Sulfydryl-alkene click reaction post-modified covalent organic framework solid-phase microextraction fiber coating as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of molecular adsorption separation solid-phase microextraction, and discloses a covalent organic framework solid-phase microextraction fiber coating modified after sulfydryl-alkene click reaction as well as a preparation method and application of the covalent organic framework solid-phase microextraction fiber coating. The preparation method comprises the following steps: mixing a covalent organic framework, a derivatization reagent, a first initiator and a first solvent, and carrying out a click reaction under a protective atmosphere to obtain a post-modified covalent organic framework; and mixing the post-modified covalent organic framework, a cross-linking agent, a second initiator and a second solvent, and carrying out polymerization reaction in a protective atmosphere to obtain the thiol-ene click reaction post-modified covalent organic framework solid-phase microextraction fiber coating. Groups with different recognition capabilities are introduced into the porous structure of the covalent organic framework, the adsorption performance of the covalent organic framework is remarkably improved, the solid-phase microextraction fiber coating is further prepared by adopting a thermal polymerization method, and the use form of the covalent organic framework is enriched.

Description

Technical Field

[0001] The invention relates to the technical field of molecular adsorption separation solid phase microextraction, and in particular to a covalent organic skeleton solid phase microextraction fiber coating modified after a thiol-ene click reaction, and a preparation method and application thereof. Background Art

[0002] Covalent organic frameworks are porous crystalline polymers composed of light elements such as C, H, O, and N. They have attracted widespread attention in sample pretreatment due to their adjustable pore size and structure, permanent porosity, and high surface area. In recent years, various covalent organic frameworks have been used as fiber coatings. Most of these fiber coatings are prepared by physical adhesion methods, and the COF material is fixed to the fiber surface by epoxy resin glue and silicone sealant. However, the coatings prepared by the above methods are easy to fall off from the fiber coating and the coating is uneven due to the lack of stable chemical bonding with the fiber surface, which greatly affects the use of the fiber coating. Therefore, it is necessary to develop a chemical method for the preparation and modification of covalent organic framework solid phase microextraction fiber coatings. Summary of the invention

[0003] The purpose of the present invention is to provide a covalent organic framework solid phase microextraction fiber coating modified after a thiol-ene click reaction and its preparation method and application, so as to solve the problems of low extraction amount of existing covalent organic frameworks, complex sample enrichment process and easy shedding of covalent organic framework coatings.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The present invention provides a method for preparing a covalent organic framework solid phase microextraction fiber coating modified by a thiol-ene click reaction, comprising the following steps:

[0006] (1) mixing a covalent organic framework, a derivatization reagent, a first initiator and a first solvent, and performing a click reaction under a protective atmosphere to obtain a post-modified covalent organic framework;

[0007] (2) mixing the post-modified covalent organic framework, the cross-linking agent, the second initiator and the second solvent described in step (1), and performing a polymerization reaction under a protective atmosphere to obtain a covalent organic framework solid phase microextraction fiber coating modified by a thiol-ene click reaction;

[0008] Wherein, the covalent organic framework in step (1) comprises a vinyl covalent organic framework or a covalent organic framework post-modified with 1,2-ethanedithiol;

[0009] The derivatization reagent in step (1) includes mono(6-mercapto-6-deoxy)-β-cyclodextrin, L-cysteine, reduced glutathione, 1,2-ethanedithiol or 4-vinylphenylboronic acid.

[0010] Preferably, in the preparation method, the structure of the vinyl covalent organic skeleton is as shown in Formula I:

[0011]

[0012] The structure of the covalent organic framework post-modified with 1,2-ethanedithiol is shown in Formula II:

[0013]

[0014] Preferably, in the preparation method, in step (1), when the derivatization agent is solid, the mass ratio of the covalent organic framework, the derivatization agent and the first initiator is 100-500 mg: 600 mg-3 g: 50 mg;

[0015] When the derivatization reagent is a liquid, the ratio of the mass of the covalent organic framework, the volume of the derivatization reagent and the mass of the first initiator is 100-500 mg: 4-20 mL: 50 mg.

[0016] Preferably, in the preparation method, in step (1), when the derivatization agent is mono(6-mercapto-6-deoxy)-β-cyclodextrin, the covalent organic skeleton is a vinyl covalent organic skeleton, and the first solvent is trifluorotoluene;

[0017] When the derivatization agent is L-cysteine ​​or reduced glutathione, the covalent organic skeleton is a vinyl covalent organic skeleton, and the first solvent is dimethyl sulfoxide;

[0018] When the derivatization agent is 1,2-ethanedithiol, the covalent organic skeleton is a vinyl covalent organic skeleton, and the first solvent is 1,2-ethanedithiol;

[0019] When the derivatization agent is 4-vinylphenylboronic acid, the covalent organic framework is a covalent organic framework post-modified with 1,2-ethanedithiol, and the first solvent is dimethyl sulfoxide;

[0020] Step (1) The first initiator includes azobisisobutyronitrile, azobismethylvaleronitrile or 4,4'-azo(4-cyanovaleric acid).

[0021] Preferably, in the preparation method, in step (1), the temperature of the click reaction is 70 to 80° C., and the time is 12 to 48 hours.

