A method for preparing anionic metal-organic framework materials and their applications

Abstract

This invention provides a method for preparing anionic metal-organic framework materials and their applications. The method involves mixing anionic metal salts, organic ligands, and a solvent, and then reacting the mixture in a microwave environment at 60–150°C to obtain the anionic metal-organic framework material. This preparation method has wide applicability. Under microwave conditions, the high energy density of microwave irradiation rapidly generates heat within the solvent, overcoming the energy barrier for forming anionic metal-organic framework materials. It offers advantages such as rapid heating, high thermal energy utilization, homogeneity, and selectivity, overcoming the shortcomings of diffusion methods. It allows for the large-scale synthesis of anionic metal-organic framework materials with low solvent consumption, facilitating solvent recovery and reuse. This promotes the green preparation of anionic metal-organic framework materials and is of great significance for their widespread application.

Description

Technical Field

[0001] This invention belongs to the field of MOF material preparation technology, specifically relating to a method for preparing anionic metal-organic framework materials and their applications. Background Technology

[0002] Metal-organic frameworks (MOFs) are novel organic-inorganic hybrid crystalline porous materials that self-assemble from organic ligands and metal ions through coordination bonds. They possess advantages such as large specific surface area, tunable pore size, and customizability, showing excellent application prospects in hydrogen purification, hydrogen storage, methane storage, carbon dioxide capture, and light hydrocarbon separation. Ionic MOFs, as a special type of MOF material, have attracted widespread attention from researchers in recent years. Among them, anionic MOFs, by introducing anions into traditional MOF materials, significantly enhance the adsorption potential energy of gas molecules within the MOF channels, thereby significantly improving their separation performance for gases such as CO2, SO2, and CH4, exhibiting particular advantages in fields such as hydrogen purification.

[0003] Currently, various types of anionic metal-organic frameworks (MOFs) have been reported. However, most anionic MOFs are synthesized using diffusion methods, which have demanding synthesis conditions and require a long time to obtain even small quantities. Furthermore, diffusion methods consume large amounts of solvent, and often require mixed solvents, making solvent recovery difficult. These factors result in low synthesis efficiency and high production costs for anionic MOFs, hindering their widespread application. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a method for preparing anionic metal-organic framework materials and their applications. This method can synthesize anionic metal-organic framework materials in large quantities, consumes little solvent, facilitates solvent recovery and reuse, and is simple and easy to implement.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a method for preparing anionic metal-organic framework materials, comprising the following steps:

[0007] The anionic metal-organic framework material is obtained by mixing anionic metal salts, organic ligands, and solvents and reacting them in a microwave environment at 60–150 °C.

[0008] Preferably, the molar ratio of the organic ligand to the metal ion in the anion-containing metal salt is (0.5–2):1.

[0009] Preferably, the ratio of the organic ligand to the solvent is 1 mmol:(15-30) mL.

[0010] Preferably, the reaction temperature is 80–120°C and the reaction time is 10–120 min.

[0011] Preferably, the anion-containing metal salt includes a transition metal salt containing a fluorinated anion.

[0012] Preferably, the fluorinated anion is selected from any one or more of hexafluorosilicate ions, hexafluorotitanate ions, hexafluorogermanate ions, hexafluorozirconate ions, hexafluorophosphate ions, or hexafluoroaluminate ions.

[0013] Preferably, the transition metal salt is selected from any one or more of the transition metal nitrates, sulfates, hydrochlorides, or perchlorates.

[0014] Preferably, the organic ligand is selected from any one of pyrazine, 4,4-bipyridine, 2-ethynylpyridine, or 2-vinylpyridine.

[0015] Preferably, the solvent is selected from any one or more of methanol, ethanol, N,N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, acetonitrile, or water.

[0016] Secondly, the present invention provides an application of anionic metal-organic framework materials prepared according to the above preparation method in hydrogen purification, methane purification or carbon dioxide capture.

