Side chain functionalized D-A type hydrazone bond covalent organic framework material as well as preparation method and application thereof

Abstract

The invention provides a side chain functionalized D-A type hydrazone bond covalent organic framework material as well as a preparation method and application thereof, belongs to the technical field of photocatalysis, and is used for solving the technical problem of low activity of a current covalent organic framework in preparation of hydrogen peroxide. The preparation method of the side chain functionalized D-A type hydrazone bond covalent organic framework material comprises the following steps: uniformly mixing a reactant donor monomer 2, 5-dimethoxy terephthaloyl hydrazine and an acceptor monomer with a solvent and a catalyst, and reacting to obtain the side chain functionalized D-A type hydrazone bond covalent organic framework material after the reaction is finished. The preparation method is easy to operate and environmentally friendly, the prepared material has good thermal stability, and efficient visible light photocatalysis preparation of hydrogen peroxide can be achieved; meanwhile, the catalyst can be recycled and has good photocatalytic stability.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of photocatalysis, and particularly relates to a covalent organic framework material. BACKGROUND

[0002] H2O2 as a green oxidant has unique advantages such as high active oxygen content, good environmental storage stability, and harmless decomposition products (H2O and O2) to the environment, and therefore is widely used in industrial applications such as drug synthesis, wastewater treatment, and disinfection. However, more than 95% of industrial H2O2 still relies on the anthraquinone process, which involves an energy-intensive multi-step hydrogenation / oxidation cycle and produces toxic anthraquinone derivatives. This energy-intensive and environmentally harmful approach conflicts with the principles of green chemistry, and therefore there is an urgent need for sustainable carbon dioxide production technology. The conversion of solar energy into chemical energy is a key strategy to solve global energy and environmental crises, and the sustainable synthesis of hydrogen peroxide (H2O2) from water (H2O) and oxygen (O2) in a solar-driven reaction has attracted great attention.

[0003] The photocatalytic production of H2O2 through the oxygen reduction reaction (ORR) has become a promising alternative method, which utilizes sunlight as a renewable energy source while avoiding harmful byproducts. Although various photocatalysts have been explored for the generation of H2O2 (such as inorganic semiconductors, carbon nitrides, and MOFs), their practical applications are hindered by inherent limitations: amorphous frameworks hinder precise structure-property analysis, and slow charge carrier mobility hinders redox kinetics. In contrast, covalent organic frameworks (COFs) have high crystallinity, tunable framework structures, and a wide range of active sites, making them ideal candidates for photocatalytic generation of H2O2. For example, patent publication CN117843898A discloses a fluorinated covalent organic framework material, its preparation method, and its application in photocatalytic production of hydrogen peroxide. The preparation method includes adding fluorinated phenylenediamine and functionalized trimesylformal in a molar ratio of 6:5-2:1 into a reaction container, then adding a solvent to dissolve all the solid powders, vacuumizing the reaction container in a refrigerated environment, reacting at 100-180℃ for 24-80h, cooling the product to room temperature after the reaction is complete, and washing, centrifuging, and vacuum drying to obtain the fluorinated covalent organic framework material. The prepared covalent organic framework material F-COF-1 serves as a catalyst material, has the advantages of high efficiency, greenness, and low cost in reducing O2 and photocatalytically producing H2O2. The structure of COFs affects the yield and reaction pathway of photocatalytic generation of H2O2, and the design of introducing different functional side chain functional groups, donor-acceptor for promoting charge separation, and hydrophilic hydrazone bonds for strong adsorption of O2 in the COF framework will help reveal the new mechanism of side chain engineering regulating photocatalytic reaction pathways and provide a theoretical basis for developing efficient H2O2 generation systems. SUMMARY

[0004] The present application aims to solve the problems existing in the H2O2 system of various catalysts, and proposes a side chain functionalized D-A type hydrazone covalent organic framework material, a preparation method and application thereof. The prepared side chain functionalized D-A type hydrazone covalent organic framework material has a wide visible light absorption range and a high photo-generated carrier mobility, and has high photocatalytic activity in a photocatalytic reaction. Another object of the present application is to provide a preparation method of the side chain functionalized D-A type hydrazone covalent organic framework material. Specifically, the method is realized by condensation reaction of 2,5-dimethoxy terephthaldehyde and monomers containing different side chain functional groups. Another object of the present application is the application of the side chain functionalized D-A type hydrazone covalent organic framework material in photocatalytic production of H2O2. The side chain functionalized D-A type hydrazone covalent organic framework material of the present application exhibits excellent photocatalytic performance in pure water system.