[0022] Preferably, in the preparation method, the cross-linking agent in step (2) includes ethylene glycol dimethacrylate, trimethylolpropane triacrylate or divinylbenzene; the second initiator in step (2) includes azobisisobutyronitrile, azodimethylvaleronitrile or 4,4'-azo(4-cyanovaleric acid); and the second solvent in step (2) includes one or more of dimethyl sulfoxide, methanol, acetonitrile and dichloromethane.

[0023] Preferably, in the preparation method, in step (2), in the mixture of the post-modified covalent organic framework and the second solvent, the mass concentration of the post-modified covalent organic framework is 10 to 50 mg / L; the ratio of the volume of the mixture of the post-modified covalent organic framework and the second solvent, the volume of the cross-linking agent and the mass of the second initiator is 5 mL: 0.5 to 2.5 mL: 20 to 50 mg.

[0024] Preferably, in the preparation method, in step (2), the polymerization reaction temperature is 45 to 80° C. and the reaction time is 12 to 25 hours.

[0025] The present invention also provides a covalent organic skeleton solid phase microextraction fiber coating modified after a thiol-ene click reaction prepared by the preparation method.

[0026] The present invention also provides an application of the covalent organic skeleton solid phase microextraction fiber coating modified after the thiol-ene click reaction in solid phase microextraction.

[0027] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The present invention utilizes the thiol-ene click reaction to post-modify the covalent organic skeleton, and introduces groups with different recognition capabilities into the porous structure of the covalent organic skeleton. These groups can not only form specific binding with the target molecule through intermolecular interactions (such as hydrogen bonds, π-π interactions, electrostatic effects, etc.), but also can regulate the pore size of the material, the hydrophilicity and polarity of the pores, and further refine the recognition of the target molecule. This method significantly improves the extraction effect of the covalent organic skeleton on the target analyte. The covalent organic skeleton modified by the thiol-ene click reaction is further prepared into the form of a solid phase microextraction fiber coating by a thermal polymerization method, which enriches the use of the covalent organic skeleton and improves the difficulty of adsorption and desorption of the powdered covalent organic skeleton, and the difficulty of recycling.

[0029] (2) The present invention utilizes the thiol-ene click reaction to post-modify the covalent organic framework. This method is universal and applicable to covalent organic frameworks with thiol or vinyl groups, providing a reference for the post-synthesis modification of covalent organic frameworks. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the description of the embodiments or the prior art are briefly introduced below.

[0031] Figure 1 The solid phase microextraction fiber coating of comparative example 1 is a sample injection chromatogram of the extraction effect of five bisphenol compounds, wherein curve a is a direct sample injection chromatogram of bisphenol compounds, and curve b is a sample injection chromatogram of the extraction effect of comparative example 1;

[0032] Figure 2 The solid phase microextraction fiber coating of Example 1 is a sample injection chromatogram of the extraction effect of five bisphenol compounds, wherein curve a is a direct sample injection chromatogram of bisphenol compounds, curve b is a sample injection chromatogram of the extraction effect of Comparative Example 1, and curve c is a sample injection chromatogram of the extraction effect of Example 1;

[0033] Figure 3 The solid phase microextraction fiber coating of Example 2 is a sample injection chromatogram of the extraction effect of five bisphenol compounds, wherein curve a is a direct sample injection chromatogram of the bisphenol compounds, curve b is a sample injection chromatogram of the extraction effect of Comparative Example 1, and curve c is a sample injection chromatogram of the extraction effect of Example 2;

[0034] Figure 4 The solid phase microextraction fiber coating of Example 3 is a sample injection chromatogram of the extraction effect of five bisphenol compounds, wherein curve a is a direct injection chromatogram of the bisphenol compound, curve b is a sample injection chromatogram of the extraction effect of Comparative Example 1, and curve c is a sample injection chromatogram of the extraction effect of Example 3;

[0035] Figure 5 The solid phase microextraction fiber coating of Example 4 is a sample injection chromatogram of the extraction effect of five bisphenol compounds, wherein curve a is a direct sample injection chromatogram of the bisphenol compound, curve b is a sample injection chromatogram of the extraction effect of Comparative Example 1, and curve c is a sample injection chromatogram of the extraction effect of Example 4;

[0036] Figure 6 The solid phase microextraction fiber coating of Example 5 is a sample injection chromatogram of the extraction effect of five bisphenol compounds, wherein curve a is a direct sample injection chromatogram of the bisphenol compound, curve b is a sample injection chromatogram of the extraction effect of Comparative Example 1, and curve c is a sample injection chromatogram of the extraction effect of Example 5;

[0037] exist Figures 1 to 6 Among them, peak 1 represents bisphenol F, peak 2 represents bisphenol S, peak 3 represents bisphenol A, peak 4 represents bisphenol B, and peak 5 represents bisphenol AF. DETAILED DESCRIPTION

[0038] The present invention provides a method for preparing a covalent organic framework solid phase microextraction fiber coating modified by a thiol-ene click reaction, comprising the following steps:

[0039] (1) mixing a covalent organic framework, a derivatization reagent, a first initiator and a first solvent, and performing a click reaction under a protective atmosphere to obtain a post-modified covalent organic framework;

[0040] (2) mixing the post-modified covalent organic framework, the cross-linking agent, the second initiator and the second solvent described in step (1), and performing a polymerization reaction under a protective atmosphere to obtain a covalent organic framework solid phase microextraction fiber coating modified by a thiol-ene click reaction;

[0041] Wherein, the covalent organic framework in step (1) comprises a vinyl covalent organic framework or a covalent organic framework post-modified with 1,2-ethanedithiol;

[0042] The derivatization reagent in step (1) includes mono(6-mercapto-6-deoxy)-β-cyclodextrin, L-cysteine, reduced glutathione, 1,2-ethanedithiol or 4-vinylphenylboronic acid.

