A method for preparing a pyrazine monomer and its covalent organic framework material and its application.
Vinyl COFs were prepared by designing a condensation reaction between pyrazine monomers and aromatic dialdehydes, which solved the problem of insufficient types of vinyl COFs and achieved a highly efficient separation effect for C2H2/CO2 gas separation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-12
- Publication Date
- 2026-04-03
AI Technical Summary
The limited variety of vinyl covalent organic frameworks (COFs) in the current technology restricts their application in gas separation, especially in the efficiency of C2H2/CO2 separation.
Three monomers containing pyrazine groups, DPZ, TPZ and HMB, were designed and synthesized. They were condensed with aromatic dialdehydes to form vinyl covalent organic framework materials (COFs). The addition of N atoms by the pyrazine groups enhanced the host-guest interaction of C2H2/CO2.
It broadens the range of vinyl COFs and improves gas selectivity, especially in the separation of C2H2 and CO2 mixtures, showing good gas selectivity and stability.
Smart Images
Figure CN119350348B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of organic framework materials technology, specifically relating to a pyrazine monomer and its covalent organic framework material preparation method and application. Background Technology
[0002] Covalent organic frameworks (COFs) are a new class of porous crystalline polymers that can precisely integrate organic units into highly ordered network structures. Recently, sp... 2 -C-linked COFs (olefin-linked or vinyl-linked) have attracted much attention due to their π-electron conjugation structure and irreversibility. However, vinyl COFs have been less developed compared to other types of COFs (such as imine COFs). This is because the carbon-carbon double bonds in the skeleton are mainly prepared by the condensation reaction of methyl or methylene groups with aldehyde groups in the presence of specific catalysts, and the methods currently used to synthesize vinyl-linked COFs are very limited. Therefore, it is necessary to design more suitable monomers to enrich the variety of vinyl COFs.
[0003] COFs, with their high specific surface area, ordered structure, and tunable pore size, have attracted considerable research interest in the field of gas separation. By introducing nitrogen atoms into the structure, the host-guest interaction between C2H2 molecules and nitrogen atoms is increased, thereby achieving highly efficient separation of C2H2 / CO2. Summary of the Invention
[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a compound containing a pyrazine group, a covalent organic framework material, and a method for preparing the same. This invention designs three nitrogen-rich methyl monomers containing pyrazine groups: DPZ, TPZ, and HMB. These monomers can undergo condensation reactions with aromatic dialdehydes to form a series of vinyl covalent organic frameworks (COFs).
[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:
[0006] A pyrazinyl monomer, wherein the pyrazinyl monomer is one of DPZ, TPZ and HMB, has the following chemical structural formula:
[0007] , , .
[0008] The preparation method of DPZ is as follows: 1,2,4,5-phenyltetramine tetrahydrochloride is used as raw material, and reacted with 2,3-butanedione, sodium acetate and ethanol for 24 h. After filtration, the reaction product is washed with water and ethanol in sequence to obtain 2,3,7,8-tetramethylpyrazine[2,3-g]quinoxaline, which is DPZ; the molar ratio of the raw material to 2,3-butanedione and sodium acetate is 1:20:4.
[0009] The preparation method of TPZ monomer includes the following steps:
[0010] (1) Using 1,2,4,5-phenyltetramine tetrahydrochloride as raw material, sodium acetate was added and reacted in an air atmosphere to obtain the intermediate 2,3,7,8-phenazine tetraamine trihydrochloride;
[0011] (2) The intermediate 2,3,7,8-phenazine tetraamine trihydrochloride, 2,3-butanedione, sodium acetate and ethanol were reacted for 24 h, filtered, and the reaction product was washed with water and ethanol in sequence to obtain 2,3,9,10-tetramethylbispyrazine [2,3-b:2',3'i]phenazine, which is TPZ; the molar ratio of the intermediate to 2,3-butanedione and sodium acetate is 1:20:4.
[0012] The method for preparing HMB monomer is as follows: 2,3,6,7,10,11-hexaaminotriphenylhexahydrochloride is used as the starting material, and reacted with 2,3-butanedione, sodium acetate and ethanol for 24 h. After filtration, the reaction product is washed with water and ethanol sequentially to obtain 2,3,8,9,14,15-hexamethylbenzo[1,2-g:3,4-g':5,6g'']triquinoxaline, which is HMB; the molar ratio of the starting material to 2,3-butanedione and sodium acetate is 1:30:6.
[0013] A covalent organic framework material, wherein the covalent organic framework material is obtained by condensation of any of the above-mentioned pyrazinyl monomers with an aromatic dialdehyde.