[0005] In order to achieve the above-mentioned objects, the technical scheme of the present application is as follows:

[0006] A side chain functionalized D-A type hydrazone covalent organic framework material, the side chain functionalized D-A type hydrazone covalent organic framework is composed of several repeated structural units, wherein the structural formula of the structural unit is as follows:

[0007]

[0008] In the formula, X is at least one of methoxy, fluorine and hydroxyl, represents the omitted repeating structural unit.

[0009] Specifically, the side chain functionalized D-A type hydrazone covalent organic framework is FMP-COF, DFF-COF and FHP-COF, wherein the structural formula of the structural unit is as shown in formula I, formula II or formula III,

[0010]

[0011] In the formula represents the omitted repeating structural unit.

[0012] The preparation method of the side chain functionalized D-A type hydrazone covalent organic framework material comprises the following steps: mixing the reactants 2,5-dimethoxy terephthaldehyde and monomers containing different side chain functional groups with a solvent and a catalyst uniformly, and then reacting, and obtaining the D-A type hydrazone covalent organic framework material after the reaction is completed.

[0013] The molar ratio of the donor monomer and the acceptor monomer 5'-(4-formyl-3-methoxyphenyl)-3,3"-dimethoxy-[1,1':3',1"-terphenyl]-4,4"-dicarboxaldehyde, 1,3,5-tris(3-fluoro-4-formylphenyl)benzene or 5'-(4-formyl-3-hydroxyphenyl)-3,3"-dihydroxy-[1,1':3',1"-terphenyl]-4,4"-dicarboxaldehyde is (2-5):(2-5).

[0014] The catalyst is acetic acid.

[0015] Preferably, the concentration of the acetic acid is 4-8 mol / L.

[0016] The solvent comprises dioxane and mesitylene, and the volume ratio of the dioxane to the mesitylene is 1:(1-5).

[0017] The mass-volume ratio of the reactant to the solvent is 5-30 mg / mL, and the volume ratio of the catalyst to the solvent is 0.05-0.2:1.

[0018] The temperature of the reaction is 120-160 DEG C, and the reaction time is 72-120 h. After the reaction is completed, the product is sequentially washed by using anhydrous acetone or methanol and tetrahydrofuran, and then vacuum drying is performed, the drying temperature is 60-80 DEG C, and the drying time is 6-10 h.

[0019] The application of the side-chain functionalized D-A type hydrazone covalent organic framework material, the covalent organic framework material is used as a catalyst in the photocatalytic preparation of hydrogen peroxide in a pure water system, and the steps are as follows: the covalent organic framework is added into pure water, visible light irradiation reaction is performed in a saturated oxygen atmosphere.

[0020] The addition amount of the side-chain functionalized D-A type hydrazone covalent organic framework material in water is 0.5-250 mg / L.

[0021] The beneficial effects of the present application are as follows:

[0022] (1) The present application uses 2,5-dimethoxy terephthalic hydrazide and 5'-(4-formyl-3-methoxyphenyl)-3,3"-dimethoxy-[1,1':3',1"-terphenyl]-4,4"-dicarboxaldehyde, 1,3,5-tris(3-fluoro-4-formylphenyl)benzene or 5'-(4-formyl-3-hydroxyphenyl)-3,3"-dihydroxy-[1,1':3',1"-terphenyl]-4,4"-dicarboxaldehyde as raw materials to synthesize a new type of side chain functionalized D-A hydrazone covalent organic framework material, and the ratio of 2,5-dimethoxy terephthalic hydrazide and different side chain functionalized monomers needs to be appropriate; the preparation method is simple to operate and can be prepared by common solvothermal method. The obtained side chain functionalized D-A hydrazone covalent organic framework material has hydrophilic hydrazone bond, donor-acceptor (D-A) structure and different characteristic side chain functional groups, and by regulating the types of side chain functional groups in the skeleton structure, the light absorption capacity and the migration rate of photo-generated carriers of the material can be regulated. At the same time, as a photocatalytic material, the catalytic reaction is carried out at room temperature, only visible light irradiation is needed, the requirement for catalytic conditions is simple, and the catalytic process is green and environmentally friendly.

