Enhanced Chiral Recognition Abilities of Cyclodextrin Covalent Organic Frameworks via Chiral/Achiral Functional Modification

Abstract

β-Cyclodextrin covalent organic frameworks (β-CD COFs) show great potential in enantioseparation due to their uniformly distributed chiral recognition sites and good chemical stability. The hydroxyl and amino groups of β-CD COFs enable facile post-modification to introduce the desired functionality into the frameworks. In this study, we perform post-modification of β-CD COF BPDA with 1,4-butane sultone and [(3R,4R)-4-acetyloxy-2,5-dioxooxolan-3-yl] acetate to construct two kinds of novel functional β-CD COFs. The capillary columns prepared with these two functional β-CD COFs separated chiral dihydropyridines and fluoroquinolones with excellent selectivity and repeatability in capillary electrochromatography, while β-CD COF BPDA -modified capillary columns did not present the chiral recognition ability for these drugs. The mechanism of chiral recognition and the enhanced enantioselectivity of functional β-CD COFs were further demonstrated by molecular docking simulation. The divergent chiral separation performances of β-CD COFs suggest that the introduction of functional groups enables the modification of β-CD COF properties and tuning of its chiral recognition abilities for the diversity of enantioseparation.

Macrocycle‐Based Covalent Organic Frameworks

“…The vinyl-functionalized COFs were postmodified with β-CDs, which selectively bind l-histidine (Figure 12b). Wang et al [88] introduced chiral and achiral groups to β-CD-COFs by postfunctionalization with sulfonic groups and diacetyl tartaric acid, where the original COFs synthesized from the condensation of heptakis (6-amino-6-deoxy)-β-CD and 4,4′-biphenyldicarboxaldehyde.…”

“…Wang et al. [ 88 ] introduced chiral and achiral groups to β‐CD‐COFs by postfunctionalization with sulfonic groups and diacetyl tartaric acid, where the original COFs synthesized from the condensation of heptakis (6‐amino‐6‐deoxy)‐β‐CD and 4,4′‐biphenyldicarboxaldehyde. The postfunctionalized COFs with dual‐chiral groups showed excellent separation efficiency toward acidic chiral drugs.…”

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

“…Cui et al introduced crown ether into the preparation of COF for chiral separation . Ji’s group enhanced the chiral recognition abilities of cyclodextrin COF by functional modification . Generally, COF can be directly prepared by a bottom-up approach.…”

“…35 Ji's group enhanced the chiral recognition abilities of cyclodextrin COF by functional modification. 36 Generally, COF can be directly prepared by a bottom-up approach. However, functional groups usually cannot be introduced into COFs directly by this approach, which can be grafted onto COFs by a postmodification method to provide additional active sites for boosting the interaction of analytes and COFs.…”

Postmodification of an Amine-Functionalized Covalent Organic Framework for Enantioselective Adsorption of Tyrosine

“…Covalent organic frameworks (COFs) emerge as a novel class of porous crystalline materials, in which organic building blocks are covalently stitched into extended ordered networks. − COFs have been widely exploited in the domains of heterogeneous catalysis, − gas adsorption, − chromatographic separation, − electronic device, − and chemical sensing − by virtue of lightweight characters, large specific surface area, long-range periodic structure, and tunable pore metrics. The extraordinary structural diversity of COFs empowers the construction of chiral COFs, which have revealed enormous application prospects in asymmetric catalysis, − chiral optical devices, − chiral recognition, − and enantioselective separation. − Although remarkable progress has been made since the first report in 2014, the divergent synthesis of chiral COFs remains a grand challenge due to the symmetry trade-off between crystallinity and chirality. Two common strategies have been adopted to introduce chirality into COFs.…”