Covalent organic framework material, and preparation method therefor and use thereof

Abstract

The present invention relates to the technical field of polymer preparation. Disclosed are a covalent organic framework material, and a preparation method therefor and a use thereof. The preparation method for the covalent organic framework material comprises the following step: subjecting an organic aldehyde and an organic amine to a condensation reaction in a deep eutectic solvent to obtain the covalent organic framework material, wherein the deep eutectic solvent is a two-component eutectic liquid composed of menthol and acetic acid. The temperature for the reaction is 25-120ºC, and the time for the reaction is 1-72 hours. The deep eutectic solvent composed of menthol and acetic acid used in the present invention has good dissolution properties for organic matters, and can also efficiently catalyze the condensation reaction between the organic amine and the organic aldehyde. The prepared covalent organic framework material exhibits high crystallinity and has good applications in the fields of adsorptive separation, heterogeneous catalysis, energy storage, etc. The present method has mild reaction conditions, simple operation, and good universality, is conducive to industrial large-scale production, and conforms to the concept of green chemistry.

Description

A covalent organic framework material, its preparation method and application Technical Field

[0001] This invention belongs to the field of polymer preparation technology, and particularly relates to a covalent organic framework material, its preparation method and application. Background Technology

[0002] Covalent organic frameworks (COFs) are novel crystalline porous polymer materials constructed from organic building blocks through covalent bonds, primarily composed of light elements such as C, H, O, N, and B. Among them, imine COFs linked by imines have attracted considerable attention in numerous fields due to their highly ordered and tunable pore structure, excellent chemical stability, and thermal stability. The main method for preparing imine COFs is the solvothermal method; however, this method requires highly toxic organic solvents and necessitates stringent reaction conditions and complex processes (high temperature and pressure, freeze-vacuum-thaw cycles, and long reaction times). Furthermore, the solvothermal method is highly dependent on the solvent composition and catalyst dosage. For monomers with varying chemical reactivity, strict control of solvent composition and catalyst dosage is necessary to obtain highly crystalline products, requiring extensive exploratory experiments. Therefore, from both a green chemistry perspective and an economic standpoint, it is essential to develop a universally applicable green solvent system for the synthesis of imine COFs.

[0003] Current research on the green synthesis of imine COFs mainly focuses on solvents and catalysts, but these two areas of study are relatively independent. Eutectic solvents (DES) are a novel type of green solvent composed of hydrogen bond donors (HBDs) and hydrogen bond acceptors (HBAs). Due to their tunable physicochemical properties and excellent solubility for organic building blocks, they have been increasingly applied in recent years to the synthesis of imine COFs under mild conditions.

[0004] Existing technology CN110894299B discloses a method for synthesizing covalent organic framework materials using a eutectic solvent. The method involves adding an organic amine, an organic aldehyde, and a eutectic solvent to a reactor and mixing them uniformly to obtain a first mixture; adding a catalyst to the first mixture to obtain a second mixture; rapidly freezing the reactor containing the second mixture with liquid nitrogen and then flame-sealing the reactor under vacuum; subjecting the sealed reactor to an aldehyde-amine condensation reaction to obtain a crude covalent organic framework product; and post-processing the crude covalent organic framework product to obtain the covalent organic framework material. However, this preparation method requires complex operations such as liquid nitrogen freezing and high-temperature flame sealing to obtain high-yield covalent organic framework materials.

[0005] Existing technology CN113817116B discloses a method for preparing covalent organic framework materials. The method involves dissolving organic aldehydes and organic amines in a eutectic solvent, adding acetic acid as a catalyst, stirring to dissolve, forming a homogeneous solution, and allowing the reaction to proceed at room temperature for 2-72 hours. After centrifugation, washing, and drying, the covalent organic framework material is obtained. The organic aldehyde is one of trialdehyde-resorcinol, 2,5-divinyl-1,4-phenylenedialdehyde, or 2,5-dimethoxybenzene-1,4-dicarboxaldehyde; the organic amine is one of p-phenylenediamine, tris(4-aminophenyl)amine, or 1,3,5-tris(4-aminophenyl)benzene; the hydrogen bond acceptor of the eutectic solvent is choline chloride; and the hydrogen bond donor of the eutectic solvent is one of oxalic acid dihydrate, formic acid, acetic acid, or lactic acid. However, the PXRD pattern of the prepared covalent organic framework material shows only weak diffraction peaks at the corresponding crystal plane positions. Furthermore, no obvious lattice fringes were observed in the transmission electron microscopy image, indicating that the covalent organic framework material prepared by this prior art has poor crystal structure and low crystallinity. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the defects and shortcomings of existing covalent organic framework material preparation methods, which are harsh and complicated, and the resulting covalent organic framework materials have low crystallinity. The present invention provides a method for preparing covalent organic framework materials with mild synthesis conditions, simple operation, and high crystallinity of the synthesized covalent organic framework materials.

