Ion imprinted covalent organic framework material and preparation method and application thereof

Abstract

The application discloses an ion imprinted covalent organic framework material and a preparation method and application thereof, and belongs to the technical field of organic polymer porous materials. 2v The symmetrical functional monomer, the planar six-coordination metal marked ion and the solvent are ultrasonically mixed to obtain a C3 symmetrical six-site coordination complex; a solvent-dispersed C3 symmetrical node monomer is added into the C3 symmetrical six-site coordination complex system and ultrasonically mixed again, then a catalyst solution is added and ultrasonically reacted to obtain a reaction product; the reaction product is post-treated to obtain a metal covalent organic framework ion imprinted COFs precursor; the metal covalent organic framework ion imprinted COFs precursor is dispersed in a sulfuric acid solution for elution, and then post-treated to obtain the ion imprinted covalent organic framework material. The method solves the problems of difficult control of crystallinity, difficult scale synthesis and inability to construct a specific coordination environment.

Description

Technical Field

[0001] This invention belongs to the field of porous organic polymer materials technology, specifically relating to an ion-imprinted covalent organic framework material, its preparation method, and its application. Background Technology

[0002] Covalent organic frameworks (COFs) are a class of porous crystalline organic materials composed of lightweight elements linked by covalent bonds, representing a rapidly developing new field in chemical research. Due to their low structural density, high stability, and ease of designing structures and active sites, COFs exhibit enormous application potential in gas storage and separation, pollutant removal, catalysis, photoelectric applications, and energy storage. Their highly ordered crystalline structure and tunable organic functional components enable COFs to efficiently separate and store guest molecules, and they have been frequently used in recent years for the removal of guest metal ions (such as uranium, technetium, and mercury) as pollutants. However, current functional materials for COFs are typically based on simple pre- or post-functionalization of the framework, making it difficult to design specific coordination pore structures, thus limiting their application potential in complex environments (such as spent fuel reprocessing, industrial wastewater, seawater uranium extraction, and precision catalysis). Therefore, designing and constructing stable and precise ion traps within COFs for the selective adsorption of guest ions in complex environments is of great significance and presents significant challenges.

[0003] Ion-imprinted polymers are high-molecular materials capable of specifically recognizing target ions. They possess unique coordination cavities, promising for the precise separation of target ions from complex environments. However, traditional ion-imprinted polymers are typically amorphous substances with irregular and predictable structures. Therefore, in addition to low imprinting efficiency, some imprinting sites are easily deformed or damaged during pretreatment, affecting the polymer's ability to remove target ions and limiting its application in complex environments such as high acidity and high salinity. Furthermore, the irregular and ordered pore structure of ion-imprinted polymers hinders the transport of target ions within the polymer, affecting the adsorption rate. Therefore, improving the crystallinity of ion-imprinted materials and designing regular pore structures are crucial for enhancing their performance. Based on this, we envision combining ion imprinting strategies with COFs to design ion-imprinted COFs (II-COFs), which rationally combine the advantages of both materials. Similar to traditional ion-imprinted methods, suitable ions and functional monomers are pre-assembled to form a coordination complex with a specific internal cavity structure. Then, appropriate peripheral linker monomers are polymerized to form a highly crystalline ion-imprinted COF material. Finally, template ions are eluted to obtain the ion-imprinted COF. The constructed ion-imprinted COF possesses both the specific selective cavity structure of ion-imprinted materials for target ions and the high crystallinity and highly regular structure of COF materials. Due to the presence of the covalent framework structure of COFs, ion-imprinted COFs have a stable framework and regular one-dimensional channels, which is beneficial for the processing and transport of target ions within the material, improving the adsorption and recycling performance.

[0004] To achieve the ion-imprinted COF synthesis strategy, the key lies in designing metal-covalent organic frameworks (MCOFs) that contain both a stable outer framework and a specific coordination environment. M-COFs, an emerging derivative of COFs, are porous crystalline framework materials containing both covalent and coordination bonds within their structural framework. Metal coordination exhibits directional and highly reversible properties, which are beneficial for directional growth of COFs and improving crystallinity. The M-COF design strategy is currently commonly used in the preparation of COF woven materials and metal-supported catalysts. Based on the topological structure of COFs, it is known that the configuration of the coordination complex formed by the template ion and the functional monomer directly affects the final topological structure of the constructed COFs; therefore, the selection of the functional monomer is crucial. According to the construction rules of COFs, if the coordination complex formed by the metal ion and the functional monomer is C2, C3, C4, D… 2hConventional symmetrical monomers typically form pores with conventional topological configurations such as triangles, quadrilaterals, and hexagons. This results in the presence of coordinated metal ion nodes within the framework, which can disrupt the entire framework structure during template ion elution. Poor structural stability and the lack of stable, specifically selective pore structures limit the application of M-COFs in fields such as ion adsorption. Therefore, designing a continuously expanding organic framework free of metal ion nodes is crucial for the successful synthesis of ion-imprinted COFs. Summary of the Invention

[0005] The purpose of this invention is to provide an ion-imprinted covalent organic framework material, its preparation method, and its application, in order to solve the technical problems of existing methods, such as difficulty in controlling crystallinity, difficulty in large-scale synthesis, and inability to construct a specific coordination environment.

