A covalent organic framework material and its preparation method and application

Abstract

The invention discloses a covalent organic framework material and a preparation method and application thereof, belonging to the technical field of polymer preparation. The preparation method of the covalent organic framework material comprises the following steps: condensing an organic aldehyde and an organic amine in a low eutectic solvent to obtain a covalent organic framework material; wherein the low eutectic solvent is a two-component eutectic liquid composed of menthol and acetic acid; the reaction temperature is 25°C to 120°C, and the reaction time is 1 hour to 72 hours. The present invention adopts a low eutectic solvent composed of menthol and acetic acid, which not only has good solubility for organic matter, but also can efficiently catalyze the condensation reaction of organic amine and organic aldehyde. The prepared covalent organic framework material has high crystallinity and has good applications in the fields of adsorption separation, heterogeneous catalysis and energy storage. The method has mild reaction conditions, simple operation, good universality, is conducive to industrial large-scale production, and conforms to the concept of green chemistry.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer preparation, and in particular relates to a covalent organic framework material and a preparation method and application thereof. Background Art

[0002] Covalent organic frameworks (COFs) are a new type of crystalline porous polymer material constructed by organic building blocks through covalent bonds, mainly composed of light elements such as C, H, O, N, and B. Among them, imine COFs connected by imines have attracted great attention in many fields due to their highly ordered and controllable pore structure, excellent chemical stability, thermal stability and other physical and chemical properties. The main method for preparing imine COFs is the solvothermal method. However, the organic solvents required for the solvothermal method are highly toxic, and the preparation process requires harsh reaction conditions and cumbersome preparation processes (high temperature and high pressure, freeze-pump-thaw cycles, and long reaction time). In addition, the solvothermal method is highly dependent on the composition of the solvent and the amount of the catalyst. For monomers with different chemical activities, the composition of the solvent and the amount of the catalyst need to be strictly controlled to obtain highly crystalline products, and a large number of exploratory experiments are required for this purpose. Therefore, whether from the perspective of green chemistry or economic efficiency, it is necessary to develop a fairly universal green solvent system for the synthesis of imine COFs.

[0003] At present, the focus of the green synthesis of imine COFs is mainly on solvents and catalysts, but the research on the two is relatively independent. Deep eutectic solvent (DES) is a new type of green solvent composed of hydrogen bond donors (HBD) and hydrogen bond acceptors (HBA). Due to its many advantages such as adjustable physical and chemical properties and excellent solubility for organic building blocks, it has been gradually used in the synthesis of imine COFs under mild conditions in recent years.

[0004] Prior art CN110894299B discloses a method for synthesizing a covalent organic framework material using a low eutectic solvent, wherein an organic amine, an organic aldehyde and a low eutectic solvent are added to a reactor and mixed evenly to obtain a first mixed solution; a catalyst is added to the first mixed solution to obtain a second mixed solution; the reactor containing the second mixed solution is quickly frozen with liquid nitrogen, and the reactor is flame-sealed under vacuum; the sealed reactor is subjected to an aldehyde-amine condensation reaction to obtain a covalent organic framework crude product; the covalent organic framework crude product is post-processed to obtain a covalent organic framework material. However, this preparation method requires complex operations such as liquid nitrogen freezing and high-temperature flame sealing to obtain a high-yield covalent organic framework material.

[0005] Prior art CN113817116B discloses a method for preparing a covalent organic framework material, wherein an organic aldehyde and an organic amine are dissolved in a low eutectic solvent, a catalyst acetic acid is added, the mixture is stirred and dissolved to form a homogeneous solution, the mixture is allowed to stand for reaction at room temperature for 2 hours to 72 hours, and the covalent organic framework material is obtained by centrifugation, washing, and drying, wherein the organic aldehyde is one of trialdehyde phloroglucinol, 2,5-divinyl-1,4-benzenedicaldehyde, and 2,5-dimethoxybenzene-1,4-diformaldehyde; the organic amine is one of p-phenylenediamine, tris(4-aminophenyl)amine, and 1,3,5-tris(4-aminophenyl)benzene; the hydrogen bond acceptor of the low eutectic solvent is choline chloride, and the hydrogen bond donor of the low eutectic solvent is one of oxalic acid dihydrate, formic acid, acetic acid, and lactic acid. However, it can be seen from the PXRD pattern of the covalent organic framework material prepared therefrom that the prepared material has only a diffraction peak of relatively weak intensity at the peak position of the corresponding crystal plane. Furthermore, no obvious lattice fringes were observed from the transmission electron microscope image, indicating that the covalent organic framework material prepared by the prior art has a poor crystal form 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 the existing preparation methods of covalent organic framework materials, such as harsh conditions and complicated operations, and low crystallinity of the prepared covalent organic framework materials, and to provide a preparation method of covalent organic framework materials with mild synthesis conditions, simple operations, and high crystallinity of the synthesized covalent organic framework materials.