[0007] Another object of the present invention is to provide a covalent organic framework material.

[0008] Another object of the present invention is to provide an application of a covalent organic framework material as an adsorbent, photocatalyst, solid electrolyte or electrode material.

[0009] The above-mentioned objective of this invention is achieved through the following technical solution:

[0010] A method for preparing a covalent organic framework material includes the following steps: condensing organic aldehydes and organic amines in a eutectic solvent to obtain a covalent organic framework material;

[0011] The eutectic solvent is a two-component eutectic liquid composed of menthol and acetic acid;

[0012] The reaction temperature is 25℃ to 120℃, and the reaction time is 1 hour to 72 hours.

[0013] The condensation reaction temperature of this invention can be 25℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, 100℃, 110℃, or 120℃.

[0014] The condensation reaction time of this invention can be 1 hour, 10 hours, 20 hours, 30 hours, 40 hours, 50 hours, 60 hours, 70 hours, or 72 hours.

[0015] Preferably, the reaction temperature is 70℃~120℃, and the reaction time is 24 hours~72 hours.

[0016] Preferably, in the eutectic solvent, the molar ratio of menthol to acetic acid is (0.1-6):1.

[0017] The molar ratio of menthol to acetic acid can be, for example, 1:6, 1:5, 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, 4:1, 5:1 or 6:1.

[0018] Acetic acid, as a hydrogen bond donor component, forms a eutectic solvent that can not only dissolve organic aldehydes and organic amines, but also act as a catalyst for condensation reactions. Therefore, in this system, the solubility of the eutectic solvent and the reaction rate can be controlled by changing the molar ratio of menthol and acetic acid.

[0019] The eutectic solvent used in this invention can adapt to different monomer combinations by adjusting the molar ratio of menthol and acetic acid when facing organic amine monomers or organic aldehyde monomers with different chemical activities.

[0020] More preferably, in the eutectic solvent, the molar ratio of menthol to acetic acid is (0.1-1):1.

[0021] Within this range, the molar ratio of menthol to acetic acid results in covalent organic framework materials with higher crystallinity.

[0022] Preferably, the organic aldehyde is terephthalaldehyde (CAS No. 623-27-8), 2,5-divinyl-1,4-phenylenedialdehyde (CAS No. 2065232-74-6), 2,5-dimethoxy-1,4-phenylenedialdehyde (CAS No. 7310-97-6), 2,5-dihydroxy-1,4-phenylenedialdehyde (CAS No. 1951-36-6), or 2,5-difluoro-1, One or more of the following: 4-phenylenedialdehyde (CAS No. 608145-27-3), 2,5-dibromo-1,4-phenylenedialdehyde (CAS No. 63525-48-4), 2,3,5,6-tetrafluoro-terephthalaldehyde (CAS No. 3217-47-8), pyromellitic pyrogallol (CAS No. 3163-76-6), or trialdehyde-resorcinol (CAS No. 34374-88-4).

[0023] Preferably, the organic amine is one or more of p-phenylenediamine (CAS No. 106-50-3), 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (CAS No. 14544-47-9), 1,3,5-tris(4-aminophenyl)benzene (CAS No. 118727-34-7), tris(4-aminophenyl)amine (CAS No. 5981-09-9), tetra(4-aminophenyl)porphyrin (CAS No. 22112-84-1), or tetra(4-aminophenyl)methane (CAS No. 60532-63-0).

[0024] Preferably, the molar ratio of the organic amine to the organic aldehyde is (0.5-1):1.

[0025] The molar ratio of the organic amine to the organic aldehyde can be 0.5:1, 0.6:1, 0.67:1, 0.7:1, 0.8:1, 0.9:1 or 1:1.

[0026] Preferably, the concentration of the organic amine monomer in the eutectic solvent is 0.01 mol / L to 0.02 mol / L, and the concentration of the organic aldehyde monomer in the eutectic solvent is 0.01 mol / L to 0.04 mol / L.

[0027] Preferably, after the condensation reaction, a purification process is further included, wherein the purification process involves Soxhlet extraction of the crude covalent organic framework product using tetrahydrofuran and ethanol as organic solvents.