[0017] Thirdly, the present invention provides a carbon dioxide capture agent, comprising an anionic metal-organic framework material prepared according to the above preparation method.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] This invention provides a method for preparing anionic metal-organic frameworks (MOFs), which has wide applicability. Under microwave conditions, the high energy density of microwave irradiation rapidly generates heat within the solvent, overcoming the energy barrier for MOF formation. This method offers advantages such as rapid heating, high thermal energy utilization, homogeneity, and selectivity. It overcomes the shortcomings of diffusion methods, enabling large-scale synthesis of MOFs with low solvent consumption and easy solvent recovery and reuse. This significantly reduces the preparation cost of MOFs and decreases waste emissions, facilitating the green preparation of MOFs and promoting their widespread application. Furthermore, the method features rapid reaction time, allowing for the rapid preparation of the target product, and the resulting anionic MOFs exhibit excellent gas adsorption and separation properties. Attached Figure Description

[0020] Figure 1 This is a schematic diagram illustrating the synthesis of the anionic metal-organic framework material obtained in Example 1;

[0021] Figure 2 The XRD patterns of the anionic metal-organic framework materials prepared in Examples 1 and 2 are shown below.

[0022] Figure 3 SEM image of the anionic metal-organic framework material obtained in Example 1;

[0023] Figure 4 The image shows the adsorption isotherms of the anionic metal-organic framework material obtained in Example 1 at 298K for single gases CO2, CH4, and H2.

[0024] Figure 5 The diagram shows the separation and breakthrough curves of the anionic metal-organic framework material obtained in Example 1 for the mixed gas CO2 / H2.

[0025] Figure 6 The XRD pattern of the anionic metal-organic framework material prepared in Comparative Example 1 is shown.

[0026] Figure 7 The XRD pattern of the anionic metal-organic framework material prepared in Comparative Example 2 is shown below.

[0027] Figure 8 The XRD pattern of the anionic metal-organic framework material prepared in Comparative Example 3 is shown below.

[0028] Figure 9 The image shows the XRD pattern of the anionic metal-organic framework material prepared in Comparative Example 4. Detailed Implementation

[0029] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0030] To address the problems of low synthesis efficiency, high preparation cost, and time-consuming and labor-intensive processes associated with the traditional diffusion method for preparing anionic metal-organic framework materials, this invention provides a method for preparing anionic metal-organic framework materials, comprising the following steps:

[0031] The anionic metal-organic framework material is obtained by mixing anionic metal salts, organic ligands, and solvents and reacting them in a microwave environment at 60–150 °C.

[0032] According to the present invention, the anionic metal-organic framework material is obtained by mixing an anionic metal salt, an organic ligand, and a solvent and reacting the mixture under microwave conditions at 60–150°C. In some embodiments of the present invention, the anionic metal salt can be a transition metal salt with a fluorinated anion, wherein the fluorinated anion is selected from hexafluorosilicate (SiF6). 2- ) ions, hexafluorotitanate (TiF6) 2- ) ions, hexafluorogermanate (GeF6) 2- ) ions, zirconate hexafluorozirconate (ZrF6) 2- ) ions, hexafluorophosphate (PF6) 2- ) ions or hexafluoroaluminate (AlF6) 2- The transition metal salt is selected from any one or more of the following ions: Cu. 2+ Co 2+ Ni 2+ Zn 2+ or Fe 2+The metal salt contains any one or more of the following transition metal ions: nitrate, sulfate, hydrochloride, or perchlorate. In some other embodiments of the invention, the anion-containing metal salt can also be obtained by reacting a salt containing a fluorinated anion with a transition metal salt, or by reacting an acid containing a fluorinated anion with an oxide of a transition metal. The fluorinated anion salt is an alkali metal salt and / or ammonium salt containing the aforementioned fluorinated anions, specifically selected from sodium hexafluorosilicate (NaSiF6), ammonium hexafluorosilicate (NH4SiF6), ammonium hexafluorogermanate (NH4GeF6), sodium hexafluorotitanate (NaTiF6), ammonium hexafluorotitanate (NH4SiF6), or ammonium hexafluorozirconate (NH4ZrF6), etc. The transition metal salt is as described in the above technical solutions and will not be repeated here. The acid containing the fluorinated anion and the oxide of the transition metal can be selected according to what is well known to those skilled in the art.

