A method for preparing a dimethylamino-containing functionalized covalent organic framework material

Abstract

A functionalized covalent organic framework material containing dimethylamino and its preparation method are disclosed. This invention relates to a C2-type aldehyde monomer containing a dimethylamino functional group and a functionalized covalent organic framework material containing dimethylamino and its preparation method. The purpose of this invention is to solve the problems of insufficient functionalized monomers, easy pore blockage leading to decreased specific surface area, and insufficient selectivity and pH responsiveness in existing COF materials used for the adsorption and separation of biomolecules such as peptides. The method includes: 1. Weighing; 2. Anhydrous and anaerobic reaction; 3. Filtration; 4. Column chromatography purification; 5. Drying; 6. Weighing; 7. Anhydrous and anaerobic reaction; 8. Washing; 9. Deep washing with a Soxhlet extractor; 10. Drying and grinding. The invention innovatively introduces a new monomer with a basic recognition site, and through a "bottom-up" strategy, directly and uniformly introduces the dimethylamino functional group into the COF framework. The material exhibits good crystallinity and a high specific surface area (up to 2481 m²). 2 ( / g), and has significant pH responsiveness.

Description

Technical Field

[0001] This invention belongs to the field of organic porous materials technology, specifically relating to a novel C2-type aldehyde monomer containing a dimethylamino functional group, its preparation method, and functionalized covalent organic framework materials containing dimethylamino prepared from the monomer. Background Technology

[0002] Nanoporous materials play an irreplaceable role in gas storage, separation engineering, heterogeneous catalysis, and environmental pollutant enrichment due to their huge specific surface area, abundant pore structure, and tunable physicochemical properties. While traditional nanoporous materials such as zeolites and activated carbon are widely used, their wide pore size distribution or difficult structural modification makes it challenging to achieve precise recognition and efficient adsorption of specific complex molecules.

[0003] As a novel type of crystalline porous material, covalent organic frameworks (COFs) have attracted widespread attention in recent years. COFs not only inherit the high specific surface area advantage of traditional porous materials, but also possess unique advantages such as strong structural designability, ease of functionalization, and low density. This makes COFs demonstrate great potential in solving the separation and analysis of complex mixtures (such as chromatographic stationary phases and solid-phase extraction adsorbents). In recent years, researchers have developed various COF materials for molecular adsorption separation by utilizing the unique pore confinement effect and the interactions between the framework and guest molecules (such as hydrogen bonding, π-π stacking, and electrostatic interactions). However, research on the selective recognition and separation of biomacromolecules (especially peptides) using COF materials remains relatively limited. In 2024, Chen et al. (Chen, Y., He, Q., Liu, Y., et al. Analytica Chimica Acta, 1287, 342061.) reported a size-controlled synthesis method for large-sized spherical three-dimensional COFs (COF-320 and COF-300) and successfully applied it to the online solid-phase extraction of bisphenol F (BPF). This study achieved precise control of COF particle size by controlling the synthesis conditions and verified its effectiveness in the enrichment and separation of small molecule pollutants. However, this study mainly focused on the adsorption of small molecule organic pollutants and did not involve application research on biomacromolecules such as peptides.