[0028] Preferably, the purification process further includes a post-processing step, wherein the post-processing method is as follows: the product after Soxhlet extraction is soaked in n-hexane and dried to obtain a covalent organic framework material.

[0029] The purpose of post-treatment is to prevent the covalent organic framework from collapsing during the drying process.

[0030] This invention also protects covalent organic framework materials prepared by any of the above-described methods.

[0031] Preferably, the structural formula of the covalent organic framework material is any one of formula 1, formula 2, formula 3 or formula 4;

[0032] Formula 1, wherein R1 is a benzene ring, a triazine ring, or N; and R2 is one or more of H, F, Br, C=C, OCH3, or OH;

[0033] Formula 2, wherein R is one or more of H, F, Br, OCH3 or OH;

[0034] Formula 3, wherein R is one or more of H, F, Br, OCH3 or OH;

[0035] Formula 4, where R is N, a benzene ring, or a triazine ring.

[0036] This invention also protects the use of the aforementioned covalent organic framework materials as adsorbents, photocatalysts, solid electrolytes, or electrode materials.

[0037] The covalent organic framework material prepared by this invention has high crystallinity and specific surface area, and has wide applications in adsorption separation, heterogeneous catalysis and energy storage.

[0038] The covalent organic framework material prepared by this invention can be used as an adsorbent to adsorb flavonoids.

[0039] The covalent organic framework material prepared by this invention can be used as a photocatalyst to catalyze the generation of hydrogen peroxide from water and oxygen in the air.

[0040] The covalent organic framework material prepared by this invention can be used as a solid electrolyte in solid-state lithium metal batteries.

[0041] The covalent organic framework material prepared by this invention can be used as an electrode material in lithium-ion, zinc-ion, or sodium-ion batteries.

[0042] Compared with the prior art, the present invention has at least the following beneficial effects:

[0043] This invention discloses a method for preparing covalent organic framework materials. The eutectic solvent composed of menthol and acetic acid not only has good solubility for organic matter, but also can efficiently catalyze the condensation reaction of organic amines and organic aldehydes. Therefore, the eutectic solvent serves as both solvent and catalyst during the synthesis process, eliminating the need for additional catalysts. Under mild conditions, imine COFs with high crystallinity, high specific area and high yield are prepared.

[0044] Compared with existing technologies, the method of this invention has mild synthesis conditions and simple operation, and can synthesize highly crystalline covalent organic framework materials without complex operations such as freezing-vacuuming-thawing cycles and high-temperature flame sealing.

[0045] Compared with traditional synthesis methods, this method has low pollution, mild reaction conditions, simple operation, good universality, and is conducive to large-scale industrial production, which is in line with the concept of green chemistry. Attached Figure Description

[0046] Figure 1 shows the powder X-ray diffraction (PXRD) patterns of a series of covalent organic framework materials obtained in Example 1 of the present invention;

[0047] Figure 2 shows the Fourier Transform Infrared (FT-IR) spectrum of the covalent organic framework material obtained in Example 1 of the present invention (molar ratio of menthol to acetic acid is 1:2);

[0048] Figure 3 shows the scanning electron microscope (SEM) image of the covalent organic framework material obtained in Example 1 of the present invention (molar ratio of menthol and acetic acid is 1:2);

[0049] Figure 4 is a nitrogen adsorption-desorption curve of the covalent organic framework material obtained in Example 1 of the present invention (molar ratio of menthol and acetic acid is 1:2);

[0050] Figure 5 is a transmission electron microscope (TEM) image of the covalent organic framework material obtained in Example 1 of the present invention (molar ratio of menthol and acetic acid is 1:2);

[0051] Figure 6 shows the powder X-ray diffraction (PXRD) pattern of the covalent organic framework material obtained in Example 2 of the present invention;

[0052] Figure 7 shows the powder X-ray diffraction (PXRD) pattern of the covalent organic framework material obtained in Example 3 of the present invention;

[0053] Figure 8 shows the powder X-ray diffraction (PXRD) pattern of the covalent organic framework material obtained in Example 19 of the present invention;

[0054] Figure 9 shows the powder X-ray diffraction (PXRD) pattern of the covalent organic framework material obtained in Example 20 of the present invention;

[0055] Figure 10 shows the comparative powder X-ray diffraction (PXRD) patterns of Comparative Example 1 and Example 1. Detailed Implementation

[0056] The present invention will be further illustrated below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in this technical field.

