A method for preparing a three-dimensional single-crystalline covalent organic framework in aqueous phase

Abstract

The present invention discloses a method for preparing a three-dimensional single crystal covalent organic framework in water phase. The present invention reduces the synthesis time of synthesizing a three-dimensional single crystal covalent organic framework in water phase, shortening it from 3 days in the prior art to 1 hour. The present invention utilizes the surface active polyether functional group polyether group to form hydrogen bond with imine bond, and the imine bond compound is enriched on the surface of the polyether polymer, thereby guiding the imine molecules to self-assemble around the ether bond to increase the reaction rate. At the same time, the preparation method is universal, and the synthesis of three-dimensional single crystals can be quickly achieved for different inorganic salts, acids, amino monomers and aldehyde monomers.

Description

Technical Field

[0001] The invention relates to the field of covalent organic framework synthesis, and in particular to an aqueous phase preparation method for a three-dimensional single crystal covalent organic framework. Background Art

[0002] Two-dimensional and three-dimensional single-crystalline covalent organic frameworks (COFs) have broad applications in electronics, optoelectronics, and energy storage. However, the current traditional COF synthesis has many disadvantages, such as the use of toxic organic solvents, the high temperature required for synthesis greater than 120°C, and the long synthesis time of 3-7 days.

[0003] To solve the above problems, researchers have proposed a method for synthesizing COF materials in water phase, which improves the problem of toxic organic solvents. However, there are few reports on the synthesis of COF materials in water phase. Therefore, expanding the research on the synthesis of COF materials in water phase has very important practical significance and industrial application prospects.

[0004] Zhipeng Zhou et al. reported a method of controlling the growth morphology of COFs in aqueous phase using hydrophobic amino acid derivatives, and successfully synthesized imine COFs single crystals in aqueous solution (reference: Nat. Chem. 15, 841–847 (2023)). However, the process of converting its amorphous structure into a crystalline state requires a long process (greater than 7 days). In addition, a surfactant of sodium dodecyl sulfate was used to synthesize three-dimensional COFs flake crystals, but the reaction time of this method was as long as 2 weeks, and the problem of slow reaction kinetics was still not solved (reference: J. Am. Chem. Soc. 2023, 145, 40, 22079–22085). In the prior art, Wei Zhao et al. used ultrasonic synthesis to achieve the synthesis of several two-dimensional COFs. This document uses a sonochemical method to achieve the rapid synthesis of imine covalent organic frameworks, and the crystallinity and porosity of the obtained COFs are higher than those of solvent thermal synthesis. Although the synthesis time of this method is less than 1 hour, this method does not obtain single crystal samples of COFs (reference source: Nat Synth 1, 87–95 (2022)).

[0005] To solve the above technical problems, the present invention proposes a water-phase synthesis method for rapidly synthesizing three-dimensional single crystal COF. This method avoids the toxicity of organic solvents based on water-phase synthesis, and expands the application prospects of the method by performing a series of regulation on precursors such as amino monomers, aldehyde monomers, acids, inorganic salts, and polyethylene glycol. The present invention can achieve the synthesis of three-dimensional single crystal COF in 1 hour, accelerating the process of chemical reaction kinetics. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a preparation method for rapidly synthesizing a covalent organic framework of a three-dimensional single crystal in an aqueous phase; the preparation method can rapidly synthesize high-quality single crystal materials within 1 hour, thereby improving the chemical reaction kinetics.

[0007] The first aspect of the present invention provides a method for preparing a three-dimensional single crystal covalent organic framework in water, which specifically comprises the following steps:

[0008] A surfactant, an inorganic salt, an acid, an aldehyde monomer and an amino monomer are added to water to form a mixed solution, and the mixed solution is allowed to stand to obtain a covalent organic skeleton; the surfactant is selected from EO / PO block polyether and / or polyethylene glycol.

[0009] Furthermore, the concentration of the surfactant is 16.6-100 mg / ml.

[0010] Furthermore, the EO / PO block polyether is selected from one or more of F127, L65 or P124; more preferably F127 and / or L65.

[0011] Furthermore, the molecular weight of the polyethylene glycol is preferably 400-8000Da; more preferably 6000Da.

