Uranium-based metal organic framework material and preparation method and application thereof

Abstract

The invention discloses a uranium-based metal organic framework material and a preparation method and application thereof, the chemical formula of the uranium-based metal organic framework material is [(UO2 < 2 + >) (H2L2-). H2O] n, [(UO2 < 2 + >) 3 (HL3-) 2 (H2O) 3. 3H2O] n or [(UO2 < 2 + >) (H2L2-). 2H2O] n, n is an integer greater than 0, and L is aromatic tetracarboxylic acid. A series of uranium-based MOF materials are synthesized by adopting a solvothermal method, the X-ray stability of the MOF structure is remarkably improved by adopting a strategy of preparing the luminous uranium-based MOF material by adopting a carboxylic acid aromatic ligand with increased flexibility, and the prepared uranium-based MOF material is diversified in structure, stable in property, excellent in performance, wide in application range and suitable for industrial production. And the uranium-based MOF material is applied to the field of imaging for the first time.

Description

Technical Field

[0001] The present invention relates to the technical field of metal organic framework materials, and in particular to a uranium-based metal organic framework material and a preparation method and application thereof. Background Art

[0002] X-ray imaging technology has shown its wide application value in many fields due to its excellent penetrating ability. In medical diagnosis, X-ray imaging, as a key diagnostic tool, is of great significance for the early detection and treatment of diseases. In the field of daily life, various security inspection equipment also widely uses X-ray imaging technology to detect prohibited items and ensure public safety. In the industrial field, especially in the aviation, automotive, electronics and other industries, X-ray imaging, as an important means of non-destructive testing (NDT), can detect defects and cracks inside materials, which is crucial to ensure product quality and safety. In addition, X-ray imaging also plays an important role in radiation detection and scientific research, providing strong support for the observation and analysis of the microstructure of samples.

[0003] However, the effect of X-ray imaging technology depends largely on the imaging materials used. At present, a variety of materials have been developed for X-ray imaging, such as inorganic scintillator materials and organic scintillator materials. Inorganic scintillator materials, such as CsI:Tl (cesium iodide doped with thallium), NaI:Tl (sodium iodide doped with thallium), Bi4Ge3O 12 (BGO), LaBr3:Ce (lanthanum bromide doped cerium), etc., although they have advantages such as high light output, fast response time and high density, they are easy to deliquesce, have poor stability and need to be replaced frequently, which not only causes a lot of resource waste and cost increase, but also creates additional pressure on the environment. In contrast, organic scintillator materials, such as plastic scintillators polystyrene and polyethylene, liquid scintillators aromatic compound solutions, and crystalline organic scintillators anthracene and phenanthrene, have good stability, but their preparation process is complicated, and due to the lack of heavy atoms to deposit radiation, the performance improvement is limited and the energy utilization rate is not high.

[0004] In order to overcome the shortcomings of the above materials, organic-inorganic hybrid materials, such as metal-organic frameworks (MOFs) and perovskite materials, have attracted much attention in recent years because they combine the advantages of inorganic and organic materials and avoid the disadvantages of both to a certain extent. Among them, perovskite materials have excellent photoelectric properties and adjustable band gaps, which can achieve efficient conversion of X-rays to photons. Metal-organic frameworks (MOFs) can precisely control the pore size, performance and surface properties of the material by combining inorganic metal ions and organic ligands, thereby optimizing its absorption of X-rays and energy transfer efficiency, showing good application prospects for X-ray imaging.

[0005] MOF materials usually contain heavy elements to improve the absorption efficiency of X-rays. For example, lead-based MOF materials use heavy metal inorganic units with high X-ray attenuation efficiency as X-ray absorption functional units to transfer energy to luminescent ligands, allowing the material to exhibit good performance. Metal cluster-based MOF materials use high-density metal clusters to improve X-ray deposition capabilities, and then use luminescent ligands to improve the luminescence performance of MOF materials. In addition, the luminescence properties of metal elements themselves can also be used. For example, metal elements such as lanthanides emit light due to their large atomic number and antenna effect, and are also used in MOF materials.

[0006] However, although uranium has a larger atomic number, a stronger ability to deposit radiation, and intrinsic fluorescence, making it a promising X-ray imaging material, it is limited by the radiation stability of X-rays, and there is no case of uranium-based MOF materials being successfully applied in the field of imaging. In addition, existing X-ray imaging materials have problems such as low X-ray utilization efficiency, poor stability, and complex preparation, while some uranium-based MOF materials cannot be successfully applied in the field of imaging due to insufficient radiation stability or poor fluorescence performance.

[0007] Therefore, developing a uranium-based MOF material that has both excellent X-ray absorption and energy conversion efficiency and good radiation stability is of great significance for promoting the development of X-ray imaging technology. Summary of the invention

[0008] In order to solve the above technical problems, the present invention provides a uranium-based metal organic framework material and a preparation method and application thereof.

