A hollow covalent organic framework-based chromatographic stationary phase and a preparation method and application thereof

Abstract

The present application relates to a kind of hollow covalent organic framework-based chromatographic stationary phase and its preparation method and application, belong to chromatographic stationary phase material technical field.The preparation method of the present application includes the following steps: under the action of catalyst, first monomer and second monomer are condensed in organic solvent, and the hollow covalent organic framework-based chromatographic stationary phase is obtained;Wherein, the number of X1 and X2 is independently one or more, and each is independently optionally connected at any substitutable position of its corresponding benzene ring;When R1 is aldehyde group, X1 is electron-donating group, R2 is amino, and X2 is electron-withdrawing group;When R1 is amino, X1 is electron-withdrawing group, R2 is aldehyde group, and X2 is electron-donating group.By thermodynamic and kinetic synergistic control, the hollow covalent organic framework-based chromatographic stationary phase is prepared, and the stationary phase can be used as high-resolution separation isomer, special chromatographic stationary phase of homologues.

Description

Technical Field

[0001] This invention belongs to the field of chromatographic stationary phase materials technology, and particularly relates to a chromatographic stationary phase based on a hollow covalent organic framework, its preparation method and application. Background Technology

[0002] Covalent organic frameworks (COFs) are a class of crystalline porous polymers formed by the precise atomic-level assembly of organic units. They possess periodically ordered two-dimensional or three-dimensional topological structures, precisely tunable functional properties, and excellent stability.

[0003] COFs (Cellular Coefficients) have shown great promise as chromatographic stationary phases in the separation of homologues, isomers, and chiral enantiomers. Current research largely focuses on modifying COFs with functional groups such as chiral biomolecules (amino acids, peptides, enzymes), fluorine, amino groups, and glutathione, aiming to adjust their thermodynamic properties to enhance stationary phase stability and improve chromatographic separation through specific interactions between functional groups and analytes. However, relying solely on thermodynamic regulation is insufficient to achieve optimal separation performance, as the efficiency and selectivity of chromatographic separation are jointly governed by thermodynamics and kinetics. On one hand, thermodynamics determines the equilibrium distribution of analytes between the mobile and stationary phases, serving as the core basis for measuring the inherent resolvability of mixed compounds; key parameters such as retention factor (k) and selectivity factor (α) fall within the thermodynamic domain. On the other hand, kinetics controls the rate at which the system approaches equilibrium, directly affecting the sharpness of chromatographic peaks and separation quality. According to the Van Deemter equation, the theoretical plate height (H), an indicator of chromatographic kinetic efficiency, is jointly determined by eddy diffusion, molecular diffusion, and mass transfer resistance. Current research focuses on the thermodynamics of chromatographic separation, lacking an understanding of the regulation of chromatographic separation kinetics and the synergistic effect between the two.

[0004] Therefore, a high-performance chromatographic stationary phase should possess both strong thermodynamic selectivity to accurately distinguish target analytes and structural features that facilitate rapid mass transfer to minimize band broadening and ensure high-resolution separation. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a chromatographic stationary phase based on a hollow covalent organic framework, its preparation method, and its application. Through the synergistic regulation of thermodynamics and kinetics, a chromatographic stationary phase based on a hollow covalent organic framework is prepared. This stationary phase can be used as a dedicated chromatographic stationary phase for high-resolution separation of isomers and homologues.

[0006] The first objective of this invention is to provide a method for preparing a chromatographic stationary phase based on a hollow covalent organic framework, comprising the following steps: under the action of a catalyst, a first monomer and a second monomer undergo a condensation reaction in an organic solvent to obtain the chromatographic stationary phase based on the hollow covalent organic framework. The structures of the first monomer and the second monomer are as follows. , ; Wherein, X1 and X2 are each independently one or more, and each is independently and arbitrarily attached to any substituted position on its corresponding benzene ring; When R1 is an aldehyde group and X1 is an electron-donating group, R2 is an amino group and X2 is an electron-withdrawing group; When R1 is an amino group and X1 is an electron-withdrawing group, R2 is an aldehyde group and X2 is an electron-donating group.