[0043] In the present invention, the structure of the vinyl covalent organic skeleton is preferably as shown in Formula I:

[0044]

[0045] In the present invention, the method for preparing the vinyl covalent organic framework preferably comprises the following steps: mixing 1,3,5-tris(4-aminophenyl)benzene, 2,5-divinylterephthalaldehyde, acetonitrile and acetic acid solution, reacting, and sequentially standing, centrifuging, washing and vacuum drying to obtain a vinyl covalent organic framework.

[0046] In the present invention, the acetic acid solution is preferably an aqueous solution of acetic acid.

[0047] In the present invention, the concentration of the acetic acid solution is preferably 8 to 12 mol / L, more preferably 10 to 12 mol / L, and more preferably 12 mol / L.

[0048] In the present invention, the molar ratio of the 1,3,5-tris(4-aminophenyl)benzene to the 2,5-divinylterephthalaldehyde is preferably 1-6:1-6, more preferably 2:1-3, and more preferably 2:3.

[0049] In the present invention, the ratio of the molar amount of the 1,3,5-tris(4-aminophenyl)benzene, the volume of the acetonitrile and the volume of the acetic acid solution is preferably 0.04mmol:5mL:0.2-0.6mL, more preferably 0.04mmol:5mL:0.4-0.6mL, and more preferably 0.04mmol:5mL:0.4mL.

[0050] In the present invention, the mixing time is preferably 5 to 15 seconds, preferably 10 to 15 seconds, and more preferably 10 seconds.

[0051] In the present invention, the standing temperature is preferably room temperature; the standing time is preferably 12 to 72 hours, more preferably 48 to 72 hours, and more preferably 72 hours.

[0052] In the present invention, the washing reagents are preferably tetrahydrofuran and ethanol; the number of washing with tetrahydrofuran and the number of washing with ethanol are independently preferably 3 to 5 times, more preferably 3 to 4 times, and more preferably 3 times.

[0053] In the present invention, the vacuum drying temperature is preferably 55 to 65° C., more preferably 55 to 60° C., and more preferably 60° C.; the time is preferably 12 to 48 h, more preferably 24 to 48 h, and more preferably 24 h.

[0054] In the present invention, the structure of the covalent organic skeleton post-modified with 1,2-ethanedithiol is preferably as shown in Formula II:

[0055]

[0056] In the present invention, the method for preparing the 1,2-ethanedithiol post-modified covalent organic framework preferably comprises the following steps: mixing a vinyl covalent organic framework, 1,2-ethanedithiol, and a first initiator, and performing a click reaction under a protective atmosphere to obtain a 1,2-ethanedithiol post-modified covalent organic framework, wherein the parameter conditions are the same as those in step (1).

[0057] In the present invention, in step (1), when the derivatization agent is mono(6-mercapto-6-deoxy)-β-cyclodextrin, the covalent organic skeleton is preferably a vinyl covalent organic skeleton, and the first solvent is preferably trifluorotoluene;

[0058] When the derivatization agent is L-cysteine ​​or reduced glutathione, the covalent organic skeleton is preferably a vinyl covalent organic skeleton, and the first solvent is preferably dimethyl sulfoxide;

[0059] When the derivatization agent is 1,2-ethanedithiol, the covalent organic skeleton is preferably a vinyl covalent organic skeleton, and the first solvent is preferably 1,2-ethanedithiol;

[0060] When the derivatization agent is 4-vinylphenylboronic acid, the covalent organic skeleton is preferably a covalent organic skeleton post-modified with 1,2-ethanedithiol, and the first solvent is preferably dimethyl sulfoxide.

[0061] In the present invention, in step (1), when the derivatization agent is solid, the mass ratio of the covalent organic framework, the derivatization agent and the first initiator is preferably 100-500 mg: 600 mg-3 g: 50 mg, more preferably 100-300 mg: 600 mg-1 g: 50 mg, and more preferably 100 mg: 600 mg: 50 mg;

[0062] When the derivatization reagent is a liquid, the ratio of the mass of the covalent organic skeleton, the volume of the derivatization reagent and the mass of the first initiator is preferably 100-500 mg:4-20 mL:50 mg, more preferably 100-300 mg:8-15 mL:50 mg, and more preferably 100 mg:10 mL:50 mg.

[0063] In the present invention, the first initiator in step (1) preferably includes azobisisobutyronitrile, azobismethylvaleronitrile or 4,4'-azo(4-cyanovaleric acid), further preferably includes azobisisobutyronitrile or azobismethylvaleronitrile, and more preferably is azobisisobutyronitrile.

[0064] In the present invention, the ratio of the mass of the covalent organic framework in step (1) to the volume of the first solvent is preferably 100 mg: 4-15 mL, more preferably 100 mg: 10-15 mL, and more preferably 100 mg: 10 mL.

[0065] In the present invention, the protective atmosphere in step (1) is preferably nitrogen.

[0066] In the present invention, the temperature of the click reaction in step (1) is preferably 70-80°C, more preferably 75-80°C, and more preferably 80°C; the time is preferably 12-48h, more preferably 24-48h, and more preferably 48h.