[0012] Further, the inorganic salt is selected from one or more of lithium perchlorate, sodium perchlorate, lithium iodide, sodium iodide, calcium chloride, sodium acetate, potassium chloride, sodium chloride, lithium chloride, magnesium chloride, potassium iodide and sodium nitrate; more preferably one or more of lithium perchlorate, sodium perchlorate, lithium iodide, sodium iodide and calcium chloride.

[0013] Furthermore, the concentration range of the inorganic salt is 13-150 mg / ml.

[0014] Furthermore, the amino monomer is tetrakis(4-aminophenyl)methane (TAM).

[0015] Furthermore, the concentration of the amino monomer is 6.7-33 mg / ml.

[0016] Furthermore, the aldehyde monomer is selected from one or more of terephthalaldehyde, 2,5-dihydroxy-terephthalaldehyde, 2,5-dimethoxy-terephthalaldehyde, 2,3,5,6-4-fluoro-terephthalaldehyde and [1,1'-biphenyl]-4,4'-dicarboxaldehyde.

[0017] Further, the acid is a strong acid and / or a weak acid;

[0018] Furthermore, the weak acid is selected from one or more of acetic acid, formic acid and oxalic acid; the molar ratio of amino monomer: aldehyde monomer: weak acid is 1:2:(7.9-79).

[0019] Furthermore, the strong acid is p-toluenesulfonic acid; the molar ratio of amino monomer: aldehyde monomer: strong acid is 1:2:(0.46-4.6).

[0020] Furthermore, the preparation process of the covalent organic framework needs to maintain a certain temperature, the temperature range is 10-90°C; preferably 20-90°C, more preferably 50°C.

[0021] Furthermore, the standing step time is greater than 30 minutes; more preferably 1 hour to 6 hours; most preferably 4 hours.

[0022] The second aspect of the present invention provides a covalent organic framework prepared by the preparation method described in the first aspect.

[0023] Beneficial effects of the present invention:

[0024] 1. The synthesis process of the present invention has fast reaction time kinetics; a three-dimensional single crystal covalent organic framework can be synthesized when the reaction time reaches 1 hour, and the maximum yield of 82% is achieved in 4 hours. The surfactant used in the present invention has a polyether group, which can form a hydrogen bond with an imine bond, and the imine bond compound is enriched on the surface of the polyether polymer, thereby guiding the imine molecules to self-assemble around the ether bond to increase the reaction rate.

[0025] 2. The present invention is simple to operate, has a low reaction temperature, and a high yield, and is suitable for the synthesis of different imine covalent organic frameworks.

[0026] 3. The surface catalyst and acid catalyst used in the present invention have a wide range of options and are low in price and are suitable for industrial production and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is the electron microscope image and powder XRD of COF prepared in Example 1 at room temperature;

[0028] Figure 2 Example 2 uses NaClO 4 Electron microscope images and powder XRD (g), Fourier transform infrared spectra (h) of COF synthesized from salt after different standing times of 10min (a), 30min (b), 1h (c), 2h (d), 4h (e), 6h (f), and yields at different times (i);

[0029] Figure 3 Example 3 uses NaClO 4 SAED pattern of COF synthesized from salt;

[0030] Figure 4 Example 3 uses NaI and CaCl 2 , LiI or LiClO 4Electron microscopy and powder XRD of COF synthesized from salts;

[0031] Figure 5 This is the powder XRD of COF synthesized with other inorganic salts used in Example 3;

[0032] Figure 6 It is the electron microscope image and powder XRD of COF prepared in Example 4;

[0033] Figure 7 The electron microscope image, powder XRD and Fourier transform infrared spectrum of the COF prepared in Example 6;

[0034] Figure 8 are the electron microscope image and powder XRD of the COF prepared in Example 7;

[0035] Fig. 9 is the electron microscope image and powder XRD of the COF prepared in Example 8;

[0036] Fig.10 are the electron microscope image and powder XRD of the COF prepared in Example 9;

[0037] Fig.11 is the electron microscope image and powder XRD of the COF prepared using the block copolymer L65 in Example 10;

[0038] Fig.12 is an electron microscope image of the COF prepared in Example 11;

[0039] Fig.13 is the powder XRD of the COF prepared in Example 11;

[0040] Fig.14 are electron micrographs of the COF prepared in Example 12, p-toluenesulfonic acid (a), oxalic acid (b), and formic acid (c);

[0041] Fig.15 is the powder XRD of the COF prepared in Example 12;

[0042] Fig.16 These are the electron microscope image and powder XRD of the COF prepared in Example 15.