[0014] Furthermore, the aromatic dialdehyde is terephthalaldehyde, and the molar ratio of the aldehyde group in the aromatic dialdehyde to the methyl group in the pyrazine monomer is 1:1.
[0015] Furthermore, the structure of the covalent organic framework material is as follows:
[0016]
[0017]
[0018] .
[0019] Furthermore, the specific surface area of the valence organic framework material is 532.6~1246.4 m². 2 / g.
[0020] The above-mentioned covalent organic framework material is used in gas adsorption and separation, wherein the gas is C2H2 and CO2.
[0021] The beneficial effects of this invention are as follows:
[0022] (1) The present invention can prepare three pyrazine monomers through simple experimental steps without further purification.
[0023] (2) All three monomers prepared can be used to obtain vinyl covalent organic frameworks by melt polycondensation, which broadens the types of vinyl covalent organic frameworks.
[0024] (3) The three vinyl COFs prepared have an abundant number of N sites and exhibit good gas selectivity for mixtures of acetylene (C2H2) and carbon dioxide (CO2). Attached Figure Description
[0025] Figure 1 For DPZ 1 H-NMR spectrum.
[0026] Figure 2 For TPZ 1 H-NMR spectrum.
[0027] Figure 3 For HMB 1 H-NMR spectrum.
[0028] Figure 4 This is a schematic diagram illustrating the synthesis of three COFs.
[0029] Figure 5 The diagram shows the topology of DPZ-COF, where gray represents C, blue represents N, and white represents H.
[0030] Figure 6 The diagram shows the topology of TPZ-COF, where gray represents C, blue represents N, and white represents H.
[0031] Figure 7 The diagram shows the topology of HMB-COF, where gray represents C, blue represents N, and white represents H.
[0032] Figure 8 Thermogravimetric analysis spectra of DPZ-COF, TPZ-COF, and HMB-COF under nitrogen atmosphere.
[0033] Figure 9 This is the BET plot for DPZ-COF.
[0034] Figure 10 This is the BET graph for TPZ-COF.
[0035] Figure 11 This is the BET graph for HMB-COF.
[0036] Figure 12 The image shows the gas adsorption curve of DPZ-COF.
[0037] Figure 13 The image shows the gas adsorption curve of TPZ-COF.
[0038] Figure 14 The image shows the gas adsorption curve of HMB-COF.
[0039] Figure 15 IAST gas selectivity curves for DPZ-COF, TPZ-COF, and HMB-COF. Detailed Implementation
[0040] To further disclose, and not limit, the present invention, the invention will be further described in detail below with reference to examples.
[0041] Example 1: Synthesis of DPZ
[0042] (1) Under nitrogen atmosphere, 1,2,4,5-phenyltetramine tetrahydrochloride (2.84 g, 10 mmol) was used as the starting material, and 2,3-butanedione (17 mL, 0.2 mol) and sodium acetate (3.3 g, 40 mmol) were refluxed in ethanol (250 mL) for 24 h. After cooling to room temperature, the mixture was filtered, and the reaction product was washed successively with water and ethanol to obtain 2,3,7,8-tetramethylpyrazine[2,3-g]quinoxaline (DPZ) in 46.2% yield. NMR data are as follows: 1 ¹H-NMR (500 M Hz, chloroform-d) δ (ppm): 2.84 (s, 12 H), 8.67 (s, 2 H).
[0043] The reaction equation is as follows:
[0044]
[0045] Example 2 Synthesis of TPZ
[0046] (1) Using 1,2,4,5-phenyltetramine tetrahydrochloride (0.642 g, 2.26 mmol) as the starting material, sodium acetate (2.6 g, 31.64 mmol) and water (30 mL) were added and refluxed under compressed air for 5 h. After cooling to room temperature, the mixture was filtered and the product was washed with water to obtain the intermediate product 2,3,7,8-phenazine tetraamine trihydrochloride with a yield of 40.5%.
[0047] (2) The intermediate 2,3,7,8-phenazine tetraamine trihydrochloride (0.314 g, 0.9 mmol) was refluxed in ethanol (30 mL) with 2,3-butanedione (1.57 mL, 18 mmol) and sodium acetate (0.295 g, 3.6 mmol) for 24 h. After cooling to room temperature, the mixture was filtered. The reaction product was washed successively with water and ethanol to obtain 2,3,9,10-tetramethylbispyrazine [2,3-b:2',3'i]phenazine (TPZ) in 98% yield. NMR data are as follows: 1 H-NMR (500 M Hz, TFA-d) δ (ppm): 2.98 (s, 12 H), 7.67 (s, 4 H).