[0057] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0058] The covalent organic framework materials prepared in Examples 1 to 23 below have the general structural formulas of Formula 1, Formula 2, Formula 3 or Formula 4;

[0059] Formula 1, wherein R1 is a benzene ring, a triazine ring, or N; and R2 is one or more of H, F, Br, C=C, OCH3, or OH;

[0060] Formula 2, wherein R is one or more of H, F, Br, OCH3 or OH;

[0061] Formula 3, wherein R is one or more of H, F, Br, OCH3 or OH;

[0062] Formula 4, where R is N, a benzene ring, or a triazine ring.

[0063] Example 1

[0064] This embodiment provides a series of methods for preparing covalent organic framework materials, including the following steps: First, menthol and acetic acid are mixed in a certain molar ratio (6:1, 4:1, 2:1, 1:1, 1:2, 1:4, 1:6) to obtain a eutectic solvent. Then, 0.0080 g (0.06 mM) of terephthalaldehyde (PDA) and 0.0141 g (0.04 mM) of 1,3,5-tris(4-aminophenyl)benzene (TAPB) are added to a 10 mL plastic centrifuge tube, and then 2 mL of the eutectic solvent is added as both the reaction medium and catalyst. After mixing thoroughly, the mixture is kept at a constant temperature of 70 °C for 24 hours. After the reaction, the obtained solid precipitate is extracted using a Soxhlet extractor with tetrahydrofuran and ethanol, respectively. Finally, the extracted solid is soaked in n-hexane and dried in a vacuum drying oven for 12 hours to obtain the covalent organic framework material.

[0065] The molar ratio of organic amines to organic aldehydes is 2:3.

[0066] The concentration of the organic amine monomer in the eutectic solvent is 0.02 mol / L;

[0067] The concentration of organic aldehyde monomer in the eutectic solvent is 0.03 mol / L.

[0068] The structural formula of the covalent organic framework material is the same as the general formula 1 above, where R1 is a benzene ring and R2 is H.

[0069] The yields of covalent organic framework materials obtained by menthol and acetic acid in molar ratios of 6:1, 4:1, 2:1, 1:1, 1:2, 1:4, and 1:6 were 23.5%, 24.9%, 27.6%, 85.9%, 99.5%, 99.3%, and 95%, respectively.

[0070] Figure 1 shows the powder X-ray diffraction (PXRD) patterns of a series of covalent organic framework materials prepared in Example 1 of this invention. As can be seen from Figure 1, the product obtained with a molar ratio of menthol to acetic acid of 1:2 exhibits obvious diffraction peaks at positions of 2.7°, 4.8°, 5.5°, and 7.5°, corresponding to the (100), (110), (200), and (210) crystal planes, respectively, indicating that the material has a high degree of crystallinity.

[0071] The covalent organic framework material prepared in Example 1 of the present invention with a molar ratio of menthol and acetic acid of 1:2 was characterized as follows.

[0072] Figure 2 is the FT-IR spectrum of the covalent organic framework material obtained in Example 1 of this invention (molar ratio of menthol to acetic acid is 1:2). It can be seen that at 1601 cm⁻¹... -1 The newly observed absorption peak corresponds to the C=N stretching vibration, indicating that the amino group of TAPB successfully condensed with the aldehyde group of PDA to form an imine bond. Simultaneously, the amino group of TAPB shows an absorption peak at 3434 cm⁻¹. -1 and 3353cm -1 The stretching vibration peak and the aldehyde group of PDA at 1700 cm⁻¹ -1 The disappearance of the absorption peak further indicates that the C=O double bond and NH bond have been completely transformed into C=N, which also proves that the target covalent organic framework material has been successfully synthesized.

[0073] Figure 3 is a scanning electron microscope (SEM) image of the covalent organic framework material obtained in Example 1 of this invention (molar ratio of menthol to acetic acid is 1:2). It can be seen that the morphology of the material is a relatively regular nanoflower-like structure.

[0074] Figure 4 shows the nitrogen adsorption-desorption curves of the covalent organic framework material obtained in Example 1 of this invention (molar ratio of menthol to acetic acid is 1:2). It can be seen that the prepared covalent organic framework material has a very high specific surface area, reaching 1834 m². 2 / g.

[0075] Figure 5 is a transmission electron microscope (TEM) image of the covalent organic framework material obtained in Example 1 of the present invention (molar ratio of menthol to acetic acid is 1:2). As can be seen from Figure 5, the prepared covalent organic framework material has very obvious lattice fringes, reflecting its high crystallinity.

[0076] Example 2

[0077] This embodiment provides a series of methods for preparing covalent organic framework materials, which are the same as the preparation steps in Example 1, except that 0.0080 g (0.06 mM) of terephthalaldehyde is replaced with 0.0100 g (0.06 mM) of 2,5-dihydroxy-1,4-phenylenedialdehyde.