[0007] In one embodiment of the present invention, the electron-withdrawing group is selected from nitro, trifluoromethyl, cyano, sulfonic acid, halogen, aldehyde, carboxyl or ester. And / or, the electron-donating group is selected from alkoxy, hydroxy, alkyl, amide or acyloxy groups.

[0008] In one embodiment of the present invention, the molar ratio of the first monomer to the second monomer is 1:(1-5).

[0009] In one embodiment of the present invention, the catalyst is selected from acetic acid and / or scandium trifluoromethanesulfonate.

[0010] In one embodiment of the present invention, the amount of catalyst used is 5%-20% of the total molar amount of the first monomer and the second monomer.

[0011] In one embodiment of the present invention, the condensation reaction is carried out at a temperature of 60°C-120°C for 2-5 days.

[0012] In one embodiment of the present invention, the organic solvent is selected from one or more of acetonitrile, dimethyl sulfoxide, dichloromethane, mesitylene, dioxane, o-dichlorobenzene, n-butanol and chloroform.

[0013] A second objective of this invention is to provide a chromatographic stationary phase based on a hollow covalent organic framework prepared by the method described above.

[0014] A third objective of this invention is to provide a capillary column prepared from the aforementioned chromatographic stationary phase based on a hollow covalent organic framework.

[0015] A fourth object of the present invention is to provide an application of the described capillary column in the separation of halogenated isomers and halogenated homologues.

[0016] The technical solution of the present invention has the following advantages compared with the prior art: (1) The chromatographic stationary phase based on hollow covalent organic framework described in this invention has both a high specific surface area and a rich, interconnected porous network structure. It possesses unique hollow morphology characteristics and introduces strong electron-withdrawing groups. Compared to the dense structure formed by the close stacking of solid covalent organic frameworks, this hollow COF stationary phase, with its unique physical morphology of hollow core-thin porous shell, can effectively shorten the diffusion path of sample molecules in the stationary phase and significantly reduce mass transfer resistance. At the same time, its porous shell can increase the specific surface area of ​​the material and provide more active sites. This not only improves column efficiency to obtain sharp chromatographic peaks and improves resolution, but also has a sample loading capacity superior to that of non-porous solid core particles, thus achieving An excellent balance between separation efficiency and practical application performance is achieved. Furthermore, the trifluoromethyl and other strong electron-withdrawing groups introduced into the framework act as excellent halogen bond acceptors, generating specific halogen bond interactions with halogen atoms that act as halogen bond donors in the halogen isomers. This significantly enhances the adsorption selectivity of the stationary phase for halogen isomers, optimizes separation thermodynamics, and improves the chromatographic separation effect of halogen isomers. It is worth noting that existing covalent organic framework chromatographic stationary phases often rely on functional group modification to achieve thermodynamic control, while this invention innovatively introduces a hollow structure to further optimize the separation performance of the stationary phase from a kinetic perspective. By controlling the kinetic behavior of the separation process, highly efficient separation of halogen isomers is achieved.

[0017] (2) The chromatographic stationary phase based on the hollow covalent organic framework described in this invention is completely constructed by covalent bonds and has excellent thermal stability. It exhibits significant advantages in chromatographic separation applications. The stationary phase is bonded to the inner wall of the capillary column through in-situ growth, which effectively improves the reproducibility and recycling rate of the chromatographic column.

[0018] (3) The chromatographic stationary phase based on the hollow covalent organic framework described in this invention has excellent separation efficiency for common substances such as halogenated isomers. It can successfully achieve high-efficiency gas chromatography separation of isomers such as chloroaniline, fluoroaniline, chlorobiphenyl, dichloroethylene, dibromopropane and dichloropropane, fully demonstrating the outstanding separation performance advantages of the chromatographic column and its great application potential in the field of halogenated isomer separation. Attached Figure Description