[0006] To achieve the above objectives, the present invention employs the following technical solution: This invention discloses a method for preparing ion-imprinted covalent organic framework materials, comprising the following steps: S1: C 2v Symmetrical functional monomers, planar six-coordinate metal-imprinted ions, and solvents were ultrasonically mixed to obtain C3 symmetric six-site coordination complexes. S2: Subsequently, solvent-dispersed C3 symmetric node monomers were added to the C3 symmetric six-site coordination complex system and ultrasonically mixed again. Then, catalyst solution was added and ultrasonicated to carry out the reaction, and the reaction product was obtained. S3: Post-process the reaction products to obtain metal covalent organic framework ion-imprinted COFs precursors; S4: The metal covalent organic framework ion-imprinted COF precursor is dispersed in sulfuric acid solution and eluted, followed by a second post-processing to obtain the ion-imprinted covalent organic framework material.

[0007] Furthermore, in S1, the C 2v The molar ratio of the symmetrical functional monomer to the planar six-coordinate metal imprinted ion is (2~4):1, more preferably 3:1; the ratio of the planar six-coordinate metal imprinted ion to the solvent is 10~50 mg:3 mL.

[0008] Furthermore, in S1, the ultrasonic mixing time is 0.5~4 h; The C 2v The symmetrical functional monomers are one or more of the following: 3,5-diaminobenzoic acid monomers, 3,5-diaminobenzoamide oxime monomers, and 3,5-dicarboxybenzoic acid monomers; The structural formula of the 3,5-diaminobenzoic acid monomer is: ; R1, R2, and R3 are each independently selected from H, halogen, hydroxyl, substituted or unsubstituted C1-C5 alkyl, alkoxy, or ester groups; The structural formula of the 3,5-diaminobenzamide oxime monomer is as follows: ; R1, R2, and R3 are each independently selected from H, halogen, hydroxyl, substituted or unsubstituted C1-C5 alkyl, alkoxy, or ester groups; The structural formula of the 3,5-dicarboxybenzoic acid monomer is: ; R1, R2, and R3 are each independently selected from H, halogen, hydroxyl, substituted or unsubstituted C1-C5 alkyl, alkoxy, or ester groups.

[0009] Furthermore, in S2, when C is used 2v When the symmetrical functional monomer is a 3,5-diaminobenzoic acid or a 3,5-diaminobenzoamide oxime functional monomer, the C3 symmetrical node monomer is a pyromellitic trimethylaldehyde monomer, a pyromellitic triamine monomer, or an olefinic monomer. When the C3 symmetry node monomer is a pyromellitic trimethylaldehyde monomer or a pyromellitic triamine monomer, an imine bond linkage reaction is carried out using a catalyst solution. The catalyst solution used at this time is acetic acid solution, trifluoroacetic acid solution, p-toluenesulfonic acid solution, or trifluoromethanesulfonate. When the C3 symmetry node monomer is an alkene-bonded monomer, an alkene bond linkage reaction is carried out using a catalyst solution. The catalyst solution used at this time is NaOH or KOH aqueous solution, cesium carbonate, 1,8-diazabicyclo[5.4.0]undec-7-ene, or piperidine catalyst. The structural formula of the pyromellitic trimethylaldehyde monomer is:

[0010] R1, R2, and R3 are each independently selected from H, halogen, hydroxyl, substituted or unsubstituted C1-C5 alkyl, alkoxy, or ester groups; The structural formula of the pyromellitic triamine monomer is: ; R1, R2, and R3 are each independently selected from H, halogen, hydroxyl, substituted or unsubstituted C1-C5 alkyl, alkoxy, or ester groups; The structural formula of the olefinic monomer is: , , or ; R1, R2, and R3 are each independently selected from H, halogen, hydroxyl, substituted or unsubstituted C1-C5 alkyl, alkoxy, or ester groups.

[0011] Further, in S1, the planar six-coordinate metal imprinted ion is one or more of indium acetate, nitrate, sulfate, chloride and uranyl ion salts.

[0012] Furthermore, the solvents used in S1 and S2 are all mixtures of ethanol / water, DMF / water, mesitylene / dioxane, or o-dichlorobenzene / n-butanol.

[0013] Furthermore, in S2, the ratio of the C3 symmetric six-site coordination complex to the solvent is 10~50 mg:1 mL; The ratio of the amount of C3 symmetric six-site coordination complex to the C3 symmetric node monomer is 1.5~2.5:1, preferably 2:1.

[0014] Furthermore, the amount of catalyst solution added is 1% to 15% of the total solvent volume in S1 and S2; In S2, the time for the second ultrasonic mixing is 1~10 min; The time for ultrasonication after adding the catalyst solution is 0.5~5 min; The reaction time is 1 to 7 days, and the reaction temperature is 50 to 150°C, preferably 80 to 120°C, and most preferably 90°C; In S3, the post-processing includes sequential washing and vacuum drying. In S4, the ratio of the metal covalent organic framework ion-imprinted COFs precursor to the sulfuric acid solution is 30 mg: 10~30 mL; The concentration of the sulfuric acid solution is 0.25~0.5 M; The post-processing includes sequential washing and drying.

[0015] The present invention also discloses an ion-imprinted covalent organic framework material prepared by the above preparation method.

