Controllable defect type three-dimensional COF material and preparation and application thereof

Abstract

The invention belongs to the technical field of polymer photocatalytic material synthesis, and particularly relates to a controllable defect type three-dimensional COF material and preparation and application thereof. The controllable defect type three-dimensional COF material is a COF formed by connecting a Td symmetric ligand and a C3 planar ligand with a linear connector and a side chain substituted linear connector through covalent bonds. According to the invention, through a general node connection number reduction strategy, a C3 planar ligand part is used for replacing a Td symmetric ligand node, a light absorption unit is introduced into a three-dimensional COF under the condition that a basic topological structure is kept unchanged, and a linear connector part replaced by a side chain is used for replacing a linear connector, so that a space electron supply-absorption characteristic is introduced, and the light absorption unit is introduced into the three-dimensional COF; benefited from the introduction of a light absorption unit and donor-acceptor arrangement in a 3D space, the optimized photoelectric structure can realize efficient charge separation through the three-dimensional donor-acceptor arrangement, so that efficient photocatalysis is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer photocatalytic material synthesis, and specifically relates to a controllable defect-type three-dimensional COF material and its preparation and application. Background Art

[0002] Hydrogen peroxide (H2O2) is an important industrial product with widespread applications in biotreatment, water purification, and chemical synthesis. However, 95% of H2O2 is produced via a noble metal-catalyzed anthraquinone process, which is energy-intensive and produces toxic byproducts. Photocatalytic H2O2 generation offers advantages such as renewable energy utilization, mild reaction conditions, high selectivity to minimize waste byproducts, avoidance of hazardous precursors, and the potential for continuous production. Covalent organic frameworks (COFs), crystalline nonmetallic polymers, have emerged as viable and promising platforms for artificial photosynthesis due to their porous structure, optoelectronic properties, and photochemical stability. The structural tunability and regularity of COFs are readily achieved through practical building blocks with diverse topologies and sizes, endowing them with broad light absorption, favorable mass transfer, and fast charge carrier mobility. This conjugated linker acts as an efficient light absorber, powering the photocatalytic reaction and facilitating the transport of photogenerated charge carriers. Pioneering research in designing 2D COF-based photocatalysts has primarily involved optimizing band structures to modulate reaction thermodynamics, creating donor-acceptor connections, and engineering chemical bonds to promote in-plane charge carrier separation and enhance the chemical stability of the 2D layers. These approaches have proven effective in promoting the photogeneration of H2O2. However, these efforts have focused solely on in-plane layered structures. The weak chemical stability and inefficient interlayer charge transport between layers have seen little improvement.

[0003] Three-dimensional COFs have unique characteristics and usually require at least one three-dimensional spatially extended structural unit, such as T d Only when the nodes have a certain symmetry can they be connected to another linker to form a three-dimensional skeleton. These three-dimensional networks not only provide a structure for chemical bonds to connect with each other to avoid dissociation, but also provide channels and chemical spaces that are more conducive to the mutual penetration of catalytic reactions. However, the number of links in the three-dimensional space-extended nodes is usually equal to or greater than 4, which makes their degree of conjugation low and is not conducive to light absorption. Although efforts have been made to synthesize large and complex three-dimensional nodes with 6 or 8 vertices, or to add planar C3 or C4 symmetrical linkers to improve the degree of conjugation, their photocatalytic performance is still insufficient. These strategies also make it extremely challenging to introduce additional functional groups to adjust the electronic configuration of the framework to conform to the reaction thermodynamics, and the synthesis of such building blocks usually involves quite complex operations, and the cost of scaling up is quite expensive. Summary of the Invention

[0004] To address this challenge, we propose a general strategy to reduce the number of node connections by replacing the T with C3 planar ligands. d Symmetric ligand nodes, but keep the basic topology unchanged ( Figure 1 ), thereby introducing a light absorption unit into the three-dimensional COF and synthesizing a defective three-dimensional COF (abbreviated as COF-300-D). This operation greatly improves the light absorption capacity of the original COF. Further, by modifying the linear linker so that it carries electron-withdrawing or electron-donating functional groups, the electronic structure of the overall framework is systematically regulated to obtain a defective three-dimensional COF with spatial electron-donating and electron-withdrawing properties (abbreviated as COF-300-DR). This optimized photoelectric structure can achieve efficient charge separation through a three-dimensional donor-acceptor arrangement, thereby improving the photocatalytic performance. Thanks to the introduction of the light absorption unit and the donor-acceptor arrangement in 3D space, taking COF-300-DF (meaning that the side chain functional groups of the side chain-substituted linear linker include fluorine) as an example, it can achieve a photocatalytic hydrogen peroxide generation rate of 19.09 mmol g under H2O2 conditions at pH = 3. -1 h -1 At the same time, its stable chemically bonded three-dimensional structure and optimized electronic structure enable COF-300-DF to have a long-term continuous working stability of more than 200 hours, an apparent quantum efficiency (AQY) of 11.95%, and excellent photocatalytic activity in the benzylamine coupling reaction.