[0007] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0008] A method for preparing a covalent organic framework material comprises the following steps: subjecting an organic aldehyde and an organic amine to a condensation reaction in a low eutectic solvent to obtain a covalent organic framework material;

[0009] Wherein, the deep eutectic solvent is a two-component eutectic liquid composed of menthol and acetic acid;

[0010] The reaction temperature is 25° C. to 120° C., and the reaction time is 1 hour to 72 hours.

[0011] The temperature of the condensation reaction of the present invention can be 25°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, or 120°C.

[0012] The condensation reaction time of the present invention can be 1 hour, 10 hours, 20 hours, 30 hours, 40 hours, 50 hours, 60 hours, 70 hours, or 72 hours.

[0013] Preferably, the reaction temperature is 70° C. to 120° C., and the reaction time is 24 hours to 72 hours.

[0014] Preferably, in the low eutectic solvent, the molar ratio of menthol to acetic acid is (0.1-6):1.

[0015] The molar ratio of menthol to acetic acid may 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.

[0016] The low eutectic solvent composed of acetic acid as a hydrogen bond donor component can not only serve as a solvent to dissolve organic aldehydes and organic amines, but also serve as a catalyst to catalyze the condensation reaction. Therefore, in this system, the solubility properties of the low eutectic solvent can be regulated and the reaction rate can be controlled by changing the molar ratio of menthol and acetic acid.

[0017] When facing organic amine monomers or organic aldehyde monomers with different chemical activities, the low eutectic solvent used in the present invention can adapt to different monomer combinations by adjusting the molar ratio of menthol and acetic acid.

[0018] More preferably, in the low eutectic solvent, the molar ratio of menthol to acetic acid is (0.1-1):1.

[0019] When the molar ratio of menthol to acetic acid is within this range, the prepared covalent organic framework material has higher crystallinity.

[0020] Preferably, the organic aldehyde is terephthalaldehyde (CAS No. 623-27-8), 2,5-divinyl-1,4-benzenedicarbaldehyde (CAS No. 2065232-74-6), 2,5-dimethoxy-1,4-benzenedicarbaldehyde (CAS No. 7310-97-6), 2,5-dihydroxy-1,4-benzenedicarbaldehyde (CAS No. 1951-36-6), 2,5-difluoro-1, One or more of 4-benzenedicarboxaldehyde (CAS No. 608145-27-3), 2,5-dibromo-1,4-benzenedicarboxaldehyde (CAS No. 63525-48-4), 2,3,5,6-tetrafluoroterephthalaldehyde (CAS No. 3217-47-8), trimesicarboxaldehyde (CAS No. 3163-76-6) or trialdehyde phloroglucinol (CAS No. 34374-88-4).

[0021] 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), 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (CAS No. 14544-47-9), tris(4-aminophenyl)amine (CAS No. 5981-09-9), tetrakis(4-aminophenyl)porphyrin (CAS No. 22112-84-1) or tetrakis(4-aminophenyl)methane (CAS No. 60532-63-0).

[0022] Preferably, the molar ratio of the organic amine to the organic aldehyde is (0.5-1):1.

[0023] The molar ratio of the organic amine to the organic aldehyde may be 0.5:1, 0.6:1, 0.67:1, 0.7:1, 0.8:1, 0.9:1 or 1:1.