[0019] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein: Figure 1 This is a schematic diagram illustrating the synthesis of HTpBPa-F in Example 1 and STpBPa in Comparative Example 1 of the present invention. Figure 2 Transmission electron microscopy (TEM) images of HTpBPa-F prepared at different condensation reaction times in Test Example 1 of this invention; Figure 3 The images show the characterization patterns of HTpBPa-F and STpBPa-F in Test Example 2 of this invention; where a is the X-ray diffraction pattern (PXRD) and b is the characterization pattern of HTpBPa-F after Pawley refinement. Figure 4 The image shown is a transmission electron microscope image from test example 2 of this invention; where a is HTpBPa-F and b is STpBPa-F. Figure 5 The characterization diagrams of HTpBPa-F and STpBPa-F in Test Example 2 of the present invention are shown; where a is the full spectrum of X-ray photoelectron energy spectrum and b is the fine spectrum of X-ray photoelectron energy spectrum. Figure 6 Characterization diagrams of HTpBPa-F and STpBPa-F in Test Example 2 of the present invention are shown; where a is the Fourier Transmission Infrared Spectrometer (FT-IR) and b is the thermogravimetric analysis diagram. Figure 7 The image shows the characterization of STpBPa in Test Example 2 of this invention; where a is the X-ray diffraction pattern (PXRD) and b is the characterization of STpBPa after Pawley refinement. Figure 8 The image shows the characterization of STpBPa in Test Example 2 of this invention; where a is a scanning electron microscope image and b is a transmission electron microscope image. Figure 9 The image shows the characterization of STpBPa in Test Example 2 of this invention; where a is the Fourier Transform Infrared Spectrum (FT-IR) and b is the thermogravimetric analysis image. Figure 10 The nitrogen adsorption-desorption isotherms of HTpBPa-F, STpBPa-F, and STpBPa in Test Example 2 of this invention are shown below. Figure 11 The image shows the characterization of the HTpBPa-F bonded capillary column in Test Example 3 of this invention; where a is the X-ray diffraction pattern (PXRD), b is the infrared spectrum (FT-IR), c is the scanning electron microscope cross-sectional image, and d is the transmission electron microscope image. Figure 12 The image shows the X-ray diffraction pattern (PXRD) of Test Example 3 of the present invention; where a is an STpBPa-F bonded capillary column and b is an STpBPa bonded capillary column. Figure 13 The image shows the Fourier Transform Infrared (FT-IR) spectrum of Test Example 3 of this invention; where a is the STpBPa-F bonded capillary column and b is the STpBPa bonded capillary column. Figure 14 The image shows the characterization of the STpBPa-F bonded capillary column in Test Example 3 of this invention; where a is a cross-sectional view of a scanning electron microscope and b is a transmission electron microscope image. Figure 15 The image shows the characterization of the STpBPa bonded capillary column in Test Example 3 of this invention; where a is a cross-sectional view of a scanning electron microscope and b is a transmission electron microscope image. Figure 16 The image shows a chromatogram of halogenated isomers separated by gas chromatography using an HTpBPa-F bonded capillary column in Test Example 4 of this invention; wherein, a is the chloroaniline isomer; b is the fluoroaniline isomer; c is the chlorobiphenyl isomer; d is the 1,2-dichloroethylene isomer; e is the dibromopropane isomer; and f is the dichloropropane isomer. Figure 17 The image shows a chromatogram of halogenated isomers separated by gas chromatography using an STpBPa-F bonded capillary column in Test Example 4 of this invention; wherein, a is the chloroaniline isomer; b is the fluoroaniline isomer; c is the chlorobiphenyl isomer; d is the 1,2-dichloroethylene isomer; e is the dibromopropane isomer; and f is the dichloropropane isomer. Figure 18 The image shows a chromatogram of halogenated isomers separated by gas phase chromatography using an STpBPa bonded capillary column in Test Example 4 of this invention; wherein, a is the chloroaniline isomer; b is the fluoroaniline isomer; c is the chlorobiphenyl isomer; d is the 1,2-dichloroethylene isomer; e is the dibromopropane isomer; and f is the dichloropropane isomer. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0021] In this invention, unless otherwise stated, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0022] In this invention, unless otherwise stated, the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0023] In this invention, unless otherwise specified, the experimental methods used in the embodiments of this invention are conventional methods, and the materials and reagents used are commercially available unless otherwise specified. Example 1