[0078] The structural formula of the covalent organic framework material is the same as the general formula 1 above, where R1 is a benzene ring and R2 is H and OH.

[0079] Figure 6 shows the powder X-ray diffraction (PXRD) patterns of a series of covalent organic framework materials prepared in Example 2 of this invention. As can be seen from Figure 6, the product obtained when the molar ratio of menthol to acetic acid is 1:1 shows obvious diffraction peaks at positions of 2.7°, 4.8°, 5.6°, and 7.4°, corresponding to the (100), (110), (200), and (210) crystal planes, respectively, indicating that the material has a high degree of crystallinity.

[0080] Example 3

[0081] This embodiment provides a series of methods for preparing covalent organic framework materials, which are the same as the preparation steps in Example 1, except that 0.0080g (0.06mM) terephthalaldehyde is replaced with 0.0102g (0.06mM) 2,5-difluoro-1,4-phenylenedialdehyde.

[0082] The structural formula of the covalent organic framework material is the same as the general formula 1 above, where R1 is a benzene ring and R2 is H and F.

[0083] Figure 7 shows the powder X-ray diffraction (PXRD) patterns of a series of covalent organic framework materials prepared in Example 3 of this invention. As can be seen from Figure 7, the product obtained when the molar ratio of menthol to acetic acid is 1:6 shows obvious diffraction peaks at positions of 2.7°, 4.7°, 5.5°, and 7.4°, corresponding to the (100), (110), (200), and (210) crystal planes, respectively, indicating that the material has a high degree of crystallinity.

[0084] Example 4

[0085] This embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps in Example 1, except that the molar ratio of menthol and acetic acid is 1:1, and 0.0080 g (0.06 mM) of terephthalaldehyde is replaced with 0.0116 g (0.06 mM) of 2,5-dimethoxy-1,4-phenylenedialdehyde.

[0086] The structural formula of the covalent organic framework material is the same as the general formula 1 above, where R1 is a benzene ring and R2 is H and OCH3.

[0087] Example 5

[0088] This embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps in Example 1, except that the molar ratio of menthol and acetic acid is 1:4, and 0.0080g (0.06mM) of terephthalaldehyde is replaced with 0.0065g (0.04mM) of trimesaldehyde.

[0089] The structural formula of the covalent organic framework material is the same as the general formula 4 above, where R is a benzene ring.

[0090] Example 6

[0091] This embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps in Example 1, except that the molar ratio of menthol and acetic acid is 1:4, and 0.0141 g (0.04 mM) of 1,3,5-tris(4-aminophenyl)benzene is replaced with 0.0142 g (0.04 mM) of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine.

[0092] The structural formula of the covalent organic framework material is the same as the general formula 1 above, where R1 is a triazine ring and R2 is H.

[0093] Example 7

[0094] This embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps in Example 1, except that the molar ratio of menthol and acetic acid is 1:1, 0.0141 g (0.04 mM) of 1,3,5-tris(4-aminophenyl)benzene is replaced with 0.0142 g (0.04 mM) of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, and 0.0080 g (0.06 mM) of terephthalaldehyde is replaced with 0.0100 g (0.06 mM) of 2,5-dihydroxy-1,4-phenylenedialdehyde.

[0095] The structural formula of the covalent organic framework material is the same as the general formula 1 above, wherein R1 is a triazine ring and R2 is H and OH.

[0096] Example 8

[0097] This embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps in Example 1, except that the molar ratio of menthol to acetic acid is 1:6, 0.0141 g (0.04 mM) of 1,3,5-tris(4-aminophenyl)benzene is replaced with 0.0142 g (0.04 mM) of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, and 0.0080 g (0.06 mM) of terephthalaldehyde is replaced with 0.0102 g (0.06 mM) of 2,5-difluoro-1,4-phenylenedialdehyde.

[0098] The structural formula of the covalent organic framework material is the same as the general formula 1 above, where R1 is a triazine ring and R2 is H and F.

[0099] Example 9

[0100] This embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps in Example 1, except that the molar ratio of menthol and acetic acid is 1:1, 0.0141 g (0.04 mM) of 1,3,5-tris(4-aminophenyl)benzene is replaced with 0.0142 g (0.04 mM) of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, and 0.0080 g (0.06 mM) of terephthalaldehyde is replaced with 0.0116 g (0.06 mM) of 2,5-dimethoxy-1,4-phenylenedialdehyde.