[0004] Current research on COFs materials for peptide separation still faces the following major challenges: First, there is a lack of functionalized monomers. Existing commercial COFs have a limited variety of monomers, particularly lacking functionalized aldehyde monomers containing specific recognition sites (such as basic groups, hydrophilic / hydrophobic groups), making it difficult to achieve selective recognition of peptides. Second, pH responsiveness is insufficient. Peptide compounds typically exhibit different charge states and solubilities under different pH conditions. Existing COFs materials lack effective pH-responsive functional groups, making it impossible to achieve selective adsorption and controlled release of peptides in complex biological matrices. Furthermore, designing recognition sites is difficult: traditional COFs functionalization modifications usually require post-synthetic modifications, which are cumbersome and prone to causing pore blockage and a decrease in specific surface area. Introducing functional recognition sites (such as basic groups like dimethylamino) into the COF backbone from the bottom up while maintaining high crystallinity and open pores remains a technical challenge. Finally, the application scope is limited; currently reported functionalized COFs are mostly used for the adsorption and separation of small molecule pollutants or gases, with limited research on the selective enrichment and separation of biomacromolecules (such as peptides and proteins), restricting the expansion of COF materials' applications in bioanalysis and life sciences. Therefore, developing novel functionalized COF materials containing specific functional groups (such as basic recognition sites like dimethylamino) to achieve highly selective recognition and pH-responsive adsorption of peptides in complex matrices has significant scientific and practical value. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a novel C2-type aldehyde monomer containing a dimethylamino functional group and its preparation method. Another purpose of this invention is to provide a functionalized covalent organic framework material prepared using this monomer, which has high specific surface area, good crystallinity, and pH responsiveness.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing a C2-type aldehyde monomer containing a dimethylamino functional group, comprising the following steps:

[0008] Step 1: Weigh 2,5-dibromo-terephthalaldehyde, 4-(N,N-dimethylamino)phenylboronic acid pinacol ester, potassium carbonate, and tetra(triphenylphosphine)palladium in a molar ratio of 1:(2.0-2.5):(5-8):(0.03-0.08) and add them to the reaction solvent. The mass ratio of the reaction solvent to 2,5-dibromo-terephthalaldehyde is (800-1200):1. The reaction solvent is one or more of 1,4-dioxane, toluene, N,N-dimethylformamide, tetrahydrofuran, or water.

[0009] Step 2: Place the mixture from Step 1 in an anaerobic environment and react at 75–95°C for 36–60 h;

[0010] Step 3: After the reaction is complete, cool and filter the mixture to obtain the crude product;

[0011] Step 4: The crude product is purified by column chromatography. The eluent is a mixed solvent of dichloromethane, petroleum ether and triethylamine, with a volume ratio of (70-80):(20-30):(2-5).

[0012] Step 5: Collect the purified components, evaporate the solvent, and vacuum dry at 30-50℃ for 8-15 h to obtain the C2 type aldehyde monomer containing the dimethylamino functional group.

[0013] Secondly, this invention provides a method for preparing a functionalized covalent organic framework material containing dimethylamino groups, comprising the following steps:

[0014] Step 6: Weigh 1,3,5-tris(4-aminophenyl)benzene, 2,5-dimethoxybenzene-1,4-dicarboxaldehyde and the above C2 type aldehyde monomers in a molar ratio of 4:(4-6):(0.5-2) and add them to a mixed system composed of a catalyst and a reaction solvent. The volume ratio of the catalyst to the reaction solvent is 1:(15-25). The catalyst is acetic acid or an aqueous solution of acetic acid, and the reaction solvent is one or more of n-butanol, o-dichlorobenzene, m-xylene, mesitylene or tetrahydrofuran.

[0015] Step 7: Place the mixture from Step 6 in an anaerobic environment and react at 100–130°C for 60–84 h;

[0016] Step 8: After the reaction is complete, cool and filter, and wash the product with tetrahydrofuran 4 to 8 times;

[0017] Step 9: Place the washed product in a Soxhlet extractor and wash with one or more of tetrahydrofuran, methanol, ethanol or acetone for 18–30 h.

[0018] Step 10: The product after step 9 is vacuum dried at 100-140°C for 18-30 h and then ground using an agate grinding bowl to obtain the functionalized covalent organic framework material containing dimethylamino.

[0019] The beneficial effects of this invention are:

[0020] 1. Monomer Innovation: For the first time, a C2-type aldehyde monomer containing dimethylamino group was designed and successfully synthesized. Its dimethylamino structure is stable under Schiff base reaction conditions and can be directly used as a building unit in COF synthesis, which greatly enriches the variety of functionalized COF monomers.