[0024] Preferably, the concentration of the organic amine monomer in the low eutectic solvent is 0.01 mol / L to 0.02 mol / L, and the concentration of the organic aldehyde monomer in the low eutectic solvent is 0.01 mol / L to 0.04 mol / L.

[0025] Preferably, after the condensation reaction, a purification process is further included, and the purification process is as follows: subjecting the crude covalent organic framework product to Soxhlet extraction, and the organic solvents are tetrahydrofuran and ethanol.

[0026] Preferably, after the purification treatment, post-treatment is further included, and the post-treatment method is: soaking the product after Soxhlet extraction in n-hexane and drying to obtain a covalent organic framework material.

[0027] The role of post-treatment is to prevent the structural collapse of the covalent organic framework during the drying process.

[0028] The structural formula of the covalent organic framework material prepared by any of the above-mentioned methods for preparing the covalent organic framework material is any one of Formula 1, Formula 2, Formula 3 or Formula 4;

[0029]

[0030] Formula 1, wherein R1 is a benzene ring, a triazine ring or N; R2 is one or more of H, F, Br, C=C, OCH3 or OH;

[0031]

[0032] Formula 2, wherein R is one or more of H, F, Br, OCH3 or OH;

[0033]

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

[0035]

[0036] General formula 4, wherein R is N, a benzene ring or a triazine ring.

[0037] The covalent organic framework material described above can be used as an adsorbent, a photocatalyst, a solid electrolyte or an electrode material.

[0038] The covalent organic framework material prepared by the present invention has high crystallinity and specific surface area, and is widely used in the fields of adsorption separation, heterogeneous catalysis and energy storage.

[0039] The covalent organic framework material prepared by the invention can be used as an adsorbent to adsorb flavonoid compounds.

[0040] The covalent organic framework material prepared by the invention can be used as a photocatalyst to catalyze water and oxygen in the air to generate hydrogen peroxide.

[0041] The covalent organic framework material prepared by the present invention can be used as a solid electrolyte in solid-state lithium metal batteries.

[0042] The covalent organic framework material prepared by the present invention can be used as an electrode material in lithium ion batteries, zinc ion batteries or sodium ion batteries.

[0043] Compared with the prior art, the present invention has at least the following beneficial effects:

[0044] The present invention discloses a method for preparing a covalent organic framework material. A low 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, in the synthesis process, the low eutectic solvent is used as both a solvent and a catalyst, and no additional catalyst needs to be added. Imine COFs with high crystallinity, high specific area and high yield are prepared under mild conditions.

[0045] Compared with the prior art, the method of the present invention has mild synthesis conditions and simple operation, and can synthesize covalent organic framework materials with high crystallinity without the need for complex operations such as freeze-evacuation-thaw cycles and high-temperature flame sealing.

[0046] Compared with traditional synthesis methods, this method has low pollution, mild reaction conditions, simple operation, good universality, is conducive to industrial large-scale production, and is in line with the concept of green chemistry. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 The powder X-ray diffraction (PXRD) patterns of a series of covalent organic framework materials obtained in Example 1 of the present invention;

[0048] Figure 2 This is an infrared spectrum (FT-IR) spectrum of the covalent organic framework material obtained in Example 1 of the present invention (the molar ratio of menthol to acetic acid is 1:2);

[0049] Figure 3 This is a scanning electron microscope (SEM) spectrum of the covalent organic framework material obtained in Example 1 of the present invention (the molar ratio of menthol to acetic acid is 1:2);

[0050] Figure 4 This is a nitrogen adsorption-desorption curve of the covalent organic framework material obtained in Example 1 of the present invention (the molar ratio of menthol to acetic acid is 1:2);

[0051] Figure 5 This is a transmission electron microscope (TEM) image of the covalent organic framework material obtained in Example 1 of the present invention (the molar ratio of menthol to acetic acid is 1:2);

[0052] Figure 6 The powder X-ray diffraction (PXRD) pattern of the covalent organic framework material obtained in Example 2 of the present invention;

[0053] Figure 7 The powder X-ray diffraction (PXRD) pattern of the covalent organic framework material obtained in Example 3 of the present invention;

