Covalent organic frameworks (COFs), a type of crystalline polymers, have attracted increasing interest because of their controllability of geometry and functionality. Featuring infinitely extended networks and tremendous interaction sites, COFs emerge as a potential platform for separation science. Here, a novel chiral COF (β-CD COFBPDA) constructed by the imine condensation of 4,4'-biphenyldicarboxaldehyde and heptakis(6-amino-6-deoxy)-β-cyclodextrin was introduced into an electrochromatographic system via a photopolymerization method and applied to the separation of enantiomers. The structure and properties of as-synthesized β-CD COFBPDA were investigated by powder X-ray diffraction (PXRD) patterns, Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), and N2adsorption-desorption isotherms. It was proved that β-CD COFBPDA was provided with larger pore size and BET surface area. The β-CD COFBPDA coating endowed the chiral stationary phase with superior three-dimensional orientation, and realized satisfactory separation with improved selectivity and column efficiency for a dozen racemic drugs. Under the optimized conditions, homatropine, ondansetron, metoprolol, terbutaline, tulobuterol, and promethazine were all baseline separated with resolution values of 2.24, 2.03, 1.65, 1.62, 1.60, and 1.58, respectively. The results indicate the high perspective of COF modified stationary in enantioseparation.
Keywords: Capillary electrochromatography; Chiral drugs; Covalent organic framework; Enantioseparation; Photopolymerization; β-Cyclodextrin.
© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.