[0021] 2. Excellent material properties: The prepared functionalized COF material exhibits good crystallinity, a regular two-dimensional layered structure (characteristic diffraction peak at 2.77°), and a high BET specific surface area of ​​2481 m². 2 / g, with uniform pore size, providing an ideal adsorption space for guest molecules.

[0022] 3. High efficiency in functional integration: Through a one-step "bottom-up" strategy, the dimethylamino basic recognition site is directly and uniformly introduced into the COF backbone, avoiding the defects of post-modification, achieving a high-density and orderly distribution of functional groups, and endowing the material with excellent pH-responsive adsorption-release capabilities. Attached Figure Description

[0023] Figure 1 The 1H NMR spectrum of the C2-type aldehyde monomer containing the dimethylamino functional group prepared in Example 1.

[0024] Figure 2 The image shows the carbon NMR spectrum of the C2-type aldehyde monomer containing the dimethylamino functional group prepared in Example 1.

[0025] Figure 3 Fourier transform infrared spectrum of the C2 type aldehyde monomer containing dimethylamino functional group prepared in Example 1.

[0026] Figure 4 The powder X-ray diffraction pattern of the dimethylamino-containing functionalized covalent organic framework material prepared in Example 1 is shown.

[0027] Figure 5 Scanning electron microscope image of the dimethylamino-containing functionalized covalent organic framework material prepared in Example 1.

[0028] Figure 6 The nitrogen adsorption-desorption isotherm and pore size distribution of the dimethylamino-containing functionalized covalent organic framework material prepared in Example 1 are shown.

[0029] Figure 7 The graph shows the zeta potential changes of the dimethylamino-containing functionalized covalent organic framework material prepared in Example 1 in aqueous solutions at different pH values.

[0030] Figure 8 Scanning electron microscope image of the dimethylamino-containing functionalized covalent organic framework material prepared in Example 2.

[0031] Figure 9 Scanning electron microscope image of the dimethylamino-containing functionalized covalent organic framework material prepared in Example 3.

[0032] Figure 10The unit adsorption mass of the dimethylamino-containing functionalized covalent organic framework material prepared in Example 1 to growth hormone-releasing peptide-6 solutions at different pH values ​​in Example 4. Detailed Implementation

[0033] The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any combination of the specific embodiments.

[0034] Specific Implementation Method 1: This implementation method describes a method for preparing a C2-type aldehyde monomer containing a dimethylamino functional group and a functionalized covalent organic framework material containing a dimethylamino group, specifically carried out according to the following steps:

[0035] In a first aspect, the present invention provides a method for preparing a C2-type aldehyde monomer containing a dimethylamino functional group, comprising the following steps:

[0036] Step 1: Weigh 2,5-dibromo-terephthalaldehyde, 4-(N,N-dimethylamino)phenylboronic acid pinacol ester, potassium carbonate, and tetra(triphenylphosphine)palladium according to the molar ratio (1:2.2:6:0.05); then weigh the reaction solvent, with a mass ratio of reaction solvent to 2,5-dibromo-terephthalaldehyde of 1000:1;

[0037] Step 2: Mix the 2,5-dibromo-terephthalaldehyde, 4-(N,N-dimethylamino)phenylboronic acid pinacol ester, potassium carbonate, tetra(triphenylphosphine)palladium and reaction solvent weighed in Step 1 evenly. Use the Schlenk freeze-thaw method to ensure that the environment is under oxygen-free conditions. After three cycles of liquid nitrogen freezing-vacuuming-nitrogen purging, continue the reaction at 85°C under nitrogen-filled conditions for 48 h.

[0038] Step 3: After waiting for the reaction mixture from Step 2 to cool to room temperature, filter the reaction mixture to obtain the crude product;

[0039] Step 4: After removing the solvent from the crude product obtained in Step 3 by rotary evaporation, fine purification was performed using column chromatography. During purification, 200-300 mesh silica gel powder was used as the stationary phase, and dry column packing and dry sample loading techniques were employed. A mixed solvent system of dichloromethane / petroleum ether / triethylamine (75:25:3, v / v / v) was used as the eluent for elution.