[0033] In some embodiments of the present invention, the organic ligand is a nitrogen-containing heterocyclic ligand, specifically selected from one or more of pyrazine, 4,4-bipyridine, 2-ethynylpyridine, or 2-vinylpyridine. The solvent is selected from one or more of polar organic solvents such as methanol (MeOH), ethanol (EtOH), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMF), acetonitrile (CH3CN), or water, preferably methanol, ethanol, DMF, or water. The mass ratio of the organic ligand to the metal ion in the anion-containing metal salt is a factor in the synthesis of ionic metal-organic framework materials. Too much or too little organic ligand may result in failure to obtain the target product, or may lead to the formation of products with other structures. Therefore, through continuous experimental exploration, this application has determined the molar ratio of the organic ligand to the metal ion in the anionic metal salt to be (0.5–2):1. This (0.5–2):1 can be 0.5:1, 0.75:1, 1:1, 1.25:1, 1.5:1, 1.75:1, or 2:1, etc. Other values ​​within the above range are also acceptable and will not be elaborated upon here. The present invention prefers (0.75–1.25):1. In some embodiments of the present invention, preferably, the anionic metal salt, organic ligand, and solvent are mixed according to the above molar ratio of organic ligand to metal ion and then loaded into a polytetrafluoroethylene reaction vessel. The mixture is stirred evenly, and then the reaction vessel is sealed and placed in a microwave reactor, reacting at 60–150°C for 10–120 min. The 60–150°C range can be selected from 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, or 120°C, etc. The 10–120 min range can be selected from 10 min, 15 min, 20 min, 25 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, or 120 min, etc. Other values ​​within the above ranges are also acceptable and will not be elaborated upon here. Preferably, the reaction is carried out at 80–120°C for 10–120 min, more preferably at 80–120°C for 10–30 min.

[0034] In some embodiments of the present invention, after the microwave reaction is completed, post-processing operations such as filtration, washing, and drying are preferably included to ensure that the product is a pure phase substance free of salt or water. The filtration can be performed using techniques well known to those skilled in the art, without any particular limitation; however, a cloth filter is preferred in this invention. The washing reagent can be any one or more of organic solvents such as methanol (MeOH), ethanol (EtOH), N,N-dimethylformamide (DMF), tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMF), acetonitrile (CH3CN), or water. The drying is preferably carried out at 60–120°C for 1–3 hours. In some embodiments of the present invention, drying at 60–70°C for 1–2 hours is preferred.

[0035] This invention provides a method for preparing the above-mentioned anionic metal-organic framework materials, which has wide applicability. Under microwave conditions, the high energy density of microwave irradiation is used to rapidly generate heat inside the solvent to overcome the energy barrier for forming anionic metal-organic framework materials. It has the advantages of rapid heating, homogeneity and selectivity. Compared with the traditional direct solvothermal method and diffusion method, the microwave-assisted solvothermal method has the following advantages: (1) Fast heating speed. Since microwaves can penetrate into the interior of the material, rather than relying on the heat conduction of the material itself, the entire heating process can be completed in only one-tenth to one-hundredth of the time of conventional methods; (2) High thermal energy utilization rate, saving energy and pollution-free. Therefore, this invention uses the microwave-assisted solvothermal method to synthesize anionic metal-organic framework materials, which can achieve the purpose of shortening the reaction time, increasing the synthesis rate, reducing the reaction energy consumption and saving the reaction cost. It is a high-efficiency, low-cost and green method for synthesizing anionic metal-organic framework materials, providing an effective way for the promotion and application of anionic metal-organic framework materials.

[0036] This invention also provides an anionic metal-organic framework obtained according to the above preparation method. XRD and SEM characterization revealed that the above preparation method can produce corresponding anionic metal-organic framework materials with excellent crystallinity, suitable for applications in hydrogen purification, methane purification, or carbon dioxide capture. The anionic metal-organic framework material prepared by the above method was tested for single-gas adsorption performance. The study found that the material exhibits extremely high adsorption performance for carbon dioxide at room temperature, and as the pressure continues to rise, the adsorption isotherm for carbon dioxide shows a unique step-shaped isotherm, while the adsorption capacity for methane and hydrogen is relatively low. Adsorption tests of the material on mixed gases CO2 and H2 showed that the material exhibits excellent separation ability for CO2 / H2, indicating that it can effectively achieve CO2 / H2 separation. Therefore, the anionic metal-organic framework material can be used as a carbon dioxide capture agent.

[0037] To further illustrate the present invention, the following embodiments provide a detailed description. The experimental materials used in the following embodiments of the present invention can be purchased commercially or prepared using conventional techniques well-known to those skilled in the art.