[0054] Figure 8 The powder X-ray diffraction (PXRD) pattern of the covalent organic framework material obtained in Example 19 of the present invention;

[0055] Fig. 9 The powder X-ray diffraction (PXRD) pattern of the covalent organic framework material obtained in Example 20 of the present invention;

[0056] Fig.10 The following are the comparative powder X-ray diffraction (PXRD) patterns of Comparative Example 1 and Example 1. DETAILED DESCRIPTION

[0057] The present invention is further described below with reference to specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0058] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0059] The structural formula of the covalent organic framework materials prepared in the following Examples 1 to 23 is Formula 1, Formula 2, Formula 3 or Formula 4;

[0060]

[0061] Formula 1, wherein R1 is a benzene ring, a triazine ring or N; R2 is one or more of H, F, Br, C=C, OCH3 or OH;

[0062]

[0063] Formula 2, wherein R is one or more of H, F, Br, OCH3 or OH;

[0064]

[0065] Formula 3, wherein R is one or more of H, F, Br, OCH3 or OH;

[0066]

[0067] General formula 4, wherein R is N, a benzene ring or a triazine ring.

[0068] Example 1

[0069] This embodiment provides a series of preparation methods of 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 low eutectic solvent. Then, 0.0080g (0.06mM) of terephthalaldehyde (PDA) and 0.0141g (0.04mM) of 1,3,5-tris(4-aminophenyl)benzene (TAPB) are added to a 10mL plastic centrifuge tube, and 2mL of the low eutectic solvent is added as a reaction medium and catalyst at the same time. After mixing evenly, the mixed solution is kept at a constant temperature of 70°C for 24 hours. After the reaction is completed, the obtained solid precipitate is Soxhlet extracted with tetrahydrofuran and ethanol respectively. Finally, the extracted solid is immersed in n-hexane and placed in a vacuum drying oven for 12 hours to obtain a covalent organic framework material;

[0070] Wherein, the molar ratio of organic amine to organic aldehyde is 2:3;

[0071] The concentration of the organic amine monomer in the deep eutectic solvent is 0.02 mol / L;

[0072] The concentration of the organic aldehyde monomer in the deep eutectic solvent is 0.03 mol / L.

[0073] The structural formula of the covalent organic framework material is the same as the above-mentioned general structural formula 1, wherein R1 is a benzene ring and R2 is H.

[0074] The yields of covalent organic framework materials obtained at molar ratios of menthol and acetic acid 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.

[0075] Figure 1 The following are powder X-ray diffraction (PXRD) patterns of a series of covalent organic framework materials prepared in Example 1 of the present invention. Figure 1 It can be seen that when the molar ratio of menthol to acetic acid is 1:2, the product obtained shows obvious diffraction peaks at 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.

[0076] The covalent organic framework material prepared in Example 1 of the present invention when the molar ratio of menthol to acetic acid was 1:2 was characterized as follows.

[0077] Figure 2 This is the FT-IR image of the covalent organic framework material obtained in Example 1 of the present invention (the molar ratio of menthol to acetic acid is 1:2). It can be seen that at 1601 cm -1 The new absorption peak corresponds to the stretching vibration of C=N, which indicates that the amino group of TAPB successfully condenses with the aldehyde group of PDA to form an imine bond. -1 and 3353cm -1 The stretching vibration peak of PDA is at 1700 cm -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 the successful synthesis of the target covalent organic framework material.

[0078] Figure 3 This is a scanning electron microscope (SEM) image of the covalent organic framework material obtained in Example 1 of the present invention (the 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 shape.

[0079] Figure 4 This is a nitrogen adsorption-desorption curve of the covalent organic framework material obtained in Example 1 of the present invention (the 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, up to 1834 m² / g.

[0080] Figure 5This is a transmission electron microscope (TEM) image of the covalent organic framework material obtained in Example 1 of the present invention (the molar ratio of menthol to acetic acid is 1:2). Figure 5 It can be seen that the prepared covalent organic framework material has obvious lattice fringes, reflecting its high crystallinity.