[0005] Specifically, the present invention provides a controllable defect three-dimensional COF material, which is composed of T d The COF is formed by covalently linking the symmetrical ligand and the C3 planar ligand with the linear linker and the side chain substituted linear linker.

[0006] As used herein, T d A symmetrical ligand is a ligand with T d Symmetrical ligand. T d Symmetry is a common category of molecular symmetry, belonging to the regular tetrahedral symmetry in point group theory, which describes a highly symmetrical three-dimensional spatial arrangement, which is common in molecules with a regular tetrahedral structure.

[0007] Furthermore, the T dSymmetrical ligands include tetrakis(4-aminophenyl)methane, tetrakis(4-formylphenyl)methane, tetrakis(4-boronic acid phenyl)methane, tetrakis(4-hydroxyphenyl)methane, tetrakis(4-cyanophenyl)methane, tetrakis(4-mercaptophenyl)methane, tetrakis(4-vinylphenyl)methane, tetrakis(4-ethynylphenyl)methane, tetrakis(4-pyridyl)methane, tetrakis(4-bipyridyl)methane, tetrakis(4-aminobipyridyl)methane, tetrakis(4-formylbipyridyl)methane, tetrakis(4-aminotriazinyl)methane, tetrakis(4-formyltriazinyl)methane, 1,3,5,7-tetrakis(4-amino ... One or more of: (1,1':3',1"-terphenyl)-4,4"-dicarboxaldehyde, ((3,6-difluorobenzene-1,2,4,5-tetrayl)tetrakis(azetidine))octa([1,1'-biphenyl]-4-carboxaldehyde), 5,5',5",5",5',5',5""'-(triphenyl-2,3,6,7,10,11-hexyl)hexa(isophenylhydrazide), 5,10,15,20-tetrayl([1,1':3',1"-terphenyl]-4,4"-dicarboxaldehyde)-porphyrin, and 4-[tris(4-formylphenyl)methyl]benzaldehyde.

[0008] As used herein, a C3 planar ligand refers to a ligand having a three-fold symmetry axis (C3 axis) and the main skeleton or coordination groups are approximately in one plane.

[0009] Further, the C3 planar ligands include tris(4-aminophenyl)amine, tris(4-aminophenyl)methane, tris(4-aminophenyl)methanol, tris(4-aminophenyl)boric acid, tris(4-aminophenyl)phosphine, tris(4-aminophenyl)silane, tris(4-aminophenyl)benzene, tris(4-aminophenyl)triazine, tris(4-aminobipyridyl)amine, tris(4-aminophenoxy)benzene, tris(4-formylphenyl)amine, tris(4-formylphenyl)methane, tris(4-formylphenyl)benzene, tris(4-formylphenyl)triazine, tris(4-formylbipyridyl)amine, tris( One or more of: 4-boronic acid phenyl)amine, tris(4-boronic acid phenyl)benzene, tris(4-boronic acid bipyridyl)amine, tris(4-hydroxyphenyl)amine, tris(4-hydroxyphenyl)methane, tris(4-hydroxyphenyl)benzene, tris(4-aminopyridyl)amine, tris(4-aminotriazinyl)amine, 5,10,15-tris(4-aminophenyl)porphyrin, 5,10,15-tris(4-formylphenyl)porphyrin, melamine, 2,4,6-triaminopyrimidine, melem, 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, p-phenylenediamine, and terephthalaldehyde.

[0010] As used herein, linear linkers refer to a type of organic molecule whose end groups are linearly distributed at 180° in space, which is used to connect other ligand nodes through covalent bonds.

[0011] Furthermore, the linear linker includes terephthalaldehyde, 4,4'-biphenyldicarboxaldehyde, 2,6-naphthalenedicarbaldehyde, 2,2'-bipyridine-5,5'-dicarboxaldehyde, terephthalic acid, dimethyl terephthalate, terephthaloyl chloride, p-phenylenediamine, 4,4'-biphenylenediamine, 2,6-naphthalenediamine, 2,2'-bipyridine-5,5'-diamine, 1,4-phenylenediboronic acid, 4,4 One or more of '-biphenyldiboronic acid, 1,4-diethynylbenzene, 4,4'-diethynylbiphenyl, terephthaloyl dihydrazide, 4,4'-biphenyl dihydrazide, 1,4-dicyanobenzene, 4,4'-dicyanobiphenyl, 2,5-dicyano-p-phenylenediamine, 2,5-pyridinedicarboxaldehyde, 2,5-thiophenedicarboxaldehyde, 2,5-furandicarboxaldehyde, and 4,4'-dialdo-2,2'-bipyridine.