[0023] (2) The side chain functionalized D-A hydrazone covalent organic framework material prepared in the present application has good thermal stability and keeps stable structure below 310 DEG C.

[0024] (3) The side chain functionalized D-A hydrazone covalent organic framework material prepared in the present application shows excellent performance in the photocatalytic preparation of hydrogen peroxide, and FMP-COF has high light absorption capacity and photo-generated carrier migration rate, which is due to the synergistic effect of the strong electron-donating effect of the methoxy side chain and the hydrophilic hydrazone bond in FMP-COF. In addition, the unique structure of the material optimizes the reaction process through a double path: the hydrophilic hydrazone bond strengthens O2 adsorption, and the side chain methoxy promotes H2O interface enrichment through a hydrogen bond network, promoting the ORR and WOR synergistic mechanism. The yield of hydrogen peroxide prepared by FMP-COF photocatalysis reaches 5.384 mmol·g -1 h -1 , which is 1.9 times and 3.5 times the yield of hydrogen peroxide prepared by DFF-COF photocatalysis 2.825 mmol·g -1 h -1 and FHP-COF photocatalysis 1.546 mmol·g -1 h -1 .

[0025] (4) The side chain functionalized D-A hydrazone covalent organic framework material prepared in the present application can be recycled, and after being recycled for 4 times, the catalytic activity does not change obviously, showing good photocatalytic stability. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced. Obviously, the accompanying drawings in the following description only represent some embodiments of the present application, and all other drawings obtained by those of ordinary skill in the art without creative effort based on these drawings also belong to the protection scope of the present application.

[0027] Figure 1 Synthesis chart of FMP-COF, DFF-COF and FHP-COF materials;

[0028] Figure 2 Powder XRD chart of FMP-COF, DFF-COF and FHP-COF materials;

[0029] Figure 3 FT-IR chart of FMP-COF, DFF-COF and FHP-COF materials;

[0030] Figure 4 Thermogravimetric analysis chart of FMP-COF, DFF-COF and FHP-COF materials;

[0031] Figure 5 UV-Vis diffuse reflectance spectrum chart of FMP-COF, DFF-COF and FHP-COF materials.

[0032] Figure 6 Visible light photocatalytic preparation of hydrogen peroxide performance chart of FMP-COF, DFF-COF and FHP-COF materials under different gas atmospheres in pure water system;

[0033] Figure 7 Impedance chart of FMP-COF, DFF-COF and FHP-COF materials;

[0034] Figure 8 XRD and SEM charts of FMP-COF before and after photocatalytic reaction. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments only represent some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort also belong to the protection scope of the present application.

[0036] Embodiment 1

[0037] A preparation method of a side chain functionalized D-A type hydrazone bond FMP-COF material, as shown in Figure 1As shown, specifically comprising the following steps:

[0038] (1) 5'-(4-formyl-3-methoxyphenyl)-3,3"-dimethoxy-[1,1':3',1"-terphenyl]-4,4"-dicarboxaldehyde (24 mg, 0.05 mmol) and 2,5-dimethoxyterephthalic dihydrazide (19.05 mg, 0.075 mmol) were loaded into a Pyrex tube, then a mixed solution of solvent dioxane (1.5 mL), mesitylene (4.5 mL) and 6 mol / L acetic acid (0.6 mL) was added dropwise, and magnetic stirring was carried out at room temperature, and ultrasonic treatment was carried out.

[0039] (2) The test tube was reacted at a temperature of 120°C for 72 h; after the reaction was completed, the product was washed with anhydrous acetone 3 times and washed with tetrahydrofuran 3 times; then vacuum drying was carried out at 60°C for 10 h, and the FMP-COF material was prepared.