[0038] Example 1

[0039] This embodiment provides an anionic metal-organic framework material, and the synthesis schematic diagram is shown below. Figure 1 As shown, the preparation method is as follows:

[0040] 288.3 mg (3.6 mmol) of pyrazine and 1281.6 mg (3.6 mmol) of copper fluorotantalate were weighed and placed in a microwave hydrothermal reactor, and 72 mL of methanol was added. The microwave reactor was sealed and placed in a microwave reactor. The reaction was carried out at 85 °C for 20 min. The mixture was filtered using a Buchner funnel, washed with 5 mL of methanol, and dried at 70 °C for 1 h to obtain the anionic metal-organic framework material TaOFFIVE-1-Cu.

[0041] Example 2

[0042] This embodiment provides an anionic metal-organic framework material, and the preparation method is as follows:

[0043] 288.3 mg (3.6 mmol) of pyrazine and 964.8 mg (3.6 mmol) of copper fluoroniobate were weighed and placed in a microwave reactor, along with 72 mL of methanol. The microwave reactor was sealed and placed in a microwave reactor. The reaction was carried out at 85 °C for 20 min. The mixture was filtered using a Buchner funnel, washed with 5 mL of methanol, and dried at 60 °C for 2 h to obtain the ionic metal-organic framework material NbOFFIVE-1-Cu.

[0044] The XRD patterns of the anionic metal-organic framework materials obtained in Examples 1 and 2 are shown below. Figure 2 As shown, the spectra of TaOFFIVE-1-Cu and NbOFFIVE-1-Cu have corresponding characteristic peaks, which are: 11.2 degrees (001), 12.8 degrees (100), 22.5 degrees (002), 25.7 degrees (200), 28.1 degrees (201), and 40.7 degrees (301), indicating that TaOFFIVE-1-Cu and NbOFFIVE-1-Cu were synthesized.

[0045] Scanning electron microscopy (SEM) was performed on the TaOFFIVE-1-Cu obtained in Example 1, and the resulting SEM image is shown below. Figure 3 As shown, the obtained TaOFFIVE-1-Cu has a distinct cuboid crystal morphology and excellent crystallinity.

[0046] Performance testing

[0047] The CO2 adsorption performance of TaOFFIVE-1-Cu obtained in Example 1 was tested, including the following steps:

[0048] First, the TaOFFIVE-1-Cu powder sample was activated under vacuum at a temperature of 80℃ for 12 hours. After the sample was fully activated, its performance was tested. The adsorption performance of the sample for CO2, CH4, and H2 was tested at different temperatures and under a pressure range of 0–1 bar.

[0049] Test results are as follows Figure 4 As shown, Figure 4 The image shows the adsorption isotherms of TaOFFIVE-1-Cu for CO2, CH4, and H2 at 298 K. It can be seen that TaOFFIVE-1-Cu exhibits extremely high adsorption performance for carbon dioxide at room temperature, and the adsorption isotherm for carbon dioxide shows a unique step-shaped pattern as the pressure continues to increase. At 298 K and 0.15 bar, its adsorption capacity reaches 40 cm⁻¹. 3 The adsorption capacity of this MOF material is higher than that of other types of MOF, carbon, and molecular sieve materials reported to date. However, its adsorption capacity for methane and hydrogen is lower than that for carbon dioxide. The carbon dioxide / hydrogen adsorption selectivity calculated based on ideal solution adsorption theory reaches 1000–5000. This selectivity is higher than that of other types of MOF, carbon, and molecular sieve materials reported to date, placing it among the top performers.

[0050] The TaOFFIVE-1-Cu obtained in Example 1 was used to test its performance in separating CO2 and H2. The test included the following steps:

[0051] First, the TaOFFIVE-1-Cu powder sample was activated under vacuum at a temperature of 80℃ for 12 hours. After complete activation, the sample was tested for performance. The separation performance of the sample for mixed gases CO2 and H2 was tested at 25℃ and a pressure range of 1 bar.

[0052] Test results are as follows Figure 5 As shown in the breakthrough curves of the TaOFFIVE-1-Cu sample for CO2 and H2 at 25℃ and 1 bar, it can be seen that the material exhibits excellent separation ability for CO2 / H2, indicating that it can effectively separate CO2 / H2.

