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

Abstract

The separation of enantiomers using high-performance chromatography technologies represents great importance and interest. In this aspect, β-cyclodextrin (β-CD) and its derivatives have been extensively studied as chiral stationary phases (CSPs). Nevertheless, β-CD that was immobilized on a traditional matrix often exhibited low stabilities and limited operating ranges. Recently, covalent organic frameworks (COFs) with highly ordered nanopores are emerging as promising CSPs for enantioseparations, but their practical applications are still hampered by the difficulty of monomer and COF synthesis. Herein, two β-CD-driven COFs are synthesized via a fast and facile plasma-induced polymerization combined postsynthesis modification strategy. The precisely defined COF channels enhanced the accessibility of the accommodated β-CD to the analytes and acted as robust protective barriers to safeguard the β-CD from harsh environments. Therefore, the β-CD-modified COFs can be potentially general CSPs for extensive enantioseparation in both gas chromatography and high-performance liquid chromatography, and a wide range of racemates were separated. Compared to the commonly employed commercial chiral columns, these COF-based columns exhibited comparable resolution capability and superior application versatility. This work integrates the advantages and overcomes the defects of COFs and β-CD, thus advancing COFs as platforms for chiral selector modification and giving great promise for practical chromatographic enantioseparation.

Chiral Memory in Dynamic Transformation from Porous Organic Cages to Covalent Organic Frameworks for Enantiorecognition Analysis

“…The separation of chiral compounds has garnered significant interest owing to their extensive presence in the realms of chemistry, food science, and pharmacy . This is primarily because chiral compounds frequently demonstrate unique biological and pharmacological effects, underscoring the importance of their separation in these areas. , Chromatography using chiral stationary phases (CSPs) has emerged as a highly favored and widely recognized technique for chiral analysis and separation. − TGA was employed to evaluate the thermal stability of CM-COFs, demonstrating that most of the CM-COFs exhibited great thermal stability and stayed undecomposed under 400 °C (Figure S4). The remarkable thermal stability exhibited by the CM-COFs motivated us to explore their potential applications as CSPs for chiral gas chromatography (GC) separation.…”

Expanding the horizons of covalent organic frameworks: sub-stoichiometric synthesis as an emerging toolkit for functional COFs

“…49–52 The field has also witnessed the utilization of unreacted sites, the introduction of non-interfering functional groups, and post-synthetic modifications that functionalize the pores or transform the linkages. 30,33,53 The functional versatility of such framework materials has led to various applications, including gas adsorption/separation, 54–57 host–guest chemistry, 58–61 sensing, 62–68 ion capture/transport, 69 catalysis, 70–76 and electrochemical applications. 77…”

Assembly of Homochiral Aluminum Oxo Clusters for Circularly Polarized Luminescence

“…Chiral materials have promising applications in many aspects, including chiral optoelectronics, − enantiomeric separation, − asymmetric catalysis, , etc. Chiral metal organic/oxo clusters (cMOCs) can be regarded as bridges connecting individual microscopic chiral molecules with the macroscopic structures of chiral materials.…”