[0067] In the present invention, after the click reaction in step (1), the following steps are further performed: filtering, washing, and vacuum drying in sequence.

[0068] In the present invention, when the derivatization reagent in step (1) is mono(6-mercapto-6-deoxy)-β-cyclodextrin, reduced glutathione or L-cysteine, the washing reagent is preferably N,N-dimethylformamide, water, tetrahydrofuran and diethyl ether;

[0069] When the derivatization reagent in step (1) is 1,2-ethanedithiol or 4-vinylphenylboronic acid, the washing reagent is preferably acetone.

[0070] In the present invention, the vacuum drying temperature is preferably 50 to 65°C, more preferably 55 to 60°C, and even more preferably 60°C.

[0071] In the present invention, the method of mixing the post-modified covalent organic framework, the cross-linking agent, the second initiator and the second solvent in step (2) is preferably as follows: the post-modified covalent organic framework is mixed with the second solvent to form a post-modified covalent organic framework dispersion, and then the cross-linking agent and the second initiator are added thereto for mixing.

[0072] In the present invention, the cross-linking agent in step (2) preferably includes ethylene glycol dimethacrylate, trimethylolpropane triacrylate or divinylbenzene, further preferably includes ethylene glycol dimethacrylate or trimethylolpropane triacrylate, and more preferably is ethylene glycol dimethacrylate.

[0073] In the present invention, the second initiator in step (2) preferably includes azobisisobutyronitrile, azobismethylvaleronitrile or 4,4'-azo(4-cyanovaleric acid), further preferably includes azobisisobutyronitrile or azobismethylvaleronitrile, and more preferably is azobisisobutyronitrile.

[0074] In the present invention, the second solvent in step (2) preferably includes one or more of dimethyl sulfoxide, methanol, acetonitrile and dichloromethane, further preferably includes dimethyl sulfoxide, methanol, acetonitrile or dichloromethane, and more preferably is dimethyl sulfoxide.

[0075] In the present invention, in the mixing of the post-modified covalent organic framework and the second solvent in step (2), the mass concentration of the post-modified covalent organic framework is preferably 10 to 50 mg / L, more preferably 10 to 25 mg / L, and more preferably 10 mg / L.

[0076] In the present invention, in step (2), the ratio of the volume of the post-modified covalent organic skeleton mixed with the second solvent, the volume of the cross-linking agent and the mass of the second initiator is preferably 5mL:0.5~2.5mL:20~50mg, further preferably 5mL:1~1.5mL:30~40mg, and more preferably 5mL:1mL:30mg.

[0077] In the present invention, the protective atmosphere in step (2) is preferably nitrogen.

[0078] In the present invention, the temperature of the polymerization reaction in step (2) is preferably 45-80°C, more preferably 50-70°C, and more preferably 60°C; the time is preferably 12-25h, more preferably 18-24h, and more preferably 24h; and the polymerization reaction is preferably carried out in a water bath.

[0079] In the present invention, the polymerization reaction in step (2) preferably further includes washing and drying.

[0080] In the present invention, the washing reagent preferably comprises a mixture of methanol and acetic acid. The volume ratio of the methanol to the acetic acid is preferably 9:1-3, more preferably 9:1-2, and more preferably 9:1.

[0081] The present invention also provides a covalent organic skeleton solid phase microextraction fiber coating modified after a thiol-ene click reaction prepared by the preparation method.

[0082] In the present invention, the length of the covalent organic framework solid phase microextraction fiber coating modified after the thiol-ene click reaction is preferably 15 to 18 mm.

[0083] The present invention also provides an application of the covalent organic skeleton solid phase microextraction fiber coating modified after the thiol-ene click reaction in solid phase microextraction.

[0084] In the present invention, the application method is not limited, and a method well known to those skilled in the art may be used.

[0085] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0086] Example 1

[0087] This embodiment provides a method for preparing a covalent organic framework solid phase microextraction fiber coating modified by a thiol-ene click reaction, comprising the following steps:

[0088] (1) 0.04 mmol 1,3,5-tris(4-aminophenyl)benzene and 0.06 mmol 2,5-divinylterephthalaldehyde were pre-loaded in a 15 mL centrifuge tube, and then 5 mL acetonitrile was added to the test tube and ultrasonicated for 1 min to completely dissolve the building blocks; then, 0.4 mL 12 mol / L acetic acid aqueous solution was added to the test tube, the mixture was vigorously shaken on a vortex mixer for 10 s, and allowed to stand at room temperature for 72 h, the yellow precipitate was collected by centrifugation, and then washed three times with dry tetrahydrofuran and ethanol respectively; finally, the powder was vacuum dried at 60 ° C for 24 h to obtain a vinyl covalent organic framework;

[0089] (2) 100 mg of vinyl covalent organic framework, 600 mg of mono(6-mercapto-6-deoxy)-β-cyclodextrin and 50 mg of initiator azobisisobutyronitrile were mixed in a 25 mL Schlenk tube, 10 mL of trifluorotoluene was introduced under N2 atmosphere, and after stirring at 80°C for 48 h, the mixture was filtered and separated, and washed thoroughly with N,N-dimethylformamide, water, tetrahydrofuran and diethyl ether, and dried in vacuum at 60°C to obtain a post-modified covalent organic framework, the structure of which is shown below:

[0090]