[0081] Example 2

[0082] This example provides a method for preparing a series of covalent organic framework materials, which are the same as the preparation steps of Example 1, except that 0.0080 g (0.06 mM) of terephthalaldehyde is replaced by 0.0100 g (0.06 mM) of 2,5-dihydroxy-1,4-benzenedicarbaldehyde.

[0083] The structural formula of the covalent organic framework material is the same as the above general structural formula 1, wherein R1 is a benzene ring, and R2 is H and OH.

[0084] Figure 6 The following are powder X-ray diffraction (PXRD) patterns of a series of covalent organic framework materials prepared in Example 2 of the present invention. Figure 6 It can be seen that when the molar ratio of menthol to acetic acid is 1:1, the product obtained shows obvious diffraction peaks at 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.

[0085] Example 3

[0086] This example provides a method for preparing a series of covalent organic framework materials, which are the same as the preparation steps of Example 1, except that 0.0080 g (0.06 mM) of terephthalaldehyde is replaced by 0.0102 g (0.06 mM) of 2,5-difluoro-1,4-benzenedicarbaldehyde.

[0087] The structural formula of the covalent organic framework material is the same as the above-mentioned general structural formula 1, wherein R1 is a benzene ring, and R2 is H and F.

[0088] Figure 7 The following are powder X-ray diffraction (PXRD) patterns of a series of covalent organic framework materials prepared in Example 3 of the present invention. Figure 7 It can be seen that when the molar ratio of menthol to acetic acid is 1:6, the product obtained shows obvious diffraction peaks at 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.

[0089] Example 4

[0090] This embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps of Example 1, except that the molar ratio of menthol to acetic acid is 1:1, and 0.0080 g (0.06 mM) of terephthalaldehyde is replaced by 0.0116 g (0.06 mM) of 2,5-dimethoxy-1,4-benzenedicarbaldehyde.

[0091] The structural formula of the covalent organic framework material is the same as the above-mentioned general structural formula 1, wherein R1 is a benzene ring, and R2 is H and OCH3.

[0092] Example 5

[0093] This embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps of Example 1, except that the molar ratio of menthol to acetic acid is 1:4, and 0.0080 g (0.06 mM) of terephthalaldehyde is replaced by 0.0065 g (0.04 mM) of trimesaldehyde.

[0094] The structural formula of the covalent organic framework material is the same as the above-mentioned general structural formula 4, wherein R is a benzene ring.

[0095] Example 6

[0096] This embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps of Example 1, except that the molar ratio of menthol to acetic acid is 1:4, and 0.0141 g (0.04 mM) of 1,3,5-tris(4-aminophenyl)benzene is replaced by 0.0142 g (0.04 mM) of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine.

[0097] The structural formula of the covalent organic framework material is the same as the above general structural formula 1, wherein R1 is a triazine ring and R2 is H.

[0098] Example 7

[0099] The present embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps of Example 1, except that the molar ratio of menthol to acetic acid is 1:1, 0.0141 g (0.04 mM) of 1,3,5-tris(4-aminophenyl)benzene is replaced by 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 by 0.0100 g (0.06 mM) of 2,5-dihydroxy-1,4-benzenedicarbaldehyde.

[0100] The structural formula of the covalent organic framework material is the same as the above general structural formula 1, wherein R1 is a triazine ring, and R2 is H and OH.

[0101] Example 8

[0102] The present embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps of 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 by 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 by 0.0102 g (0.06 mM) of 2,5-difluoro-1,4-benzenedicarbaldehyde.

[0103] The structural formula of the covalent organic framework material is the same as the above general structural formula 1, wherein R1 is a triazine ring, and R2 is H and F.

[0104] Example 9

[0105] The present embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps of Example 1, except that the molar ratio of menthol to acetic acid is 1:1, 0.0141 g (0.04 mM) of 1,3,5-tris(4-aminophenyl)benzene is replaced by 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 by 0.0116 g (0.06 mM) of 2,5-dimethoxy-1,4-benzenedicarbaldehyde.

[0106] The structural formula of the covalent organic framework material is the same as the above general structural formula 1, wherein R1 is a triazine ring, and R2 is H and OCH3.