[0016] The present invention also discloses the application of the above-mentioned ion-imprinted covalent organic framework material in the separation and enrichment of indium ions and uranyl ions and in the catalysis of loaded cobalt, copper, nickel and silver ions.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses a method for preparing ion-imprinted covalent organic framework materials, which involves using C 2v Using symmetrical functional monomers, planar six-coordinate metal-imprinted ions, and C3 symmetric node monomers as raw materials, due to C2v The functional monomer coordinates with a planar six-coordinated metal, making C 2v Non-centrosymmetric building blocks are transformed into centrosymmetric C3 six-site coordination complex building nodes. The increased symmetry enhances interlayer conjugation, reducing the difficulty of synthesizing COFs materials. At the same time, the reversibility of coordination bonds is beneficial to assisting the directional crystallization and growth of COFs, solving the problems of difficult crystallinity control, difficulty in large-scale synthesis, and inability to construct specific coordination environments. Attached Figure Description

[0018] Figure 1 The powder X-ray diffraction pattern of In-COF-OCH3; Figure 2 The powder X-ray diffraction pattern for In-COF-CH3; Figure 3 Infrared spectrum; Among them: a) infrared spectra of II-COF-0 and its monomers; b) infrared spectra of II-COF-1 and its monomers; c) infrared spectra of II-COF-2 and its monomers; Figure 4 Theoretical and experimental powder X-ray diffraction patterns of In-COFs; Wherein: a) Theoretical and experimental powder X-ray diffraction patterns of In-COF-0; b) Theoretical and experimental powder X-ray diffraction patterns of In-COF-1; c) Theoretical and experimental powder X-ray diffraction patterns of In-COF-2. Figure 5 Thermogravimetric curves of In-COF-0 and II-COF-0; Figure 6 Theoretical and experimental powder X-ray diffraction patterns of II-COFs; Among them: a) Theoretical and experimental powder X-ray diffraction patterns of II-COF-0; b) Theoretical and experimental powder X-ray diffraction patterns of II-COF-1; c) Theoretical and experimental powder X-ray diffraction patterns of II-COF-2; Figure 7 The adsorption properties of indium ions for the II-COFs series materials; Among them: a) adsorption kinetics curve; b) removal rate of adsorption kinetics; c) effect curve of concentration on adsorption performance; d) selective separation performance of indium ions; e) cyclic adsorption experiment; f) powder X-ray diffraction pattern of II-COF-2 during the cycle. Figure 8 The adsorption performance of uranyl ions by II-COFs series materials; Among them: a) adsorption kinetic curve; b) effect curve of concentration on adsorption performance; c) cyclic adsorption experiment; d) powder X-ray diffraction pattern of II-COF-2 during the cycle. Figure 9 PXRD patterns of Co, Cu, Ni, and Ag metal ions adsorbed by II-COFs; Among them: a) PXRD pattern of II-COF-0 after adsorption of Co, Cu, Ni and Ag metal ions; b) PXRD pattern of II-COF-1 after adsorption of Co, Cu, Ni and Ag metal ions; c) PXRD pattern of II-COF-2 after adsorption of Co, Cu, Ni and Ag metal ions. Figure 10 The structural formula is In-COF-0; Figure 11 Powder X-ray diffraction patterns of indium adsorbed in In-COF-0, II-COF-0 and II-COF-0. Detailed Implementation

[0019] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0020] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0021] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0022] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0023] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0024] This invention provides a method for preparing ion-imprinted covalent organic framework materials, comprising the following steps: A certain amount of C2v The symmetrical functional monomer and the planar six-coordinated metal-imprinted ion (molar ratio 3:1) were weighed together, added to a solvent, and sonicated for 0.5-4 h to form a C3 symmetrical six-site coordination complex. Subsequently, C3 symmetric node monomers with equimolar functional groups dispersed in the same solvent were added to the system and sonicated for 1 to 10 min to mix. Then, catalyst solution of 1% to 15% of the total solvent volume was added, and the mixture was briefly sonicated for 0.5 to 5 min before sealing. The system was reacted at 90℃ for 1 to 7 days. The reaction product was washed with deionized water, ethanol and acetone multiple times and dried under vacuum to obtain the metal covalent organic framework ion-imprinted COFs precursor, named M-COFs. Then, by washing away the ion-imprinted COFs precursor M-COFs, the ion-imprinted material can be obtained. The specific elution steps are as follows: a certain amount of M-COFs is weighed and dispersed in a 0.25~0.5 M sulfuric acid solution. The system is stirred at room temperature for 24 h. After washing with deionized water, ethanol, acetone and other solutions multiple times and vacuum drying, ion-imprinted COFs are obtained and named II-COFs.

[0025] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0026] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0027] Example 1 3,5-Diaminobenzoic acid (30.4 mg; 0.2 mmol) and indium acetate (19.5 mg; 0.067 mmol) were weighed together and added to 3 mL of a solvent of ethanol:water = 9:1 (v / v). The mixture was sonicated for 1 h to form a coordination complex (C3 symmetric six-site coordination complex). Subsequently, 1 mL of 1,3,5-benzenetrialdehyde (21.6 mg; 0.133 mmol) dispersed in the same solvent was added to the system, and the mixture was sonicated for 5 min. Then, 0.4 mL of 6 M acetic acid solution was added, and the mixture was briefly sonicated for 30 s before sealing. The system was reacted at 90 °C for 4 days. The resulting reaction product was washed repeatedly with deionized water, ethanol, acetone, and tetrahydrofuran, and then vacuum dried to obtain a metal covalent organic framework ion-imprinted COF precursor, named In-COF-0. The structural formula of this product is shown below. Figure 10 As shown.

[0028] The reaction formula for this preparation process is as follows: .

