High-performance
liquid chromatography (HPLC) and gas chromatography
(GC) over chiral stationary phases (CSPs) represent the most popular
and highly applicable technology in the field of chiral separation,
but there are currently no CSPs that can be used for both liquid and
gas chromatography simultaneously. We demonstrate here that two olefin-linked
covalent organic frameworks (COFs) featuring chiral crown ether groups
can be general CSPs for extensive separation not only in GC but also
in normal-phase and reversed-phase HPLC. Both COFs have the same 2D
layered porous structure but channels of different sizes and display
high stability under different chemical environments including water,
organic solvents, acids, and bases. Chiral crown ethers are periodically
aligned within the COF channels, allowing for enantioselective recognition
of guest molecules through intermolecular interactions. The COF-packed
HPLC and GC columns show excellent complementarity and each affords
high resolution, selectivity, and durability for the separation of
a wide range of racemic compounds, including amino acids, esters,
lactones, amides, alcohols, aldehydes, ketones, and drugs. The resolution
performances are comparable to and the versatility is superior to
those of the most widely used commercial chiral columns, showing promises
for practical applications. This work thus advances COFs with high
stability as potential universal CSPs for chromatography that are
otherwise hard or impossible to produce.
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