[0053] In summary, it can be seen that the preparation method provided by the present invention can accurately synthesize anionic metal-organic framework materials with good crystallinity. The prepared anionic metal-organic framework materials exhibit excellent adsorption performance for CO2 and separation performance for mixed gases CO2 / H2.

[0054] Example 3

[0055] This embodiment provides an anionic metal-organic framework material, and the preparation method is as follows:

[0056] Weigh out 288.3 mg (3.6 mmol) of pyrazine, 418.7 mg (1.8 mmol) of copper nitrate pentahydrate, and 320.7 mg (1.8 mmol) of ammonium hexafluorosilicate, and dissolve them in 72 mL of methanol. Seal the microwave reactor and place it in the microwave reactor. React at 85 °C for 15 min. Filter using a Buchner funnel, wash the sample with 5 mL of methanol, and dry at 70 °C for 1 h to obtain the ionic metal-organic framework material SiFSIX-3-Cu.

[0057] Example 4

[0058] This embodiment provides an anionic metal-organic framework material, and the preparation method is as follows:

[0059] Weigh out 562.2 mg (3.6 mmol) of 4,4-bipyridine, 418.7 mg (1.8 mmol) of copper nitrate pentahydrate, and 320.7 mg (1.8 mmol) of ammonium hexafluorosilicate, dissolve them in 72 mL of methanol, and add 72 mL of methanol. Seal the microwave reactor and place it in the microwave reactor. React at 85 °C for 15 min. Filter using a Buchner funnel, wash the sample with 5 mL of methanol, and dry at 70 °C for 1 h to obtain the ionic metal-organic framework material SiFSIX-3-Cu.

[0060] Example 5

[0061] This embodiment provides an anionic metal-organic framework material, and the preparation method is as follows:

[0062] 288.3 mg (3.6 mmol) of pyrazine and 967.5 mg (3.6 mmol) of copper fluorozirconate were weighed and placed in a microwave reactor, and 72 mL of methanol was added. The microwave reactor was sealed and placed in a microwave reactor. The reaction was carried out at 85 °C for 10 min. The mixture was filtered using a Buchner funnel, washed with 5 mL of methanol, and dried at 60 °C for 2 h to obtain the ionic metal-organic framework material ZrFFIVE-1-Cu.

[0063] Example 6

[0064] This embodiment provides an anionic metal-organic framework material, and the preparation method is as follows:

[0065] 288.3 mg (3.6 mmol) of pyrazine and 2563.2 mg (7.2 mmol) of copper fluorotantalate were weighed and placed in a microwave hydrothermal reactor, and 72 mL of methanol was added. The microwave reactor was sealed and placed in a microwave reactor. The reaction was carried out at 85 °C for 15 min. The mixture was filtered using a Buchner funnel, washed with 5 mL of methanol, and dried at 70 °C for 1 h to obtain the ionic metal-organic framework material TaOFFIVE-1-Cu.

[0066] Example 7

[0067] This embodiment provides an anionic metal-organic framework material, and the preparation method is as follows:

[0068] 288.3 mg (3.6 mmol) of pyrazine and 1281.6 mg (3.6 mmol) of copper fluorotantalate were weighed and placed in a microwave hydrothermal reactor, and 72 mL of methanol was added. The microwave reactor was sealed and placed in a microwave reactor. The reaction was carried out at 120 °C for 15 min. The mixture was filtered using a Buchner funnel, washed with 5 mL of methanol, and dried at 70 °C for 1 h to obtain the ionic metal-organic framework material TaOFFIVE-1-Cu.

[0069] Comparative Example 1

[0070] This comparative example provides an anionic metal-organic framework material, prepared by the following method:

[0071] 288.3 mg (3.6 mmol) of pyrazine and 967.5 mg (3.6 mmol) of copper fluorozirconate were weighed and placed in a hydrothermal reactor, and 72 mL of methanol was added. The hydrothermal reactor was sealed and placed in an oven at 85 °C for 24 h. The mixture was filtered using a Buchner funnel, washed with 5 mL of methanol, and dried at 60 °C for 2 h, yielding a blue and white powder, indicating that the powder was not a pure phase substance. Its XRD pattern is shown below. Figure 6 As shown, the diffraction pattern of the powder is broad and lacks the characteristic peaks of the corresponding ionic metal-organic framework material, indicating that the corresponding ionic metal-organic framework material ZrFFIVE-1-Cu cannot be obtained by hydrothermal method.