[0043] Fig.17 The electron microscope images of COF prepared by adjusting the concentration of F127 at different concentrations of 16.6 mg / ml (a), 33.3 mg / ml (b), and 66.6 mg / ml (c) in Example 16;

[0044] Fig.18 is an electron microscope image of the COF prepared in Example 17;

[0045] Fig.19 This is an electron microscope image of the COF prepared in Comparative Example 1;

[0046] Fig. 20 This is an electron microscope image of the COF prepared in Comparative Example 2;

[0047] Fig.21 This is an electron microscope image of the COF prepared in Comparative Example 3;

[0048] Fig. 22 This is an electron microscope image of the COF prepared in Comparative Example 4;

[0049] Fig.23 This is an electron microscope image of the COF prepared in Comparative Example 5. DETAILED DESCRIPTION

[0050] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0051] Example 1

[0052] At room temperature, 6 ml of aqueous solution was added with F127, NaClO 4 , tetrakis(4-aminophenyl)methane amino monomer, terephthalaldehyde and 50ul of glacial acetic acid to form a mixed solution; the concentration of F127 in the mixed solution is 20mg / ml, NaClO 4 The concentration of tetrakis(4-aminophenyl)methane amino monomer is 30 mg / ml, the concentration of terephthalaldehyde is 6.7 mg / ml, and the concentration of terephthalaldehyde is 4 mg / ml. The mixed solution is allowed to stand at room temperature and washed to obtain a COF single crystal.

[0053] Example 2

[0054] At 50°C, 6 ml of aqueous solution was added with F127, NaClO 4 , tetrakis(4-aminophenyl)methane amino monomer, terephthalaldehyde and 50ul of glacial acetic acid to form a mixed solution. The concentration of F127 in the mixed solution is 20mg / ml, the concentration of salt is 30mg / ml, the concentration of tetrakis(4-aminophenyl)methane amino monomer is 6.7mg / ml, and the concentration of terephthalaldehyde is 4mg / ml. The mixed solution is allowed to stand at 50°C for different time periods (10min, 30min, 1h, 2h, 4h, 6h), and washed to obtain a COF single crystal. The molar ratio of the amino monomer: aldehyde monomer: acetic acid is 1:2:7.9.

[0055] Example 3

[0056] At 50°C, 6 ml of aqueous solution was added with F127, salt, tetrakis(4-aminophenyl)methane amino monomer, terephthalaldehyde and 50ul of glacial acetic acid to form a mixed solution; the types of salts were lithium perchlorate, sodium perchlorate, lithium iodide, sodium iodide, calcium chloride, sodium acetate, potassium chloride, sodium chloride, lithium chloride, magnesium chloride, potassium iodide and sodium nitrate. The concentration of F127 in the mixed solution was 20 mg / ml, the concentration of salt was 30 mg / ml, the concentration of tetrakis(4-aminophenyl)methane amino monomer was 6.7 mg / ml, and the concentration of terephthalaldehyde was 4 mg / ml. The mixed solution was allowed to stand at 50°C and washed to obtain COF-300 single crystals. The results show that COF single crystals can be formed by changing the types of salts.

[0057] Example 4

[0058] At 70°C, 6 ml of aqueous solution was added with F127, NaClO 4 , tetrakis(4-aminophenyl)methane amino monomer, terephthalaldehyde and 50ul of glacial acetic acid to form a mixed solution; the concentration of F127 in the mixed solution is 20mg / ml, NaClO 4 The concentration of tetrakis(4-aminophenyl)methane amino monomer is 30 mg / ml, the concentration of terephthalaldehyde is 6.7 mg / ml, and the concentration of terephthalaldehyde is 4 mg / ml. The mixed solution is allowed to stand at 70°C and washed to obtain a COF single crystal.

[0059] Example 5

[0060] At 90°C, 6 ml of aqueous solution was added with F127, NaClO 4 , tetrakis(4-aminophenyl)methane amino monomer, terephthalaldehyde and 50ul of glacial acetic acid to form a mixed solution; the concentration of F127 in the mixed solution is 20mg / ml, NaClO 4 The concentration of tetrakis(4-aminophenyl)methane amino monomer is 30 mg / ml, the concentration of terephthalaldehyde is 6.7 mg / ml, and the concentration of terephthalaldehyde is 4 mg / ml. The mixed solution is allowed to stand at 90°C and washed to obtain a COF single crystal.