[0048] The reaction equation is as follows:
[0049]
[0050] Example 3: Synthesis of HMB
[0051] (1) Under nitrogen atmosphere, 2,3,6,7,10,11-hexaaminotriphenylhexahydrochloride (0.537 g, 1 mmol) was refluxed with 2,3-butanedione (2.6 mL, 30 mmol) and sodium acetate (0.492 g, 6 mmol) in ethanol (60 mL) for 24 h. After cooling to room temperature, the mixture was filtered, and the product was washed with water and ethanol to obtain 2,3,8,9,14,15-hexamethylbenzo[1,2-g:3,4-g':5,6g'']triquinoxaline (HMB) in 96.7% yield. NMR data are as follows: 1 H-NMR (500 M Hz, TFA-d) delta (ppm): 3.34 (s, 18 H), 9.91 (s, 6 H).
[0052] The reaction equation is as follows:
[0053]
[0054] Example 4 Synthesis of DPZ-COF
[0055] DPZ (0.1 mmol, 23.8 mg), terephthalaldehyde (0.2 mmol, 26.8 mg), and benzoic anhydride (0.4 mmol, 90.5 mg) were added to a 5 mL Pyrex tube. The mixture was rapidly frozen at 77 K (using a liquid nitrogen bath) and then degassed by three freeze-evacuation-thawing cycles. It was then sealed under vacuum using a Schlenk line and oil pump. The tube containing the mixture was heated to 200 ˚C for 5 days. After cooling to room temperature, the precipitate was collected by filtration and washed successively with acetone and methanol. Soxhlet extraction with tetrahydrofuran was then performed for 24 hours, followed by vacuum drying at 60 ˚C overnight to give 45.2 mg of dark brown powder, with a yield of approximately 89%.
[0056] Example 5 Synthesis of TPZ-COF
[0057] TPZ (0.05 mmol, 17 mg), terephthalaldehyde (0.1 mmol, 13.4 mg), and benzoic anhydride (0.2 mmol, 45.2 mg) were added to a 5 mL Pyrex tube. The mixture was rapidly frozen at 77 K (using a liquid nitrogen bath) and then degassed by three freeze-evacuation-thawing cycles. The tube was then sealed under vacuum using a Schlenk line and oil pump. The Pyrex tube containing the mixture was heated to 180 ˚C for 5 days. After cooling to room temperature, the precipitate was collected by filtration, washed successively with acetone and methanol, and then Soxhlet extracted with tetrahydrofuran for 24 hours. The extract was dried under vacuum overnight at 60 ˚C to give 26 mg of a dark brown powder, with a yield of approximately 85%.
[0058] Example 6 Synthesis of HMB-COF
[0059] HMB (0.04 mmol, 18.7 mg), terephthalaldehyde (0.12 mmol, 16.1 mg), and benzoic anhydride (0.24 mmol, 54.3 mg) were added to a 5 mL Pyrex tube. The mixture was rapidly frozen at 77 K (using a liquid nitrogen bath) and then degassed by three freeze-evacuation-thawing cycles. Subsequently, the tube was sealed under vacuum using a Schlenk line and oil pump. The Pyrex tube containing the mixture was heated to 200 ˚C for 5 days. After cooling to room temperature, the precipitate was collected by filtration, washed successively with acetone and methanol, and then Soxhlet extracted with tetrahydrofuran for 24 hours. The extract was dried under vacuum overnight at 60 ˚C to give 32 mg of a deep red powder, with a yield of approximately 92%.
[0060] Figure 1-3 The three monomers DPZ, TPZ and HMB synthesized in Examples 1-3 are respectively. 1The H-NMR spectrum shows the successful synthesis of the three monomers.
[0061] Figure 4 The diagram shows the synthesis of the three COFs, DPZ-COF, TPZ-COF and HMB-COF, synthesized in Examples 4-6.
[0062] Figure 5-7 The topological structures of DPZ-COF, TPZ-COF and HMB-COF synthesized in Examples 4-6 are shown respectively. The results show that all three COFs are in AA stacking form.
[0063] Figure 8 Thermogravimetric curves of the three COFs synthesized in Examples 4-6 (DPZ-COF, TPZ-COF, and HMB-COF) are shown. The results indicate that all COFs maintain good stability at temperatures below 400 °C.
