A Preparation Method of In-Situ Growing Nitro-Functionalized Microporous Organic Network Solid-Phase Microextraction Fiber Coating

Abstract

The present invention provides a preparation method for an in-situ grown nitro-functionalized microporous organic network solid-phase microextraction fiber coating. The nitro-functionalized microporous organic network solid-phase microextraction fiber coating is prepared by modifying the surface of a hydroxylated fiber substrate with a thiol-containing silanization reagent, and then allowing an alkynyl-containing aromatic monomer to undergo a "thiol-alkyne" click reaction with its thiol group. An aryl halide is added to the system, and after stirring evenly, under the catalytic action of bis(triphenylphosphine)palladium dichloride and copper iodide, the growth of the microextraction fiber coating is carried out through an in-situ polymerization reaction. The nitro-functionalized microporous organic network solid-phase microextraction fiber coating prepared by the present invention has a simple preparation process and strong thermal stability; the fiber coating has a uniform thickness and a loose and porous surface, with a large specific surface area and a fast mass transfer rate; the functionalized coating enriches the interaction mechanism with the analyte, improves the adsorption capacity, and can be applied to the technical field of solid-phase microextraction sample pretreatment.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical analysis and detection and sample pretreatment, and specifically relates to a preparation method of an in-situ grown nitro-functionalized microporous organic network solid-phase microextraction fiber coating. Background Art

[0002] As one of the mainstream technologies in the field of sample pretreatment, solid-phase microextraction (SPME) technology integrates extraction, enrichment, and purification, and has the advantages of being fast, efficient, and easy to be coupled with instruments. It has been widely used in the efficient extraction, separation, and enrichment of trace target components in the fields of environment, food, and biomedicine. During the SPME process, the fiber coating material is one of the key factors to improve the extraction ability of the target analyte. In the past thirty-odd years, different types of solid-phase microextraction coatings have been developed and prepared, but analysts are still striving to explore new coating materials, such as new coating materials with higher extraction ability and faster mass transfer rate.

[0003] As a class of emerging porous materials, microporous organic network materials are constructed by the Sonogashira coupling reaction of aromatic alkynes and halides, and have advantages such as a large specific surface area, good solvent and thermal stability, adjustable porosity, and excellent designability. On the other hand, microporous organic network materials have good hydrophobicity due to the conjugated aromatic skeletons in their structures, and can interact with aromatic compounds through hydrophobic interaction, π-π interaction, etc., endowing them with the application potential as solid-phase microextraction fiber coatings for the extraction and enrichment of aromatic compounds in complex samples. However, the application of microporous organic network materials in the field of solid-phase microextraction is still in its infancy, and there are no relevant reports on the preparation of microporous organic network fiber coatings by in-situ growth. Therefore, it is very necessary and challenging to design and develop an in-situ grown microporous organic network microextraction fiber coating for expanding its application in the field of sample pretreatment. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method of an in-situ grown nitro-functionalized microporous organic network solid-phase microextraction fiber coating, so as to obtain a microextraction fiber coating with a loose and porous surface, a large specific surface area, a fast mass transfer rate, good thermal stability, and a uniform thickness. Applying this fiber coating to the field of solid-phase microextraction can expand its application in the field of sample pretreatment.

[0005] The present invention is realized as follows:

[0006] A preparation method of an in-situ grown nitro-functionalized microporous organic network solid-phase microextraction fiber coating. First, the extraction fiber filament is hydroxylated with a strong acid, and then the hydroxylated extraction fiber filament is modified with a mercapto-silylating reagent in N,N-dimethylformamide to obtain a mercapto-modified extraction fiber filament. Using the mercapto-modified extraction fiber filament as the substrate and a mixed solvent of toluene and triethylamine as the reaction solvent, under the action of an azobisisobutyronitrile initiator, an extraction fiber filament modified with an alkynyl aromatic monomer is prepared through a "thiol-ene" click reaction (i.e., covalently grafting the alkynyl aromatic monomer onto the surface of the extraction fiber filament). Then, using a nitro-aromatic halide as the functional monomer, copper iodide and bis(triphenylphosphine)palladium dichloride as catalysts, and a mixed solvent of toluene and triethylamine as the reaction solvent, a nitro-functionalized microporous organic network solid-phase microextraction fiber coating is prepared by in-situ polymerization through the Sonogashira coupling reaction.

[0007] The specific steps of the above solution are as follows:

[0008] (1) Immerse the extraction fiber filament in a strongly corrosive acid solution such as hydrofluoric acid or aqua regia for 5 - 10 min, then ultrasonically clean it with carbon tetrachloride, acetone, and methanol for 10 - 20 min respectively, and finally dry it at 80 °C.