[0101] The structural formula of the covalent organic framework material is the same as the general formula 1 above, wherein R1 is a triazine ring and R2 is H and OCH3.

[0102] Example 10

[0103] This embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps in Example 1, except that the molar ratio of menthol to acetic acid is 1:6, the temperature is changed from 70℃ to 90℃, 0.0141g (0.04mM) of 1,3,5-tris(4-aminophenyl)benzene is replaced with 0.0142g (0.04mM) of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, and 0.0080g (0.06mM) of terephthalaldehyde is replaced with 0.0065g (0.04mM) of pyromellitic methyl methacrylate.

[0104] The structural formula of the covalent organic framework material is the same as the general structural formula 4 above, where R is a triazine ring.

[0105] Example 11

[0106] This embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps in Example 1, except that the molar ratio of menthol and acetic acid is 1:1, and 0.0141 g (0.04 mM) of 1,3,5-tris(4-aminophenyl)benzene is replaced with 0.0116 g (0.04 mM) of tris(4-aminophenyl)amine.

[0107] The structural formula of the covalent organic framework material is the same as the general formula 1 above, where R1 is N and R2 is H.

[0108] Example 12

[0109] This embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps in Example 1, except that the molar ratio of menthol and acetic acid is 1:1, 0.0141 g (0.04 mM) of 1,3,5-tris(4-aminophenyl)benzene is replaced with 0.0116 g (0.04 mM) of tris(4-aminophenyl)amine, and 0.0080 g (0.06 mM) of terephthalaldehyde is replaced with 0.0100 g (0.06 mM) of 2,5-dihydroxy-1,4-phenylenedialdehyde.

[0110] The structural formula of the covalent organic framework material is the same as the general structural formula 1 above, where R1 is N and R2 is H and OH.

[0111] Example 13

[0112] This embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps in Example 1, except that the molar ratio of menthol and acetic acid is 1:2, 0.0141 g (0.04 mM) of 1,3,5-tris(4-aminophenyl)benzene is replaced with 0.0116 g (0.04 mM) of tris(4-aminophenyl)amine, and 0.0080 g (0.06 mM) of terephthalaldehyde is replaced with 0.0102 g (0.06 mM) of 2,5-difluoro-1,4-phenylenedialdehyde.

[0113] The structural formula of the covalent organic framework material is the same as the general formula 1 above, where R1 is N, and R2 is H and F.

[0114] Example 14

[0115] This embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps in Example 1, except that the molar ratio of menthol and acetic acid is 1:1, 0.0141 g (0.04 mM) of 1,3,5-tris(4-aminophenyl)benzene is replaced with 0.0116 g (0.04 mM) of tris(4-aminophenyl)amine, and 0.0080 g (0.06 mM) of terephthalaldehyde is replaced with 0.0116 g (0.06 mM) of 2,5-dimethoxy-1,4-phenylenedialdehyde.

[0116] The structural formula of the covalent organic framework material is the same as the general formula 1 above, where R1 is N, and R2 is H and OCH3.

[0117] Example 15

[0118] This embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps in Example 1, except that the molar ratio of menthol and acetic acid is 1:2, 0.0141 g (0.04 mM) of 1,3,5-tris(4-aminophenyl)benzene is replaced with 0.0116 g (0.04 mM) of tris(4-aminophenyl)amine, and 0.0080 g (0.06 mM) of terephthalaldehyde is replaced with 0.0065 g (0.04 mM) of pyromellitic methyl ester.

[0119] The structural formula of the covalent organic framework material is the same as the general formula 4 above, where R is N.

[0120] Example 16

[0121] This embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps in Example 1, except that the molar ratio of menthol and acetic acid is 1:2, 0.0141 g (0.04 mM) of 1,3,5-tris(4-aminophenyl)benzene is replaced with 0.0152 g (0.04 mM) of tetra(4-aminophenyl)methane, and 0.0080 g (0.06 mM) of terephthalaldehyde is replaced with 0.0107 g (0.08 mM) of terephthalaldehyde.

[0122] The structural formula of the covalent organic framework material is the same as the general structural formula 2 above, where R is H.

[0123] Example 17

[0124] This embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps in Example 1, except that the molar ratio of menthol and acetic acid is 1:1, 0.0141 g (0.04 mM) of 1,3,5-tris(4-aminophenyl)benzene is replaced with 0.0152 g (0.04 mM) of tetra(4-aminophenyl)methane, and 0.0080 g (0.06 mM) of terephthalaldehyde is replaced with 0.0133 g (0.08 mM) of 2,5-dihydroxy-1,4-phenylenedialdehyde.