[0029] Example 2 3,5-Diaminobenzoic acid (304 mg; 2 mmol) and indium acetate (195 mg; 0.67 mmol) were weighed together and added to 20 mL of a solvent of ethanol:water = 9:1 (v / v). The mixture was sonicated for 2 h to form a coordination complex (C3 symmetric six-site coordination complex). Subsequently, 5 mL of 1,3,5-benzenetrialdehyde (216 mg; 1.33 mmol) dispersed in the same solvent was added to the system and sonicated for 5 min to mix. Then, 2.5 mL of 6 M acetic acid solution was added, and the mixture was briefly sonicated for 30 s before sealing. The system was reacted at 90 °C for 4 days. The resulting reaction product was washed multiple times with deionized water, ethanol, acetone, and tetrahydrofuran, and then vacuum dried to obtain a metal covalent organic framework ion-imprinted COF precursor, named In-COF-0.

[0030] Example 3 3,5-Diaminobenzoic acid (1.824 g; 12 mmol) and indium acetate (1.17 g; 4 mmol) were weighed together and added to 160 mL of ethanol:water = 9:1 (v / v) solvent. The mixture was sonicated for 4 h to form a coordination complex (C3 symmetric six-site coordination complex). Subsequently, 40 mL of 1,3,5-benzenetrialdehyde (1.296 g; 8 mmol) dispersed in the same solvent was added to the system and sonicated for 5 min to mix. Then, 15 mL of 6 M acetic acid solution was added, and the mixture was briefly sonicated for 30 s before sealing. The system was reacted at 90 °C for 4 days. The prepared reaction product was washed multiple times with deionized water, ethanol, acetone, and tetrahydrofuran, and then vacuum dried to obtain a metal covalent organic framework ion-imprinted COF precursor, named In-COF-0.

[0031] Example 4 3,5-Diaminobenzoic acid (30.4 mg; 0.2 mmol) and indium acetate (19.5 mg; 0.067 mmol) were weighed together and added to 3 mL of a solvent of ethanol:water = 9:1 (v / v). The mixture was sonicated for 1 h to form a coordination complex (C3 symmetric six-site coordination complex). Subsequently, 1 mL of 2-hydroxy-1,3,5-benzenetrialdehyde (23.8 mg; 0.133 mmol) dispersed in the same solvent was added to the system and sonicated for 30 s to mix. Then, 0.4 mL of 6 M acetic acid solution was added, and the mixture was briefly sonicated for 15 s before sealing. The system was reacted at 90 °C for 4 days. The prepared reaction product was washed multiple times with deionized water, ethanol, acetone, and tetrahydrofuran, and then vacuum dried to obtain a metal covalent organic framework ion-imprinted COF precursor, named In-COF-1. The reaction equations for the above reaction process are as follows: .

[0032] Example 5 3,5-Diaminobenzoic acid (304 mg; 2 mmol) and indium acetate (195 mg; 0.67 mmol) were weighed together and added to 20 mL of a solvent of ethanol:water = 9:1 (v / v). The mixture was sonicated for 2 h to form a coordination complex. Subsequently, 5 mL of 2-hydroxy-1,3,5-benzenetrialdehyde (238 mg; 1.33 mmol) dispersed in the same solvent was added to the system, and the mixture was sonicated for 60 s. Then, 2.5 mL of 6 M acetic acid solution was added, and the mixture was briefly sonicated for 30 s before sealing. The system was reacted at 90 °C for 4 days. The prepared reaction product was washed repeatedly with deionized water, ethanol, acetone, and tetrahydrofuran, and then vacuum dried to obtain a metal covalent organic framework ion-imprinted COF precursor, named In-COF-1.

[0033] Example 6 3,5-Diaminobenzoic acid (1.824 g; 12 mmol) and indium acetate (1.17 g; 4 mmol) were weighed together and added to 160 mL of ethanol:water = 9:1 (v / v) solvent. The mixture was sonicated for 4 h to form a coordination complex (C3 symmetric six-site coordination complex). Subsequently, 40 mL of 2-hydroxy-1,3,5-benzenetrialdehyde (1.425 g; 0.133 mmol) dispersed in the same solvent was added to the system and sonicated for 60 s to mix. Then, 15 mL of 6 M acetic acid solution was added, and the mixture was briefly sonicated for 30 s before sealing. The system was reacted at 90 °C for 4 days. The resulting reaction product was washed multiple times with deionized water, ethanol, acetone, and tetrahydrofuran, and then vacuum dried to obtain a metal covalent organic framework ion-imprinted COF precursor, named In-COF-1.

[0034] Example 7 3,5-Diaminobenzoic acid (30.4 mg; 0.2 mmol) and indium acetate (19.5 mg; 0.067 mmol) were weighed together and added to 3 mL of DMF:water = 1:1 (v / v) solvent. The mixture was sonicated for 1 h to form a coordination complex (C3 symmetric six-site coordination complex). Subsequently, 1 mL of 2,4-dihydroxy-1,3,5-benzenetrialdehyde (25.9 mg; 0.133 mmol) dispersed in the same solvent was added to the system and sonicated for 5 min to mix. Then, 0.4 mL of 6 M acetic acid solution was added and sonicated for 5 min before sealing. The system was reacted at 90 °C for 4 days. The prepared material was washed repeatedly with deionized water, ethanol, acetone, and tetrahydrofuran, and then vacuum dried to obtain a metal covalent organic framework ion-imprinted COF precursor, named In-COF-2. The reaction formulas for the above preparation process are as follows: .