[0009] The present invention is achieved through the following technical solutions:

[0010] The first aspect of the present invention provides a uranium-based metal organic framework material, the chemical formula of the uranium-based metal organic framework material is [(UO2 2+ )(H2L 2- )·H2O] n 、[(UO2 2+ )3(HL 3- )2(H2O)3·3H2O] n or [(UO2 2+ )(H2L 2- )·2H2O] n , wherein n is an integer greater than 0, and L is an organic ligand having the following structure:

[0011]

[0012] Furthermore, uranium-based metal-organic framework materials [(UO2 2+ )(H2L 2- )·H2O]n The chemical formula can also be (C 14 H 10 N2O 11 U) n .

[0013] Furthermore, uranium-based metal-organic framework materials [(UO2 2+ )3(HL 3- )2(H2O)3·3H2O] n The chemical formula can also be (C 28 H 34 N4O 32 U3) n .

[0014] Furthermore, uranium-based metal-organic framework materials [(UO2 2+ )(H2L 2- )·2H2O] n The chemical formula can also be (C 14 H 12 N2O 12 U) n .

[0015] The second aspect of the present invention provides a method for preparing a uranium-based metal organic framework material, comprising the following steps:

[0016] At 80-140° C., aromatic tetracarboxylic acid and uranyl nitrate are dissolved in a mixed solvent of an organic solvent and water, and after adding nitric acid, a coordination reaction occurs to obtain the uranium-based metal organic framework material; the organic solvent is selected from one of acetonitrile, N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), N-methylpyrrolidone (NMP) and N,N-diethylformamide (DEF).

[0017] The present invention adopts a solvent-thermal method to synthesize a series of uranium-based MOF materials, and the prepared uranium-based MOF materials have diverse structures, stable properties, excellent performance, and a wide range of applications. The preparation method provided by the present invention is simple and easy to implement, the conditions are relatively mild, the requirements for equipment are low, the requirements for experimental operation accuracy and substrate purity are not high, the operation is simple, and the waste of manpower and material resources can be effectively avoided.

[0018] The present invention adopts a strategy of preparing luminescent uranium-based MOF materials by increasing the flexibility of carboxylic acid aromatic ligands, which significantly improves the X-ray stability of the MOF structure, allowing it to be more widely used in the field of imaging. The synthesized new uranium-based MOF material can not only effectively detect low-dose X-rays, but also exhibits excellent X-ray imaging effects, thus opening up a new application direction for uranium-based MOF materials and greatly expanding their potential application value.

[0019] Furthermore, the aromatic tetracarboxylic acid is an organic ligand, which may be 1-(3,5-dicarboxybenzyl)-1H-pyrazole-3,5-dicarboxylic acid, having the structural formula

[0020] Furthermore, the molar ratio of the aromatic tetracarboxylic acid to uranyl nitrate is (0.5-2):1.

[0021] Furthermore, the volume ratio of the organic solvent to water is (0.5-5):(1.5-6).

[0022] Furthermore, the amount of nitric acid added is 1-14 drops, and one drop is 0.02-0.05 mL.

[0023] Furthermore, the volume ratio of the organic solvent to nitric acid is (0.5-5):(0.02-0.7).

[0024] Furthermore, the coordination reaction takes 2-14 days.

[0025] Further, at 100-140° C., aromatic tetracarboxylic acid (L) and uranyl nitrate are dissolved in a mixed solvent of an organic solvent and water, and after adding nitric acid, the volume ratio of the organic solvent, water and nitric acid is (3-5):(1.5-3):(0.14-0.7), and after the coordination reaction occurs for 2-7 days, the uranium-based metal organic framework material [(UO2 2+ )(H2L 2- )·H2O] n .

[0026] In a specific embodiment, 0.03-0.1mmol of aromatic tetracarboxylic acid (L) and 0.03-0.1mmol of uranyl nitrate are dissolved in a mixed solvent of 3-5mL of an organic solvent and 1.5-3mL of water, 7-14 drops of nitric acid are added, and then heated at 100-140°C for 1-3 days, cooled for 5-10 minutes, and then heated at 100-140°C for 1-4 days to obtain the uranium-based metal organic framework material [(UO2 2 + )(H2L 2- )·H2O] n .

[0027] Further, at 80-110° C., the aromatic tetracarboxylic acid (L) and uranyl nitrate are dissolved in a mixed solvent of an organic solvent and water, and after adding nitric acid, the volume ratio of the organic solvent, water and nitric acid is (0.5-2):(3-6):(0.02-0.1), and after the coordination reaction occurs for 4-10 days, the uranium-based metal organic framework material [(UO2 2+ )3(HL 3- )2(H2O)3·3H2O] n.