[0012] Furthermore, the side chain substituted linear linker is a linear linker having a side chain functional group after side chain substitution, wherein the side chain functional group includes one or more of fluorine, chlorine, bromine, iodine, hydroxyl, ether bond, ketone group, aldehyde group, carboxyl group, sulfonic acid group, nitro group, ester group, amino group, imino group, cyano group, azide group, sulfonic acid amine group, thiol group, sulfonate group, thiazole ring, pyridine ring, imidazole ring, pyrrole ring, furan ring, methoxy group, alkyl group, alkenyl group, alkynyl group, and phosphate group.

[0013] Furthermore, the T d The molar ratio of the symmetrical ligand to the C3 planar ligand is 1-0.5:0-0.5.

[0014] Preferably, the molar amount of C3 planar ligand is non-zero.

[0015] Furthermore, the sum of the molar amounts of the linear linker and the side chain substituted linear linker is equal to T d The molar ratio of the symmetrical ligand is 2:0.8-1.2.

[0016] Furthermore, the molar ratio of the linear linker to the side chain substituted linear linker is 1-0:0-1.

[0017] Preferably, the molar amount of the linear linker and / or the side chain substituted linear linker is not zero.

[0018] Furthermore, the C3 planar ligand is d The molar content of the symmetrical ligand and the C3 planar ligand is 0-50%.

[0019] The present invention also provides a method for preparing the controllable defect three-dimensional COF material as described herein, which comprises: dThe symmetrical ligand, the C3 planar ligand, the linear linker and the side chain substituted linear linker undergo a solvothermal reaction in a reaction solvent under the action of an acid, and the reaction product is collected, washed and dried to obtain the controllable defect-type three-dimensional COF material.

[0020] Furthermore, the reaction solvent is one of 1,4-dioxane, mesitylene, N-methylpyrrolidone, o-dichlorobenzene, n-butanol, tetrahydrofuran, toluene, N,N-dimethylformamide, N,N-dimethylacetamide, chloroform, n-butane, benzyl alcohol, methanol, ethanol, dimethyl sulfoxide, acetonitrile, and cyclohexane, or a mixed solvent of several thereof.

[0021] Furthermore, the reaction solvent is a mixed solvent of N,N-dimethylacetamide and o-dichlorobenzene.

[0022] Furthermore, the volume ratio of N,N-dimethylacetamide to o-dichlorobenzene in the mixed solvent is 3:6-8.

[0023] Furthermore, the acid is 3-6 mol / L acetic acid.

[0024] Furthermore, the volume ratio of the reaction solvent to the acid is 10:1-3.

[0025] Furthermore, when the reaction solvent is a mixed solvent of N,N-dimethylacetamide and o-dichlorobenzene, the volume ratio of N,N-dimethylacetamide, o-dichlorobenzene and the acid is 3:7:2.

[0026] Furthermore, the T d The molar ratio of the symmetrical ligand to the C3 planar ligand is 1-0.5:0-0.5.

[0027] Preferably, the molar amount of C3 planar ligand is non-zero.

[0028] Furthermore, the sum of the molar amounts of the linear linker and the side chain substituted linear linker is equal to T d The molar ratio of the symmetrical ligand is 2:0.8-1.2.

[0029] Furthermore, the molar ratio of the linear linker to the side chain substituted linear linker is 1-0:0-1.

[0030] Preferably, the molar amount of the linear linker and / or the side chain substituted linear linker is not zero.

[0031] Furthermore, the C3 planar ligand is d The molar content of the symmetrical ligand and the C3 planar ligand is 0-50%.

[0032] Furthermore, the preparation method may further include adding a regulator to the reaction system to adjust the rate of aldehyde-amine condensation. For example, the regulator may include aniline.

[0033] Furthermore, the solvent thermal reaction comprises reacting at 85-120° C. for 3-7 days.

[0034] Furthermore, the solvent thermal reaction is carried out under degassing and vacuum sealing conditions.

[0035] Furthermore, the degassing includes direct vacuum degassing and degassing using a freeze-thaw cycle method, such as rapid freezing in a liquid nitrogen bath and degassing through three freeze pump-thaw cycles.

[0036] Furthermore, the reaction system is subjected to ultrasonic treatment before degassing, for example, ultrasonic treatment for 5-30 minutes.

[0037] Furthermore, the reagent used for washing includes one or more of tetrahydrofuran, methanol, ethanol, dimethyl sulfoxide, deionized water and acetone.

[0038] Furthermore, the washing method includes one or more of filtration, centrifugation, multiple soaking and Soxhlet extraction.

[0039] Furthermore, the preparation method also includes further purifying the obtained controllable defect three-dimensional COF material.

[0040] Furthermore, the further purification includes multiple soaking and Soxhlet extraction.

[0041] Furthermore, the drying includes vacuum drying, freeze drying and supercritical carbon dioxide drying.

[0042] Furthermore, the drying comprises vacuum drying at 120° C. for 16-24 hours.

[0043] The present invention also provides the use of the controllable defect three-dimensional COF material as described herein as a photocatalyst.