[0035] Example 8 3,5-Diaminobenzoic acid (304 mg; 2 mmol) and indium acetate (195 mg; 0.67 mmol) were weighed together and added to 20 mL of a DMF:water = 1:1 (v / v) solvent. The mixture was sonicated for 2 h to form a coordination complex (C3 symmetric six-site coordination complex). Subsequently, 5 mL of 2,4-dihydroxy-1,3,5-benzenetrialdehyde (259 mg; 1.33 mmol) dispersed in the same solvent was added to the system, and the mixture was sonicated for 5 min to mix. Then, 2.5 mL of 6 M acetic acid solution was added, and the mixture was sonicated for 5 min before sealing. The system was reacted at 90 °C for 4 days. The prepared material was washed repeatedly with deionized water, ethanol, acetone, and tetrahydrofuran, and then vacuum dried to obtain a metal covalent organic framework ion-imprinted COF precursor, named In-COF-2.

[0036] Example 9 3,5-Diaminobenzoic acid (30.4 mg; 0.2 mmol) and indium acetate (19.5 mg; 0.067 mmol) were weighed together and added to 3 mL of a solvent of ethanol:water = 9:1 (v / v). The mixture was sonicated for 1 h to form a coordination complex (C3 symmetric six-site coordination complex). Subsequently, 1 mL of 2,4,6-trimethylbenzene-1,3,5-tricarboxaldehyde (27.2 mg; 0.133 mmol) dispersed in the same solvent was added to the system, and the mixture was sonicated for 5 min. Then, 0.4 mL of 6 M acetic acid solution was added, and the mixture was briefly sonicated for 30 s before sealing. The system was reacted at 90 °C for 4 days. The prepared material was washed multiple times with deionized water, ethanol, acetone, and tetrahydrofuran, and then vacuum dried to obtain a metal-covalent organic framework ion-imprinted COF precursor, named In-COF-CH3. The diffraction structure is shown below. Figure 2 As shown.

[0037] The reaction formulas for the above preparation process are as follows:

[0038] Example 10 3,5-Diaminobenzoic acid (30.4 mg; 0.2 mmol) and indium acetate (20 mg; 0.067 mmol) were weighed together and added to 3 mL of a solvent of ethanol:water = 9:1 (v / v). The mixture was sonicated for 1 h to form a coordination complex. Subsequently, 1 mL of 1,3,5-trimethoxy-2,4,6-tricarboxyphenyl (33.6 mg; 0.133 mmol) dispersed in the same solvent was added to the system. The mixture was briefly sonicated for 30 s to mix, and then 0.4 mL of 6 M acetic acid solution was added. The mixture was sonicated for 15 s and then sealed. The system was reacted at 90 °C for 4 days. The prepared material was washed repeatedly with deionized water, ethanol, acetone, and tetrahydrofuran, and then vacuum dried to obtain a metal covalent organic framework ion-imprinted COF precursor, named In-COF-OCH3. The diffraction structure is shown below. Figure 1 As shown.

[0039] The reaction formulas for the above preparation process are as follows:

[0040] Example 11 The ion-imprinted material II-COF-0 can be obtained by eluting the metal covalent organic framework ion-imprinted COF precursor In-COF-0. The specific steps are as follows: Weigh 30 mg of In-COF-0 from Example 3 and disperse it in 15 mL of 0.25 M sulfuric acid solution. The system is stirred at room temperature for 24 h. After washing with deionized water, ethanol, and acetone multiple times and vacuum drying, II-COF-0 ion-imprinted COFs are obtained. The specific reaction formula for the above elution is as follows: .

[0041] Example 12 The ion-imprinted material II-COF-1 can be obtained by eluting the metal covalent organic framework ion-imprinted COF precursor In-COF-1. The specific steps are as follows: 30 mg of In-COF-1 from Example 6 was weighed and dispersed in 15 mL of 0.5 M sulfuric acid solution. The system was stirred at room temperature for 24 h. After washing with deionized water, ethanol, and acetone multiple times and vacuum drying, II-COF-1 ion-imprinted COFs were obtained.

[0042] Example 13 The ion-imprinted material II-COF-2 can be obtained by eluting In-COF-2 from the metal covalent organic framework ion-imprinted COF precursor in Example 8. The specific steps are as follows: Weigh 30 mg of In-COF-2 and disperse it in 15 mL of 0.5 M sulfuric acid solution. Stir the system at room temperature for 24 h. After washing with deionized water, ethanol and acetone multiple times and vacuum drying, II-COF-2 ion-imprinted COFs are obtained.

[0043] Example 14 The ion-imprinted material II-COF-CH3 can be obtained by eluting the metal-covalent organic framework (MOF) precursor In-COF-CH3. The specific steps are as follows: Weigh 30 mg of In-COF-CH3 and disperse it in 15 mL of sulfuric acid solution with pH=2. Stir the system at room temperature for 1 h, centrifuge, and repeat the above process 3 times. After washing with deionized water, ethanol, and acetone multiple times, and vacuum drying, II-COF-CH3 ion-imprinted COFs are obtained.

[0044] Example 15 The ion-imprinted material II-COF-OCH3 can be obtained by eluting the metal-covalent organic framework (MOF) precursor In-COF-OCH3. The specific steps are as follows: 30 mg of In-COF-OCH3 from Example 10 was weighed and dispersed in 15 mL of 0.5 M sulfuric acid solution. The system was stirred at room temperature for 24 h. After washing with deionized water, ethanol, and acetone multiple times and vacuum drying, II-COF-OCH3 ion-imprinted COFs were obtained.