[0024] Reference Figure 1 As shown, the chromatographic stationary phase based on the hollow covalent organic framework and its preparation method in this embodiment specifically include the following steps: S1. Weigh 1,3,5-tris(p-formylphenyl)benzene (TpB, 29.3 mg, 0.075 mmol) and 2,5-diaminotrifluorotoluene (Pa-F, 19.8 mg, 0.113 mmol), add them to a mixed solvent of o-dichlorobenzene (o-DCB, 0.38 mL) and n-butanol (n-BuOH, 2.62 mL), and sonicate for 10 min to obtain a uniformly dispersed solution; S2. While maintaining sonication, add acetic acid solution (3 mol / L, 0.3 mL) to the dispersion and continue sonication for 5 min to obtain a prepolymer solution. After the prepolymer solution is subjected to three freeze-vacuum-thaw cycles, it is placed at 90℃ for 72 h. After the reaction is completed, it is cooled to room temperature and the precipitate is collected by centrifugation. S3. The precipitate was washed three times each with tetrahydrofuran and ethanol to remove unreacted monomers. After washing, the precipitate was dried under vacuum at 60°C for 24 hours to obtain a yellow powder product with a yield of 57.4%, which is the chromatographic stationary phase (HTpBPa-F) based on a hollow covalent organic framework. Example 2

[0025] The process is basically the same as in Example 1, except that 2,5-diaminotrifluorotoluene is replaced with 1,4-diamino-2-nitrobenzene. The chromatographic characterization results of the prepared stationary phase based on the hollow covalent organic framework are similar to those in Example 1. Example 3

[0026] The results were basically the same as in Example 1, except that 2,5-diaminotrifluorotoluene was replaced with p-phenylenediamine. The chromatographic stationary phase based on the hollow covalent organic framework was similar to that in Example 1. Example 4

[0027] The process is basically the same as in Example 1, except that 1,3,5-tris(p-formylphenyl)benzene is replaced with 1,3,5-trimethoxy-2,4,6-tris(4-formylphenyl)benzene, and 2,5-diaminotrifluorotoluene is replaced with p-phenylenediamine. The chromatographic characterization results of the prepared stationary phase based on the hollow covalent organic framework are similar to those in Example 1. Example 5

[0028] The process is basically the same as in Example 1, except that 1,3,5-tris(p-formylphenyl)benzene is replaced with 4,4''-diamino-5'-(4-aminophenyl)-[1,1':3',1''-terphenyl]-2'-ol, and 2,5-diaminotrifluorotoluene is replaced with p-phenylenedialdehyde. The chromatographic characterization results of the prepared stationary phase based on the hollow covalent organic framework are similar to those in Example 1. Example 6

[0029] The process is basically the same as in Example 1, except that 1,3,5-tris(p-formylphenyl)benzene is replaced with 1,3,5-tris(4-aminophenyl)benzene, and 2,5-diaminotrifluorotoluene is replaced with 2,5-dimethoxy-p-phenylenedialdehyde. The chromatographic characterization results of the prepared stationary phase based on the hollow covalent organic framework are similar to those in Example 1. Example 7

[0030] The process is basically the same as in Example 1, except that 1,3,5-tris(p-formylphenyl)benzene is replaced with 1,3,5-tris(4-aminophenyl)benzene, and 2,5-diaminotrifluorotoluene is replaced with p-phenylenedialdehyde. The chromatographic characterization results of the prepared stationary phase based on the hollow covalent organic framework are similar to those in Example 1. Comparative Example 1

[0031] The reaction was basically the same as in Example 1, except that the reaction time at 90°C for 72 hours was changed to 12 hours at 90°C to obtain a solid covalent organic framework chromatographic stationary phase (STpBPa-F). Comparative Example 2

