Covalent organic framework material for regulating metal coordination distance, preparation method thereof and application of activated pms in degrading pollutants

Abstract

The application discloses a kind of covalent organic framework materials for regulating metal coordination distance and its preparation method and the application of activated PMS degradation pollutants, on the basis of original metal porphyrin, by the coordination connection metal atom in the position of intermediate connecting group, not only increase the load of metal, also greatly shorten the distance between two adjacent metal atoms, enhance electron transfer efficiency, improve the catalytic activity of framework material;Make the framework material show excellent catalytic activity.Covalent organic framework material is prepared by solvothermal reaction, continue to react with metal precursor can be loaded on metal, the preparation method is simple, does not need complex reaction process and harsh reaction condition, can be prepared in large scale.

Description

Technical Field

[0001] This invention belongs to the field of environmental catalytic materials technology, specifically relating to a covalent organic framework material for regulating metal coordination distance, its preparation method, and its application in activating PMS to degrade pollutants. Background Technology

[0002] Metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) have regular pore structures, high specific surface areas, and tunable chemical compositions. They can adsorb pollutants and then activate PMS to oxidize and degrade pollutants, thus making them ideal catalyst supports for activating PMS.

[0003] The coordination environment of metals in organic framework materials, especially the coordination distance between metal atoms, is one of the key factors affecting the catalytic performance of the materials. Differences in metal coordination distance directly affect electron transfer efficiency, the activation pathway of PMS, and the adsorption and oxidation capacity for target pollutants. Traditional framework materials are limited by the monomer structure and distances constituting the framework, making it difficult to adjust the metal coordination positions. For example, some methods use fixed-structure COF supports to load metals. Due to the fixed spatial arrangement of ligands in the support, the coordination environment of metal ions is singular, making it impossible to flexibly adjust the coordination distance according to the characteristics of different pollutants, thus limiting the broad applicability of the materials. On the other hand, some control methods rely on complex template agents or harsh reaction conditions (such as high-temperature calcination, high-pressure treatment, etc.), which not only increases the preparation cost but may also damage the framework structure of the COF material, leading to a decrease in specific surface area or loss of active sites.

[0004] Therefore, developing a method for precisely controlling the metal coordination distance based on COF carriers with different structures and through differences in ligand spatial arrangement is of great significance for improving the PMS activation efficiency of metal-COFs materials and expanding their application in pollutant degradation. Summary of the Invention

[0005] Based on the above reasons, the first objective of this invention is to provide a covalent organic framework material for regulating metal coordination distance, using metalporphyrin as the structural unit and bipyridine as the linking monomer; the two pyridines of bipyridine are respectively coordinated to two metal atoms, and two metal atoms are added between the two metal atoms of the metalporphyrin, shortening the distance between adjacent metal atoms, thereby achieving precise regulation of metal coordination distance and enhancing the catalytic performance of the covalent organic framework material.

[0006] The second objective of this invention is to provide a method for preparing covalent organic framework materials that regulate metal coordination distance. The method involves using COF materials to provide metal coordination sites by connecting monomers, and then achieving metal loading through the coordination reaction between COF and metal precursors. The preparation method is simple, requires no complex reaction process or harsh reaction conditions, and can be prepared on a large scale.

[0007] A third objective of this invention is to provide an application of covalent organic framework materials with adjustable metal coordination distances in the degradation of pollutants using room-temperature activated PMS. Covalent organic framework materials with adjustable metal coordination distances have more metal loading sites and shorter metal-to-metal inter-spacing, significantly improving PMS activation efficiency.

[0008] The first objective of this invention can be achieved by adopting the following technical solution:

[0009] A covalent organic framework material for regulating metal coordination distance, having the molecular structure shown in Formula I:

[0010]

[0011] Where M is any one of Fe, Co, Ni, Mn, Pt, Au, and Pd.

[0012] Furthermore, the BET specific surface area of ​​covalent organic framework materials with modulated metal coordination distance is 400-600 m². 2 g -1 The metal loading is 1.5-1.9 wt%.

[0013] The second objective of this invention can be achieved by adopting the following technical solution:

[0014] A method for preparing a covalent organic framework material with adjustable metal coordination distance includes the following steps:

[0015] The COF structure shown in Formula II reacts with the M metal precursor in a solvent to obtain the covalent organic framework material that regulates the metal coordination distance.