[0125] The structural formula of the covalent organic framework material is the same as the general structural formula 2 above, where R is H and OH.

[0126] Example 18

[0127] This embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps in Example 1, except that the molar ratio of menthol to acetic acid is 1:6, 0.0141 g (0.04 mM) of 1,3,5-tris(4-aminophenyl)benzene is replaced with 0.0152 g (0.04 mM) of tetra(4-aminophenyl)methane, and 0.0080 g (0.06 mM) of terephthalaldehyde is replaced with 0.0136 g (0.08 mM) of 2,5-difluoro-1,4-phenylenedialdehyde.

[0128] The structural formula of the covalent organic framework material is the same as the general structural formula 2 above, where R represents H and F.

[0129] Example 19

[0130] This embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps in Example 1, except that the molar ratio of menthol and acetic acid is 1:1, the temperature is changed from 70℃ to 90℃, 0.0141g (0.04mM) of 1,3,5-tris(4-aminophenyl)benzene is replaced with 0.0152g (0.04mM) of tetra(4-aminophenyl)methane, and 0.0080g (0.06mM) of terephthalaldehyde is replaced with 0.0155g (0.08mM) of 2,5-dimethoxy-1,4-phenylenedialdehyde.

[0131] The structural formula of the covalent organic framework material is the same as the general formula 2 above, where R is H and OCH3.

[0132] Figure 8 shows the powder X-ray diffraction (PXRD) pattern of the covalent organic framework material of Example 19 of the present invention. As can be seen from Figure 8, the product obtained when the molar ratio of menthol and acetic acid is 1:1 shows obvious diffraction peaks at 6.5° and 8.8°, corresponding to the (200) and (220) crystal planes, respectively, indicating that the material has a high degree of crystallinity.

[0133] Example 20

[0134] This embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps in Example 1, except that the molar ratio of menthol to acetic acid is 1:2, the temperature is changed from 70℃ to 120℃, the reaction time is changed from 24 hours to 72 hours, 0.0141 g (0.04 mM) of 1,3,5-tris(4-aminophenyl)benzene is replaced with 0.0270 g (0.04 mM) of tetra(4-aminophenyl)porphyrin, and 0.0080 g (0.06 mM) of terephthalaldehyde is replaced with 0.0155 g (0.08 mM) of 2,5-dimethoxy-1,4-phenylenedialdehyde.

[0135] The structural formula of the covalent organic framework material is the same as the general formula 3 above, where R is H and OCH3.

[0136] Figure 9 shows the powder X-ray diffraction (PXRD) pattern of the covalent organic framework material of Example 20 of the present invention. As can be seen from Figure 9, the product obtained when the molar ratio of menthol to acetic acid is 1:2 shows a relatively obvious diffraction peak at the 3.6° position, corresponding to the (110) crystal plane, indicating that the material has good crystallinity.

[0137] Example 21

[0138] This embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps in Example 1, except that the molar ratio of menthol and acetic acid is 1:2, and 0.0080 g (0.06 mM) of terephthalaldehyde is replaced with 0.0112 g (0.06 mM) of 2,5-divinyl-1,4-phenylenedialdehyde.

[0139] The structural formula of the covalent organic framework material is the same as the general formula 1 above, where R1 is a benzene ring, and R2 is H and C=C.

[0140] Example 22

[0141] This embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps in Example 1, except that the molar ratio of menthol and acetic acid is 1:1, and 0.0080 g (0.06 mM) of terephthalaldehyde is replaced with 0.0175 g (0.06 mM) of 2,5-dibromo-1,4-phenylenedialdehyde.

[0142] The structural formula of the covalent organic framework material is the same as the general formula 1 above, where R1 is a benzene ring and R2 is H and Br.

[0143] Example 23

[0144] This embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps in Example 1, except that the molar ratio of menthol and acetic acid is 1:4, and 0.0080g (0.06mM) of terephthalaldehyde is replaced with 0.0124g (0.06mM) of 2,3,5,6-tetrafluoro-terephthalaldehyde.

[0145] The structural formula of the covalent organic framework material is the same as the general formula 1 above, where R1 is a benzene ring and R2 is F.

[0146] Example 24

[0147] This embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps in Example 1, except that the molar ratio of menthol and acetic acid is 1:2, 0.0141 g (0.04 mM) of 1,3,5-tris(4-aminophenyl)benzene is replaced with 0.0130 g (0.12 mM) of p-phenylenediamine, and 0.0080 g (0.06 mM) of terephthalaldehyde is replaced with 0.0168 g (0.08 mM) of trialdehyde-resorcinol.

