Facile one-pot preparation of chiral metal–organic framework L-His-ZIF-67@SiO2 composite for HPLC enantioseparation

A chiral core–shell microsphere composite, L-His-ZIF-67@SiO₂, was constructed by a one-pot method using SiO₂-COOH as the carrier. The density of the MOF shell was regulated by altering the reaction time and the mixing ratio of the precursor to SiO₂-COOH. As a new chiral stationary phase (CSP), the core–shell composite was applied to the  enantiomeric separation in HPLC. With n-hexane/isopropanol as the mobile phase, a great variety of positional isomers and racemates were separated on the L-His-ZIF-67@SiO₂ packed column. There are 6 positional isomers and 12 chiral compounds including alcohols, ketones, epoxides, and esters that can be separated on this chiral column with good separation efficiency. The separation performance of the chiral column was examined in relation to injection masses, temperature, and mobile phase composition. Its application in the determination of enantiomeric excess and isomeric impurities in actual samples demonstrated its feasibility for practical HPLC analysis. Additionally, the chiral resolution capabilities of the L-His-ZIF-67@SiO₂ packed column were compared with those of two commercial chiral columns, indicating that the L-His-ZIF-67@SiO₂ packed column can serve as a complementary alternative. The results demonstrate that optimizing reaction conditions to construct uniform chiral MOFs@SiO₂ composites for HPLC enantioseparation offers novel insights into the development of MOF materials in chromatography.

Graphical Abstract