Chiral metal-organic framework [Co2(d-cam)2(TMDPy)]@SiO2 core-shell microspheres for HPLC separation

Chiral metal-organic frameworks (MOFs), an emerging class of chiral porous materials, possess many excellent characteristics such as uniform and adjustable cavities, abundant chiral active sites and excellent chemical stability, which make them a promising candidate as new chiral stationary phases (CSPs) for usage in HPLC. Up to now, there are some homochiral MOFs that have been applied as CSPs for HPLC enantioseparations. Nevertheless, the irregular morphology of most prepared MOF crystals with wide size distribution often cause high column backpressure and low column efficiency for MOF packed columns, which is the main impediment for the practical applications of chiral MOFs in chiral separation. In this article, we adopted an in-situ growth method to prepare monodisperse homochiral MOF [Co2(d-cam)2(TMDPy)]@SiO2 core-shell composites as chiral selector for HPLC enantioseparation. The fabricated [Co2(d-cam)2(TMDPy)]@SiO2 column (column A) exhibited excellent chiral resolution ability toward various racemates. In addition, some positional isomers can be well separated on column A. Compared with the resolution ability of [Co2(d-cam)2(TMDPy)] packed column (column B), the column A shows higher column efficiency (e.g., 17,000 plates/m for trans-stilbene oxide) and lower background pressure (column pressure = 27 bar) than those of column B. The results indicated that the monodisperse chiral MOF [Co2(d-cam)2(TMDPy)]@SiO2 core-shell composites as CSP greatly improve the column efficiency and chiral resolution ability of the chiral MOF columns, providing a promising platform for chiral MOFs widely used in chiral separation.