[0009] (2) Mix the extraction fiber filament after hydroxylation with a strong acid and a mixed solvent of a mercapto-silylating reagent - N,N-dimethylformamide thoroughly under stirring at 60 - 80 °C and carry out a silylation reaction to obtain an extraction fiber filament with mercapto groups on its surface.

[0010] (3) Insert the extraction fiber filament obtained in step (2) into a toluene - triethylamine mixed solvent dissolving azobisisobutyronitrile and an alkynyl aromatic monomer, deoxygenate it, and carry out a "thiol-ene" click reaction at 70 - 90 °C under nitrogen protection for 24 - 36 h to obtain an extraction fiber filament with an alkynyl aromatic monomer on its surface.

[0011] (4) Add copper iodide, bis(triphenylphosphine)palladium dichloride, and a nitro-aromatic halide to a toluene - triethylamine mixed solvent, ultrasonically disperse them evenly, then immerse the extraction fiber filament with an alkynyl aromatic monomer on its surface into the above mixed solution, and carry out an in-situ polymerization reaction at 60 - 80 °C in a sealed environment for 12 - 24 h to obtain a nitro-functionalized microporous organic network solid-phase microextraction fiber coating.

[0012] In the above solution, in step (2), the silylation reaction is carried out under a magnetic stirring speed of 200 - 600 r / min.

[0013] In the above solution, in step (3), deoxygenation is achieved through the following steps: Insert the needle filled with nitrogen into the liquid surface and purge for 10 - 15 minutes.

[0014] In the above solution, in step (4), when the extraction fiber filament with alkynyl aromatic monomer on the surface is immersed in the mixed solution for in-situ polymerization reaction, the system is in a non-stirred state.

[0015] In the above solution, in step (2), the mercapto-silane coupling agent is (3-mercaptopropyl)trimethoxysilane; the volume ratio of the mercapto-silane coupling agent to N,N-dimethylformamide is 1:14 - 1:5.

[0016] In the above solution, in steps (3) and (4), the volume of toluene in the toluene - triethylamine mixed solvent is 1 - 3 times that of triethylamine.

[0017] In the above solution, in step (3), the concentration of the alkynyl aromatic monomer is 4.8 - 9.6 μmol / mL, and in step (4), the concentration of the nitroaromatic halide is 9.6 μmol / mL; the molar ratio of the alkynyl aromatic monomer is 0.5 - 1 times that of the nitroaromatic halide.

[0018] In the above solution, in step (3), the alkynyl aromatic monomer is tris(4-ethynylphenyl)amine, and in step (4), the nitroaromatic halide is 4,4'-dibromo-2,2'-dinitrobiphenyl.

[0019] In the above solution, in step (4), the concentration of cuprous iodide is 1 μmol / mL, the concentration of bis(triphenylphosphine)palladium dichloride is 1 μmol / mL, and the molar ratio of cuprous iodide to bis(triphenylphosphine)palladium dichloride is 1:1.

[0020] The nitro-functionalized microporous organic network solid-phase microextraction fiber coating prepared by the present invention can be used as a novel extraction fiber coating in the field of sample pretreatment, for example, it has the application potential of efficiently extracting and enriching aromatic compounds.

[0021] From the above technical solutions, it can be seen that compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The present invention prepares a nitro-functionalized microporous organic network solid-phase microextraction fiber coating through covalent grafting modification and in-situ polymerization reaction of the microporous organic network. The obtained fiber coating has good mechanical stability and thermal stability, and improves the service life of the extraction fiber.

[0023] (2) The nitro-functionalized microporous organic network solid-phase microextraction fiber coating prepared by the in-situ polymerization reaction of the present invention has a large specific surface area and exhibits a through-porous structure, which is beneficial to improving the mass transfer rate of the analyte, and the coating thickness is uniform, which is beneficial to improving the reproducibility of the analysis.

[0024] (3) The conjugated structure and nitro functional groups contained in the nitro-functionalized microporous organic network solid-phase microextraction fiber coating prepared by the present invention can generate interaction forces with the analyte through hydrophobic interaction, π-π stacking and hydrogen bond interaction, and can exhibit high-efficiency enrichment ability for aromatic compounds. Description of the Drawings

[0025] Figure 1 Scanning electron microscope images of the overall view (A), partial view (B) and cross-sectional view (C) of the nitro-functionalized microporous organic network solid-phase microextraction fiber coating in Example 1.