[0061] Example 6

[0062] At 50°C, 6 ml of aqueous solution was added with F127, NaClO 4 , tetrakis(4-aminophenyl)methane amino monomer, 2,5-dihydroxy-terephthalaldehyde and 300ul of glacial acetic acid to form a mixed solution. The concentration of F127 in the mixed solution is 20mg / ml, NaClO 4The concentration of tetrakis(4-aminophenyl)methane is 30 mg / ml, the concentration of 2,5-dihydroxy-terephthalaldehyde is 3.3 mg / ml, and the concentration of 2,5-dihydroxy-terephthalaldehyde is 2.5 mg / ml. The mixed solution is allowed to stand at 50° C. and washed to obtain a COF single crystal.

[0063] Example 7

[0064] At 50°C, 6 ml of aqueous solution was added with F127, NaClO 4 , tetrakis(4-aminophenyl)methane amino monomer, 2,5-dimethoxy-terephthalaldehyde and 400ul of glacial acetic acid to form a mixed solution. The concentration of F127 in the mixed solution is 20mg / ml, NaClO 4 The concentration of tetrakis(4-aminophenyl)methane is 66 mg / ml, the concentration of 2,5-dimethoxy-terephthalaldehyde is 6.7 mg / ml, and the concentration of 2,5-dimethoxy-terephthalaldehyde is 5 mg / ml. The mixed solution is allowed to stand at 50° C. and washed to obtain a COF single crystal.

[0065] Example 8

[0066] At 50°C, 6 ml of aqueous solution was added with F127, NaClO 4 , tetrakis(4-aminophenyl)methane amino monomer, 2,3,5,6-4-fluoro-terephthalaldehyde and 200ul of glacial acetic acid to form a mixed solution. The concentration of F127 in the mixed solution is 20mg / ml, NaClO 4 The concentration of tetrakis(4-aminophenyl)methane is 166 mg / ml, the concentration of 2,3,5,6-4-fluoro-terephthalaldehyde is 6.7 mg / ml. The mixed solution is allowed to stand at 50°C and washed to obtain a COF single crystal.

[0067] Example 9

[0068] At 50°C, 6 ml of aqueous solution was added with F127, NaClO 4 , tetrakis(4-aminophenyl)methane amino monomer, [1,1'-biphenyl]-4,4'-dicarboxaldehyde and 300ul of glacial acetic acid to form a mixed solution. The concentration of F127 in the mixed solution is 20mg / ml, NaClO 4 The concentration of tetrakis(4-aminophenyl)methane is 30 mg / ml, the concentration of [1,1'-biphenyl]-4,4'-dicarboxaldehyde is 6.7 mg / ml, and the concentration of [1,1'-biphenyl]-4,4'-dicarboxaldehyde is 7.3 mg / ml. The mixed solution is allowed to stand at 50°C and washed to obtain a COF single crystal.

[0069] Example 10

[0070] At 50°C, 6 ml of aqueous solution was added with block copolymer, NaClO 4 , tetrakis(4-aminophenyl)methane amino monomer, terephthalaldehyde and 50ul of glacial acetic acid to form a mixed solution; the block copolymer is L65 or P124. The concentration of the block copolymer in the mixed solution is 20mg / ml, NaClO 4 The concentration of is 30 mg / ml, the concentration of amino monomer is 6.7 mg / ml, and the concentration of terephthalaldehyde is 4 mg / ml. The mixed solution is allowed to stand at 50°C and washed to obtain a COF single crystal.

[0071] Embodiment 11

[0072] At 50°C, 6 ml of aqueous solution was added with polyethylene glycol, NaClO 4 , tetrakis(4-aminophenyl)methane amino monomer, terephthalaldehyde and 50ul glacial acetic acid to form a mixed solution; the molecular weight of the polyethylene glycol is 400, 2000, 6000, 8000Da. The concentration of polyethylene glycol in the mixed solution is 20mg / ml, NaClO 4 The concentration of 30 mg / ml, the concentration of amino monomer is 6.7 mg / ml, and the concentration of terephthalaldehyde is 4 mg / ml. The mixed solution is allowed to stand at 50°C and washed to obtain a COF single crystal.