[0044] Furthermore, the controllable defect-type three-dimensional COF material is used for photocatalytic production of hydrogen peroxide, carbon dioxide reduction, hydrogen production, organic pollutant degradation, heavy metal ion removal, air purification, sterilization and disinfection, and high-value-added conversion of organic matter.

[0045] Advantageous Effects of the Invention

[0046] The present invention proposes a novel and generalizable functionalization strategy, namely a method for reducing the number of node connections, which includes partially replacing the multi-connection nodes and linear connectors in the three-dimensional COF (i.e., partially replacing the T with C3 planar ligands). dSymmetrical ligand nodes and partial replacement of linear linkers with side chain-substituted linear linkers) to achieve efficient photocatalysis. This strategy simultaneously introduced multiple active sites, enhanced the π-conjugated system, and constructed a spatially distributed electron donor-acceptor structure within the three-dimensional framework. COF-300-DF derived from the node connection number reduction strategy of the present invention achieved excellent photocatalytic H2O2 generation (19.09mmol g- 1 h-1), demonstrating stable catalytic performance for over 200 hours of operation and robust structural stability after repeated use. Furthermore, the strategy of reducing the number of node connections shows great promise in photocatalytic benzylamine coupling. This work establishes a new paradigm for the design of photoactive three-dimensional COFs, with potential applications in energy conversion, catalysis, and biomedicine. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 A schematic diagram of the node connection number reduction strategy is shown.

[0048] Figure 2 Schematic diagram of the synthesis of COF-300-DF is shown.

[0049] Figure 3 Fourier transform infrared spectra of COF-300, COF-300-D-15%, and COF-300-DF are shown.

[0050] Figure 4 The structural units of COF-300 (a), COF-300-D-15% (b), and COF-300-DF (c) are shown. (d) Solid-state images of COF-300, COF-300-D-15%, and COF-300-DF 13 C CP / MAS NMR spectra and corresponding carbon signal assignments (*, sidebands). (e) Acid-degraded COF-300 and COF-300-D-15% solution 13 C NMR spectrum. (f) In the COF-300-D series, by 1 Observed ratio versus input ratio for tris(4-aminophenyl)amine (TAPA) linker as determined by H NMR.

[0051] Figure 5 PXRD patterns of COF-300, COF-300-D-15%, and COF-300-DF are shown.

[0052] Figure 6Nitrogen adsorption isotherms of COF-300, COF-300-D-15% and COF-300-DF are shown (filled circles, adsorption; open circles, desorption). P, pressure; P0, baseline pressure.

[0053] Figure 7 Figure 3 shows the H2O2 production performance of functional three-dimensional COFs. (a) Photocatalytic activity of COF-300-D for H2O2 production with different TAPA doping levels. (b) Photocatalytic activity of COF-300-DR and COF-300-F for H2O2 production. (c) Corresponding photocatalytic H2O2 yields of COF-300-DF over five repetition cycles. (d) Effect of initial solution pH on the H2O2 yield of COF-300-DF under visible light irradiation. (f) Apparent quantum yield of COF-300-DF. (g) COF-300-DF continuously and stably produces H2O2 over 200 hours. DETAILED DESCRIPTION

[0054] The present invention is further described below with reference to specific examples, which, however, are not intended to limit the present invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the art.

[0055] Example 1: Preparation of defective three-dimensional COF materials with spatial electron-donating and electron-withdrawing properties

[0056] Using terephthalaldehyde (BDA), tetrakis(4-aminophenyl)methane (TAM), tris(4-aminophenyl)amine (TAPA) and 2,5-difluoroterephthalaldehyde (BDA-F) as raw materials, a solvothermal method was used to heat at 120°C for 72h to obtain an imine-linked defective three-dimensional COF with spatial electron-donating and electron-withdrawing properties (abbreviated as COF-300-DF). The synthesis diagram of COF-300-DF is shown in the figure below. Figure 2 The specific steps are as follows.

[0057] Synthesis of COF-300-DF:

[0058] BDA (6 mg), TAM (16.8 mg), TAPA (2.3 mg), 2,5-difluoroterephthalaldehyde (BDA-F, 7.7 mg), 0.3 mL N,N-dimethylacetamide, 0.7 mL 1,2-dichlorobenzene (DCB), and 0.2 mL 3M aqueous acetic acid were added to a heat-resistant glass tube. The mixture was uniformly dispersed by sonication for 10 minutes, subjected to three freeze-degassing-thaw cycles, and then flame-sealed under vacuum. After the sealed glass tube cooled naturally to room temperature, it was transferred to a 120°C oven and heated for 3 days. After the reaction was completed, the sealed glass tube was removed and allowed to cool to room temperature. It was then washed sequentially with methanol and tetrahydrofuran to obtain COF powder. Finally, the COF powder was extracted with tetrahydrofuran in a Soxhlet extractor for 24 hours and then dried in a vacuum oven at 120°C for 24 hours to obtain the final product, COF-300-DF.