[0040] Step 5: After removing the solvent by rotary evaporation again, the product obtained in step 4 is dried in a vacuum drying oven (40℃, 10 h) to obtain a C2 type aldehyde monomer containing a dimethylamino functional group.

[0041] Secondly, this invention provides a method for preparing a functionalized covalent organic framework material containing dimethylamino groups, comprising the following steps:

[0042] Step 6: Weigh 1,3,5-tris(4-aminophenyl)benzene, 2,5-dimethoxybenzene-1,4-dicarboxaldehyde and the C2-type aldehyde monomer containing the dimethylamino functional group synthesized in Step 5 according to the molar ratio (4:5:1); then weigh the catalyst and the reaction solvent, with the volume ratio of catalyst to reaction solvent being (1:20).

[0043] Step 7: The C2 type aldehyde monomer containing the dimethylamino functional group synthesized in Step 5, 1,3,5-tris(4-aminophenyl)benzene, 2,5-dimethoxybenzene-1,4-dicarboxaldehyde and catalyst were mixed evenly in the reaction solvent. The environment was kept in an oxygen-free condition by using the Schlenk freeze-thaw method. After three cycles of freezing-degassing-thawing-gas filling, the reaction was carried out at a constant temperature of 120℃ in a vacuum environment for 72 h.

[0044] Step 8: After the reaction is complete, wait for the mixture from Step 7 to cool to room temperature under vacuum, remove the solvent by filtration, and wash the product 6 times with tetrahydrofuran.

[0045] Step 9: Collect the yellow mixture powder obtained in Step 8 and wash it with tetrahydrofuran in a Soxhlet extractor for 24 h to remove the captured guest molecules, and finally obtain the yellow powder.

[0046] Step 10: Take out the yellow powder from step 9, vacuum dry it at 120℃ for 24 h, and grind it in an agate grinding bowl to obtain a functionalized covalent organic framework material containing dimethylamino.

[0047] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the molar ratio of 2,5-dibromo-terephthalaldehyde, 4-(N,N-dimethylamino)phenylboronic acid pinacol ester, potassium carbonate, and tetrakis(triphenylphosphine)palladium in step 1 can be 1:(2.0~2.5):(5~8):(0.03~0.08). Everything else is the same as in Specific Implementation Method One.

[0048] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One in that the reaction solvent in step 1 is one or more mixtures of 1,4-dioxane, toluene, xylene, N,N-dimethylformamide, tetrahydrofuran, or water. Everything else is the same as in Specific Implementation Method One.

[0049] Specific Implementation Method Four: This implementation method differs from Specific Implementation Method One in that the mass ratio of the reaction solvent to 2,5-dibromo-terephthalaldehyde in step 1 is (800-1200):1. Everything else is the same as in Specific Implementation Method One.

[0050] Specific Implementation Method Five: This implementation method differs from Specific Implementation Method One in that the reaction temperature in step 2 is 75–95°C, and the reaction time is 36–60 hours. Everything else is the same as in Specific Implementation Method One.

[0051] Specific Implementation Method Six: This implementation method differs from Specific Implementation Method One in that: the silica gel powder used for column chromatography in step 4 has a mesh size of 150-400; the volume ratio of the eluent dichloromethane / petroleum ether / triethylamine is (70-80):(20-30):(2-5). Everything else is the same as in Specific Implementation Method One.

[0052] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Method One in that the vacuum drying temperature in step 5 is 30–50°C, and the drying time is 8–15 hours. Everything else is the same as in Specific Implementation Method One.

[0053] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Method One in that: the catalyst in step 6 is acetic acid or an aqueous solution of acetic acid, preferably a 3 mol / L aqueous solution of acetic acid; the reaction solvent is one or more of n-butanol, o-dichlorobenzene, m-xylene, mesitylene, or tetrahydrofuran.