[0040] The prepared FMP-COF was subjected to powder X-ray diffraction (XRD) test, and the results are shown in Figure 2 (a). As can be seen from Figure 2 (a), there is a clear crystallization peak at 2θ = 2.50°, which confirms that the FMP-COF material has good crystallinity. Fourier transform infrared spectroscopy (FT-IR) was used to study the coordination state of the amino functional group, and the results are shown in Figure 3 (a). The characteristic stretching vibration band of C=N bond at 1650-1660 cm -1 indicates that the FMP-COF forms a hydrazone bond. Combined with the XRD spectrum of the sample, it can be inferred that the hydrazone bond connected FMP-COF material has been successfully synthesized. Through thermogravimetric analysis, the material structure is stable before 310°C under nitrogen protection (as shown in Figure 4 (a)). In addition, through ultraviolet-visible diffuse reflectance spectroscopy analysis (as shown in Figure 5 (a)), it shows a wide light absorption performance, and the absorption edge extends to more than 750 nm.

[0041] Example 2

[0042] A preparation method of a side chain functionalized D-A type hydrazone bond FMP-COF material, comprising the following steps:

[0043] (1) 5'-(4-formyl-3-methoxyphenyl)-3,3"-dimethoxy-[1,1':3',1"-terphenyl]-4,4"-dicarboxaldehyde (24 mg, 0.05 mmol) and 2,5-dimethoxyterephthalic dihydrazide (19.05 mg, 0.075 mmol) were loaded into a Pyrex tube, then a mixed solution of solvent dioxane (3 mL), mesitylene (3 mL) and 6 mol / L acetic acid (0.8 mL) was added dropwise, and magnetic stirring was carried out at room temperature, and ultrasonic was used.

[0044] (2) The test tube was reacted at a temperature of 160°C for 72h; after the reaction was completed, the product was washed with anhydrous methanol for 5 times, and washed with tetrahydrofuran for 5 times; then, vacuum drying was carried out at 80°C for 10h, and the FMP-COF material was prepared.

[0045] Example 3

[0046] A preparation method of a side chain functionalized D-A type hydrazone bond DFF-COF material, comprising the following steps:

[0047] (1) 1,3,5-tris(3-fluoro-4-formylphenyl)benzene (22 mg, 0.05 mmol) and 2,5-dimethoxyterephthalic dihydrazide (19.05 mg, 0.075 mmol) were loaded into a Pyrex tube, then a mixed solution of solvent dioxane (3 mL), mesitylene (3 mL) and 6 mol / L acetic acid (0.6 mL) was added dropwise, and magnetic stirring was carried out at room temperature, and ultrasonic was used.

[0048] (2) The test tube was reacted at a temperature of 150°C for 72h; after the reaction was completed, the product was washed with anhydrous methanol for 3 times, and washed with tetrahydrofuran for 4 times; then, vacuum drying was carried out at 80°C for 12h, and the DFF-COF material was prepared.

[0049] Example 4

[0050] A preparation method of a side chain functionalized D-A type hydrazone bond DFF-COF material, as shown in Figure 1 , specifically comprising the following steps:

[0051] (1) 1,3,5-tris(3-fluoro-4-formylphenyl)benzene (22 mg, 0.05 mmol) and 2,5-dimethoxyterephthalic dihydrazide (19.05 mg, 0.075 mmol) were loaded into a Pyrex tube, then a mixed solution of solvent dioxane (1.5 mL), mesitylene (4.5 mL) and 6 mol / L acetic acid (0.8 mL) was added dropwise, and magnetic stirring was carried out at room temperature, and ultrasonic was used;

[0052] (2) The test tube is at a temperature of 140°C for 70h of reaction; after the reaction is completed, the product is washed with anhydrous acetone for 3 times, washed with tetrahydrofuran for 4 times; then vacuum dried at 60°C for 10h to obtain the DFF-COF material.

[0053] The prepared DFF-COF is subjected to XRD test, and the result is shown in Figure 2 (b). It can be seen from Figure 2 (b) that there is a clear crystallization peak at 2θ = 2.48°, which proves that the DFF-COF material has crystallization phenomenon. There are two vibration peaks at 1650-1660cm -1 , which correspond to the stretching vibration peaks of the hydrazone bond structure in the DFF-COF. In combination with the XRD spectrum of the sample, it can be inferred that the hydrazone bond connected DFF-COF material has been successfully synthesized (as shown in Figure 3 ). Through thermogravimetric analysis, the material structure is stable before 310°C under nitrogen protection (as shown in Figure 4 (b)), which indicates that the catalyst material has excellent thermal stability. In addition, through ultraviolet-visible diffuse reflectance spectroscopy analysis (as shown in Figure 5 (b)), the light absorption edge of the material extends to more than 750nm.