[0059] Example 2: Preparation of defective three-dimensional COF material (ie, COF-300-D) without introducing spatial electron-donating-withdrawing properties

[0060] The synthesis method for preparing defective three-dimensional COF materials without the introduction of spatial electron-donating and electron-withdrawing properties differs from the synthesis method for COF-300-DF in Example 1 in that the raw materials do not contain 2,5-difluoroterephthalaldehyde (BDA-F). By controlling the molar content of TAPA in the TAM+TAPA matrix, COF-300-D with TAPA contents of 5%, 10%, 15%, and 20% were prepared, designated COF-300-D-5%, COF-300-D-10%, COF-300-D-15%, and COF-300-D-20%, respectively. For example, the preparation process for COF-300-D-15% is as follows: BDA (12 mg), TAM (16.8 mg), TAPA (2.3 mg), 22.78 μL of aniline, 1 mL of 1,4-dioxane, and 0.2 mL of 6 M aqueous acetic acid were added to a heat-resistant glass tube. The mixture was ultrasonically dispersed for 10 minutes, subjected to three freeze-degassing-thaw cycles, and then flame-sealed under vacuum. After the sealed tube cooled naturally to room temperature, it was transferred to a 120°C oven and heated for 3 days. After the reaction, the sealed tube was removed and allowed to cool to room temperature. The COF powder was then washed sequentially with methanol and tetrahydrofuran. Finally, the COF powder was extracted with tetrahydrofuran in a Soxhlet extractor for 24 hours and then dried in a vacuum oven at 120°C for 24 hours to obtain the final product, COF-300-D-15%.

[0061] Example 3: Preparation of defective three-dimensional COF materials with spatial electron-donating and electron-withdrawing properties using linear linkers with different side chain substitutions

[0062] The COF-300-DR material was synthesized according to the method of Example 1 using terephthalaldehyde substituted with Tz, OMe and OH side chains in the same molar amount as BDA-F instead of 2,5-difluoroterephthalaldehyde, except that the masses were different, namely 8.6 mg of BDA-Tz, 8.7 mg of BDA-OMe, and 7.5 mg of BDA-OH, which were respectively recorded as COF-300-D-Tz, COF-300-D-OMe, and COF-300-D-OH.

[0063] Comparative Example 1: Preparation of COF-300

[0064] COF-300 was prepared using the same method as described in Example 2, except that the starting materials did not contain TAPA. Specifically, BDA (12 mg), TAM (19.8 mg), 22.78 μL of aniline, 1 mL of 1,4-dioxane, and 0.2 mL of 6M aqueous acetic acid were added to a heat-resistant glass tube. The tube was ultrasonically dispersed for 10 minutes, subjected to three freeze-degassing and thawing cycles, and then flame-sealed under vacuum. After the sealed tube cooled naturally to room temperature, it was transferred to a 120°C oven and heated for 3 days. After the reaction was completed, the sealed tube was removed and allowed to cool to room temperature. It was then washed sequentially with methanol and tetrahydrofuran to obtain COF powder. Finally, the COF powder was extracted with tetrahydrofuran in a Soxhlet extractor for 24 hours and then dried in a vacuum oven at 120°C for 24 hours to obtain the final product, COF-300.

[0065] Comparative Example 2: Preparation of COF-300-F

[0066] In this comparative example, a TAPA-free BDA-F-based crystalline COF was prepared and named COF-300-F. The preparation method was the same as that described in Example 1, except that the raw materials did not contain TAPA. Specifically, BDA (6 mg), TAM (19.8 mg), 2,5-difluoroterephthalaldehyde (BDA-F, 7.7 mg), 0.3 mL N,N-dimethylacetamide, 0.7 mL 1,2-dichlorobenzene (DCB), and 0.2 mL 3M aqueous acetic acid were added to a heat-resistant glass tube. Ultrasonication was performed for 10 minutes to achieve uniform dispersion. Three freeze-degassing and thawing cycles were performed, and the tube was then flame-sealed under vacuum. After the sealed tube was cooled naturally to room temperature, it was transferred to a 120°C oven and heated for 3 days. After the reaction was completed, the sealed glass tube was removed and allowed to cool to room temperature. It was then washed with methanol and tetrahydrofuran to obtain COF powder. Finally, the COF powder was placed in a Soxhlet extractor and extracted with tetrahydrofuran for 24 h, and then dried in a vacuum oven at 120° C. for 24 h to obtain the final product COF-300-F.

