Click Chemistry for the Preparation of β-Cyclodextrin Grafting Uniform Spherical Covalent Organic Framework Materials for Chiral Separation

Abstract

Covalent organic framework (COF) as a kind of crystalline porous material possesses intriguing advantages, including low density, large surface area, permanent porosity, and excellent chemical stability. This novel material has shown great potential in the development of chromatographic stationary-phase materials. In this work, a room-temperature solvothermal method was utilized to yield a uniformly spherical COF-modified silica named Sil-COF. Then, the thiol-ene click chemistry was further used to modify thiolated β-cyclodextrin on the spherical Sil-COF composite for chiral separation called Sil-COF-CD. A series of characterization methods were performed to identify the successful construction of COF-modified stationary-phase materials. Then, three types of nonpolar substances realized baseline separation on the Sil-COF column. In addition, 2-phenylpropionic acid and 1-phenyl-1-propanol were selected as model enantiomers to identify the chiral recognition capability of the Sil-COF-CD column. Sil-COF and commercial β-CD columns were compared to further confirm the superiority of the prepared chiral column. In addition, both COF-modified columns possessed good repeatability. The results open a new avenue to apply spherical chiral COF for the preparation of the HPLC stationary phase.