[0026] Figure 2 Elemental analysis diagram of the nitro-functionalized microporous organic network solid-phase microextraction fiber coating in Example 1, composite element distribution diagram (A), C element distribution diagram (B), N element distribution diagram (C), O element distribution diagram (D) and Br element distribution diagram (E).

[0027] Figure 3 Infrared spectrum diagram of the nitro-functionalized microporous organic network solid-phase microextraction fiber coating in Example 1.

[0028] Figure 4 Contact angle experiment diagram of the nitro-functionalized microporous organic network solid-phase microextraction fiber coating in Example 1.

[0029] Figure 5 Thermogravimetric analysis diagram of the nitro-functionalized microporous organic network solid-phase microextraction fiber coating in Example 1. Detailed Description of the Invention

[0030] The following further elaborates on the present invention in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0031] The present invention will be introduced in detail below with specific examples.

[0032] Example 1

[0033] A preparation method for in-situ growing a nitro-functionalized microporous organic network solid-phase microextraction fiber coating.

[0034] (1) Select stainless steel wire as the extraction fiber. The front end of the extraction fiber (2 cm) is corroded with aqua regia for 5 min. After washing with pure water, it is assembled with a 5 μL micro-syringe, and then ultrasonically cleaned with carbon tetrachloride, acetone, and methanol for 10 min respectively. Finally, it is dried overnight at 80 °C for standby.

[0035] (2) The treated extraction fiber is inserted into a mixed solvent of (3-mercaptopropyl)trimethoxysilane - N,N-dimethylformamide (1:14, v / v, 30 mL in total), and a silanization reaction is carried out for 24 h under stirring conditions at 80 °C (magnetic stirring speed 200 r / min) to obtain an extraction fiber with a thiol group on its surface (i.e., the thiol-modified extraction fiber).

[0036] (3) The extraction fiber with a thiol group on its surface is immersed in a mixed solvent of toluene - triethylamine (1:1, v / v, 10 mL in total) dissolved with 0.1 mmol of azobisisobutyronitrile and 0.048 mmol of tris(4-ethynylphenyl)amine. After purging oxygen with nitrogen for 15 min, a "thiol-alkyne" click reaction is carried out at 80 °C under nitrogen protection for 24 h to obtain an extraction fiber with alkynyl aromatic monomers on its surface.

[0037] (4) Take out the extraction fiber, weigh 0.096 mmol of 4,4'-dibromo-2,2'-dinitrobiphenyl and ultrasonically disperse and dissolve it in a mixed solvent of toluene - triethylamine (1:1, v / v, 10 mL in total). Then add 0.01 mmol of copper iodide and 0.01 mmol of bis(triphenylphosphine)palladium dichloride, mix and stir to dissolve, and then insert the extraction fiber. An in-situ polymerization reaction is carried out at 80 °C for 12 h in a sealed environment (reaction in a static state), and finally a nitro-functionalized microporous organic network solid-phase microextraction fiber coating is obtained.

[0038] Example 2

[0039] Characterize the nitro-functionalized microporous organic network solid-phase microextraction fiber coating obtained in Example 1.

[0040] The morphology and structure of the nitro-functionalized microporous organic network solid-phase microextraction fiber coating are characterized by scanning electron microscopy, as Figure 1 shown, which are the overall view of the in-situ grown nitro-functionalized microporous organic network solid-phase microextraction fiber coating ( Figure 1 A), the local view of the nitro-functionalized microporous organic network solid-phase microextraction fiber coating ( Figure 1 B), and the cross-sectional view of the nitro-functionalized microporous organic network solid-phase microextraction fiber coating ( Figure 1 C). From Figure 1 A and Figure 1It can be seen that the surface coating of the nitro-functionalized microporous organic network solid-phase microextraction fiber coating grows uniformly and the coating presents an interconnected porous structure, which is beneficial to the internal mass transfer of target molecules and the coating material, and helps the rapid adsorption and desorption of analytes. Figure 1 In C, the coating shows a uniform thickness of 5 μm. The uniform thickness is beneficial to the reproducibility of the fiber coating in use on the one hand, and on the other hand, the thinner coating is also beneficial to further improving the mass transfer rate.

[0041] The specific surface area of the nitro-functionalized microporous organic network solid-phase microextraction fiber coating was calculated by the Barret-Joyner-Halenda method to be 214.7 m 2 g -1 , and the large specific surface area increases the adsorption capacity of the coating, which is beneficial to improving the extraction efficiency of the coating. Elemental analysis was used to analyze the C, N, O, and Br elements of the nitro-functionalized microporous organic network solid-phase microextraction fiber coating. As Figure 2 shown, the four elements of C, N, O, and Br are evenly distributed in the fiber coating polymer, indicating the successful preparation of the nitro-functionalized microporous organic network fiber coating.