[0067] Experimental Example 1: Structural Characterization of COF-300-DF

[0068] Fourier transform infrared spectroscopy (FTIR, Figure 3 ) confirmed the successful introduction of TAPA. 1697cm -1 The new peak at 1624 cm represents the unreacted C=O stretching vibration in BDA, which confirms that the TAPA molecule successfully replaces TAM; -1 The peak at represents C=N vibration, indicating the formation of imine linkage. 1 H and 13 C nuclear magnetic resonance spectroscopy (NMR) further confirmed the quantitative replacement of TAPA ( Figure 4 ). In solid-state cross-polarization 13 In C NMR, two new peaks attributed to TAPA were found at 142.41 and 132.18 ppm in COF-300-D-15%, compared with the original COF-300, which directly indicated the presence of TAPA. 13 In the C NMR spectrum, the additional peaks of TAPA at 146.28, 125.16, and 125.38 ppm confirmed the same conclusion, but with higher signal-to-noise ratio and resolution. 1 HNMR was used to quantify the TAPA content in the COF-300-D series, and it was found that the actual TAPA content in the material was linearly related to the input ratio. After this multi-ligand doping, the crystallinity and basic topology of the original COF were well preserved, forming the COF-300-D and COF-300-DR series. Sharp peaks can be clearly observed in the powder X-ray diffraction (PXRD) pattern, indicating that they have high crystallinity, and no additional peaks from other phases are found ( Figure 5 The nitrogen isotherm types of COF-300, COF-300-D-15%, and COF-300-DF are distinctive due to their unique dynamic response structures, with Brunner-Emmett-Teller (BET) surface areas of 595, 1288, and 1463 m 2 g -1 When P / P0=0.95, the pore volumes are 0.67 cm 3 g -1 , 0.75cm 3 g -1 and 0.81cm 3 g -1 ( Figure 6 The increase in pore volume in COF-300-D-15% and COF-300-DF may be due to the partial replacement of TAM with TAPA, which creates additional space and is more conducive to mass transfer.

[0069] Experimental Example 2: Photocatalytic Hydrogen Peroxide Production Performance of COF-300-DF

[0070] The photocatalytic performance of COF-300-D series for producing H2O2 was evaluated in a two-phase system consisting of water and benzyl alcohol under visible light (λ>420nm) irradiation. In the range of 0% to 20%, the photocatalytic H2O2 yield of the COF-300-D series first increased and then decreased with the addition of TAPA, with COF-300-D-15% achieving the highest yield, reaching 1742.8μmol / g / h. Figure 7 Furthermore, the introduction of functionalized BDA linkers with electron-withdrawing or electron-donating groups to form COF-300-DR significantly affected the generation rate of H2O2, with its electronic configuration systematically altered. After 180 minutes of light irradiation, its generation rate exhibited a trend of -F > -Tz > -OMe > -OH, indicating that strong electron-withdrawing linkers are crucial for the formation of three-dimensional donor-acceptor structures. Figure 7 ). Among all reported three-dimensional COFs and even two-dimensional COFs with similar chemical compositions, COF-300-DF achieved a record-breaking rate of 10086.4 μmol / g / h, which is 21.6 times and 5.8 times that of COF-300 (467.8 μmol / g / h) and COF-300-D-15% (1742.8 μmol / g / h), respectively. In order to verify whether it is necessary to introduce the TAPA connector in COF-300-DF, we synthesized a BDA-F-based crystalline COF without TAPA in a control experiment and named it COF-300-F. The results show that the photocatalytic activity of COF-300-F to produce H2O2 is only 1980.1 μmol / g / h, which is less than 20% of that of COF-300-DF ( Figure 7 ), which indicates that the introduction of TAPA ligand is crucial, and the synergistic effect of light absorption unit and electron modulation unit can effectively carry out photocatalysis.

[0071] In addition to its excellent H2O2 generation activity, COF-300-DF also exhibited excellent photocatalytic recyclability, with no significant decrease in productivity after 5 consecutive cycles ( Figure 7 This excellent stability also allows for use under a wide range of working conditions, from pH 3 to 11. Notably, at pH 3, the productivity reached 19093.2 μmol / g / h, which is likely due to the effect of the acidified imine chain ( Figure 7The above-mentioned excellent performance, structural stability and high apparent quantum yield (AQY) (11.9% at 400nm wavelength) determine that COF-300-DF is an excellent photocatalyst among the reported three-dimensional COFs and even two-dimensional COFs constructed with the same linker. It is worth noting that this unique synthetic strategy gives COF-300-DF remarkable long-term photocatalytic stability, which can work continuously for more than 200 hours without obvious attenuation, and the final H2O2 concentration reaches 0.95wt%, which can be directly used for daily applications such as surface disinfection ( Figure 7 ).

[0072] Experimental Example 3: Photocatalytic Benzylamine Coupling Performance of COF-300-DF

[0073] To explore the broader potential of the node-connectivity reduction strategy, we also investigated the aerobic oxidation of benzylamine. We first performed the reaction at room temperature under an O atmosphere using CH₃CN as solvent and benzylamine as a model substrate. As shown in Table 1, COF-300-DF achieved a conversion of 98.38% within 11 hours, while COF-300 and COF-300-D-15% exhibited much lower conversions. Furthermore, compared to COF-300-D-15% and COF-300, COF-300-DF exhibited higher catalytic activity in the oxidation of a range of benzylamine derivatives. These results demonstrate the broad photocatalytic potential of COF-300-DF, prepared using the node-connectivity reduction strategy.