[0054] Example 5

[0055] A preparation method of a side chain functionalized D-A type hydrazone bond FHP-COF material, comprising the following steps:

[0056] (1) Pyrex tube is weighed with 5'-(4-formyl-3-hydroxyphenyl)-3,3"-dihydroxy-[1,1':3',1"-terphenyl]-4,4"-dicarboxaldehyde (21.9mg, 0.05mmol) and 2,5-dimethoxyterephthalic dihydrazide (19.05mg, 0.075mmol), then a mixed solution of solvent dioxane (1.5mL), mesitylene (4.5mL) and 6mol / L acetic acid (0.6mL) is added dropwise, and it is magnetically stirred at room temperature and ultrasonicated;

[0057] (2) The test tube is at a temperature of 150°C for 60h of reaction; after the reaction is completed, the product is washed with anhydrous propanol for 4 times, washed with tetrahydrofuran for 5 times; then vacuum dried at 60°C for 10h to obtain the FHP-COF material.

[0058] The prepared FHP-COF is subjected to XRD test, and the result is shown in Figure 2 (c). It can be seen from Figure 2 (c) that there is a clear crystallization peak at 2θ = 2.44°, which proves that the FHP-COF material has crystallization phenomenon. There are two vibration peaks at 1650-1660cm -1two vibration peaks, corresponding to the stretching vibration peak of the hydrazone bond structure in FHP-COF. Combined with the XRD spectrum of the sample, it can be inferred that the hydrazone bond connected FHP-COF material has been successfully synthesized (as shown in Figure 3 ). Through thermogravimetric analysis, the material structure is stable before 310℃ under nitrogen protection (as shown in Figure 4 (c)), indicating that the catalyst material has excellent thermal stability. In addition, through ultraviolet-visible diffuse reflectance spectroscopy analysis (as shown in Figure 5 (c)), the light absorption edge of the material extends to more than 750nm.

[0059] Example 6

[0060] A preparation method of a side chain functionalized D-A type hydrazone bond FHP-COF material, comprising the following steps:

[0061] (1) Weigh 5'-(4-formyl-3-hydroxyphenyl)-3,3"-dihydroxy-[1,1':3',1"-terphenyl]-4,4"-diformaldehyde (21.9mg, 0.05mmol) and 2,5-dimethoxyterephthalic dihydrazide (19.05mg, 0.075mmol) into a Pyrex tube, then drop a mixed solution of solvent dioxane (1mL), mesitylene (5mL) and 6mol / L acetic acid (0.5mL), magnetic stirring at room temperature, ultrasonic;

[0062] (2) The test tube is at a temperature of 150℃, and the reaction is carried out for 80h; after the reaction is completed, the product is washed with anhydrous methanol 4 times and tetrahydrofuran 5 times; then vacuum drying at 75℃ for 12h, to obtain the FHP-COF material.

[0063] Application Example 1

[0064] Application of a side chain functionalized D-A type hydrazone bond FMP-COF in a visible light photocatalytic hydrogen peroxide preparation system:

[0065] The FMP-COF prepared in Example 1 is used for photocatalytic preparation of hydrogen peroxide, and the covalent organic framework catalyst is added to an aqueous solution, and the addition concentration of the covalent organic framework catalyst is 0.5mg / L, and the photocatalytic reaction is carried out under oxygen atmosphere and under light with wavelength λ≥420nm.

[0066] Through ultraviolet-visible diffuse reflectance spectroscopy test, after 1h of light irradiation, the hydrogen peroxide production reaches 5384μmol·g -1 h -1 (as shown in Figure 6 ).

[0067] Application Example 2

[0068] A side chain functionalized D-A type hydrazone bond FMP-COF is applied in a visible light photocatalytic hydrogen peroxide preparation system in a cyclic manner:

[0069] The solution reacted in application example 1 is filtered and separated, and then washed, and the obtained FMP-COF material is repeatedly applied to the steps in application example 1, and the FMP-COF is cyclically applied to photocatalytic preparation of hydrogen peroxide.