[0042] Figure 3 It is the infrared spectrum diagram of the nitro-functionalized microporous organic network solid-phase microextraction fiber coating in Example 1. Among them, the absorption peak at 2200 cm -1 is attributed to the stretching vibration of the triple bond binary substitution; the absorption peaks at 1531 cm -1 and 1346 cm -1 are respectively attributed to the asymmetric and symmetric stretching vibrations of the aromatic nitro (-NO2); the strong absorption peak at 1498 cm -1 is attributed to the C=C stretching vibration on the benzene ring; the absorption peak at 831 cm -1 is attributed to the out-of-plane bending vibration of -CH on the benzene ring. These groups are all derived from 4,4'-dibromo-2,2'-dinitrobiphenyl and tris(4-ethynylphenyl)amine. The above results indicate that the nitro-functionalized microporous organic network microextraction fiber coating was successfully in-situ grown and prepared on the surface of the extraction fiber filament.

[0043] Figure 4 It is the contact angle experiment diagram of the nitro-functionalized microporous organic network solid-phase microextraction fiber coating in Example 1. Its contact angle is 140 degrees, and it can be clearly observed that the water droplet suspends on the surface of the nitro-functionalized microporous organic network material. The results show that it has strong hydrophobicity and is expected to interact with non-polar targets through hydrophobic interaction, enriching the adsorption mechanism of the coating for non-polar targets.

[0044] Figure 5The figure shows the thermogravimetric analysis diagram of the nitro-functionalized microporous organic network solid-phase microextraction fiber coating prepared in Example 1. Under a high-purity argon environment, it was heated from 30 °C to 800 °C at a rate of 10 °C min -1 to characterize the thermal stability of the material. The mass loss at 100 °C can be attributed to the evaporation of physically adsorbed water molecules, and the slight mass loss at 300 °C can be attributed to the degradation of some oxygen-containing functional groups (-NO2). The thermogravimetric analysis results show that the nitro-functionalized microporous organic network material has good thermal stability within 310 °C and has the potential to be applied to the solid-phase microextraction fiber coating.

[0045] Example 3

[0046] A preparation method for in-situ growing a nitro-functionalized microporous organic network solid-phase microextraction fiber coating.

[0047] (1) Select a stainless steel wire as the extraction fiber wire. The front end of the extraction fiber wire, 2 cm in length, is corroded with aqua regia for 8 min. After being washed with pure water, it is assembled with a 5 μL microsyringe, and then ultrasonically cleaned with carbon tetrachloride, acetone, and methanol for 15 min respectively. Finally, it is dried overnight at 80 °C for standby.

[0048] (2) The treated extraction fiber wire is inserted into a (3-mercaptopropyl)trimethoxysilane-N,N-dimethylformamide mixed solvent (1:14, v / v, a total of 30 mL), and a silanization reaction is carried out for 24 h under stirring conditions at 70 °C (magnetic stirring speed 300 r / min) to obtain an extraction fiber wire with a thiol group on its surface.

[0049] (3) The extraction fiber wire with a thiol group on its surface is immersed in a toluene-triethylamine mixed solvent (1:1, v / v, a total of 10 mL) dissolved with 0.1 mmol of azobisisobutyronitrile and 0.048 mmol of tris(4-ethynylphenyl)amine. After purging oxygen with nitrogen for 10 min, a "thiol-yne" click reaction is carried out at 90 °C under nitrogen protection for 30 h to obtain an extraction fiber wire with alkynyl aromatic monomers on its surface.

[0050] (4) The extraction fiber wire is taken out, 0.096 mmol of 4,4'-dibromo-2,2'-dinitrobiphenyl is ultrasonically dispersed and dissolved in a toluene-triethylamine mixed solvent (1:1, v / v, a total of 10 mL), then 0.01 mmol of copper iodide and 0.01 mmol of bis(triphenylphosphine)palladium dichloride are added. After mixing and stirring to dissolve, the extraction fiber wire is inserted, and an in-situ polymerization reaction is carried out at 60 °C for 24 h (reaction in a static state) in a sealed environment, and finally a nitro-functionalized microporous organic network solid-phase microextraction fiber coating is obtained.

[0051] The performance of the nitro-functionalized microporous organic network solid-phase microextraction fiber coating prepared in this example is the same as that of the material obtained in Example 1.

