Chiral Metal-Organic Framework D-his-ZIF-8@SiO2 Core-Shell Microspheres Used for HPLC Enantioseparations.

Chiral metal-organic frameworks (MOFs) show great potential in chiral separation due to their unusual properties and fascinating structures such as high surface area, uniform and adjustable pore/channel sizes, multiple active sites and good chemical stability. However, the irregular shape and wide size distribution of the synthesized MOFs particles cause high column backpressure and low column efficiency of MOFs packed columns, which significantly affects the separation performance of them. Herein, we prepared homochiral MOF-based composite D-his-ZIF-8@SiO2 core-shell microspheres by growing of D-his-ZIF-8 shell on the carboxylic-functionalized silica microspheres via a facile one-pot synthesis method. The D-his-ZIF-8@SiO2 core-shell microspheres were characterized by powder X-ray diffraction, scanning electron microscope, fourier transform infrared spectroscopy, and circular dichroism. The uniform D-his-ZIF-8@SiO2 core-shell microspheres with narrow size distribution were used as chiral stationary phase (CSP) for HPLC enantioseparations. Various racemates were separated by using different ratios of n-hexane/isopropanol as mobile phase on the D-his-ZIF-8@SiO2 packed column. Eighteen racemates including alcohol, phenol, amine, ketone, and organic acid were well separated on the homochiral D-his-ZIF-8@SiO2 CSP. The results indicated that the D-his-ZIF-8@SiO2 core-shell microspheres CSP possess excellent chiral recognition ability towards various racemates with good reproducibility and stability. Hence, the fabrication of chiral MOF@SiO2 core-shell microspheres is an effective strategy to improve the application of chiral MOFs in HPLC.