[0070] Application Example 3

[0071] A side chain functionalized D-A type hydrazone bond DFF-COF is applied in a visible light photocatalytic hydrogen peroxide preparation system:

[0072] The DFF-COF prepared in Example 4 is used for photocatalytic preparation of hydrogen peroxide, and the DFF-COF is added to an aqueous solution, and the addition concentration of the DFF-COF is 0.5 mg / L; under an oxygen atmosphere, the photocatalytic reaction is carried out under light with a wavelength of λ≥420 nm.

[0073] Through UV-Vis diffuse reflectance spectroscopy test, after 1 h of light irradiation, the hydrogen peroxide production reaches 2825 μmol g -1 h -1 (as Figure 6 ).

[0074] Application Example 4

[0075] A side chain functionalized D-A type hydrazone bond FHP-COF is applied in a visible light photocatalytic hydrogen peroxide preparation system:

[0076] The FHP-COF prepared in Example 5 is used for photocatalytic preparation of hydrogen peroxide, and the FHP-COF is added to an aqueous solution, and the addition concentration of the FHP-COF is 0.5 mg / L; under an oxygen atmosphere, the photocatalytic reaction is carried out under light with a wavelength of λ≥420 nm.

[0077] Through UV-Vis diffuse reflectance spectroscopy test, after 1 h of light irradiation, the hydrogen peroxide production reaches 2825 μmol g -1 h -1 (as Figure 6 ).

[0078] Compared with application examples 3 and 4, the hydrogen peroxide performance of the FMP-COF catalyst is obviously higher than that of the DFF-COF and FHP-COF catalysts. Subsequently, electrochemical impedance tests are carried out, as Figure 7 , the impedance curve of the FMP-COF sample has a smaller curvature than that of the DFF-COF and FHP-COF samples, indicating that the FMP-COF has a higher photogenerated carrier separation efficiency, thereby improving the photocatalytic activity of the sample, which is completely consistent with the above experimental results.Figure 8 The stable peaks of XRD and the stable morphology of SEM of FMP-COF before and after the photocatalytic reaction show that FMP-COF has excellent photocatalytic stability

[0079] The FMP-COF prepared in Example 1 and the DFF-COF and FHP-COF prepared in Examples 4 and 5 are subjected to a test of photocatalytic production of hydrogen peroxide, and the FMP-COF, the DFF-COF and the FHP-COF are respectively added to pure water, and the concentration of each is 0.5 mg / L; in the dark, photocatalytic reaction is carried out. Through UV-Vis diffuse reflectance spectroscopy monitoring, after 1 h of illumination, almost no hydrogen peroxide is produced for the three materials.

[0080] As can be seen from the above, the FMP-COF, a functionalized D-A type hydrazone covalent organic framework material, benefits from the synergistic promotion of the hydrophilic hydrazone in the framework structure and the D-A structure to the efficiency of photogenerated carrier separation, and under the condition of pure water and saturated oxygen atmosphere, the efficient production of hydrogen peroxide can be realized by selecting a suitable ratio. In addition, the methoxy side chain of FMP-COF enhances the H2O adsorption energy through hydrogen bonding, and the hydrophilic skeleton promotes the chemical adsorption of O2 at the active site, so that the photocatalysis of FMP in pure water system presents a double reaction path (ORR and WOR) mechanism, which is one of the important reasons for the efficient production of H2O2 by FMP. As can be seen, at the molecular level, the structure of COF can be adjusted to introduce specific functional groups, donor-acceptor structures and functional connecting bonds into the side chain of the skeleton, so as to further fine-tune the functionalization of COF, thereby providing a new strategy for how to realize efficient photocatalytic production of hydrogen peroxide.

[0081] Example 7

[0082] A preparation method of a side chain functionalized D-A type hydrazone FMP-COF material, comprising the following steps:

[0083] (1) 5'-(4-formyl-3-methoxyphenyl)-3,3"-dimethoxy-[1,1':3',1"-terphenyl]-4,4"-dicarboxaldehyde (24 mg, 0.05 mmol) and 2,5-dimethoxyterephthaldehyde hydrazine (32.17 mg, 0.125 mmol) are loaded into a Pyrex tube, then a mixed solution of solvent dioxane (1 mL), mesitylene (1 mL) and 6 mol / L acetic acid (0.4 mL) is added dropwise, and the mixture is stirred at room temperature and ultrasonicated.