[0091] (3) The post-modified covalent organic framework and dimethyl sulfoxide are mixed thoroughly to form a 10 mg / L post-modified covalent organic framework dispersion; 1 mL of cross-linking agent ethylene glycol dimethacrylate and 30 mg of initiator azobisisobutyronitrile are added to 5 mL of the above dispersion and mixed evenly, and then nitrogen is introduced to remove oxygen to obtain a mixed solution; the mixed solution is injected into a glass capillary with a diameter of 2.0 mm and one end is sealed, and then a silanized glass capillary with a diameter of 1.0 mm and one end is sealed is inserted into the glass capillary with one end sealed, and the glass capillary with one end sealed and the glass capillary with one end sealed are sealed with raw tape. The gaps between the silanized glass capillaries were sealed to isolate the air, and the polymerization reaction was carried out in a constant temperature water bath at 60°C for 24 hours. After the polymerization reaction, the glass capillary with one end blocked was removed to obtain a fiber; the click reaction-modified covalent organic framework coating on the fiber was shortened to 1.8 cm, and then the unreacted solvent was eluted by magnetic stirring in a mixed solution of methanol and acetic acid (methanol: acetic acid = 9:1, v / v) to obtain a thiol-ene click reaction-modified covalent organic framework solid phase microextraction fiber coating modified with single (6-mercapto-6-deoxy)-β-cyclodextrin, and the coating length was 18 mm.

[0092] Example 2

[0093] This embodiment provides a method for preparing a covalent organic framework solid phase microextraction fiber coating modified by a thiol-ene click reaction, comprising the following steps:

[0094] (1) The same as step (1) of Example 1;

[0095] (2) 100 mg of vinyl covalent organic framework, 600 mg of reduced glutathione and 50 mg of initiator azobisisobutyronitrile were mixed in a 25 mL Schlenk tube, 10 mL of dimethyl sulfoxide was introduced under N2 atmosphere, and after stirring at 80°C for 48 h, the mixture was filtered and separated, and washed thoroughly with N,N-dimethylformamide, water, tetrahydrofuran and diethyl ether, and dried in vacuum at 60°C to obtain a post-modified covalent organic framework, the structure of which is shown below:

[0096]

[0097] (3) The post-modified covalent organic framework and dimethyl sulfoxide are fully mixed to form a 10 mg / L post-modified covalent organic framework dispersion; 1 mL of cross-linking agent ethylene glycol dimethacrylate and 30 mg of initiator azobisisobutyronitrile are added to 5 mL of the above dispersion and mixed evenly, and then nitrogen is introduced to remove oxygen to obtain a mixed solution; the mixed solution is injected into a glass capillary with a diameter of 2.0 mm and one end is sealed, and then a silanized glass capillary with a diameter of 1.0 mm and one end is sealed is inserted into the glass capillary with one end sealed, and the glass capillary with one end sealed is sealed with a raw tape. The gap between the fiber and the silanized glass capillary with one end blocked was sealed to isolate the air, and the polymerization reaction was carried out in a constant temperature water bath at 60°C for 24 hours. After the polymerization reaction, the glass capillary with one end blocked was removed to obtain a fiber; the click reaction-modified covalent organic framework coating on the fiber was shortened to 1.8 cm, and then the unreacted solvent was eluted by magnetic stirring in a mixed solution of methanol and acetic acid (methanol: acetic acid = 9:1, v / v) to obtain a thiol-ene click reaction-modified covalent organic framework solid phase microextraction fiber coating modified with reduced glutathione, and the coating length was 18 mm.

[0098] Example 3

[0099] This embodiment provides a method for preparing a covalent organic framework solid phase microextraction fiber coating modified by a thiol-ene click reaction, comprising the following steps:

[0100] (1) The same as step (1) of Example 1;

[0101] (2) 100 mg of vinyl covalent organic framework, 600 mg of L-cysteine ​​and 50 mg of initiator azobisisobutyronitrile were mixed in a 25 mL Schlenk tube, 10 mL of dimethyl sulfoxide was introduced under N2 atmosphere, and after stirring at 80°C for 48 h, the mixture was filtered and separated, and washed thoroughly with N,N-dimethylformamide, water, tetrahydrofuran and diethyl ether, and dried in vacuum at 60°C to obtain a post-modified covalent organic framework, the structure of which is shown below:

[0102]

[0103] (3) The post-modified covalent organic framework and dimethyl sulfoxide are mixed thoroughly to form a 10 mg / L post-modified covalent organic framework dispersion; 1 mL of cross-linking agent ethylene glycol dimethacrylate and 30 mg of initiator azobisisobutyronitrile are added to 5 mL of the above dispersion and mixed evenly, and then nitrogen is introduced to remove oxygen to obtain a mixed solution; the mixed solution is injected into a glass capillary with a diameter of 2.0 mm and one end is sealed, and then a silanized glass capillary with a diameter of 1.0 mm and one end is sealed is inserted into the glass capillary with one end sealed, and the glass capillary with one end sealed is sealed with a raw tape. The gap between the tube and the silanized glass capillary with one end blocked was isolated from the air, and the polymerization reaction was carried out in a constant temperature water bath at 60°C for 24 hours. After the polymerization reaction, the glass capillary with one end blocked was removed to obtain a fiber; the click-reaction-modified covalent organic framework coating on the fiber was shortened to 1.8 cm, and then the unreacted solvent was eluted by magnetic stirring in a mixed solution of methanol and acetic acid (methanol: acetic acid = 9:1, v / v) to obtain a covalent organic framework solid phase microextraction fiber coating modified with L-cysteine ​​after the thiol-ene click reaction, and the coating length was 18 mm.