[0073] Example 12

[0074] At 50°C, 6 ml of aqueous solution was added with F127, NaClO 4 , tetrakis(4-aminophenyl)methane amino monomer, terephthalaldehyde and acid to form a mixed solution; the added acid is 5mg of p-toluenesulfonic acid, 50ul of formic acid or 70ul of oxalic acid. The concentration of F127 in the mixed solution is 20mg / ml, NaClO 4 The concentration of is 30 mg / ml, the concentration of amino monomer is 6.7 mg / ml, and the concentration of terephthalaldehyde is 4 mg / ml. The mixed solution is allowed to stand at 50°C and washed to obtain a COF single crystal. The molar ratio of the amino monomer: aldehyde monomer: p-toluenesulfonic acid is 1:2:0.46.

[0075] Embodiment 13

[0076] At 50°C, 6 ml of aqueous solution was added with F127, NaClO 4 , tetrakis(4-aminophenyl)methane amino monomer, terephthalaldehyde and 500ul glacial acetic acid to form a mixed solution; the concentration of F127 in the mixed solution is 20mg / ml, NaClO 4The concentration of is 30 mg / ml, the concentration of amino monomer is 6.7 mg / ml, and the concentration of terephthalaldehyde is 4 mg / ml. The mixed solution is allowed to stand at 50°C and washed to obtain a COF single crystal. The molar ratio of the amino monomer: aldehyde monomer: acetic acid is 1:2:79.

[0077] Embodiment 14

[0078] At 50°C, 6 ml of aqueous solution was added with F127, NaClO 4 , tetrakis(4-aminophenyl)methane amino monomer, terephthalaldehyde and 500ul glacial acetic acid to form a mixed solution; the concentration of F127 in the mixed solution is 20mg / ml, NaClO 4 The concentration of 13 mg / ml, the concentration of amino monomer is 6.7 mg / ml, and the concentration of terephthalaldehyde is 4 mg / ml. The mixed solution is allowed to stand at 50°C and washed to obtain a COF single crystal.

[0079] Embodiment 15

[0080] At 50°C, 6 ml of aqueous solution was added with F127, NaClO 4 , tetrakis(4-aminophenyl)methane amino monomer, terephthalaldehyde and 250ul glacial acetic acid to form a mixed solution; the concentration of F127 in the mixed solution is 100mg / ml, NaClO 4 The concentration of 150 mg / ml, the concentration of amino monomer is 33 mg / ml, and the concentration of terephthalaldehyde is 20 mg / ml. The mixed solution is allowed to stand at 50° C. and washed to obtain a COF single crystal.

[0081] Example 16

[0082] At 50°C, 6 ml of aqueous solution was added with F127, NaClO 4 , tetrakis(4-aminophenyl)methane amino monomer, terephthalaldehyde and 50ul glacial acetic acid to form a mixed solution; the concentration of F127 in the mixed solution is (16.6mg / ml, 33.3mg / ml or 66.6mg / ml), NaClO 4 The concentration of 30 mg / ml, the concentration of amino monomer is 6.7 mg / ml, and the concentration of terephthalaldehyde is 4 mg / ml. The mixed solution is allowed to stand at 50°C and washed to obtain a COF single crystal.

[0083] Embodiment 17

[0084] At 50°C, 6 ml of aqueous solution was added with F127, NaClO 4, tetrakis(4-aminophenyl)methane amino monomer, terephthalaldehyde and 42mg of p-toluenesulfonic acid to form a mixed solution; the concentration of F127 in the mixed solution is 20mg / ml, NaClO 4 The concentration of is 30 mg / ml, the concentration of amino monomer is 6.7 mg / ml, and the concentration of terephthalaldehyde is 4 mg / ml. The mixed solution is left to stand at 50°C for 4 hours and then washed. The results show that no single crystal of COF-300 is obtained. The molar ratio of amino monomer: aldehyde monomer: p-toluenesulfonic acid in the mixed solution is 1:2:4.6.

[0085] Comparative Example 1

[0086] At 50°C, 6 ml of aqueous solution was added with F127, NaClO 4 , tetrakis(4-aminophenyl)methane amino monomer, terephthalaldehyde and 84 mg of p-toluenesulfonic acid to form a mixed solution; the concentration of F127 in the mixed solution is 20 mg / ml, NaClO 4 The concentration of is 30 mg / ml, the concentration of amino monomer is 6.7 mg / ml, and the concentration of terephthalaldehyde is 4 mg / ml. The mixed solution is left to stand at 50°C for 4 hours and then washed. The results show that no single crystal of COF-300 is obtained. The molar ratio of amino monomer: aldehyde monomer: p-toluenesulfonic acid in the mixed solution is 1:2:9.2.

