Cyclodextrin Incorporation into Covalent Organic Frameworks Enables Extensive Liquid and Gas Chromatographic Enantioseparations

The separation of enantiomers using high-performancechromatographytechnologies represents great importance and interest. In this aspect,& beta;-cyclodextrin (& beta;-CD) and its derivatives have been extensivelystudied as chiral stationary phases (CSPs). Nevertheless, & beta;-CDthat was immobilized on a traditional matrix often exhibited low stabilitiesand limited operating ranges. Recently, covalent organic frameworks(COFs) with highly ordered nanopores are emerging as promising CSPsfor enantioseparations, but their practical applications are stillhampered by the difficulty of monomer and COF synthesis. Herein, two & beta;-CD-driven COFs are synthesized via a fast and facile plasma-inducedpolymerization combined postsynthesis modification strategy. The preciselydefined COF channels enhanced the accessibility of the accommodated & beta;-CD to the analytes and acted as robust protectivebarriers to safeguard the & beta;-CD from harsh environments. Therefore,the & beta;-CD-modified COFs can be potentially general CSPs for extensiveenantioseparation in both gas chromatography and high-performanceliquid chromatography, and a wide range of racemates were separated.Compared to the commonly employed commercial chiral columns, theseCOF-based columns exhibited comparable resolution capability and superiorapplication versatility. This work integrates the advantages and overcomesthe defects of COFs and & beta;-CD, thus advancing COFs as platformsfor chiral selector modification and giving great promise for practicalchromatographic enantioseparation.

Automated summary

The use of high-performance chromatography technologies for separating enantiomers is of great importance and interest. β-cyclodextrin (β-CD) and its derivatives have been extensively studied as chiral stationary phases (CSPs), but their low stabilities and limited operating ranges have been a challenge. Covalent organic frameworks (COFs) with highly ordered nanopores have emerged as promising CSPs, but their practical applications have been hindered by difficulties in monomer and COF synthesis. This work introduces β-CD-modified COFs as potential CSPs for extensive enantioseparation in both gas chromatography and high-performance liquid chromatography, offering comparable resolution capability and superior application versatility compared to commercial chiral columns. By integrating the advantages and overcoming the defects of COFs and β-CD, this study advances COFs as platforms for chiral selector modification and shows great promise for practical chromatographic enantioseparation.