[0104] Example 4

[0105] This embodiment provides a method for preparing a covalent organic framework solid phase microextraction fiber coating modified by a thiol-ene click reaction, comprising the following steps:

[0106] (1) The same as step (1) of Example 1;

[0107] (2) 100 mg of a vinyl covalent organic framework and 50 mg of an initiator azobisisobutyronitrile were mixed in a 25 mL Schlenk tube, 4 mL of 1,2-ethanedithiol was introduced under a N2 atmosphere, and the mixture was stirred at 80°C for 48 h, filtered and separated, washed thoroughly with acetone, and dried in a vacuum at 60°C to obtain a post-modified covalent organic framework, the structure of which is shown below:

[0108]

[0109] (3) The post-modified covalent organic framework and dimethyl sulfoxide are fully mixed to form a 10 mg / L post-modified covalent organic framework dispersion; 1 mL of cross-linking agent ethylene glycol dimethacrylate and 30 mg of initiator azobisisobutyronitrile are added to 5 mL of the above dispersion and mixed evenly, and then nitrogen is introduced to remove oxygen to obtain a mixed solution; the mixed solution is injected into a glass capillary with a diameter of 2.0 mm and one end is sealed, and then a silanized glass capillary with a diameter of 1.0 mm and one end is sealed is inserted into the glass capillary with one end sealed, and the glass capillary with one end sealed is sealed with a raw tape. The gap between the capillary and the silanized glass capillary with one end blocked was isolated from the air, and the polymerization reaction was carried out in a constant temperature water bath at 60°C for 24 hours. After the polymerization reaction, the glass capillary with one end blocked was removed to obtain a fiber; the click reaction-modified covalent organic framework coating on the fiber was shortened to 1.8 cm, and then the unreacted solvent was eluted by magnetic stirring in a mixed solution of methanol and acetic acid (methanol: acetic acid = 9:1, v / v) to obtain a thiol-ene click reaction-modified covalent organic framework solid phase microextraction fiber coating modified with 1,2-ethanedithiol, and the coating length was 18 mm.

[0110] Example 5

[0111] This embodiment provides a method for preparing a covalent organic framework solid phase microextraction fiber coating modified by a thiol-ene click reaction, comprising the following steps:

[0112] (1) The same as step (2) of Example 4, to obtain a covalent organic framework modified with 1,2-ethanedithiol;

[0113] (2) 100 mg of 1,2-ethanedithiol post-modified covalent organic framework, 600 mg of 4-vinylphenylboronic acid and 50 mg of initiator azobisisobutyronitrile were mixed in a 25 mL Schlenk tube, 10 mL of dimethyl sulfoxide was introduced under N2 atmosphere, and after stirring at 80°C for 48 h, the mixture was filtered and separated, washed thoroughly with acetone, and dried in vacuum at 60°C to obtain a post-modified covalent organic framework with the structure shown below:

[0114]

[0115] (3) The post-modified covalent organic framework and dimethyl sulfoxide are fully mixed to form a 10 mg / L post-modified covalent organic framework dispersion; 1 mL of cross-linking agent ethylene glycol dimethacrylate and 30 mg of initiator azobisisobutyronitrile are added to 5 mL of the above dispersion and mixed evenly, and then nitrogen is introduced to remove oxygen to obtain a mixed solution; the mixed solution is injected into a glass capillary with a diameter of 2.0 mm and one end is sealed, and then a silanized glass capillary with a diameter of 1.0 mm and one end is sealed is inserted into the glass capillary with one end sealed, and the glass capillary with one end sealed is sealed with a raw tape. The gap between the capillary and the silanized glass capillary with one end blocked was sealed to isolate the air, and the polymerization reaction was carried out in a constant temperature water bath at 60°C for 24 hours. After the polymerization reaction, the glass capillary with one end blocked was removed to obtain a fiber; the click reaction-modified covalent organic framework coating on the fiber was shortened to 1.8 cm, and then the unreacted solvent was eluted by magnetic stirring in a mixed solution of methanol and acetic acid (methanol: acetic acid = 9:1, v / v) to obtain a thiol-ene click reaction-modified covalent organic framework solid phase microextraction fiber coating modified with 4-vinylphenylboronic acid, and the coating length was 18 mm.

[0116] Comparative Example 1

[0117] This comparative example provides a method for preparing a vinyl covalent organic framework solid phase microextraction fiber coating, comprising the following steps:

[0118] (1) The same as step (1) of Example 1;

[0119] (2) The vinyl covalent organic framework and dimethyl sulfoxide are mixed thoroughly to form a 10 mg / mL covalent organic framework dispersion; 1 mL of crosslinking agent ethylene glycol dimethacrylate and 30 mg of initiator azobisisobutyronitrile are added to 5 mL of the above dispersion and mixed evenly, and then nitrogen is introduced to remove oxygen to obtain a mixed solution; the mixed solution is injected into a glass capillary with a diameter of 2.0 mm and one end is sealed, and then a silanized glass capillary with a diameter of 1.0 mm and one end is sealed is inserted into the glass capillary with one end sealed, and a raw rubber is used to prepare the mixed solution; The gap between a glass capillary with one end sealed and a silanized glass capillary with the other end sealed was sealed to isolate the air, and a polymerization reaction was carried out in a constant temperature water bath at 60°C for 24 hours. After the polymerization reaction, the glass capillary with one end sealed was removed to obtain a fiber; the vinyl covalent organic framework coating on the fiber was shortened to 1.8 cm, and then the unreacted solvent was eluted by magnetic stirring in a mixed solution of methanol and acetic acid (methanol: acetic acid = 9:1, v / v) to obtain a vinyl covalent organic framework solid phase microextraction fiber coating with a coating length of 18 mm.