[0107] Example 10

[0108] The present embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps of Example 1, except that the molar ratio of menthol to acetic acid is 1:6, the temperature is changed from 70°C to 90°C, 0.0141g (0.04mM) of 1,3,5-tris(4-aminophenyl)benzene is replaced by 0.0142g (0.04mM) of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, and 0.0080g (0.06mM) of terephthalaldehyde is replaced by 0.0065g (0.04mM) of trimesic acid.

[0109] The structural formula of the covalent organic framework material is the same as the above general structural formula 4, wherein R is a triazine ring.

[0110] Embodiment 11

[0111] This embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps of Example 1, except that the molar ratio of menthol to acetic acid is 1:1, and 0.0141 g (0.04 mM) of 1,3,5-tris(4-aminophenyl)benzene is replaced by 0.0116 g (0.04 mM) of tris(4-aminophenyl)amine.

[0112] The structural formula of the covalent organic framework material is the same as the above general structural formula 1, wherein R1 is N and R2 is H.

[0113] Example 12

[0114] The present embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps of Example 1, except that the molar ratio of menthol to acetic acid is 1:1, 0.0141 g (0.04 mM) of 1,3,5-tris(4-aminophenyl)benzene is replaced by 0.0116 g (0.04 mM) of tris(4-aminophenyl)amine, and 0.0080 g (0.06 mM) of terephthalaldehyde is replaced by 0.0100 g (0.06 mM) of 2,5-dihydroxy-1,4-benzenedicarbaldehyde.

[0115] The structural formula of the covalent organic framework material is the same as the above general structural formula 1, wherein R1 is N, and R2 is H and OH.

[0116] Embodiment 13

[0117] The present embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps of Example 1, except that the molar ratio of menthol to acetic acid is 1:2, 0.0141 g (0.04 mM) of 1,3,5-tris(4-aminophenyl)benzene is replaced by 0.0116 g (0.04 mM) of tris(4-aminophenyl)amine, and 0.0080 g (0.06 mM) of terephthalaldehyde is replaced by 0.0102 g (0.06 mM) of 2,5-difluoro-1,4-benzenedicarbaldehyde.

[0118] The structural formula of the covalent organic framework material is the same as the above general structural formula 1, wherein R1 is N, and R2 is H and F.

[0119] Embodiment 14

[0120] The present embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps of Example 1, except that the molar ratio of menthol to acetic acid is 1:1, 0.0141 g (0.04 mM) of 1,3,5-tris(4-aminophenyl)benzene is replaced by 0.0116 g (0.04 mM) of tris(4-aminophenyl)amine, and 0.0080 g (0.06 mM) of terephthalaldehyde is replaced by 0.0116 g (0.06 mM) of 2,5-dimethoxy-1,4-benzenedicarbaldehyde.

[0121] The structural formula of the covalent organic framework material is the same as the above general structural formula 1, wherein R1 is N, and R2 is H and OCH3.

[0122] Embodiment 15

[0123] The present embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps of Example 1, except that the molar ratio of menthol to acetic acid is 1:2, 0.0141 g (0.04 mM) of 1,3,5-tris(4-aminophenyl)benzene is replaced by 0.0116 g (0.04 mM) of tris(4-aminophenyl)amine, and 0.0080 g (0.06 mM) of terephthalaldehyde is replaced by 0.0065 g (0.04 mM) of trimesic acid.

[0124] The structural formula of the covalent organic framework material is the same as the above general structural formula 4, wherein R is N.

[0125] Example 16

[0126] This embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps of Example 1, except that the molar ratio of menthol to acetic acid is 1:2, 0.0141 g (0.04 mM) of 1,3,5-tris(4-aminophenyl)benzene is replaced by 0.0152 g (0.04 mM) of tetrakis(4-aminophenyl)methane, and 0.0080 g (0.06 mM) of terephthalaldehyde is replaced by 0.0107 g (0.08 mM) of terephthalaldehyde.

[0127] The structural formula of the covalent organic framework material is the same as the above general structural formula 2, wherein R is H.