[0016]

[0017] Furthermore, the solvent is a mixture of alcohol and water, with a volume ratio of alcohol to water of (3-10):1.

[0018] Furthermore, the alcohol is methanol or ethanol.

[0019] Furthermore, the M metal precursor is an acetate, chloride, sulfate, nitrate, or hydrate of the M metal.

[0020] Furthermore, the mass ratio of COF to the M metal precursor in the structure shown in Formula II is (1-5):1.

[0021] Furthermore, the reaction conditions are 20-45℃ for 12-72 hours.

[0022] Furthermore, the reaction includes a post-processing step: solid-liquid separation, in which the solid product is washed with water and ethanol and vacuum dried to obtain the covalent organic framework material with regulated metal coordination distance.

[0023] Furthermore, the COF structure shown in Formula II is prepared by a solvothermal reaction of 5,10,15,20-tetrakis(4-aminophenyl)porphyrin and 3,3'-bipyridine-6,6'-dicarboxaldehyde under vacuum.

[0024] Furthermore, the solvent is a mixture of 1,2-dichlorobenzene and n-butanol; the volume ratio of 1,2-dichlorobenzene to n-butanol is 1:(5-15).

[0025] Furthermore, the molar ratio of 5,10,15,20-tetra(4-aminophenyl)porphyrin to 3,3'-bipyridine-6,6'-dicarboxaldehyde is 1:(2-2.2).

[0026] Furthermore, the molar-volume ratio of 5,10,15,20-tetra(4-aminophenyl)porphyrin to the solvent is 1 mmol:(20-60) mL.

[0027] Furthermore, the reaction is carried out in the presence of trifluoroacetic acid, with a volume ratio of trifluoroacetic acid to solvent of 1:(3-8).

[0028] Furthermore, the reaction conditions are: 100-140℃ for 48-144 hours.

[0029] Furthermore, it also includes post-processing steps: after the end of the solubility heat reaction, cooling, solid-liquid separation, and washing the solid product sequentially with N,N-dimethylformamide, tetrahydrofuran, dichloromethane and ethanol; purification by Soxhlet extraction in tetrahydrofuran.

[0030] The third objective of this invention can be achieved by adopting the following technical solution:

[0031] Application of covalent organic framework materials that regulate metal coordination distance in the degradation of pollutants by activated PMS.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] 1. The covalent organic framework material for regulating metal coordination distance of the present invention, based on the original metal porphyrin, not only increases the metal loading by coordinating metal atoms at the intermediate linking group position, but also greatly shortens the distance between two adjacent metal atoms, thereby enhancing electron transfer efficiency and improving the catalytic activity of the framework material.

[0034] 2. The present invention discloses a method for preparing a covalent organic framework material with adjustable metal coordination distance. The method utilizes ligand groups of the COF material to provide metal coordination sites, allowing for the coordination of metal atoms to all sites in a single reaction. The preparation method is simple, requiring no complex reaction processes or harsh reaction conditions, and is suitable for large-scale production. Furthermore, COF materials can be prepared via a solvothermal reaction, enabling large-scale production.

[0035] 3. The covalent organic framework material metalloporphyrin, which regulates metal coordination distance in this application, possesses enzyme-mimicking properties that enhance the catalytic activity of COF, while the multiple metal sites further improve catalytic efficiency. Therefore, the covalent organic framework material that regulates metal coordination distance can activate PMS to degrade apap at room temperature. obs The value reached 0.055 min. -1 . Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the reaction for preparing COF-2-Bpy-Fe in Example 3;

[0037] Figure 2 X-ray powder diffraction patterns of COF-2-Bpy and COF-2-Bpy-Fe;

[0038] Figure 3 Infrared spectra of COF-2-Bpy and COF-2-Bpy-Fe;

[0039] Figure 4 The graph shows the BET test results for COF-2-Bpy and COF-2-Bpy-Fe.