[0148] The structural formula of the covalent organic framework material is as follows:

[0149] Comparative Example 1

[0150] This embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps in Example 1, except that the eutectic solvent is choline chloride and acetic acid, and the molar ratio of choline chloride and acetic acid is 1:1, 1:2, 1:4, and 1:6, respectively.

[0151] Figure 10 shows the powder X-ray diffraction (PXRD) patterns of the covalent organic framework materials prepared in Example 1 and Comparative Example 1 of the present invention at the same molar ratio. The molar ratios marked with * represent the molar ratios of choline chloride and acetic acid. As can be seen from Figure 10, compared to the eutectic solvent composed of menthol and acetic acid, the covalent organic framework prepared in the eutectic solvent of choline chloride and acetic acid at the same molar ratio shows only very weak diffraction peaks in the PXRD pattern test, indicating that its crystallinity is significantly lower than that of the covalent organic framework prepared in the eutectic solvent composed of menthol and acetic acid.

[0152] Furthermore, the yields of covalent organic framework materials obtained by choline chloride and acetic acid in Comparative Example 1 at molar ratios of 1:1, 1:2, 1:4, and 1:6 were 20.3%, 23.5%, 25.8%, and 39.8%, respectively, which were significantly lower than those in the embodiments of the present invention.

[0153] In summary, this invention utilizes a eutectic solvent composed of menthol and acetic acid as both a solvent and a catalyst to achieve the green synthesis of highly crystalline imine COFs under mild conditions. Furthermore, Examples 1-3 have demonstrated that this invention can obtain highly crystalline covalent organic framework materials by simply changing the molar ratio of menthol and acetic acid when dealing with monomer combinations with different chemical activities, indicating its considerable versatility.

[0154] As can be seen from Examples and Comparative Example 1, the covalent organic framework materials prepared by choline chloride as the acceptor of the eutectic solvent have low crystallinity and low yield.

[0155] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited to the specific embodiments described above. Obviously, those skilled in the art can easily make various changes or modifications within the scope of the claims of the present invention, which do not affect the substantive content of the present invention.

Claims

1. A method for preparing a covalent organic framework material, characterized in that, The process includes the following steps: condensing organic aldehydes and organic amines in a eutectic solvent to obtain a covalent organic framework material; The eutectic solvent is a two-component eutectic liquid composed of menthol and acetic acid; The reaction temperature is 25℃ to 120℃, and the reaction time is 1 hour to 72 hours.

2. The method for preparing the covalent organic framework material as described in claim 1, characterized in that, In the eutectic solvent, the molar ratio of menthol to acetic acid is (0.1–6):

1.

3. The method for preparing the covalent organic framework material as described in claim 1, characterized in that, The organic aldehyde is one or more of the following: terephthalaldehyde, 2,5-divinyl-1,4-benzaldehyde, 2,5-dimethoxy-1,4-benzaldehyde, 2,5-dihydroxy-1,4-benzaldehyde, 2,5-difluoro-1,4-benzaldehyde, 2,5-dibromo-1,4-benzaldehyde, 2,3,5,6-tetrafluoroterephthalaldehyde, pyromellitic terephthalaldehyde, or trialdehyde-resorcinol.

4. The method for preparing the covalent organic framework material as described in claim 1, characterized in that, The organic amine is one or more of p-phenylenediamine, 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, 1,3,5-tris(4-aminophenyl)benzene, tris(4-aminophenyl)amine, tetra(4-aminophenyl)porphyrin, or tetra(4-aminophenyl)methane.

5. The method for preparing the covalent organic framework material as described in claim 1, characterized in that, The molar ratio of the organic amine to the organic aldehyde is (0.5-1):

1.

6. The method for preparing the covalent organic framework material as described in claim 1, characterized in that, The concentration of the organic amine monomer in the eutectic solvent is 0.01 mol / L to 0.02 mol / L, and the concentration of the organic aldehyde monomer in the eutectic solvent is 0.01 mol / L to 0.04 mol / L.

7. The method for preparing the covalent organic framework material as described in claim 1, characterized in that, The condensation reaction is followed by purification and post-treatment. The purification method is to perform Soxhlet extraction on the crude covalent organic framework product using tetrahydrofuran and ethanol as organic solvents. The post-treatment method is to soak the Soxhlet extracted product in n-hexane and then dry it.

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