[0045] The materials prepared in the above embodiments were subjected to structural analysis and infrared spectroscopy. The In-COF series materials (taking In-COF-0 as an example) showed a structure at ~1757 cm⁻¹. -1 The characteristic peaks of the aldehyde group have largely disappeared, and a characteristic peak of the imine bond appears near 1626 cm⁻¹, indicating that the aldehyde group and the amino group reacted to form an imine bond during the reaction. Figure 3 Furthermore, the infrared spectra before and after elution showed no significant changes, indicating that the organic framework was not damaged during acid elution and exhibited good stability.

[0046] Powder XRD analysis showed that In-COFs exhibited distinct diffraction peaks at multiple positions with 2θ values ​​of 5.69°, 9.82°, 11.34°, 15.04°, 16.94°, 22.41°, and 25.52°. Figure 4 The PXRD value is basically the same as that of the theoretical AA stacked structure simulated by MS, and has a small refinement factor, indicating that it forms the highly regular and ordered MCOFs framework as expected in the experiment.

[0047] This invention describes the elution of In-COFs, the precursor of ion-imprinted COFs. The study found that under elution with 0.25–0.5 M sulfuric acid, In-COFs can completely release the imprinted indium ions to form ion-imprinted COF materials, named II-COFs. Thermogravimetric analysis revealed that In-COFs ultimately retained approximately 20.64% of their remaining mass in air, while the remaining mass of eluted II-COF-0 was almost zero in the final stage, indicating complete indium ion elution. Furthermore, thermogravimetric analysis also showed that In-COF-0 and II-COF-0 showed no significant mass loss before reaching ~400℃, indicating good thermal stability. Figure 5 ).

[0048] Furthermore, II-COFs possess a regular and ordered structure and high crystallinity. Powder XRD shows ( Figure 6 II-COFs exhibit distinct diffraction peaks, and the experimental values ​​are essentially the same as the AA stacking mode of the structure formed by removing indium ions from In-COFs, both showing small refinement coefficients. The biggest difference in the PXRD spectra before and after elution is that II-COFs have virtually no peaks near 2θ of 5.5°, while this is the main diffraction peak of In-COFs. This phenomenon suggests that changes in PXRD peaks may provide a simple way to identify the coordination cavities and coordination states of the ion trap. In summary, the design concept and implementation scheme of the ion-imprinted COFs material proposed in this invention are basically feasible.

[0049] The ion-imprinted COFs construction strategy proposed in this application uses metal ions as templates. The coordination of metal ions is directional, which transforms the non-centrosymmetric C2v building units into centrosymmetric C3 six-site building nodes. The improvement of symmetry will increase the interlayer conjugation effect and reduce the difficulty of synthesizing COFs materials. At the same time, the coordination bond is reversible, which is beneficial to assist the directional crystallization and growth of COFs, making it easier to prepare highly crystalline materials.

[0050] The materials prepared in the above embodiments were subjected to application performance tests. The prepared series of imprinted COFs, with indium ions as imprinted ions, are a potential class of indium ion adsorbents. Indium is a rare metal widely used in the preparation of electronic devices such as ITO rake materials. Its distribution is sparse and its reserves are small. Therefore, it is of great significance to separate and purify indium from waste devices or water bodies containing indium to achieve its recycling and sustainable utilization.

[0051] Therefore, this invention explored the adsorption performance of indium ions by the II-COFs series materials, and the adsorption kinetic curves showed that ( Figure 7 a) II-COF-0,1 exhibits a relatively slow adsorption rate, with equilibrium adsorption capacities of 46.1 mg g. -1 and 43.3 mgg -1 The removal rate is over 85% ( Figure 7 b) II-COF-2 exhibits rapid adsorption kinetics, reaching 80% of the equilibrium adsorption capacity for indium within 5 minutes and essentially reaching adsorption equilibrium after 2 hours, with an equilibrium adsorption capacity of 50.6 mg / g. -1 The removal rate is over 99%, and the Kd value is 7.75 × 10⁵ mL g. –1 Subsequently, this invention further investigated the adsorption isotherms of indium and examined the effect of concentration on adsorption performance at an acidity of pH 4. From Figure 7 As can be seen from c, the indium adsorption capacity of II-COFs gradually increases with increasing indium concentration. When c0 is 60 ppm, adsorption equilibrium is basically reached, at which point the adsorption capacities of II-COF-0,1, and2 can reach 56.8 mg·g⁻¹, respectively. -1 58.9 mg·g -1 and 81.9 mg·g -1 .

[0052] Indium-containing water bodies typically contain a variety of cations, making the efficient and selective separation of In3+ from complex water bodies of significant value. Research has found that Zn... 2+ Ca 2+ Al 3+ 、Sr 2+ Plasma is the main interfering ion for indium enrichment, Zn 2+The main interfering ion for extracting primary indium from zincblende is Ca. 2+ Al 3+ 、Sr 2+ These are the main interfering ions for recovering regenerated indium from LCDs. Based on this, the present invention prepared a simulated adsorption solution containing the above five coexisting ions to investigate the effect of II-COFs on In... 3+ The selective separation performance. (By...) Figure 7 As can be seen, at pH 4, the selectivity of II-COF-0,1,2 for indium was 94.4%, 88.7%, and 75.2%, respectively, with adsorption capacities reaching 43.3 mg·g⁻¹. -1 39.3 mg·g -1 and 46.7 mg·g -1 , for In 3+ It exhibits excellent selective separation performance. Furthermore, cyclic experiments revealed ( Figure 7 e), after three adsorption cycles, the adsorption amount of II-COF-2 remained essentially unchanged, and PXRD showed that the 2θ peak near 5.5° disappeared after elution and reappeared after adsorption, indicating that the elution-adsorption process can realize the recycling of II-COFs materials, making them a highly promising type of indium enrichment material. Figure 7 f).