[0032] Reference Figure 1 As shown, the chromatographic stationary phase based on a fluorine-free covalent organic framework and its preparation method in this comparative example specifically include the following steps: S1. Weigh 1,3,5-tris(p-formylphenyl)benzene (TpB, 17 mg, 0.04 mmol) and 2,5-diaminotoluene (Pa, 6.5 mg, 0.06 mmol), add them to a mixed solvent of trimethylbenzene (1 mL) and ethanol (1 mL), and sonicate for 10 min to obtain a uniformly dispersed solution. S2. While maintaining sonication, add acetic acid solution (3 mol / L, 0.2 mL) to the dispersion and continue sonication for 5 min to obtain a prepolymer solution. After the prepolymer solution is subjected to three freeze-vacuum-thaw cycles, it is reacted at room temperature for 72 h. After the reaction is completed, the precipitate is collected by centrifugation. S3. The precipitate was washed three times each with tetrahydrofuran and ethanol to remove unreacted monomers. After washing, the precipitate was dried under vacuum at 60°C for 24 hours to obtain the chromatographic stationary phase (STpBPa) based on a fluorine-free covalent organic framework. Test Example 1

[0033] Based on Example 1, the effect of condensation reaction time (1 h, 12 h, 24 h, 48 h, 72 h, 120 h) on the morphology of the covalent organic framework chromatographic stationary phase (TpBPa-F) was investigated. Transmission electron microscopy images of TpBPa-F prepared at different condensation reaction times are shown below. Figure 2 As shown. From Figure 2It can be seen that the product after 12 hours of reaction is a solid tubular structure (STpBPa-F), which is used as a control for subsequent separation experiments. As the reaction time increases, the small particles inside the solid tube, due to their high surface energy, dissolve in the surrounding solution and migrate to the surface of larger and more stable particles for deposition. After 24 hours of reaction, the microcrystals in the solid tube begin to dissolve and recrystallize on the outer surface. When the reaction time is extended to 48 hours, a larger inner cavity is formed inside the tube, with only a small number of small particles remaining. After 72 hours of reaction, a hollow tubular structure with a complete morphology (HTpBPa-F) can be obtained. However, if the reaction time is too long (120 hours), the hollow structure will partially collapse. Test Example 2

[0034] The HTpBPa-F prepared in Example 1 and the STpBPa-F prepared in Comparative Example 1 were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The results are as follows: Figures 3-6 As shown. From Figure 3 As can be seen, both HTpBPa-F and STpBPa-F exhibit a series of PXRD characteristic peaks at 2.9°, 5.0°, 5.7°, and 7.6°, corresponding to the diffraction signals of the (100), (110), (020), and (120) crystal planes, respectively. Furthermore, the experimentally measured PXRD patterns are highly consistent with the simulated patterns of the AA stacking mode, rather than the AB stacking mode, thus confirming that both materials employ a two-dimensional AA stacking structure. Figure 3 Further refinement of b reveals that the crystal possesses specific hexagonal unit cell parameters, with space group P1 and unit cell parameters satisfying α=β=90°, γ=120°, a=b=35.9927Å, and c=3.7464Å. From... Figure 4 As can be seen from this, HTpBPa-F has a hollow tubular structure, and... Figure 4 The solid tubular structure of STpBPa-F in b forms a stark contrast. From Figure 5 It can be seen that fluorine has been successfully introduced into HTpBPa-F and STpBPa-F. From Figure 6 As can be seen, the spectra of the two materials are almost identical, indicating that they have the same chemical composition, and at 1139 cm⁻¹ -1 The characteristic peak of the CF bond at 1618 cm⁻¹ is similar to that at 1618 cm� -1 The characteristic peak of the C=N bond at the location directly corroborates the smooth progress of the Schiff base reaction and the successful grafting of the fluorine group; from Figure 6 b shows that HTpBPa-F and STpBPa-F remain stable at 500℃, confirming the potential of such covalent organic framework (COF) materials as stationary phases for gas chromatography (GC).