[0040] Figure 5 Activity diagrams of COF-2-Bpy, COF-2-Bpy-Fe, and Fe-COF-biphenyl in degrading pollutant apap;

[0041] Figure 6 The kJ of COF-2-Bpy, COF-2-Bpy-Fe and Fe-COF-biphenyl for the degradation of pollutant apap obs value;

[0042] Figure 7 The graph shows the adsorption test results of COF-2-Bpy and COF-2-Bpy-Fe. Detailed Implementation

[0043] The technical solution of the present invention will now be clearly and completely described with reference to specific embodiments. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0044] The coordination environment of metals is a core factor influencing the catalytic performance of metal-COF materials, and the coordination distance between metal atoms is one of the key parameters. Studies have shown that differences in metal coordination distance directly affect electron transfer efficiency, the activation pathway of PMS, and the adsorption and oxidation capacity for target pollutants. For example, when the metal coordination distance is within a specific range, such as with iron, it can promote Fe... 2+ with Fe 3+ The cyclic transformation accelerates the decomposition of PMS, thereby increasing the degradation rate of pollutants; if the distance is too far, it will hinder electron transfer and weaken catalytic activity.

[0045] Therefore, this application provides a covalent organic framework material for regulating metal coordination distance, having the molecular structure shown in Formula I:

[0046]

[0047] Where M is any one of Fe, Co, Ni, Mn, Pt, Au, and Pd.

[0048] Covalent organic framework materials for regulating metal coordination distance contain porphyrin groups, which can bind to metals to form metalloporphyrins. However, the macrocyclic structure of porphyrins and the linking groups between porphyrins result in excessively large distances between metal atoms, affecting electron transfer efficiency. This application uses 3,3'-bipyridine as the linking group, where the nitrogen on each pyridine and the adjacent imine are coordinated with the same metal atom, thus fixing and loading the metal atom. This increases the number of active metal sites and significantly shortens the distance between metal atoms, enhancing catalytic activity.

[0049] As one implementation method, the BET specific surface area of ​​the covalent organic framework material with controlled metal coordination distance is 400-600 m². 2 g -1 The metal loading is 1.5-1.9 wt%. COF itself has abundant porosity, which facilitates the entry of metal ions into the framework for coordination; it also provides a large specific surface area, which is beneficial for substrate contact and enhances catalytic performance. The metal loading provides sufficient reactive sites without clogging the pores.

[0050] This application also provides a method for preparing a covalent organic framework material with adjustable metal coordination distance, comprising the following steps:

[0051] The COF structure shown in Formula II reacts with the M metal precursor in a solvent to obtain the covalent organic framework material with controlled metal coordination distance; as shown in Formula II. Figure 1 As shown.

[0052]

[0053] In the COF structure shown in Formula II, the four nitrogen atoms of the porphyrin ring readily coordinate with a metal to form a metalporphyrin. Meanwhile, the two nitrogen atoms on the 3,3'-bipyridine group, along with the imine in the COF structure, can simultaneously coordinate with the same metal atom. This allows the COF structure shown in Formula II to react with a metal precursor, enabling the simultaneous coordination of metal atoms onto both the porphyrin and bipyridine groups, forming a covalent organic framework material that regulates the metal coordination distance. While maintaining the properties of the COF, enhanced catalytic performance is achieved by loading metal atoms.

[0054] In one embodiment, the solvent is a mixture of alcohol and water, with a volume ratio of alcohol to water of (3-10):1. Water and ethanol are miscible, and the COF structure shown in Formula II is soluble in ethanol. Since the metal precursor is water-soluble, the COF can fully contact and react with the metal ions in the metal precursor. Preferably, the alcohol is methanol or ethanol.

[0055] In one embodiment, the M metal precursor is an acetate of the M metal. Chlorides, sulfates, nitrates, and their hydrates. Preferably, when the metal M is Fe, the precursor of the metal M is ferrous acetate, ferrous chloride, ferrous sulfate, ferrous nitrate, and their hydrates; when the metal is Co, Ni, Mn, Pt, Au, or Pd, the precursor of the metal M is its acetate, chloride, sulfate, nitrate, and their hydrates.

[0056] In one implementation, the mass ratio of COF to the M metal precursor in the structure shown in Formula II is (1-5):1. Iron is in excess to ensure sufficient reaction at the COF coordination sites; on the other hand, iron is limited to prevent metal agglomeration within the COF and blockage of the channels.

[0057] In one implementation method, the reaction conditions are 20-45℃ for 12-72 hours. Room temperature coordination can directly anchor the metal without triggering other side reactions that affect the COF structure. Preferably, the reaction is performed by shaking, a relatively gentle method that promotes metal adsorption and coordination reactions.