[0128] Embodiment 17

[0129] The present embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps of Example 1, except that the molar ratio of menthol to acetic acid is 1:1, 0.0141 g (0.04 mM) of 1,3,5-tris(4-aminophenyl)benzene is replaced by 0.0152 g (0.04 mM) of tetrakis(4-aminophenyl)methane, and 0.0080 g (0.06 mM) of terephthalaldehyde is replaced by 0.0133 g (0.08 mM) of 2,5-dihydroxy-1,4-benzenedicarbaldehyde.

[0130] The structural formula of the covalent organic framework material is the same as the above general structural formula 2, wherein R is H and OH.

[0131] Embodiment 18

[0132] The present embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps of 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 by 0.0152 g (0.04 mM) of tetrakis(4-aminophenyl)methane, and 0.0080 g (0.06 mM) of terephthalaldehyde is replaced by 0.0136 g (0.08 mM) of 2,5-difluoro-1,4-benzenedicarbaldehyde.

[0133] The structural formula of the covalent organic framework material is the same as the above general structural formula 2, wherein R is H and F.

[0134] Embodiment 19

[0135] This embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps of Example 1, except that the molar ratio of menthol to acetic acid is 1:1, the temperature is changed from 70°C to 90°C, 0.0141g (0.04mM) of 1,3,5-tris(4-aminophenyl)benzene is replaced by 0.0152g (0.04mM) of tetrakis(4-aminophenyl)methane, and 0.0080g (0.06mM) of terephthalaldehyde is replaced by 0.0155g (0.08mM) of 2,5-dimethoxy-1,4-benzenedicarbaldehyde.

[0136] The structural formula of the covalent organic framework material is the same as the above-mentioned general structural formula 2, wherein R is H and OCH3.

[0137] Figure 8 This is the powder X-ray diffraction (PXRD) pattern of the covalent organic framework material of Example 19 of the present invention. Figure 8It can be seen that when the molar ratio of menthol to acetic acid is 1:1, the product obtained 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.

[0138] Embodiment 20

[0139] This embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps of Example 1, except that the molar ratio of menthol to acetic acid is 1:2, the temperature is changed from 70°C to 120°C, 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 by 0.0270 g (0.04 mM) of tetrakis(4-aminophenyl)porphyrin, and 0.0080 g (0.06 mM) of terephthalaldehyde is replaced by 0.0155 g (0.08 mM) of 2,5-dimethoxy-1,4-benzenedicarbaldehyde.

[0140] The structural formula of the covalent organic framework material is the same as the above-mentioned general structural formula 3, wherein R is H and OCH3.

[0141] Fig. 9 This is the powder X-ray diffraction (PXRD) pattern of the covalent organic framework material of Example 20 of the present invention. Fig. 9 It can be seen that when the molar ratio of menthol to acetic acid is 1:2, the product obtained has a more obvious diffraction peak at the 3.6° position, corresponding to the (110) crystal plane, indicating that the material has good crystallinity.

[0142] Embodiment 21

[0143] This embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps of Example 1, except that the molar ratio of menthol to acetic acid is 1:2, and 0.0080 g (0.06 mM) of terephthalaldehyde is replaced by 0.0112 g (0.06 mM) of 2,5-divinyl-1,4-benzenedicarbaldehyde.

[0144] The structural formula of the covalent organic framework material is the same as the above-mentioned general structural formula 1, wherein R1 is a benzene ring, and R2 is H and C=C.

[0145] Embodiment 22

[0146] This embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps of Example 1, except that the molar ratio of menthol to acetic acid is 1:1, and 0.0080 g (0.06 mM) of terephthalaldehyde is replaced by 0.0175 g (0.06 mM) of 2,5-dibromo-1,4-benzenedicarbaldehyde.

[0147] The structural formula of the covalent organic framework material is the same as the above general structural formula 1, wherein R1 is a benzene ring, and R2 is H and Br.

[0148] Embodiment 23

[0149] This embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps of Example 1, except that the molar ratio of menthol to acetic acid is 1:4, and 0.0080 g (0.06 mM) of terephthalaldehyde is replaced by 0.0124 g (0.06 mM) of 2,3,5,6-tetrafluorobenzaldehyde.