[0054] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Method One in that the molar ratio of 1,3,5-tris(4-aminophenyl)benzene, 2,5-dimethoxybenzene-1,4-dicarboxaldehyde, and the C2-type aldehyde monomer containing the dimethylamino functional group in step 6 is 4:(4-6):(0.5-2). Everything else is the same as in Specific Implementation Method One.

[0055] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Method One in that the volume ratio of catalyst to reaction solvent in step 6 is 1:(15-25). Everything else is the same as in Specific Implementation Method One.

[0056] Specific Implementation Method Eleven: This implementation method differs from Specific Implementation Method One in that the reaction temperature in step 7 is 100–130°C, and the reaction time is 60–84 h. Everything else is the same as in Specific Implementation Method One.

[0057] Specific Implementation Method Twelve: This implementation method differs from Specific Implementation Method One in that the number of tetrahydrofuran washes in step 8 is 4 to 8. Everything else is the same as in Specific Implementation Method One.

[0058] Specific Implementation Method Thirteen: This implementation method differs from Specific Implementation Method One in that the washing time for Soxhlet extraction is 18–30 h; the washing solvent, in addition to tetrahydrofuran, can also be methanol, ethanol, acetone, or a mixture thereof. Everything else is the same as in Specific Implementation Method One.

[0059] Specific Implementation Method Fourteen: This implementation method differs from Specific Implementation Method One in that, in step 10, the vacuum drying temperature is 100–140°C, and the drying time is 18–30 hours. Everything else is the same as in Specific Implementation Method One.

[0060] The present invention will be further illustrated by the following examples, but the present invention is not limited thereto.

[0061] Example 1: A method for preparing a C2-type aldehyde monomer containing a dimethylamino functional group and a functionalized covalent organic framework material containing a dimethylamino group, specifically carried out according to the following steps:

[0062] Step 1: Weigh 0.3 g (1.028 mmol) of 2,5-dibromo-terephthalaldehyde, 0.559 g (2.261 mmol) of 4-(N,N-dimethylamino)phenylboronic acid pinacol ester, 0.852 g (6.166 mmol) of potassium carbonate, and 59.4 mg (51.4 μmol) of tetra(triphenylphosphine)palladium. Add 300 mL of 1,4-dioxane / water (95:5, v / v).

[0063] Step 2: Transfer the above mixture to a Schlenk reaction tube, and after three cycles of liquid nitrogen freezing-vacuuming-nitrogen purging, react at 85°C under nitrogen protection for 48 h.

[0064] Step 3: After cooling to room temperature, filter the reaction mixture using rapid qualitative analysis filter paper;

[0065] Step 4: Concentrate by rotary evaporation, and purify by column chromatography with 200-300 mesh silica gel powder using dichloromethane / petroleum ether / triethylamine (75:25:3, v / v / v) as eluent;

[0066] Step 5: Remove the solvent by rotary evaporation, and dry under vacuum at 40°C for 10 h to obtain 161.4 mg of a yellow solid (a C2-type aldehyde monomer containing a dimethylamino functional group), with a yield of 63.2%.

[0067] Step 6: Weigh 151.1 mg (0.4926 mmol) of 1,3,5-tris(4-aminophenyl)benzene, 104.3 mg (0.537 mmol) of 2,5-dimethoxybenzene-1,4-dicarboxaldehyde, and 40 mg (0.1104 mmol) of the C2 type aldehyde monomer containing the dimethylamino functional group obtained in Step 5. Add 0.05 mL of 6 mol / L acetic acid aqueous solution, 0.5 mL of n-butanol, and 0.5 mL of o-dichlorobenzene.

[0068] Step 7: Transfer to a Schlenk reaction tube, degas three times by freeze-thaw, and react at 120°C under vacuum for 72 h;

[0069] Step 8: Cool to room temperature, filter, and wash with tetrahydrofuran (20 mL × 6);

[0070] Step 9: Place the product in a Soxhlet extractor and wash with tetrahydrofuran under reflux for 24 h;

[0071] Step 10: Vacuum drying at 120℃ for 24 h, followed by grinding to obtain 421 mg of yellow powder product, with a yield of 77%.