[0058] In one embodiment, the reaction includes a post-processing step: solid-liquid separation, whereby the solid product is washed with water and ethanol, and then vacuum dried to obtain the covalent organic framework material that regulates metal coordination distance. Preferably, the obtained solid product is repeatedly washed with ultrapure water (50 mL × 3) and ethanol (3 mL × 3), and then dried in a vacuum oven at 50-80°C for 6-24 hours.

[0059] As one embodiment, the COF structure shown in Formula II is prepared by a solvothermal reaction of 5,10,15,20-tetrakis(4-aminophenyl)porphyrin and 3,3'-bipyridine-6,6'-dicarboxaldehyde under vacuum.

[0060] The COF structure shown in Formula II is formed by the covalent linkage of 5,10,15,20-tetra(4-aminophenyl)porphyrin and 3,3'-bipyridine-6,6'-dicarboxaldehyde through an amine-aldehyde condensation. This reaction can be achieved using a solvothermal reaction.

[0061] One implementation method involves freezing the reaction vessel in a liquid nitrogen bath, evacuating it, and then sealing it. This effectively removes air and creates a vacuum environment.

[0062] In one embodiment, the solvent is a mixture of 1,2-dichlorobenzene and n-butanol; the volume ratio of 1,2-dichlorobenzene to n-butanol is 1:(5-15).

[0063] In one embodiment, the molar ratio of 5,10,15,20-tetra(4-aminophenyl)porphyrin to 3,3'-bipyridine-6,6'-dicarboxaldehyde is 1:(2-2.2).

[0064] In one embodiment, the molar-volume ratio of 5,10,15,20-tetra(4-aminophenyl)porphyrin to the solvent is 1 mmol:(20-60) mL.

[0065] In one embodiment, the reaction is carried out in the presence of trifluoroacetic acid, with a volume ratio of trifluoroacetic acid to solvent of 1:(3-8).

[0066] As one implementation method, the reaction conditions are: 100-140℃ for 48-144 hours.

[0067] One implementation method includes a post-processing step: after the heat of dissolution reaction ends, cooling is performed, solid-liquid separation is carried out, and the solid product is washed sequentially with N,N-dimethylformamide, tetrahydrofuran, dichloromethane, and ethanol; purification is then performed by Soxhlet extraction in tetrahydrofuran. The purified COF is then used for metal loading.

[0068] Preferably, the solid product is washed sequentially with N,N-dimethylformamide (50 mL × 3), tetrahydrofuran (50 mL × 3), dichloromethane (3 mL × 3), and ethanol (3 mL × 3). Further purification is performed by Soxhlet extraction in tetrahydrofuran for 24 h.

[0069] This application provides the application of covalent organic framework materials that regulate metal coordination distance in the degradation of pollutants using activated PMS.

[0070] The following provides a further explanation using specific implementation methods.

[0071] Example 1

[0072] Add 0.025 mmol of 5,10,15,20-tetrakis(4-aminophenyl)porphyrin and 0.05 mmol of 3,3'-bipyridine-6,6'-dicarboxaldehyde to 10 mL The solid powder was dispersed in the solvent by ultrasonic treatment for 10 min, followed by the addition of 0.1 mL of 1,2-dichlorobenzene and 0.9 mL of n-butanol. 0.2 mL of trifluoroacetic acid aqueous solution was added, and the tube was placed in a liquid nitrogen bath to freeze, evacuated to an internal pressure of 50 mTorr, and sealed. The reaction mixture was then heated at 120 °C for 72 h. After the system cooled to room temperature, the solid product was collected by filtration. The obtained solid product was washed thoroughly with N,N-dimethylformamide (50 mL × 3), tetrahydrofuran (50 mL × 3), dichloromethane (3 mL × 3), and ethanol (3 mL × 3). The obtained solid product was further purified by Soxhlet extraction in tetrahydrofuran for 24 h, and then dried in a vacuum oven at 120 °C for 12 h. The resulting COF with the structure shown in Formula II was obtained and named COF-2-Bpy.