[0035] Meanwhile, the STpBPa prepared in Comparative Example 2 was characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The results are as follows: Figures 7-9 As shown. From Figures 7-9 It can be seen that STpBPa adopts a two-dimensional AA stacked structure, with a space group of P6 / m for its fine unit cell, and the unit cell parameters satisfying α=β=90°, γ=120°, a=b=35.5650Å, c=3.6275Å; its FTIR spectrum is at 1618 cm⁻¹. -1 The presence of a characteristic absorption peak for C=N bonds at the site confirms that the Schiff base reaction has proceeded smoothly. SEM and TEM images further show that the material exhibits a solid spherical morphology. Thermogravimetric analysis results indicate that STpBPa remains stable at 360℃, a characteristic that fully demonstrates the potential of this type of covalent organic framework (COF) material as a stationary phase in gas chromatography (GC).

[0036] In addition, to investigate the pore size and specific surface area characteristics of the three materials HTpBPa-F, STpBPa-F, and STpBPa, nitrogen adsorption experiments were conducted. The relevant results of degassing treatment of the three materials at room temperature are as follows: Figure 10 As shown. From Figure 10 It can be seen that the BET surface area of ​​HTpBPa-F is 1049 m². 2 / g, significantly higher than STpBPa-F's 195m 2 The two materials have similar pore sizes of approximately 2.18 nm, which confirms that the introduction of a hollow structure can effectively increase the specific surface area of ​​the material; while STpBPa has a BET surface area of ​​130 m² / g. 2 / g, with a pore size distribution of approximately 3.4nm, and a specific surface area similar to STpBPa-F, indicating that the introduction of trifluoromethyl groups has a relatively small impact on the specific surface area. Test Example 3

[0037] (1) Preparation of chromatographic stationary phase bonded capillary column: fused silica capillary (30m × 0.53mm) was pretreated sequentially with sodium hydroxide solution (1mol / L), deionized water, hydrochloric acid solution (1mol / L), and deionized water gradient. Then, a 1:1 (v / v) methanol / 3-aminopropyltriethoxysilane mixture was injected into the pretreated capillary. After sealing both ends, the capillary was incubated at 70℃ for 24h. After rinsing with ethanol and drying under nitrogen at 120℃, an amino-modified capillary was obtained. A 1,3,5-tris(4-formylphenyl)phenyl dimethyl sulfoxide solution (9.77mg / mL) was injected into the amino-modified capillary. After sealing, the capillary was incubated at 60℃ for 2h, and then rinsed with methanol. After removing residual impurities and drying with nitrogen at 120°C for 2 hours, 1,3,5-tris(4-formylphenyl)benzene-modified capillaries were obtained. HTpBPa-F prepolymer solution, STpBPa-F prepolymer solution, or STpBPa prepolymer solution were injected into the modified capillaries, and both ends were sealed. The capillaries were then incubated at 90°C for 72 hours (HTpBPa-F), 90°C for 12 hours (STpBPa-F), or at room temperature for 72 hours (STpBPa), respectively. After rinsing with ethanol and drying with nitrogen at 120°C, chromatographic stationary phase bonded capillary columns (HTpBPa-F bonded capillary column, STpBPa-F bonded capillary column, and STpBPa bonded capillary column) were obtained. (2) Characterization: The HTpBPa-F bonded capillary column, STpBPa-F bonded capillary column, and STpBPa bonded capillary column were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The results are as follows: Figures 11-15 As shown. From Figure 11 a and Figure 12 It can be seen that the diffraction peaks of each sample showed no significant changes, indicating that HTpBPa-F, STpBPa-F, and STpBPa maintained their complete crystal structure after growth on the inner wall of the capillary; from Figure 11 b and Figure 13 It can be seen that, compared to bare capillaries, the three types of COF-bonded capillaries, in addition to exhibiting the characteristic peaks of silica capillaries, all show the characteristic absorption peaks of the corresponding COFs; from Figure 11 c and Figure 14 It can be seen that HTpBPa-F, STpBPa-F, and STpBPa are all uniformly coated on the inner wall of the capillary column; from Figure 11 d and Figure 15 It can be seen that, due to the confined space of the capillary, the particle size of HTpBPa-F, STpBPa-F and STpBPa grown on the inner wall is smaller than that of the traditional externally prepared products. Furthermore, HTpBPa-F maintains a hollow structure, while STpBPa-F and STpBPa are solid structures. The above results fully demonstrate that COF-bonded capillary columns have been successfully prepared. Test Example 4

