Construction of a hydrazone-linked chiral covalent organic framework-silica composite as the stationary phase for high performance liquid chromatography

Abstract

Covalent organic frameworks (COFs), as an emerging class of crystalline porous organic polymers, have great potential for applications in chromatographic separation owning to their fascinating crystalline structures and outstanding properties. However, development of COF materials as novel stationary phases in high performance liquid chromatography (HPLC) is just in its infancy. Herein, we report the design and construction of a new hydrazone-linked chiral COF, termed BtaMth COF, from a chiral hydrazide building block (Mth) and present a one-pot synthetic method for the fabrication of BtaMth@SiO₂ composite for HPLC separation of isomers. The as-synthesized BtaMth chiral COF displays good crystallinity, high porosity, as well as excellent chemical stability. Meanwhile, the fabricated HPLC column by using BtaMth@SiO₂ composite as the new stationary phase exhibits high resolution performances for the separation of positional isomers including nitrotoluene and nitrochlorobenzene, as well as cis-trans isomers including beta-cypermethrin and metconazole. Additionally, some effects such as the composition of the mobile phase and column temperature for HPLC separations on the BtaMth@SiO₂ packed column also have been studied in detail. The successful applications indicate the great potentials of hydrazone-linked chiral COF-silica composite as novel stationary phase for the efficient HPLC separation.

Keywords: COF–silica composite; Cis-trans isomers separation; Covalent organic frameworks; High performance chromatography; Positional isomers separation.