[0053] Uranium is an important nuclear fuel resource. With the continuous and rapid development of nuclear power and the rapid consumption of uranium nuclear raw materials, the separation and recovery of uranium from spent fuel and other uranium-bearing water bodies is of great significance to the safe and sustainable development of nuclear energy. In acidic water bodies, uranium mainly exists in the form of uranyl ions. Uranyl ions have two relatively inert double-bonded oxygen atoms (U=O) along the axis, forming a hexagonal bipyramidal configuration primarily in a six-coordinate manner in the equatorial plane. This coordination mode is essentially the same as the planar six-coordinate mode of indium in prepared In-COFs, providing structural support for the use of II-COFs in uranium-bearing water bodies. Furthermore, In... 3+ The ionic radius of the ion is 0.8 Å, which is very close to the equatorial plane radius of uranyl ions (0.73 Å), indicating that the prepared ion trap cavities can match uranyl ions. Therefore, from the perspectives of coordination mode and the degree of ion compatibility of the ion trap, II-COFs are a class of highly promising uranium enrichment materials.

[0054] Therefore, this invention explores the adsorption performance of uranium for the II-COF series materials. Adsorption kinetic curves show ( Figure 8 a) Similar to indium adsorption, II-COF-0,1 exhibits a relatively slow adsorption rate, with equilibrium adsorption capacities of 130.0 mg / g. -1 and 81.1 mg g -1 ;and II-COF -2The adsorption kinetics are rapid; the adsorption capacity of uranium reaches the equilibrium adsorption capacity of 185.0 mg / g within 10 minutes. -1 80%. Subsequently, this invention investigated the effect of the initial uranium concentration on adsorption performance at an acidity of pH 4. From Figure 8 As can be seen from b, the uranium adsorption capacity of II-COFs gradually increases with increasing uranium concentration. When c0 is 100 mg / L... -1 Adsorption equilibrium was basically reached at that time. Furthermore, cyclic experiments revealed that ( Figure 8 c), II-COF in 3 adsorption cycles -2 The adsorption capacity remained essentially unchanged, and PXRD showed that the 2θ peak near 5.6° disappeared after elution, but reappeared after adsorption. Figure 8 d) indicates that II-COFs can be reused multiple times and are a class of highly promising uranium enrichment materials.

[0055] II-COFs are a class of COF framework materials with specific "ion traps." As observed from the adsorption of indium and uranium, the 2θ peak near 5.6° can disappear and reappear through an elution-adsorption process, and changes in the crystal planes within the material can be determined by observing changes in the PXRD pattern. As mentioned earlier, II-COFs can selectively adsorb indium and uranyl ions from their respective complex simulation systems. However, we also hope that these II-COFs with their special "ion traps" can play a greater role as functional platforms, such as metal-supported catalyst platforms. Therefore, we explored the feasibility of loading other metal ions onto them.

[0056] The general procedure for II-COFs to adsorb other metal ions is as follows: Weigh 30 mg of II-COFs and disperse them in 20 mL of 0.3 mmol / L metal acetate methanol solution or metal nitrate aqueous solution. Stir the system at room temperature for 24 h. Collect the solid by filtration. Wash the solid with the appropriate solution and dry it under vacuum to obtain the corresponding II-COF-0,1,2-M (M represents the supported metal) product. The preparation of Co... 2+ Cu 2+ Ni 2+ The raw material for the solution is a metal acetate, prepared using Ag. + The raw material for the solution is a metal nitrate. Meanwhile, light should be avoided as much as possible during the preparation of II-COF-0,1,2-Ag. Studies have found that in single-ion adsorption systems, after II-COF-0 adsorbs catalytically active metal ions such as Co, Cu, Ni, and Ag, its PXRD peak near 5.5° reappears. Figure 9The adsorption of these ions into the ion trap of II-COF-1 is quite pronounced, indicating that these ions are adsorbed in the ion trap of II-COF-1. Furthermore, II-COF-1 and II-COF-2 exhibit the same phenomenon, demonstrating that the ion-imprinted COFs synthesis strategy proposed in this study is a good method for preparing single-atom catalyst support platforms with precise coordination environments. The prepared II-COFs have potential applications in the field of supported catalysis.

[0057] Figure 11 The powder X-ray diffraction patterns of In-COF-0, II-COF-0, and II-COF-0 adsorbing indium show that after acid elution, the peak of 2θ near 5.5° of In-COF-0 disappears to form II-COF-0. After II-COF-0 adsorbs indium ions, the peak of 2θ near 5.5° reappears. This indicates that the organic framework does not undergo deformation after elution, forming a stable and specific coordination environment. Furthermore, the elution-adsorption process can achieve the recycling and utilization of the material.