[0072] Comparative Example 2

[0073] This comparative example provides an anionic metal-organic framework material, prepared by a diffusion method, as detailed below:

[0074] Weigh 1281.6 mg (3.6 mmol) of copper fluorotantalate and dissolve it in 10 mL of water. Weigh 288.3 mg (3.6 mmol) of pyrazine and dissolve it in 10 mL of methanol. Add 1 mL of the copper fluorotantalate / water solution to a test tube, and slowly add 1 mL of the pyrazine / methanol solution along the wall of the test tube using a dropper while the tube is standing. Place the test tube at room temperature for 7 days; a blue powder will appear in the test tube. Filter the powder, wash the sample with 5 mL of methanol, and dry it at 70 °C for 1 h to obtain the blue powder. Its XRD pattern is shown below. Figure 7 As shown, the sample does not have the characteristic peaks of the corresponding ionic metal-organic framework material, indicating that the corresponding ionic metal-organic framework material TaOFFIVE-1-Cu cannot be obtained under these conditions.

[0075] Comparative Example 3

[0076] This comparative example provides an anionic metal-organic framework material, prepared by the following method:

[0077] 288.3 mg (3.6 mmol) of pyrazine and 1281.6 mg (3.6 mmol) of copper fluorotantalate were weighed and placed in a microwave hydrothermal reactor, along with 72 mL of methanol. The reactor was sealed and placed in a microwave reactor. The reaction was carried out at 50 °C for 15 min. The sample was filtered using a Buchner funnel, washed with 5 mL of methanol, and dried at 70 °C for 1 h to obtain a light blue powder. Its XRD pattern is shown below. Figure 8 As shown, the diffraction pattern of the powder is broad and lacks the characteristic peaks of the corresponding ionic metal-organic framework material, indicating that the corresponding ionic metal-organic framework material TaOFFIVE-1-Cu cannot be obtained under these conditions.

[0078] Comparative Example 4

[0079] This comparative example provides an anionic metal-organic framework material, prepared by the following method:

[0080] 288.3 mg (3.6 mmol) of pyrazine and 1281.6 mg (3.6 mmol) of copper fluorotantalate were weighed and placed in a microwave hydrothermal reactor, along with 72 mL of methanol. The reactor was sealed and placed in a microwave reactor. The reaction was carried out at 180 °C for 15 min. The sample was filtered using a Buchner funnel, washed with 5 mL of methanol, and dried at 70 °C for 1 h to obtain a black powder. Its XRD pattern is shown below. Figure 9 As shown, the sample does not have the characteristic peaks of the corresponding ionic metal-organic framework material, indicating that the corresponding ionic metal-organic framework material TaOFFIVE-1-Cu cannot be obtained under these conditions.

[0081] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing anionic metal-organic framework materials, characterized in that, Includes the following steps: The anionic metal-organic framework material is obtained by mixing a transition metal salt containing a fluorinated anion, an organic ligand, and a solvent and reacting the mixture in a microwave environment at 80-120°C for 10-30 min. The organic ligand is a nitrogen heterocyclic ligand; The molar ratio of the organic ligand to the metal ion in the transition metal salt containing the fluorinated anion is (0.5~2):

1.

2. The preparation method according to claim 1, characterized in that, The ratio of the organic ligand to the solvent is 1 mmol:(15~30) mL.

3. The preparation method according to claim 1, characterized in that, The fluorinated anion is selected from any one or more of hexafluorosilicate ion, hexafluorotitanate ion, hexafluorogermanate ion, hexafluorozirconate ion, hexafluorophosphate ion, or hexafluoroaluminate ion. The transition metal salt is selected from any one or more of the transition metal nitrates, sulfates, hydrochlorides, or perchlorates.

4. The preparation method according to claim 1, characterized in that, The organic ligand is selected from any one of pyrazine, 4,4-bipyridine, 2-ethynylpyridine, or 2-vinylpyridine.

5. The preparation method according to claim 1, characterized in that, The solvent is selected from any one or more of methanol, ethanol, N,N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, acetonitrile, or water.

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