[0087] Comparative Example 2

[0088] At 50°C, 6 ml of aqueous solution was added with hexadecyltrimethylammonium chloride (CTAC) surfactant, NaClO 4 , tetrakis(4-aminophenyl)methane amino monomer, terephthalaldehyde and 50ul of glacial acetic acid to form a mixed solution; the concentration of hexadecyltrimethylammonium chloride in the mixed solution is 0.41mg / ml, NaClO 4 The concentration of is 13 mg / ml, the concentration of amino monomer is 6.7 mg / ml, and the concentration of terephthalaldehyde is 4 mg / ml. The mixed solution is allowed to stand at 50°C and washed to obtain a product.

[0089] Comparative Example 3

[0090] At 50°C, 6 ml of aqueous solution was added with sodium dodecylbenzene sulfonate (SDBS) surfactant, NaClO 4 , tetrakis(4-aminophenyl)methane amino monomer, terephthalaldehyde and 50ul of glacial acetic acid to form a mixed solution; the concentration of SDBS in the mixed solution is 0.45mg / ml, NaClO 4The concentration of is 13 mg / ml, the concentration of amino monomer is 6.7 mg / ml, and the concentration of terephthalaldehyde is 4 mg / ml. The mixed solution is allowed to stand at 50°C and washed to obtain a product.

[0091] Comparative Example 4

[0092] At 50°C, 6 ml of aqueous solution was added with sodium dodecyl sulfate (SDS) surfactant, NaClO 4 , tetrakis(4-aminophenyl)methane amino monomer, terephthalaldehyde and 50ul of glacial acetic acid to form a mixed solution; the concentration of SDS in the mixed solution is 0.45mg / ml, NaClO 4 The concentration of is 13 mg / ml, the concentration of amino monomer is 6.7 mg / ml, and the concentration of terephthalaldehyde is 4 mg / ml. The mixed solution is allowed to stand at 50°C and washed to obtain a product.

[0093] Comparative Example 5

[0094] At 50°C, 6 ml of aqueous solution was added with polyvinyl pyrrolidone (PVP) surfactant, NaClO 4 , tetrakis(4-aminophenyl)methane amino monomer, terephthalaldehyde and 50ul of glacial acetic acid to form a mixed solution; the concentration of PVP in the mixed solution is 70mg / ml, NaClO 4 The concentration of is 13 mg / ml, the concentration of amino monomer is 6.7 mg / ml, and the concentration of terephthalaldehyde is 4 mg / ml. The mixed solution is allowed to stand at 50°C and washed to obtain a product.

[0095] Comparative Example 6

[0096] At 50°C, 6 ml of aqueous solution was added with branched polyethyleneimine (BPEI) surfactant, NaClO 4 , tetrakis(4-aminophenyl)methane amino monomer, terephthalaldehyde and 50ul of glacial acetic acid to form a mixed solution; the concentration of BPEI in the mixed solution is 13mg / ml, NaClO 4 The concentration of is 13 mg / ml, the concentration of amino monomer is 6.7 mg / ml, and the concentration of terephthalaldehyde is 4 mg / ml. The mixed solution was allowed to stand at 50°C and washed, but no solid product was obtained.

[0097] Test Example 1

[0098] As shown in Figures 1-5, the formation of three-dimensional single crystal COF can be achieved at relatively low temperatures, and all exhibit good crystal forms. The present invention utilizes the polyether bonds and imine bonds in the block copolymer and polyethylene glycol to form hydrogen bonds. The imine products formed in the solvent are enriched on the surface of the polyether polymer. The linearly arranged polyether bonds and imine bonds are perfectly polymerized, further guiding the assembly of imine molecules and increasing the reaction rate. In order to explore the reaction rate of COF, the reaction products with different standing times are characterized. Figure 2 As shown in (g), different three-dimensional rod-like morphologies appeared at a standing time of 1 h and XRD showed good crystallinity. As the standing time increased to 4 h, the yield was as high as 82%.

