs as CSPs in the field of chromatography.

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Porous organic cages composed of discrete cage molecules have attracted considerable recent attention as gas adsorption materials and separation media. In this study, we report a homochiral porous organic cage CC5 with a large cavity and pore windows as a novel stationary phase for high-resolution gas chromatographic separations. The capillary column was prepared by a static coating method. A large number of racemic compounds have been resolved on the coated capillary column, including derivatized amino acids, alcohols, alcohol amines, esters, ethers, ketones, and epoxides. It is interesting that the CC5-coated capillary column exhibits significant chiral recognition complementarity to a commercial β-DEX 120 column and a previously reported homochiral porous organic cage CC3-R-coated column, which could expand the range of the analytes amenable to separation on porous organic cage-based capillary columns. Moreover, the fabricated column also shows excellent selectivity for the separation of positional isomers, including the challenging ethylbenzene and xylene isomers. Experimental results demonstrate an excellent separation performance and stability of the CC5-coated column, making it promising for gas chromatography applications.