[0038] Based on Test Example 3, using HTpBPa-F bonded capillary columns, STpBPa-F bonded capillary columns, and STpBPa bonded capillary columns (30m × 0.53mm) as gas chromatography stationary phases, isothermal gas chromatography separation experiments were conducted on chloroaniline, fluoroaniline, chlorobiphenyl, 1,2-dichloroethylene, dibromopropane, and a series of dichloropropane isomers under different nitrogen flow rates and temperatures. The relevant separation results are as follows: Figures 16-18 As shown.

[0039] from Figure 16 It can be seen that baseline separation of the six isomers was achieved on the HTpBPa-F bonded capillary column. The optimal separation conditions for the chloroaniline isomer were a column temperature of 150℃ and a nitrogen flow rate of 1.2 mL / min, corresponding to resolutions of 2.5–8.1 and column efficiencies of 1236–2414 plates / m, respectively. The fluoroaniline isomer achieved a resolution of 4.9–9.8 and a column efficiency of 2908–3046 plates / m at a column temperature of 150℃ and a nitrogen flow rate of 1.1 mL / min. The chlorobiphenyl isomer achieved a resolution of 12.4–15.6 at a column temperature of 150℃ and a nitrogen flow rate of 1.3 mL / min. The column efficiency range was 1365-3212 plates / meter; the separation conditions for the 1,2-dichloroethylene isomer were a column temperature of 90℃ and a nitrogen flow rate of 1.5 mL / min, with a resolution of 3.3 and a column efficiency of 2573-3359 plates / meter; the resolution and column efficiency for the dibromopropane isomer were 2.9-4.7 and 2449-2637 plates / meter, respectively, at a column temperature of 90℃ and a nitrogen flow rate of 1.2 mL / min; the separation of the dichloropropane isomer was achieved at a column temperature of 40℃ and a nitrogen flow rate of 1.4 mL / min, with a resolution and column efficiency of 2.3-6.4 and 1123-1174 plates / meter, respectively.

[0040] from Figure 17It can be seen that all six isomers can be separated on the STpBPa-F bonded capillary column, but significant tailing phenomenon exists. The separation conditions for the chloroaniline isomer are a column temperature of 140℃ and a nitrogen flow rate of 1.2 mL / min, with corresponding resolutions of 2.5-2.7 and column efficiencies of 142-1740 plates / m. For the fluoroaniline isomer, under the same conditions of 140℃ and 1.2 mL / min, the resolution is 1.4-2.0, and the column efficiency is 368-1658 plates / m. The separation of the chlorobiphenyl isomer at a column temperature of 150℃ and a nitrogen flow rate of 1.5 mL / min... The resolution and column efficiency were 1.5-2.8 and 138-2394 plates / meter, respectively. The separation conditions for the 1,2-dichloroethylene isomer were a column temperature of 80℃ and a nitrogen flow rate of 1.2 mL / min, with a resolution of 2 and a column efficiency of 612-3178 plates / meter. The resolution for the dibromopropane isomer was 1.8 and the column efficiency was 156-2859 plates / meter under the conditions of a column temperature of 80℃ and a nitrogen flow rate of 1 mL / min. The separation of the dichloropropane isomer was achieved under the conditions of a column temperature of 40℃ and a nitrogen flow rate of 1.2 mL / min, with a resolution of 1.3-1.6 and a column efficiency of 12-1446 plates / meter, respectively.