[0072] The results showed that PXRD revealed obvious diffraction peaks at 2θ = 2.77°, 4.82°, 5.56°, 7.36°, 9.65°, and 25.3°, indicating that the dimethylamino-containing functionalized covalent organic framework material has good crystallinity; FT-IR showed a peak at 1590 cm⁻¹. -1 The presence of a C=N characteristic peak at this point confirms the formation of an imine bond, indicating the synthesis of a functionalized covalent organic framework material containing dimethylamino groups; the BET specific surface area is 2481 m². 2 / g, with pore size distribution concentrated at 2.63 nm.

[0073] Example 2: A method for preparing a C2-type aldehyde monomer containing a dimethylamino functional group and a functionalized covalent organic framework material containing a dimethylamino group, specifically carried out according to the following steps:

[0074] The difference from Example 1 is as follows:

[0075] In step 1, the amount of 4-(N,N-dimethylamino)phenylboronic acid pinacol ester was reduced to 0.494 g (2 mmol), and the amount of 2,5-dibromo-terephthalaldehyde was adjusted accordingly to 0.292 g (1 mmol), potassium carbonate to 0.829 g (6 mmol), and tetra(triphenylphosphine)palladium to 57.8 mg (0.05 mmol), with the molar ratio adjusted to 2:1:6:0.05;

[0076] In step 6, the amount of 1,3,5-tris(4-aminophenyl)benzene was adjusted to 151.1 mg (0.4926 mmol), the amount of 2,5-dimethoxybenzene-1,4-dicarboxaldehyde was 62.58 mg (0.322 mmol), the amount of C2 type aldehyde monomer containing dimethylamino functional group was 120 mg (0.331 mmol), and the molar ratio was adjusted to 4:3:3;

[0077] The remaining steps are the same as in Example 1;

[0078] The results showed a yield of 78% and a BET specific surface area of ​​1696 m². 2 / g; higher dimethylamino content is beneficial for pH-responsive adsorption applications.

[0079] Example 3: A method for preparing a C2-type aldehyde monomer containing a dimethylamino functional group and a functionalized covalent organic framework material containing a dimethylamino group, specifically carried out according to the following steps:

[0080] The difference from Example 1 is as follows:

[0081] In step 2, the reaction temperature is adjusted to 90℃ and the reaction time is shortened to 40 h;

[0082] In step 7, the reaction temperature is adjusted to 115℃ and the reaction time is extended to 80 h;

[0083] The remaining steps are the same as in Example 1;

[0084] The results showed a yield of 75% and a BET specific surface area of ​​2374 m². 2 / g; The crystallinity of the material is slightly reduced, but it still maintains a good pore structure.

[0085] The dimethylamino-containing functionalized covalent organic framework materials prepared in Examples 1, 2 and 3 all exhibited high specific surface area and crystallinity.

[0086] Example 4: pH-responsive adsorption of a functionalized covalent organic framework material containing dimethylamino groups, specifically performed according to the following steps:

[0087] The difference from Example 1 is as follows:

[0088] In step 11: a 0.1 mg / mL solution of growth hormone releasing peptide-6 (a polypeptide) was prepared using different PBS (pH 3, 5, 7 and 9) as solvents.

[0089] 4 mL of growth hormone-releasing peptide-6 solution at different pH values ​​were mixed with 4 mg of the dimethylamino-containing functionalized covalent organic framework material prepared in Example 1. After shaking for 10 seconds, the mixture was centrifuged (10000 rpm, 10 min) to remove the dimethylamino-containing functionalized covalent organic framework material.

[0090] The adsorption mass of growth hormone-releasing peptide-6 by the dimethylamino-containing functionalized covalent organic framework material was calculated by measuring its absorbance at 280 nm using a UV-Vis spectrophotometer.