[0099] The addition of inorganic salts will also speed up the chemical reaction rate of the entire reaction, because the addition of inorganic salts will affect the solubility of the synthesized imine compounds, causing the compounds to precipitate from water, thereby increasing the reaction rate. Example 3 explores different types of inorganic salts. Figure 4 It is shown that COF materials exhibit good crystallinity when using lithium perchlorate, lithium iodide, sodium iodide, and calcium chloride. Figure 5 It shows that when other inorganic salts are used, such as potassium iodide and sodium nitrate, the crystallinity is poor. When sodium acetate, potassium chloride, sodium chloride, lithium chloride, and magnesium chloride inorganic salts are used, not only the crystallinity is poor, but also a large amount of amino monomers are not reacted. The experimental results show that the law of COF crystallization conforms to the Hofmann sequence as a whole.

[0100] Figure 6-11 The results show that the preparation method is suitable for the preparation of different aldehyde monomers and amino monomers under the condition of synthesis temperature of 10-90°C.

[0101] The use of different molecular weights and types of polyether groups will affect the morphology of the synthesized COF, such as Fig.12 , as shown in Figure 13: When polyethylene glycol with different molecular weights is used, the crystallinity becomes better and better with the increase of molecular weight, and the best crystallinity is shown when the molecular weight is 6000Da; the crystal form will deteriorate when the molecular weight exceeds 8000. In addition, the amount of block polymer F127 is also regulated to a certain extent, and it is found that the amount of F127 also has a certain effect on the size of the crystal ( Fig.17 ).like Figure 21-23 As shown, when other commonly used surfactants are replaced, the synthesized COF materials have irregular morphology and poor quality (Comparative Examples 2-5); there may even be a phenomenon of no product (Comparative Example 6).

[0102] The present invention is universal to various acids. The use of catalysts such as p-toluenesulfonic acid, formic acid, oxalic acid, and acetic acid can quickly synthesize three-dimensional single crystal COF materials. The method is simple to operate, highly universal, and can be quickly synthesized, greatly shortening the reaction time. The strength of the acid and the types of different acids catalyzing the COF material will produce different results. When p-toluenesulfonic acid is used as a strong acid catalyst, a three-dimensional single crystal COF material can be formed when the concentration of amino monomer and p-toluenesulfonic acid is 1: (0.46-4.6). When the concentration of p-toluenesulfonic acid is too high (Comparative Example 1), the synthesized COF will dissolve again in the p-toluenesulfonic acid solution, so that a single crystal COF material cannot be obtained. When a weaker acid acetic acid is used as a catalyst, COF can be effectively synthesized when the molar ratio of amino monomer to acetic acid is 1: (7.9-79).

[0103] The above-described embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or changes made by those skilled in the art based on the present invention are within the protection scope of the present invention. The protection scope of the present invention shall be subject to the claims.

Claims

1. A method for preparing a three-dimensional single crystal covalent organic framework in water, characterized in that: The specific steps include: Adding a surfactant, an inorganic salt, an acid, an aldehyde monomer and an amino monomer into water to form a mixed solution, and standing at 10-90° C. to obtain the three-dimensional single crystal covalent organic framework; the surfactant is selected from EO / PO block polyether and / or polyethylene glycol with a molecular weight of 400-8000Da; The inorganic salt is selected from one or more of lithium perchlorate, sodium perchlorate, lithium iodide, sodium iodide, and calcium chloride; The EO / PO block polyether is selected from one or more of F127, L65, and P124; The amino monomer is tetrakis(4-aminophenyl)methane; the aldehyde monomer is selected from one or more of terephthalaldehyde, 2,5-dihydroxy-terephthalaldehyde, 2,5-dimethoxy-terephthalaldehyde, 2,3,5,6-4-fluoro-terephthalaldehyde and [1,1'-biphenyl]-4,4'-dicarboxaldehyde; The concentration of the surfactant in the mixed solution is 16.6-100 mg / ml, and the concentration of the inorganic salt is 13-150 mg / ml; The acid is selected from a strong acid or a weak acid; The strong acid is p-toluenesulfonic acid, and the molar ratio of amino monomer: aldehyde monomer: strong acid is 1:2:(0.46-4.6); The weak acid is one or more of acetic acid, formic acid and oxalic acid, and the molar ratio of amino monomer: aldehyde monomer: weak acid is 1:2:(7.9-79).

2. A covalent organic framework prepared by the preparation method as claimed in claim 1.

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