[0058] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for preparing an ion-imprinted covalent organic framework material, characterized in that, Includes the following steps: S1: C 2v Symmetrical functional monomers, planar six-coordinate metal-imprinted ions, and solvents were ultrasonically mixed to obtain C3 symmetric six-site coordination complexes. S2: Subsequently, solvent-dispersed C3 symmetric node monomers were added to the C3 symmetric six-site coordination complex system and ultrasonically mixed again. Then, catalyst solution was added and ultrasonicated to carry out the reaction, and the reaction product was obtained. S3: Post-process the reaction products to obtain metal covalent organic framework ion-imprinted COFs precursors; S4: The metal covalent organic framework ion-imprinted COF precursor is dispersed in sulfuric acid solution and eluted, followed by a second post-processing to obtain the ion-imprinted covalent organic framework material.

2. The method for preparing an ion-imprinted covalent organic framework material according to claim 1, characterized in that, In S1, the C 2v The molar ratio of the symmetrical functional monomer to the planar six-coordinate metal imprinted ion is (2~4):1; the ratio of the planar six-coordinate metal imprinted ion to the solvent is 10~50 mg:3 mL.

3. The method for preparing an ion-imprinted covalent organic framework material according to claim 1, characterized in that, In S1, the ultrasonic mixing time is 0.5~4 h; The C 2v The symmetrical functional monomers are one or more of the following: 3,5-diaminobenzoic acid monomers, 3,5-diaminobenzoamide oxime monomers, and 3,5-dicarboxybenzoic acid monomers; The structural formula of the 3,5-diaminobenzoic acid monomer is: ； R1, R2, and R3 are each independently selected from H, halogen, hydroxyl, substituted or unsubstituted C1-C5 alkyl, alkoxy, or ester groups; The structural formula of the 3,5-diaminobenzamide oxime monomer is as follows: ； R1, R2, and R3 are each independently selected from H, halogen, hydroxyl, substituted or unsubstituted C1-C5 alkyl, alkoxy, or ester groups; The structural formula of the 3,5-dicarboxybenzoic acid monomer is: ； R1, R2, and R3 are each independently selected from H, halogen, hydroxyl, substituted or unsubstituted C1-C5 alkyl, alkoxy, or ester groups.

4. The method for preparing an ion-imprinted covalent organic framework material according to claim 3, characterized in that, In S2, when C is used 2v When the symmetrical functional monomer is a 3,5-diaminobenzoic acid or a 3,5-diaminobenzoamide oxime functional monomer, the C3 symmetrical node monomer is a pyromellitic trimethylaldehyde monomer, a pyromellitic triamine monomer, or an olefinic monomer. When the C3 symmetry node monomer is a pyromellitic trimethylaldehyde monomer or a pyromellitic triamine monomer, an imine bond linkage reaction is carried out using a catalyst solution. The catalyst solution used at this time is acetic acid solution, trifluoroacetic acid solution, p-toluenesulfonic acid solution, or trifluoromethanesulfonate. When the C3 symmetry node monomer is an alkene-bonded monomer, an alkene bond linkage reaction is carried out using a catalyst solution. The catalyst solution used at this time is NaOH or KOH aqueous solution, cesium carbonate, 1,8-diazabicyclo[5.4.0]undec-7-ene, or piperidine catalyst. The structural formula of the pyromellitic trimethylaldehyde monomer is: R1, R2, and R3 are each independently selected from H, halogen, hydroxyl, substituted or unsubstituted C1-C5 alkyl, alkoxy, or ester groups; The structural formula of the pyromellitic triamine monomer is: ; R1, R2, and R3 are each independently selected from H, halogen, hydroxyl, substituted or unsubstituted C1-C5 alkyl, alkoxy, or ester groups; The structural formula of the olefinic monomer is: , , or ; R1, R2, and R3 are each independently selected from H, halogen, hydroxyl, substituted or unsubstituted C1-C5 alkyl, alkoxy, or ester groups.

5. The method for preparing an ion-imprinted covalent organic framework material according to claim 1, characterized in that, In S1, the planar six-coordinate metal imprinted ion is one or more of indium acetate, nitrate, sulfate, chloride and uranyl ion salts.

6. The method for preparing an ion-imprinted covalent organic framework material according to claim 1, characterized in that, The solvents used in S1 and S2 are ethanol / water mixtures, DMF / water mixtures, mesitylene / dioxane mixtures, or o-dichlorobenzene / n-butanol mixtures.

7. The method for preparing an ion-imprinted covalent organic framework material according to claim 1, characterized in that, In S2, the ratio of the C3 symmetric six-site coordination complex to the solvent is 10~50 mg: 1 mL; The ratio of the amount of C3 symmetric six-site coordination complex to the C3 symmetric node monomer is 1.5~2.5:

1.

8. The method for preparing an ion-imprinted covalent organic framework material according to claim 1, characterized in that, The amount of catalyst solution added is 1% to 15% of the total solvent volume in S1 and S2; In S2, the time for the second ultrasonic mixing is 1~10 min; The time for ultrasonication after adding the catalyst solution is 0.5~5 min; The reaction time is 1 to 7 days, and the reaction temperature is 50 to 150 ℃; In S3, the post-processing includes sequential washing and vacuum drying. In S4, the ratio of the metal covalent organic framework ion-imprinted COFs precursor to the sulfuric acid solution is 30 mg: 10~30 mL; The concentration of the sulfuric acid solution is 0.25~0.5 M; The post-processing includes sequential washing and drying.

9. An ion-imprinted covalent organic framework material, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 8.

10. The application of the ion-imprinted covalent organic framework material of claim 9 in the separation and enrichment of indium ions and uranyl ions and in the catalysis of supported cobalt, copper, nickel and silver ions.

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