[0041] from Figure 18 It can be seen that baseline separation was not achieved for the six isomers on the STpBPa bonded capillary column. Specifically, the chloroaniline isomer achieved a resolution of 4.5 at a column temperature of 200℃ and a nitrogen flow rate of 2 mL / min, with a column efficiency of 206-345 plates / m; the fluoroaniline isomer achieved a resolution of 5.1 at a column temperature of 140℃ and a nitrogen flow rate of 4 mL / min, with a column efficiency of 51-103 plates / m; and the chlorobiphenyl isomer could not be separated at a column temperature of 150℃ and a nitrogen flow rate of 1.2 mL / min. The column efficiency was 1447 plates / meter; the resolution of the 1,2-dichloroethylene isomer was 1.3 at a column temperature of 140℃ and a nitrogen flow rate of 5 mL / min, with a column efficiency of 816-870 plates / meter; the resolution of the dibromopropane isomer was 0.7-0.9 at a column temperature of 140℃ and a nitrogen flow rate of 5 mL / min, with a column efficiency of only 4-11 plates / meter; and the resolution of the dichloropropane isomer was 1.2-2.2 at a column temperature of 100℃ and a nitrogen flow rate of 5 mL / min, with a column efficiency of 11-107 plates / meter.

[0042] In summary, this invention prepares a chromatographic stationary phase (HTpBPa-F) based on a hollow covalent organic framework via the Ostwald ripening method. The introduced fluorine groups not only regulate the thermodynamic behavior of the separation process but also, as electron-withdrawing groups, weaken the polarization of the imine bonds, enhancing the interlayer interactions of the covalent organic framework and inducing the Ostwald ripening process. This enables the directional synthesis of the hollow covalent organic framework, and the hollow structure effectively regulates the kinetics of halogenated isomer separation. Furthermore, the thermodynamic and kinetic properties of HTpBPa-F on the separation effect of halogenated isomers were systematically investigated, demonstrating the feasibility and guiding significance of simultaneously implementing thermodynamic and kinetic engineering control in covalent organic framework materials for high-resolution chromatography.

[0043] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An application of a capillary column in the separation of halogenated isomers, characterized in that, The capillary column is prepared from a chromatographic stationary phase based on a hollow covalent organic framework; the preparation method of the chromatographic stationary phase based on a hollow covalent organic framework includes the following steps: under the action of a catalyst, a first monomer and a second monomer undergo a condensation reaction in an organic solvent to obtain the chromatographic stationary phase based on a hollow covalent organic framework; the temperature of the condensation reaction is 60℃-120℃, and the time is 2 days-5 days; The structures of the first monomer and the second monomer are as follows. 、 ； X1 and X2 are independently selected from electron-donating groups, electron-withdrawing groups, or hydrogen; X1 and X2 are each independently one or more, and each is independently attached to any substituted position on its corresponding benzene ring; R1 and R2 are independently selected from aldehyde or amino groups; When R1 is an aldehyde group, X1 is an electron-donating group or hydrogen, R2 is an amino group, and X2 is an electron-withdrawing group; When R1 is an amino group, X1 is an electron-withdrawing group or hydrogen, R2 is an aldehyde group, and X2 is an electron-donating group.

2. The application of the capillary column according to claim 1 in the separation of halogenated isomers, characterized in that, The electron-withdrawing group is selected from nitro, trifluoromethyl, cyano, sulfonic acid, halogen, aldehyde, carboxyl, or ester. And / or, the electron-donating group is selected from alkoxy, hydroxy, alkyl, amide or acyloxy groups.

3. The application of the capillary column according to claim 1 in the separation of halogenated isomers, characterized in that, The molar ratio of the first monomer to the second monomer is 1:(1-5).

4. The application of the capillary column according to claim 1 in the separation of halogenated isomers, characterized in that, The catalyst is selected from acetic acid and / or scandium trifluoromethanesulfonate.

5. The application of the capillary column according to claim 1 in the separation of halogenated isomers, characterized in that, The amount of catalyst used is 5%-20% of the total molar amount of the first monomer and the second monomer.

6. The application of the capillary column according to claim 1 in the separation of halogenated isomers, characterized in that, The organic solvent is selected from one or more of acetonitrile, dimethyl sulfoxide, dichloromethane, mesitylene, dioxane, o-dichlorobenzene, n-butanol, and chloroform.

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