[0074] Table 1: Photocatalytic oxidative coupling reaction of benzylamine and COF conversion upon complete conversion of COF-300-DF.

[0075]

[0076] In summary, this paper constructs photoactive three-dimensional COFs via a generalizable node-connectivity reduction strategy, in which multiply connected nodes and partial replacement of planar building blocks simultaneously create an extended π-conjugated system and a spatially defined donor-acceptor structure. This approach addresses three key challenges in three-dimensional COF photocatalysis: light harvesting efficiency, charge separation, and structural stability. The optimized COF-300-DF exhibits excellent photocatalytic performance, with a H₂O₂ production rate of 19.09 mmol g⁻¹. -1 h -1, with operational stability exceeding 200 hours. Structural characterization confirmed that the integrity of the framework was maintained through prolonged catalytic cycling. The versatility of this approach further demonstrates its effectiveness in photocatalytic benzylamine coupling, suggesting broad applicability in organic transformations. This strategy establishes a new design paradigm for functional 3D COFs, with potential impact extending beyond photocatalysis to applications in energy conversion systems and selective molecular transformations. The ability to precisely control electronic and spatial properties through junction engineering opens new avenues for tailoring specific functionalities in porous organic materials.

[0077] It should be noted that the preferred embodiments of the present invention are given in the specification and drawings of the present invention. However, the present invention can be implemented in many different forms and is not limited to the embodiments described in this specification. These embodiments are not intended to be additional limitations on the content of the present invention. The purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive. In addition, the above-mentioned technical features can be combined with each other to form various embodiments not listed above, which are all considered to be within the scope of the description of the present invention. Furthermore, it is obvious to those skilled in the art that improvements or changes can be made based on the above description, and all such improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A controllable defect three-dimensional COF material, characterized in that: The three-dimensional COF material is made of T d The COF is formed by covalently linking the symmetrical ligand and the C3 planar ligand with the linear linker and the side chain substituted linear linker.

2. The controllable defect three-dimensional COF material according to claim 1, characterized in that: The T d Symmetrical ligands include tetrakis(4-aminophenyl)methane, tetrakis(4-formylphenyl)methane, tetrakis(4-boronic acid phenyl)methane, tetrakis(4-hydroxyphenyl)methane, tetrakis(4-cyanophenyl)methane, tetrakis(4-mercaptophenyl)methane, tetrakis(4-vinylphenyl)methane, tetrakis(4-ethynylphenyl)methane, tetrakis(4-pyridyl)methane, tetrakis(4-bipyridyl)methane, tetrakis(4-aminobipyridyl)methane, tetrakis(4-formylbipyridyl)methane, tetrakis(4-aminotriazinyl)methane, tetrakis(4-formyltriazinyl)methane, 1,3,5,7-tetrakis(4-amino ... One or more of: (1,1':3',1"-terphenyl)-4,4"-dicarboxaldehyde, ((3,6-difluorobenzene-1,2,4,5-tetrayl)tetrakis(azetidine))octa([1,1'-biphenyl]-4-carboxaldehyde), 5,5',5",5",5',5',5""'-(triphenyl-2,3,6,7,10,11-hexyl)hexa(isophenylhydrazide), 5,10,15,20-tetrayl([1,1':3',1"-terphenyl]-4,4"-dicarboxaldehyde)-porphyrin, and 4-[tris(4-formylphenyl)methyl]benzaldehyde.

3. The controllable defect three-dimensional COF material according to claim 1, characterized in that: The C3 planar ligands include tris(4-aminophenyl)amine, tris(4-aminophenyl)methane, tris(4-aminophenyl)methanol, tris(4-aminophenyl)boric acid, tris(4-aminophenyl)phosphine, tris(4-aminophenyl)silane, tris(4-aminophenyl)benzene, tris(4-aminophenyl)triazine, tris(4-aminobipyridyl)amine, tris(4-aminophenoxy)benzene, tris(4-formylphenyl)amine, tris(4-formylphenyl)methane, tris(4-formylphenyl)benzene, tris(4-formylphenyl)triazine, tris(4-formylbipyridyl)amine, tris(4-aminophenoxy)benzene, One or more of tris(4-boronic acid phenyl)amine, tris(4-boronic acid bipyridyl)amine, tris(4-hydroxyphenyl)amine, tris(4-hydroxyphenyl)methane, tris(4-hydroxyphenyl)benzene, tris(4-aminopyridyl)amine, tris(4-aminotriazinyl)amine, 5,10,15-tris(4-aminophenyl)porphyrin, 5,10,15-tris(4-formylphenyl)porphyrin, melamine, 2,4,6-triaminopyrimidine, melem, 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, p-phenylenediamine, and terephthalaldehyde.