[0073] Example 2

[0074] Add 0.025 mmol of 5,10,15,20-tetrakis(4-aminophenyl)porphyrin and 0.0525 mmol of 3,3'-bipyridine-6,6'-dicarboxaldehyde to 10 mL The solid powder was dispersed in the solvent by ultrasonic treatment for 10 min, followed by the addition of 0.17 mL of trifluoroacetic acid aqueous solution. The tube was then placed in a liquid nitrogen bath and frozen until an internal pressure of 50 mTorr was reached and the tube was sealed. The reaction mixture was then heated at 100 °C for 144 h. After the system cooled to room temperature, the solid product was collected by filtration. The obtained solid product was washed thoroughly with N,N-dimethylformamide (50 mL × 3), tetrahydrofuran (50 mL × 3), dichloromethane (3 mL × 3), and ethanol (3 mL × 3). The obtained solid product was further purified by Soxhlet extraction in tetrahydrofuran for 24 h. The obtained solid product was then dried in a vacuum oven at 120 °C for 12 h to obtain COF with the structure shown in Formula II, named COF-2-Bpy.

[0075] Example 3

[0076] 0.025 mmol of 5,10,15,20-tetrakis(4-aminophenyl)porphyrin and 0.053 mmol of 3,3'-bipyridine-6,6'-dicarboxaldehyde were added to 10 mL The solid powder was dispersed in the solvent by ultrasonic treatment for 10 min, followed by the addition of 0.19 mL of trifluoroacetic acid aqueous solution. The tube was then placed in a liquid nitrogen bath and frozen until an internal pressure of 50 mTorr was reached and the tube was sealed. The reaction mixture was then heated at 140 °C for 48 h. After the system cooled to room temperature, the solid product was collected by filtration. The obtained solid product was washed thoroughly with N,N-dimethylformamide (50 mL × 3), tetrahydrofuran (50 mL × 3), dichloromethane (3 mL × 3), and ethanol (3 mL × 3). The obtained solid product was further purified by Soxhlet extraction in tetrahydrofuran for 24 h. The obtained solid product was then dried in a vacuum oven at 120 °C for 12 h to obtain COF with the structure shown in Formula II, named COF-2-Bpy.

[0077] Example 4

[0078] 100 mg of COF-2-Bpy prepared in Example 1 was added to 10 mL of ethanol, followed by 2 mL of 10 mg / mL ferrous acetate aqueous solution. The solution was shaken and reacted at room temperature for 24 h, then filtered. The resulting solid product was repeatedly washed with ultrapure water (50 mL × 3) and ethanol (3 mL × 3). The product was then dried in a vacuum oven at 80 °C for 12 h to obtain a metal-active site covalent organic framework material with the structure shown in Formula I, named COF-2-Bpy-Fe.

[0079] Comparative Example 1

[0080] 0.025 mmol of 5,10,15,20-tetra(4-aminophenyl)porphyrin and 0.05 mmol of 4,4′-biphenyldicarboxaldehyde were added to a 10 mL Pyrex tube, followed by 0.1 mL of 1,2-dichlorobenzene and 0.9 mL of n-butanol. The mixture was sonicated for 10 min to disperse the solid powder in the solvent. 0.2 mL of trifluoroacetic acid aqueous solution was added, and the tube was placed in a liquid nitrogen bath to freeze, evacuated to an internal pressure of 50 mTorr, and sealed. The reaction mixture was then heated at 120 °C for 72 h. After the system cooled to room temperature, the solid product was collected by filtration. The obtained solid product was washed thoroughly with N,N-dimethylformamide (50 mL × 3), tetrahydrofuran (50 mL × 3), dichloromethane (3 mL × 3), and ethanol (3 mL × 3). The obtained solid product was further purified by Soxhlet extraction in tetrahydrofuran for 24 h, and then dried in a vacuum oven at 120 °C for 12 h to obtain COF-biphenyl.

[0081] 100 mL of the COF-biphenyl prepared above was added to 10 mL of ethanol, followed by 2 mL of 10 mg / mL ferrous acetate aqueous solution. The solution was reacted with shaking at room temperature for 24 h, then filtered. The resulting solid product was repeatedly washed with ultrapure water (50 mL × 3) and ethanol (3 mL × 3). The product was then dried in a vacuum oven at 80 °C for 12 h to obtain a metal-active site covalent organic framework material with the structure shown in Formula III, named Fe-COF-biphenyl.