[0120] Test Example 1

[0121] High performance liquid chromatography was used to analyze five bisphenol compounds with concentrations of 0.02 mg / L, 0.05 mg / L, 0.1 mg / L, 0.2 mg / L, 0.5 mg / L, 1 mg / L, 2 mg / L, 5 mg / L, and 10 mg / L, including bisphenol F, bisphenol S, bisphenol A, bisphenol B, and bisphenol AF. The chromatographic conditions were as follows: the chromatographic column was a C18 column, the mobile phase was acetonitrile: water = 50:50 (v / v), the flow rate was 1 mL / min, the column temperature was 30°C, the injection volume was 20 μL, the detection wavelength was 230 nm, and standard working curves for the five bisphenol compounds were established. The results are shown in Table 1.

[0122] Table 1. Standard working curves of five bisphenol compounds

[0123]

[0124] The solid phase microextraction fiber coatings obtained in Examples 1 to 5 and Comparative Example 1 were used to extract five bisphenol compounds, respectively. The specific process includes the following steps: 50 mL and 50 μg / L of aqueous solutions of five bisphenol compounds were added to the extraction bottle, respectively, and a stirring bar was placed. The upper ends of the solid phase microextraction fiber coatings obtained in Examples 1 to 5 and Comparative Example 1 were fixed with screw caps with silica gel gaskets, respectively, so that the other parts of the solid phase microextraction fiber coatings were suspended in the solution, and the extraction bottle was placed on a stirring table, and the extraction was stirred for 150 minutes; then ultrasonic desorption was performed in 250 μL of chromatographic grade methanol for 3 minutes; the desorbed liquid was taken and analyzed by a high performance liquid chromatograph. The conditions for liquid chromatography analysis were: the chromatographic column was a C18 column, the mobile phase was acetonitrile: water = 50:50 (v / v), the flow rate was 1 mL / min, the column temperature was 30°C, the injection volume was 20 μL, and the detection wavelength was 230 nm. The chromatographic results are as follows: Figures 1 to 6 shown.

[0125] Figure 1 This is a chromatogram of the extraction effect of the solid phase microextraction fiber coating of comparative example 1 on five bisphenol compounds. The results show that the extraction amounts of bisphenol F, bisphenol S, bisphenol A, bisphenol B and bisphenol AF by the solid phase microextraction fiber coating of comparative example 1 are 0.3856, 0.2496, 0.2804, 0.3134 and 0.4122 μg, respectively, indicating that the vinyl covalent organic framework has a certain extraction effect on bisphenol pollutants, but the extraction amount is small and there is still room for improvement.

[0126] Figure 2The injection chromatograms of the extraction effects of the solid phase microextraction fiber coating of Example 1 on five bisphenol compounds show that the extraction amounts of bisphenol F, bisphenol S, bisphenol A, bisphenol B, and bisphenol AF by the solid phase microextraction fiber coating of Example 1 are 1.1674, 1.2489, 1.4056, 1.5833, and 1.9819 μg, respectively, which are 3.03, 5.00, 5.01, 5.05, and 4.80 times of the unmodified vinyl covalent organic framework solid phase microextraction fiber coating of Comparative Example 1. This shows that the introduction of cyclodextrin molecules into the porous structure of the covalent organic framework by the thiol-ene click reaction can significantly improve the extraction performance of the covalent organic framework.

[0127] Figure 3 The injection chromatograms of the extraction effects of the solid phase microextraction fiber coating of Example 2 on five bisphenol compounds show that the extraction amounts of bisphenol F, bisphenol S, bisphenol A, bisphenol B, and bisphenol AF by the solid phase microextraction fiber coating of Example 2 are 0.9326, 1.1014, 1.3543, 1.5585, and 1.5194 μg, respectively, which are 2.42, 4.41, 4.84, 4.97, and 3.67 times of the unmodified vinyl covalent organic framework solid phase microextraction fiber coating of Comparative Example 1. This shows that the introduction of reduced glutathione into the porous structure of the covalent organic framework by the thiol-ene click reaction can significantly improve the extraction performance of the covalent organic framework.

[0128] Figure 4 The injection chromatograms of the extraction effects of the solid phase microextraction fiber coating of Example 3 on five bisphenol compounds show that the extraction amounts of bisphenol F, bisphenol S, bisphenol A, bisphenol B, and bisphenol AF by the solid phase microextraction fiber coating of Example 3 are 0.4075, 0.3865, 0.4441, 0.5043, and 0.6416 μg, respectively, which are 1.06, 1.55, 1.58, 1.61, and 1.56 times of the unmodified vinyl covalent organic framework solid phase microextraction fiber coating of Comparative Example 1. This shows that the introduction of L-cysteine ​​into the porous structure of the covalent organic framework by the thiol-ene click reaction can significantly improve the extraction performance of the covalent organic framework.