[0091] The remaining steps are the same as in Example 1;

[0092] The results showed that the dimethylamino-containing functionalized covalent organic framework material prepared in Example 1 exhibited significant differences in the adsorption capacity of peptides under different pH conditions, demonstrating its potential for pH-responsive adsorption-desorption of peptides.

Claims

1. A method for preparing a C2-type aldehyde monomer containing a dimethylamino functional group, characterized in that... The method is specifically carried out according to the following steps: Step 1: Weigh 2,5-dibromo-terephthalaldehyde, 4-(N,N-dimethylamino)phenylboronic acid pinacol ester, potassium carbonate, and tetra(triphenylphosphine)palladium in a molar ratio of 1:(2.0-2.5):(5-8):(0.03-0.08) and add them to the reaction solvent. The mass ratio of the reaction solvent to 2,5-dibromo-terephthalaldehyde is (800-1200):

1. The reaction solvent is one or more of 1,4-dioxane, toluene, N,N-dimethylformamide, tetrahydrofuran, or water. Step 2: Place the mixture from Step 1 in an oxygen-free environment and react at 75–95°C for 36–60 hours; Step 3: After the reaction is complete, cool and filter the mixture to obtain the crude product; Step 4: The crude product is purified by column chromatography. The eluent is a mixed solvent of dichloromethane, petroleum ether and triethylamine, with a volume ratio of (70-80):(20-30):(2-5). Step 5: Collect the purified components, evaporate the solvent, and vacuum dry at 30-50°C for 8-15 hours to obtain the C2 type aldehyde monomer containing the dimethylamino functional group.

2. The preparation method according to claim 1, characterized in that, In step 1, the reaction solvent is a mixture of 1,4-dioxane and water in a volume ratio of (90-100):

5.

3. The preparation method according to claim 1 or 2, characterized in that, In step 4, the silica gel powder used for column chromatography has a mesh size of 150–400 mesh.

4. A C2-type aldehyde monomer containing a dimethylamino functional group, prepared by the method described in any one of claims 1 to 3.

5. A method for preparing a functionalized covalent organic framework material containing dimethylamino groups, characterized in that... The method is specifically carried out according to the following steps: Step 6: Weigh 1,3,5-tris(4-aminophenyl)benzene, 2,5-dimethoxybenzene-1,4-dicarboxaldehyde and the C2-type aldehyde monomer containing the dimethylamino functional group as described in claim 4 in a molar ratio of 4:(4-6):(0.5-2), and add them to a mixed system consisting of a catalyst and a reaction solvent. The volume ratio of the catalyst to the reaction solvent is 1:(15-25). The catalyst is acetic acid or an aqueous solution of acetic acid, and the reaction solvent is one or more of n-butanol, o-dichlorobenzene, m-xylene, mesitylene, or tetrahydrofuran. Step 7: Place the mixture from Step 6 in an oxygen-free environment and react at 100–130°C for 60–84 hours; Step 8: After the reaction is complete, cool and filter, and wash the product with tetrahydrofuran 4 to 8 times; Step 9: Place the washed product in a Soxhlet extractor and wash with one or more of tetrahydrofuran, methanol, ethanol or acetone for 18 to 30 hours. Step 10: The product after step 9 is vacuum dried at 100-140°C for 18-30 hours to obtain the functionalized covalent organic framework material containing dimethylamino.

6. The preparation method according to claim 5, characterized in that, In step 6, the catalyst is a 3-6 mol / L aqueous solution of acetic acid; the reaction solvent is a mixture of n-butanol and o-dichlorobenzene in a volume ratio of (0.5-2):

1.

7. The preparation method according to claim 5 or 6, characterized in that, In step 7, the oxygen-free environment is a vacuum environment.

8. A functionalized covalent organic framework material containing dimethylamino groups prepared by the preparation method according to any one of claims 5 to 7.

9. The functionalized covalent organic framework material containing dimethylamino according to claim 8, characterized in that, Its BET specific surface area is not less than 1696 m² / g, and the pore size distribution is concentrated around 2.63 nm.

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