Single-Crystalline Covalent Organic Frameworks as High-Performance Liquid Chromatographic Stationary Phases for Positional Isomer Separation

Abstract

Vigorously developing new stationary phases to meet the requirements for the separation of positional isomers that have similar physicochemical properties is still an urgent topic in separation science. Herein, a single-crystalline covalent organic framework (COF-300) packed column for the separation of positional isomers in high-performance liquid chromatography (HPLC) was reported for the first time. Benefitting from its regular shape, excellent chemical and thermal stability, microporous feature, and strong hydrophobicity of single-crystalline COF-300, the single-crystalline COF-300-packed column showed excellent resolution for the separation of positional isomers, including nitroaniline, dichlorobenzene, dibromobenzene, diiodobenzene, diethylbenzene, chloronitrobenzene, bromonitrobenzene, and iodonitrobenzene isomers, which cannot be all separated on commercial columns and a polycrystalline COF-300-packed column. Especially, the resolution values for m-/p-diiodobenzene and o-/m-diiodobenzene were 4.45 and 2.53. Moreover, the alkylbenzene, monosubstituted aromatics, polycyclic aromatic hydrocarbons, and the mixture of ethylbenzene and styrene were also baseline separated on the single-crystalline COF-300-packed column. This successful application not only confirmed the great potential of single-crystalline COFs in HPLC separation of positional isomers but also pioneered the utilization of single-crystalline COFs in separation science.

Metalated covalent organic frameworks: from synthetic strategies to diverse applications

“…The colossal specific surface area of COFs makes them easy to interact with the external environment, which has been exploited to develop sensing materials. 699 Based on pore engineering of COFs, 700 the pore walls can be precisely designed to selectively interact with target analytes, thus allowing the design of various types of chemical detection systems based on the principles of colorimetry, 701,702 chemiluminescence, 336,703 photoluminescence, [704][705][706] chemoelectrical transduction, 707 chromatography, 708,709 and others to achieve highly sensitive and selective detection.…”

Fluoro-Functionalized Spherical Covalent Organic Frameworks as a Liquid Chromatographic Stationary Phase for the High-Resolution Separation of Organic Halides

“…In 2018, Ma’s group constructed chiral COFs via a postmodification strategy for the separation of chiral compounds . Our group also reported single-crystalline COFs and spherical COFs packed columns for the separation of positional isomers and hydrophobic compounds, respectively. Since the noncovalent interactions between analytes and the stationary phase dominate the separation properties, exploring more functionalized COFs for HPLC separation of specific compounds remains of great interest.…”

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

“…Especially, COF materials are drawing the close attention of separation scientists for preparing various kinds of chromatographic stationary phases, including reversed-phase (RP), mixed, and chiral separation modes . Recently, a single-crystalline COF material was prepared by Lin’s group for the separation of positional isomers . Cui’s group constructed an HPLC stationary phase using a chiral COF for the separation of racemic alcohols .…”