4. The controllable defect three-dimensional COF material according to claim 1, characterized in that: The linear linker includes terephthalaldehyde, 4,4'-biphenyldicarboxaldehyde, 2,6-naphthalenedicarboxaldehyde, 2,2'-bipyridine-5,5'-dicarboxaldehyde, terephthalic acid, dimethyl terephthalate, terephthaloyl chloride, p-phenylenediamine, 4,4'-biphenylenediamine, 2,6-naphthalenediamine, 2,2'-bipyridine-5,5'-diamine, 1,4-phenylenediboronic acid, 4,4'-biphenylenediamine, One or more of phenylenediboronic acid, 1,4-diethynylbenzene, 4,4'-diethynylbiphenyl, terephthaloyl dihydrazide, 4,4'-biphenyl dihydrazide, 1,4-dicyanobenzene, 4,4'-dicyanobiphenyl, 2,5-dicyano-p-phenylenediamine, 2,5-pyridinedicarboxaldehyde, 2,5-thiophenedicarboxaldehyde, 2,5-furandicarboxaldehyde, and 4,4'-dialdo-2,2'-bipyridine.

5. The controllable defect three-dimensional COF material according to claim 1, characterized in that: The side chain substituted linear linker is a linear linker in which the linear linker is substituted by a side chain to have a side chain functional group, wherein the side chain functional group includes one or more of fluorine, chlorine, bromine, iodine, hydroxyl, ether bond, keto group, aldehyde group, carboxyl group, sulfonic acid group, nitro group, ester group, amino group, imino group, cyano group, azido group, sulfonic acid amine group, thiol group, sulfonate group, thiazole ring, pyridine ring, imidazole ring, pyrrole ring, furan ring, methoxy group, alkyl group, alkenyl group, alkynyl group, and phosphate group.

6. The controllable defect three-dimensional COF material according to claim 1, characterized in that: The T d The molar ratio of the symmetrical ligand to the C3 planar ligand is 1-0.5:0-0.5; Furthermore, the sum of the molar amounts of the linear linker and the side chain substituted linear linker is equal to T d The molar ratio of the symmetrical ligand is 2:0.8-1.2; Furthermore, the molar ratio of the linear linker to the side chain substituted linear linker is 1-0:0-1; Furthermore, the C3 planar ligand is d The molar content of the symmetrical ligand and the C3 planar ligand is 0-50%.

7. A method for preparing a controllable defect three-dimensional COF material according to any one of claims 1 to 6, characterized in that: Including T d The symmetrical ligand, the C3 planar ligand, the linear linker and the side chain substituted linear linker undergo a solvothermal reaction in a reaction solvent under the action of an acid, and the reaction product is collected, washed and dried to obtain the controllable defect-type three-dimensional COF material.

8. The preparation method according to claim 7, characterized in that The reaction solvent is one of 1,4-dioxane, mesitylene, N-methylpyrrolidone, o-dichlorobenzene, n-butanol, tetrahydrofuran, toluene, N,N-dimethylformamide, N,N-dimethylacetamide, chloroform, n-butane, benzyl alcohol, methanol, ethanol, dimethyl sulfoxide, acetonitrile, and cyclohexane, or a mixed solvent of several thereof; Furthermore, the reaction solvent is a mixed solvent of N,N-dimethylacetamide and o-dichlorobenzene; Furthermore, the volume ratio of N,N-dimethylacetamide to o-dichlorobenzene in the mixed solvent is 3:6-8; Furthermore, the acid is 3-6 mol / L acetic acid; Furthermore, the volume ratio of the reaction solvent to the acid is 10:1 to 3; Furthermore, when the reaction solvent is a mixed solvent of N,N-dimethylacetamide and o-dichlorobenzene, the volume ratio of N,N-dimethylacetamide, o-dichlorobenzene and the acid is 3:7:2; Furthermore, the T d The molar ratio of the symmetrical ligand to the C3 planar ligand is 1-0.5:0-0.5; Furthermore, the sum of the molar amounts of the linear linker and the side chain substituted linear linker is equal to T d The molar ratio of the symmetrical ligand is 2:0.8-1.2; Furthermore, the molar ratio of the linear linker to the side chain substituted linear linker is 1-0:0-1; Furthermore, the C3 planar ligand is d The molar content of the symmetrical ligand and the C3 planar ligand is 0-50%.

9. The preparation method according to claim 7, characterized in that The solvent thermal reaction comprises reacting at 85 to 120° C. for 3 to 7 days; Furthermore, the solvent thermal reaction is carried out under degassed and vacuum sealed conditions; Furthermore, the preparation method further comprises further purifying the obtained controllable defect-type three-dimensional COF material; Furthermore, the further purification includes multiple soaking and Soxhlet extraction.

10. Use of the controllable defect three-dimensional COF material according to any one of claims 1 to 6 as a photocatalyst; Furthermore, the controllable defect-type three-dimensional COF material is used for photocatalytic production of hydrogen peroxide, carbon dioxide reduction, hydrogen production, organic pollutant degradation, heavy metal ion removal, air purification, sterilization and disinfection, and high-value-added conversion of organic matter.

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