[0064] Figure 9-11 The nitrogen adsorption isotherms for the three COFs synthesized in Examples 4-6 (DPZ-COF, TPZ-COF, and HMB-COF) are shown. The results indicate that the prepared COFs possess a porous structure, with BET specific surface areas of 876.6 m². 2 / g,1246.4m 2 / g and 532.63 m 2 / g.
[0065] The three COFs synthesized in Examples 4-6—DPZ-COF, TPZ-COF, and HMB-COF—were used for the adsorption and separation of C2H2 and CO2 gases. Specifically, adsorption isotherms of C2H2 and CO2 were collected using a surface area ratio analyzer (BET). During the testing process, the dosage of DPZ-COF, TPZ-COF, and HMB-COF was 50 mg each.
[0066] Figure 12-14 The images show the adsorption isotherms of C2H2 and CO2 for the three COFs synthesized in Examples 4-6 (DPZ-COF, TPZ-COF, and HMB-COF) at room temperature (298 K). The results show that the adsorption capacity of the three COFs for C2H2 is significantly higher than that for CO2, which is beneficial for gas separation applications.
[0067] Figure 15The ideal adsorption solution theory (IAST) calculations for the three COFs synthesized in Examples 4-6 (DPZ-COF, TPZ-COF, and HMB-COF) at 298 K for a two-component C2H2 / CO2 (50% / 50%) are presented. All three COFs are rich in N sites, thus suitable for gas adsorption separation. Compared to DPZ-COF, the increased N atoms in the pores of TPZ-COF and HMB-COF contribute to improved IAST selectivity.
[0068] The above description is only a preferred embodiment of the present invention. All changes and modifications made within the scope of the patent application of the present invention are within the scope of the present invention.
Claims
1. A covalent organic framework material, characterized in that: The covalent organic framework material is obtained by condensation of a pyrazine monomer with an aromatic dialdehyde, wherein the molar ratio of the aldehyde group in the aromatic dialdehyde to the methyl group in the pyrazine monomer is 1:1; the pyrazine monomer is one of DPZ, TPZ, and HMB, and its chemical structural formula is as follows: ， ， ； The structure of the covalent organic framework material is as follows: ， ， 。 2. The covalent organic framework material according to claim 1, characterized in that: The aromatic dialdehyde is terephthalaldehyde.
3. The covalent organic framework material according to claim 1, characterized in that: The specific surface area of the covalent organic framework material is 532.6~1246.4 m². 2 / g.
4. The covalent organic framework material according to claim 1, characterized in that: The specific preparation method of pyrazine monomer DPZ is as follows: 1,2,4,5-phenyltetramine tetrahydrochloride is used as raw material and reacted with 2,3-butanedione, sodium acetate and ethanol for 24 h. After filtration, the reaction product is washed with water and ethanol in sequence to obtain 2,3,7,8-tetramethylpyrazine[2,3-g]quinoxaline, which is DPZ; the molar ratio of the raw material to 2,3-butanedione and sodium acetate is 1:20:
4.
5. The covalent organic framework material according to claim 1, characterized in that: The preparation method of pyrazine-based monomer TPZ monomer includes the following steps: (1) Using 1,2,4,5-phenyltetramine tetrahydrochloride as raw material, sodium acetate was added and reacted in an air atmosphere to obtain the intermediate 2,3,7,8-phenazine tetraamine trihydrochloride; (2) The intermediate 2,3,7,8-phenazine tetraamine trihydrochloride, 2,3-butanedione, sodium acetate and ethanol were reacted for 24 h, filtered, and the reaction product was washed with water and ethanol in sequence to obtain 2,3,9,10-tetramethylbispyrazine [2,3-b:2',3'i]phenazine, which is TPZ; the molar ratio of the intermediate to 2,3-butanedione and sodium acetate is 1:20:
4.
6. The covalent organic framework material according to claim 1, characterized in that: The specific preparation method of the pyrazinyl monomer HMB is as follows: 2,3,6,7,10,11-hexaaminotriphenylhexahydrochloride is used as the starting material and reacted with 2,3-butanedione, sodium acetate and ethanol for 24 h. After filtration, the reaction product is washed with water and ethanol in sequence to obtain 2,3,8,9,14,15-hexamethylbenzo[1,2-g:3,4-g':5,6g'']triquinoxaline, which is HMB; the molar ratio of the starting material to 2,3-butanedione and sodium acetate is 1:30:
6.
7. An application of the covalent organic framework material as described in claim 1 in gas adsorption and separation, characterized in that: The gases are C2H2 and CO2.