[0150] The structural formula of the covalent organic framework material is the same as the above-mentioned general structural formula 1, wherein R1 is a benzene ring and R2 is F.

[0151] Embodiment 24

[0152] The present embodiment provides a method for preparing a covalent organic framework material, which has the same preparation steps as those of Example 1, except that the molar ratio of menthol to acetic acid is 1:2, 0.0141 g (0.04 mM) of 1,3,5-tris(4-aminophenyl)benzene is replaced by 0.0130 g (0.12 mM) of p-phenylenediamine, and 0.0080 g (0.06 mM) of terephthalaldehyde is replaced by 0.0168 g (0.08 mM) of trialdehyde pyroglutamic acid.

[0153] The structural formula of the covalent organic framework material is as follows:

[0154]

[0155] Comparative Example 1

[0156] This embodiment provides a method for preparing a covalent organic framework material, which is the same as the preparation steps of Example 1, except that the low eutectic solvent is choline chloride and acetic acid, and the molar ratios of choline chloride and acetic acid are 1:1, 1:2, 1:4, and 1:6, respectively.

[0157] Fig.10 The powder X-ray diffraction (PXRD) patterns of the covalent organic framework materials prepared in Example 1 of the present invention and Comparative Example 1 at the same molar ratio, wherein the molar ratio with * represents the molar ratio of the combination of choline chloride and acetic acid. Fig.10 It can be seen that at the same molar ratio, compared with the low eutectic solvent composed of menthol and acetic acid, the covalent organic framework prepared by the low eutectic solvent composed of choline chloride and acetic acid only shows a very weak diffraction peak in the powder X-ray diffraction (PXRD) spectrum test, indicating that its crystallinity is significantly lower than the covalent organic framework prepared in the low eutectic solvent composed of menthol and acetic acid.

[0158] In addition, the yields of the covalent organic framework material obtained in Comparative Example 1 at molar ratios of choline chloride and acetic acid 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.

[0159] In summary, the present invention uses a low eutectic solvent composed of menthol and acetic acid as both a solvent and a catalyst to achieve green synthesis of high-crystallinity imine COFs under mild conditions. In addition, Examples 1 to 3 have demonstrated that the present invention can obtain high-crystallinity covalent organic framework materials by simply changing the molar ratio of menthol and acetic acid when facing a combination of monomers with different chemical activities, indicating that it has fairly good universality.

[0160] It can be seen from the examples and comparative example 1 that the covalent organic framework material prepared by using choline chloride as an acceptor of the low eutectic solvent has low crystallinity and a low yield.

[0161] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited to the above specific embodiment. Obviously, those skilled in the art can easily make various changes or modifications within the scope of the claims of the present invention, which does not affect the essential content of the present invention.

Claims

1. A method for preparing a covalent organic framework material, characterized in that: The method comprises the following steps: subjecting an organic aldehyde and an organic amine to a condensation reaction in a low eutectic solvent to obtain a covalent organic framework material; Wherein, the deep eutectic solvent is a two-component eutectic liquid composed of menthol and acetic acid; The reaction temperature is 25°C to 120°C, and the reaction time is 1 hour to 72 hours; In the low eutectic solvent, the molar ratio of menthol to acetic acid is (0.1-1):

1.

2. The method for preparing a covalent organic framework material according to claim 1, characterized in that: The organic aldehyde is one or more of terephthalaldehyde, 2,5-divinyl-1,4-benzenedicaldehyde, 2,5-dimethoxy-1,4-benzenedicaldehyde, 2,5-dihydroxy-1,4-benzenedicaldehyde, 2,5-difluoro-1,4-benzenedicaldehyde, 2,5-dibromo-1,4-benzenedicaldehyde, 2,3,5,6-tetrafluoroterephthalaldehyde, trimesic acid or trialdehyde phloroglucinol.

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

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

1.

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

6. The method for preparing a covalent organic framework material according to claim 1, characterized in that: After the condensation reaction, purification and post-treatment are also included. The purification method is: subjecting the crude covalent organic framework product to Soxhlet extraction, with the organic solvents being tetrahydrofuran and ethanol; and the post-treatment method is: immersing the product after Soxhlet extraction in n-hexane and drying.

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