Department of Chemistry, Yunnan Normal University, Kunming, P.R. China.
J Sep Sci. 2021 Nov;44(21):3976-3985. doi: 10.1002/jssc.202100557. Epub 2021 Sep 16.
The unique features of uniform and adjustable cavities, abundant chiral active sites, and high enantioselectivity make chiral metal-organic frameworks popular as an emerging candidate for enantioselective separation. However, the wide particle size distribution and irregular shape of as-synthesized metal-organic frameworks result in low column efficiency, undesired chromatographic peak shape, and high column backpressure of such metal-organic frameworks packed columns. Herein, we report the fabrication of chiral core-shell microspheres [Cu (d-Cam) (4,4'-bpy)] @SiO composite for high-performance liquid chromatography enantioseparation to overcome the above-mentioned problems. The [Cu (d-Cam) (4,4'-bpy)] @SiO packed column gave high-resolution separation of racemates under low column backpressure (10-22 bar), indicating its synergistic effect of the good column packing property of the SiO microspheres and the chiral recognition ability of [Cu (d-Cam) (4,4'-bpy)] crystals. Thirteen kinds of chiral compounds including alcohols, amines, ketones, epoxides, and organic bases were well separated with good peak shapes and high column efficiency (18200 plates/m for 1-(9-anthryl)-2,2,2-trifluoroethanol) on the [Cu (d-Cam) (4,4'-bpy)] @SiO packed column. Among them, seven pairs of enantiomers achieved baseline separation and the resolution value for 1-(9-anthryl)-2,2,2-trifluoroethanol reached 11.22. Some effects such as column temperature, and analytes mass on the enantioseparations have been investigated. In addition, the [Cu (d-Cam) (4,4'-bpy)] @SiO packed column exhibited good stability and repeatability for the separation of chiral compounds. The relative standard deviations for five replicate separations of 1-phenylethanol were less than 1.0, 1.5, 3.0, and 2.0% for the retention time, peak area, number of theoretical plates, and resolution, respectively. The research results demonstrated the development of chiral metal-organic frameworks core-shell microspheres composite provide a promising platform for their practical application in chiral separation fields.
手性金属有机骨架作为一种新兴的对映体选择性分离候选物，因其具有均匀和可调的空腔、丰富的手性活性位点和高对映选择性等独特特征而受到广泛关注。然而，合成的金属有机骨架粒径分布较宽，形状不规则，导致其填充柱的柱效低、色谱峰形不理想、柱背压高。在此，我们报告了手性核壳微球[Cu（d-Cam）（4,4'-bpy）]@SiO复合材料的制备，用于高效液相色谱对映体分离，以克服上述问题。[Cu（d-Cam）（4,4'-bpy）]@SiO 填充柱在低柱背压（10-22 bar）下实现了外消旋体的高分辨率分离，表明 SiO 微球的良好柱填充性能和[Cu（d-Cam）（4,4'-bpy）]晶体的手性识别能力的协同作用。在[Cu（d-Cam）（4,4'-bpy）]@SiO 填充柱上，13 种手性化合物（包括醇、胺、酮、环氧化物和有机碱）得到了很好的分离，具有良好的峰形和高柱效（1-(9-蒽基）-2,2,2-三氟乙醇为 18200 板/m）。其中，7 对对映体达到基线分离，1-(9-蒽基）-2,2,2-三氟乙醇的分离度达到 11.22。考察了柱温、分析物质量等对映体分离的影响。此外，[Cu（d-Cam）（4,4'-bpy）]@SiO 填充柱对手性化合物的分离具有良好的稳定性和重现性。1-苯乙醇的 5 次重复分离的保留时间、峰面积、理论塔板数和分离度的相对标准偏差分别小于 1.0%、1.5%、3.0%和 2.0%。研究结果表明，手性金属有机骨架核壳微球复合材料的开发为其在手性分离领域的实际应用提供了一个有前景的平台。