[0084] (2) The test tube is reacted at a temperature of 120°C for 72 h; after the reaction is completed, the product is washed with anhydrous methanol for 5 times and washed with tetrahydrofuran for 5 times; then the product is dried at 80°C under vacuum for 6 h to obtain the FMP-COF material.

[0085] Example 8

[0086] A preparation method of a side chain functionalized D-A type hydrazone bond FMP-COF material, comprising the following steps:

[0087] (1) 5'-(4-formyl-3-methoxyphenyl)-3,3"-dimethoxy-[1,1':3',1"-terphenyl]-4,4"-dicarboxaldehyde (48 mg, 0.1 mmol) and 2,5-dimethoxyterephthalic dihydrazide (5.08 mg, 0.02 mmol) were loaded into a Pyrex tube, then a mixed solution of solvent dioxane (3 mL), mesitylene (3 mL) and 8 mol / L acetic acid (0.3 mL) was added dropwise, and magnetic stirring was performed at room temperature, and ultrasonic was performed.

[0088] (2) The test tube was reacted at a temperature of 130°C for 120 h; after the reaction was completed, the product was washed with anhydrous methanol for 5 times, and washed with tetrahydrofuran for 5 times; then, vacuum drying was performed at 60°C for 10 h, and the FMP-COF material was prepared.

[0089] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A side chain functionalized DA type hydrazone bond covalent organic framework material, characterized in that: The side chain functionalized DA type hydrazone bond covalent organic framework material is composed of several repeated structural units, wherein the structural formula of the structural unit is as follows: In the formula, X is at least one of methoxy, fluorine, and hydroxyl. Indicates omitted repeating structural units.

2. The method for preparing the side chain functionalized DA type hydrazone bond covalent organic framework material according to claim 1, characterized in that: The following steps are involved: The reactant donor monomer 2,5-dimethoxyterephthaloyl hydrazide and the acceptor monomer are uniformly mixed with a solvent and a catalyst and then reacted. After the reaction is completed, a DA-type hydrazone bond covalent organic framework material with side chain functionalization is obtained.

3. The method for preparing a side chain functionalized DA type hydrazone bond covalent organic framework material according to claim 2, characterized in that: The acceptor monomer is 5'-(4-formyl-3-methoxyphenyl)-3,3"-dimethoxy-[1,1':3',1"-terphenyl]-4,4"-dicarbaldehyde, 1,3,5-tris(3-fluoro-4-formylphenyl)benzene or 5'-(4-formyl-3-hydroxyphenyl)-3,3"-dihydroxy-[1,1':3',1"-terphenyl]-4,4"-dicarbaldehyde.

4. The method for preparing a side chain functionalized DA type hydrazone bond covalent organic framework material according to claim 3, characterized in that: The molar ratio of the acceptor monomer to the donor monomer 2,5-dimethoxyterephthaloylhydrazide is (2-5): (2-5).

5. The method for preparing a side chain functionalized DA type hydrazone bond covalent organic framework material according to any one of claims 2 to 4, characterized in that: The catalyst is acetic acid.

6. The method for preparing a side chain functionalized DA type hydrazone bond covalent organic framework material according to claim 5, characterized in that: The solvent includes dioxane and mesitylene, and the volume ratio of the dioxane to mesitylene is 1:1-5.

7. The method for preparing a side chain functionalized DA type hydrazone bond covalent organic framework material according to claim 6, characterized in that: The mass volume ratio of the reactant to the solvent is 5-30 mg / mL; the volume ratio of the catalyst to the solvent is 0.05-0.2:

1.

8. The method for preparing a side-chain functionalized DA-type hydrazone covalent organic framework material according to claim 7, wherein the reaction temperature is 120-160°C and the reaction time is 72-120 hours.

9. The use of the side chain functionalized DA type hydrazone bond covalent organic framework material according to claim 1, characterized in that: A DA-type hydrazone-bonded covalent organic framework material with side chain functionalization is used as a catalyst for photocatalytic preparation of hydrogen peroxide. The steps are: adding the DA-type hydrazone-bonded covalent organic framework material with side chain functionalization to water, and reacting in an oxygen-containing atmosphere under visible light irradiation.

10. The use of the side chain functionalized DA type hydrazone bond covalent organic framework material according to claim 8, characterized in that: The amount of the side chain functionalized DA type hydrazone bond covalent organic framework material added in water is 0.5-250 mg / L.

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