[0082]

[0083] Material characterization:

[0084] (1) The COF-2-Bpy prepared in Example 1 and the COF-2-Bpy prepared in Example 3 were compared. COF-2-Bpy-Fe X-ray powder Diffraction test, X-ray powder diffraction pattern as shown in the figure. As shown in Figure 2.

[0085] from Figure 2 As can be seen from the results, after COF-2-Bpy reacts with the metal precursor, the 3.5° characteristic peak in the PXRD of the prepared COF-2-Bpy-Fe does not shift, indicating that the COF structure maintains its complete crystal form.

[0086] (2) The COF-2-Bpy prepared in Example 1 and the COF-2-Bpy-Fe prepared in Example 3 were subjected to infrared spectroscopy tests, and the results are as follows: Figure 3 As shown.

[0087] Figure 3 In the middle, BBD, 1690cm -1The C=O peak at 1622 cm⁻¹ almost disappears in COF₂-Bpy, while it remains at 1622 cm⁻¹ in COF₂-Bpy. -1 The presence of a C=N peak at this point indicates that the porphyrin amino group reacted with the aldehyde group of bipyridine to form COF. Meanwhile, COF-2-Bpy and COF-2-Bpy-Fe showed peaks at 1622 cm⁻¹. -1 The C=N peak showed almost no change, indicating that the COF connection structure was stable.

[0088] (3) The COF-2-Bpy prepared in Example 1 and the COF-2-Bpy-Fe prepared in Example 3 were subjected to N2 adsorption-desorption tests. The N2 adsorption-desorption curves (top left), pore volume distribution diagram (top right), and specific surface area calculation (bottom) are shown below. Figure 4 As shown.

[0089] According to the pore volume distribution diagram, both COF-2-Bpy and COF-2-Bpy-Fe are mesoporous materials; after loading the metal, the pore size of COF-2-Bpy-Fe remains essentially unchanged compared to COF-2-Bpy. However, based on specific surface area calculations, COF-2-Bpy has a pore size of 470 μm. 2 g -1 The specific surface area of ​​COF-2-Bpy-Fe decreased to 443 m² after being loaded with metal. 2 g -1 .

[0090] (4) The Fe loading of COF-2-Bpy-Fe prepared in Example 3 and COF-biphenyl prepared in Comparative Example 1 was calculated by ICP, and the results are shown in Table 1.

[0091] Table 1

[0092]

[0093]

[0094] As can be seen from Table 1, the Fe loading of COF-2-Bpy-Fe in Example 3 is close to twice that of Fe-COF-biphenyl in Comparative Example 1, which also indicates that in addition to the porphyrin ring, the bipyridine group is also coordinated to connect Fe atoms.

[0095] Example 5

[0096] Activation of PMS to degrade the pollutant apap: Weigh 5 mg COF-2-Bpy-Fe into an Erlenmeyer flask, add 25 ml of deionized water, and sonicate until the catalyst and water are completely mixed. Add 50 μL of acetaminophen (apap) into the Erlenmeyer flask and immediately place it in a magnetic stirrer and stir for 15 min until adsorption equilibrium is reached. At this point, take 1 ml of the mixed liquid, filter it, and measure the phenol content by liquid chromatography, recording it as 0s. Then, add PMS (0.5 mM) and start timing immediately. Take 1 ml of samples at 0s, 15s, 30s, 45s, 60s, 75s, 90s, 105s, and 120s, filter them, and measure the apap content by liquid chromatography. The results are as follows: Figure 5 As shown; the Kobs value of the degradation pollutant APAP is as follows. Figure 6 As shown.

[0097] Comparative Example 2

[0098] The COF-2-Bpy prepared in Example 1 was tested according to the method in Example 5; the results are as follows. Figure 5 As shown; the Kobs value of the degradation pollutant APAP is as follows. Figure 6 As shown.

[0099] Comparative Example 3

[0100] The Fe-COF-biphenyl prepared in Comparative Example 1 was tested according to the method in Example 5; the results are as follows. Figure 5 As shown; the Kobs value of the degradation pollutant APAP is as follows. Figure 6 As shown.

[0101] from Figure 5 The results show that COF-2-Bpy-Fe activated PMS has a higher efficiency and more thorough degradation of apap, followed by Fe-COF-biphenyl, while COF-2-Bpy without iron loading has the worst effect. The kJ / kJ of COF-2-Bpy-Fe activated PMS for apap degradation is also shown. obs The value reached 0.055 min. -1 .

