Open Tubular Column Immobilized with Covalent Organic Frameworks for Rapid Separation of Small Molecular Compounds by Capillary Electrochromatography

Abstract

Preparation of a novel TpBD (synthesized from phloroglucinol and benzidine) covalent organic framework (COF) immobilized open-tubular (OT) capillary is described by in situ growth strategy. The stationary phase in the column was characterized by Fourier transform infrared (FTIR) spectra, X-ray diffraction (XRD), thermogravimetric analysis (TGA), nitrogen adsorption–desorption isotherms, scanning electron microscope (SEM), transmission electron microscopy (TEM) and energy-dispersive X-ray spectrum (EDS). Several families of compounds with different properties (alkylbenzenes, parabens, sulfonamides and benzoic acids) were selected to evaluate the performance of the TpBD COF immobilized capillary. The results showed that the stationary phase was uniform with about 6.0 μm thickness under the optimal preparation conditions, and the relative standard deviations (RSDs) were no more than 3.13% of alkylbenzenes on the TpBD COF immobilized capillary for 11 consecutive runs, which exhibited its excellent reproducibility and stability. A rapid baseline separation of each family of the analytes (neutral parabens, amphoteric sulfonamides and acidic benzoic acids) was obtained in less than 6 min with a resolution (Rs) of 2.79~9.30, which sufficiently verified the rapid separation, high resolution and wide application range of the TpBD COF immobilized capillary, and further revealed this strategy of fabricating COF to capillary column to show great promise in capillary electrochromatography.

In situ growth of imine‐based covalent organic framework as stationary phase for open‐tubular capillary electrochromatographic separation

“…There are two types of chemical bonding methods: post-modification and in situ growth. Since the latter can prepare more uniform and dense COFs-coated capillaries than the former, the in situ growth method has become popular in recent years [24][25][26].…”

“…Specially, COFs are widely used in OT-CEC separation as stationary phase [20,21]. Generally, COFs can be evenly distributed on the inner wall of coated capillaries based on chemical bonding [22,[24][25][26] or physical adsorption [23]. Relatively, physical adsorption has some disadvantages, such as short lifetime and low separation capacity.…”

Lattice Shrinkage of 2D-COFs under Electron Beam Irradiation

“…The network-like chemistry of covalent organic frameworks enables top-down design at the molecular level, leading to alignments guided by geometric structures [2][3][4]. The advantages of such structural diversity and control over functions 2 of 12 are perfectly reflected in COFs, which are widely used in fields such as gas storage [5,6], separation [7][8][9], catalysis [10][11][12][13], optoelectronics [14][15][16][17], sensing [18][19][20] and biological fields [6,21]. It is worth noting that the unique physical and chemical properties of COF materials are closely related to their crystal structures [22,23].…”