[0129] Figure 5The injection chromatograms of the extraction effects of the solid phase microextraction fiber coating of Example 4 on five bisphenol compounds show that the extraction amounts of bisphenol F, bisphenol S, bisphenol A, bisphenol B, and bisphenol AF by the solid phase microextraction fiber coating of Example 4 are 1.0769, 1.0614, 1.3542, 1.3223, and 1.7167 μg, respectively, which are 2.79, 4.25, 4.83, 4.22, and 4.16 times of the unmodified vinyl covalent organic framework solid phase microextraction fiber coating of Comparative Example 1. This shows that the introduction of 1,2-ethanedithiol into the porous structure of the covalent organic framework by the thiol-ene click reaction can significantly improve the extraction performance of the covalent organic framework.

[0130] Figure 6 The injection chromatograms of the extraction effects of the solid phase microextraction fiber coating of Example 5 on five bisphenol compounds show that the extraction amounts of bisphenol F, bisphenol S, bisphenol A, bisphenol B, and bisphenol AF by the solid phase microextraction fiber coating of Example 5 are 0.8354, 1.1427, 1.3520, 1.5769, and 1.9527 μg, respectively, which are 2.17, 4.58, 4.82, 5.03, and 4.74 times of the unmodified vinyl covalent organic framework solid phase microextraction fiber coating of Comparative Example 1. This shows that the introduction of 4-vinylbenzeneboronic acid into the porous structure of the covalent organic framework by the thiol-ene click reaction can significantly improve the extraction performance of the covalent organic framework.

[0131] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a covalent organic framework solid phase microextraction fiber coating modified by a thiol-ene click reaction, characterized in that: The following steps are involved: (1) mixing a covalent organic framework, a derivatization reagent, a first initiator and a first solvent, and performing a click reaction under a protective atmosphere to obtain a post-modified covalent organic framework; (2) mixing the post-modified covalent organic framework, the cross-linking agent, the second initiator and the second solvent described in step (1), and performing a polymerization reaction under a protective atmosphere to obtain a covalent organic framework solid phase microextraction fiber coating modified by a thiol-ene click reaction; Wherein, the covalent organic framework in step (1) comprises a vinyl covalent organic framework or a covalent organic framework post-modified with 1,2-ethanedithiol; The derivatization reagent in step (1) includes mono(6-mercapto-6-deoxy)-β-cyclodextrin, L-cysteine, reduced glutathione, 1,2-ethanedithiol or 4-vinylphenylboronic acid.

2. The preparation method according to claim 1, characterized in that: The structure of the vinyl covalent organic skeleton is shown in Formula I: The structure of the covalent organic framework post-modified with 1,2-ethanedithiol is shown in Formula II:

3. The preparation method according to claim 1 or 2, characterized in that: In step (1), when the derivatization agent is solid, the mass ratio of the covalent organic framework, the derivatization agent and the first initiator is 100-500 mg: 600 mg-3 g: 50 mg; When the derivatization reagent is a liquid, the ratio of the mass of the covalent organic framework, the volume of the derivatization reagent and the mass of the first initiator is 100-500 mg: 4-20 mL: 50 mg.

4. The preparation method according to claim 3, characterized in that: In step (1), when the derivatization agent is mono(6-mercapto-6-deoxy)-β-cyclodextrin, the covalent organic framework is a vinyl covalent organic framework, and the first solvent is trifluorotoluene; When the derivatization agent is L-cysteine ​​or reduced glutathione, the covalent organic skeleton is a vinyl covalent organic skeleton, and the first solvent is dimethyl sulfoxide; When the derivatization agent is 1,2-ethanedithiol, the covalent organic skeleton is a vinyl covalent organic skeleton, and the first solvent is 1,2-ethanedithiol; When the derivatization agent is 4-vinylphenylboronic acid, the covalent organic framework is a covalent organic framework post-modified with 1,2-ethanedithiol, and the first solvent is dimethyl sulfoxide; Step (1) The first initiator includes azobisisobutyronitrile, azobismethylvaleronitrile or 4,4'-azo(4-cyanovaleric acid).

5. The preparation method according to claim 1 or 4, characterized in that: In step (1), the temperature of the click reaction is 70 to 80° C. and the time is 12 to 48 hours.

6. The preparation method according to claim 1, characterized in that: The crosslinking agent in step (2) includes ethylene glycol dimethacrylate, trimethylolpropane triacrylate or divinylbenzene; the second initiator in step (2) includes azobisisobutyronitrile, azodimethylvaleronitrile or 4,4'-azo(4-cyanovaleric acid); the second solvent in step (2) includes one or more of dimethyl sulfoxide, methanol, acetonitrile and dichloromethane.

7. The preparation method according to claim 1 or 6, characterized in that: In step (2), in the mixture of the post-modified covalent organic framework and the second solvent, the mass concentration of the post-modified covalent organic framework is 10 to 50 mg / L; the ratio of the volume of the mixture of the post-modified covalent organic framework and the second solvent, the volume of the cross-linking agent and the mass of the second initiator is 5 mL: 0.5 to 2.5 mL: 20 to 50 mg.

8. The preparation method according to claim 7, characterized in that: In step (2), the polymerization reaction temperature is 45 to 80° C. and the reaction time is 12 to 25 hours.

9. A covalent organic framework solid phase microextraction fiber coating modified by a thiol-ene click reaction obtained by the preparation method according to any one of claims 1 to 8.

10. Use of the covalent organic framework solid phase microextraction fiber coating modified by thiol-ene click reaction according to claim 9 in solid phase microextraction.

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