[0102] Comparative Example 4

[0103] Following the method in Example 5, COF-2-Bpy / apap, COF-2-Bpy-Fe / apap, and PMS / apap were added respectively. The adsorption performance of COF and the change of apap under PMS without activation were detected. The results are as follows: Figure 7 As shown.

[0104] from Figure 7As can be seen, the concentration of apap in COF-2-Bpy-Fe / apap and COF-2-Bpy / apap decreased more than that in PMS / apap, but both were still above 80%, indicating that COF adsorption was not the main pathway for apap degradation, and PMS did not catalyze activation, so its degradation performance was not activated.

[0105] In summary, the covalent organic framework material for regulating metal coordination distance of this application comprises a metalloporphyrin and a bipyridine group. While the metal is loaded in the porphyrin, the two nitrogen atoms of the bipyridine are coordinated to connect the metal atoms, forming a multi-metal active site. This increases the number of metal active sites and regulates the distance between the metals, enabling the framework material to exhibit excellent catalytic activity.

[0106] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A covalent organic framework material for regulating metal coordination distance, characterized in that, It has the molecular structure shown in Formula I: ； Where M is any one of Fe, Co, Ni, Mn, Pt, Au, and Pd; The method for preparing the covalent organic framework material with regulated metal coordination distance includes the following steps: The COF structure shown in Formula II reacts with the M metal precursor in a solvent to obtain the covalent organic framework material that regulates the metal coordination distance. ； The BET specific surface area of ​​covalent organic framework materials with modulated metal coordination distance is 400-600 m². 2 g -1 The metal loading is 1.5-1.9 wt%.

2. The method for preparing the covalent organic framework material with regulated metal coordination distance as described in claim 1, characterized in that, The solvent is a mixture of alcohol and water, with a volume ratio of alcohol to water of (3-10):1; the alcohol is methanol or ethanol; the precursor of metal M is acetate, chloride, sulfate, nitrate, or hydrate of metal M. The mass ratio of COF to the M metal precursor in the structure shown in Formula II is (1-5):1; The reaction conditions are 20-45℃ for 12-72 hours.

3. The method for preparing a covalent organic framework material with controlled metal coordination distance according to claim 2, characterized in that, The reaction includes post-processing steps: solid-liquid separation, washing of the solid product with water and ethanol, and vacuum drying to obtain the covalent organic framework material with regulated metal coordination distance.

4. The method for preparing a covalent organic framework material with controlled metal coordination distance according to claim 2, characterized in that, The COF structure shown in Formula II is prepared by a solvothermal reaction of 5,10,15,20-tetrakis(4-aminophenyl)porphyrin and 3,3'-bipyridine-6,6'-dicarboxaldehyde under vacuum.

5. The method for preparing a covalent organic framework material with regulated metal coordination distance according to claim 4, characterized in that, The solvent is a mixture of 1,2-dichlorobenzene and n-butanol; the volume ratio of 1,2-dichlorobenzene to n-butanol is 1:(5-15). The molar ratio of 5,10,15,20-tetra(4-aminophenyl)porphyrin to 3,3'-bipyridine-6,6'-dicarboxaldehyde is 1:(2-2.2). The molar-volume ratio of 5,10,15,20-tetra(4-aminophenyl)porphyrin to solvent is 1 mmol:(20-60) mL.

6. The method for preparing a covalent organic framework material with controlled metal coordination distance according to claim 4, characterized in that, The reaction was carried out in the presence of trifluoroacetic acid, with a volume ratio of trifluoroacetic acid to solvent of 1:(3-8). The reaction conditions are: 100-140℃ for 48-144 hours.

7. The method for preparing a covalent organic framework material with controlled metal coordination distance according to claim 4, characterized in that, It also includes post-processing steps: after the end of the solubility heat reaction, cooling, solid-liquid separation, and washing the solid product sequentially with N,N-dimethylformamide, tetrahydrofuran, dichloromethane and ethanol; purification by Soxhlet extraction in tetrahydrofuran.

8. The application of the covalent organic framework material for regulating metal coordination distance as described in claim 1, or the covalent organic framework material for regulating metal coordination distance prepared by the preparation method of any one of claims 2-7, in the degradation of pollutants by activated PMS.

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