Claims

1. A preparation method of an in-situ grown nitro-functionalized microporous organic network solid-phase microextraction fiber coating, characterized in that, First, the extraction fiber filaments are hydroxylated with strong acid, and then modified with a mercapto-containing silanization reagent in N,N-dimethylformamide to obtain mercapto-modified extraction fiber filaments; using the mercapto-modified extraction fiber filaments as the substrate, with a mixed solvent of toluene and triethylamine as the reaction solvent, under the action of an azobisisobutyronitrile initiator, the extraction fiber filaments modified with alkynyl aromatic monomers are prepared through a "thiol-ene" click reaction, and then using nitroaromatic halides as functional monomers, with cuprous iodide and bis(triphenylphosphine)palladium dichloride as catalysts, and with a mixed solvent of toluene and triethylamine as the reaction solvent, a nitro-functionalized microporous organic network solid-phase microextraction fiber coating is prepared by in-situ polymerization; The preparation method of the in-situ grown nitro-functionalized microporous organic network solid-phase microextraction fiber coating specifically includes the following steps: (1) Soak the extraction fiber filaments with hydrofluoric acid or aqua regia for 5 - 10 min, then ultrasonically clean them with carbon tetrachloride, acetone, and methanol for 10 - 20 min respectively, and finally dry them at 80 °C; (2) Mix the extraction fiber filaments in step (1) with a mercapto-containing silanization reagent - N,N-dimethylformamide mixed solvent and stir evenly at 60 - 80 °C to carry out the silanization reaction to obtain extraction fiber filaments with mercapto groups on the surface; (3) Insert the extraction fiber filaments obtained in step (2) into a toluene - triethylamine mixed solvent dissolved with azobisisobutyronitrile and alkynyl aromatic monomers, and carry out the "thiol-ene" click reaction at 70 - 90 °C under nitrogen protection after deoxygenation to obtain extraction fiber filaments with alkynyl aromatic monomers on the surface; (4) Add cuprous iodide, bis(triphenylphosphine)palladium dichloride, and nitroaromatic halides into the toluene - triethylamine mixed solvent, ultrasonically disperse them evenly, then immerse the extraction fiber filaments obtained in step (3) into it, and carry out an in-situ polymerization reaction at 60 - 80 °C in a sealed environment to obtain a nitro-functionalized microporous organic network solid-phase microextraction fiber coating; In step (3), the concentration of the alkynyl aromatic monomer is 4.8 - 9.6 μmol / mL, and in step (4), the concentration of the nitroaromatic halide is 9.6 μmol / mL; the molar ratio of the alkynyl aromatic monomer is 0.5 - 1 times that of the nitroaromatic halide; In step (3), the alkynyl aromatic monomer is tris(4-ethynylphenyl)amine, and in step (4), the nitroaromatic halide is 4,4'-dibromo-2,2'-dinitrobiphenyl.

2. The preparation method of the in-situ grown nitro-functionalized microporous organic network solid-phase microextraction fiber coating according to claim 1, characterized in that, In step (2), the silanization reaction is carried out under the condition of a magnetic stirring speed of 200 - 600 r / min.

3. The preparation method of the in-situ grown nitro-functionalized microporous organic network solid-phase microextraction fiber coating according to claim 1, characterized in that, In step (3), deoxygenation is achieved through the following steps: Insert the needle filled with nitrogen into the liquid surface and purge for 10 - 15 min.

4. The preparation method of the in-situ grown nitro-functionalized microporous organic network solid-phase microextraction fiber coating according to claim 1, characterized in that, In step (2), the mercapto-containing silanization reagent is (3-mercaptopropyl)trimethoxysilane; the volume ratio of the mercapto-containing silanization reagent to N,N-dimethylformamide is 1:14 - 1:

5.

5. The preparation method of the in-situ grown nitro-functionalized microporous organic network solid-phase microextraction fiber coating according to claim 1, characterized in that, In steps (3) and (4), the volume of toluene in the toluene-triethylamine mixed solvent is 1 to 3 times that of triethylamine.

6. The preparation method of the in-situ grown nitro-functionalized microporous organic network solid-phase microextraction fiber coating according to claim 1, characterized in that, In step (4), the concentration of cuprous iodide is 1 μmol / mL, and the concentration of bis(triphenylphosphine)palladium dichloride is 1 μmol / mL.

7. The preparation method of the in-situ grown nitro-functionalized microporous organic network solid-phase microextraction fiber coating according to claim 1, characterized in that, The reaction time in step (3) is 24 to 36 h, and the reaction time in step (4) is 12 to 24 h.

Images