[0028] In a specific embodiment, 0.03-0.1mmol of aromatic tetracarboxylic acid (L) and 0.03-0.1mmol of uranyl nitrate are dissolved in a mixed solvent of 0.5-2mL of an organic solvent and 3-6mL of water, 1-2 drops of nitric acid are added, and the mixture is heated at 80-110°C for 1-3 days, cooled for 15-20 minutes, and then heated at 80-110°C for 3-6 days to obtain the uranium-based metal organic framework material [(UO2 2+ )3(HL 3- )2(H2O)3·3H2O] n .

[0029] Further, at 80-100° C., aromatic tetracarboxylic acid (L) and uranyl nitrate are dissolved in a mixed solvent of an organic solvent and water, and after adding nitric acid, the volume ratio of the organic solvent, water and nitric acid is (0.5-2):(3-6):(0.12-0.4), and after the coordination reaction occurs for 7-14 days, the uranium-based metal organic framework material [(UO2 2+ )(H2L 2- )·2H2O] n .

[0030] In a specific embodiment, 0.03-0.1mmol of aromatic tetracarboxylic acid (L) and 0.03-0.1mmol of uranyl nitrate are dissolved in a mixed solvent of 0.5-2mL of an organic solvent and 3-6mL of water, 6-8 drops of nitric acid are added, and the mixture is heated at 80-100°C for 1-3 days, cooled for 15-20 minutes, and then heated at 80-110°C for 3-6 days. After cooling for 1-1.5 hours, the mixture is further heated at 80-110°C for 3-5 days to obtain the uranium-based metal organic framework material [(UO2 2+ )(H2L 2- )·2H2O] n .

[0031] In a specific embodiment, the preparation method comprises the following steps:

[0032] Aromatic tetracarboxylic acid and uranyl nitrate are placed in a container, a mixed solvent of an organic solvent and water is added to the container, and then nitric acid is added. The container is then placed in an oven and heated at 80-140° C. for a period of time. After cooling at room temperature, the container is heated in an oven at 80-140° C. again to obtain the uranium-based metal organic framework material.

[0033] Furthermore, after the heating is completed, the steps of washing with an organic solvent and drying are also included.

[0034] Specifically, aromatic tetracarboxylic acid and uranyl nitrate are placed in a container, a mixed solvent of acetonitrile and water is added to the container, and then nitric acid is added, and the mixture is covered after mixing; the container is placed in an oven, heated at 80-140°C for a certain time, cooled at room temperature for a certain time, and then placed in an oven at 80-140°C for a certain time, and then washed with acetonitrile and naturally dried to obtain the uranium-based metal organic framework material.

[0035] The third aspect of the present invention provides the use of the uranium-based metal organic framework material described in the first aspect or the uranium-based metal organic framework material prepared by the method described in the second aspect in the field of X-ray imaging.

[0036] Under low-dose rate X-ray irradiation exceeding 325 μGy / s, the uranium-based metal organic framework material provided by the present invention can emit green fluorescence (qualitative detection), and the luminescence intensity is proportional to the ray dose rate (quantitative detection).

[0037] The present invention improves the radiation stability of uranium-based MOF materials in X-ray imaging. The present invention provides several uranium-based MOF materials that can emit light under X-ray excitation and can still maintain high initial performance after long-term high-dose rate X-ray irradiation, thereby overcoming the shortcomings of previous uranium-based MOF scintillating materials in radiation stability. This improved radiation stability makes it possible to use uranium-based MOF materials in X-ray imaging, and provides new material selection and research directions for the application exploration of uranium-based MOF materials and the utilization of depleted uranium resources.

[0038] Beneficial effects of the present invention:

[0039] The present invention not only significantly enhances the diversity of the structure by adopting a flexible design of the ligand, but also successfully synthesizes a series of uranium-based MOF materials with unique properties, while effectively retaining the original fluorescence properties of uranyl. In addition, the design also greatly improves the X-ray stability of the material, so that the prepared membrane material has the ability to be reused multiple times while retaining excellent imaging performance, thereby greatly expanding the utilization of depleted uranium in nuclear waste. The present invention not only provides a design method for a new type of uranium-based MOF material, but also provides new application prospects for uranium-based MOF materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Uranium-based metal organic framework materials [(UO2 2+ )(H2L 2- )·H2O] n Schematic diagram of the structure bond line.

[0041] Figure 2 Uranium-based metal organic framework materials [(UO2 2+ )(H2L2- )·H2O] n Schematic diagram of the structure.

[0042] Figure 3 Uranium-based metal organic framework materials [(UO2 2+ )3(HL 3- )2(H2O)3·3H2O] n Schematic diagram of the structure bond line.

[0043] Figure 4 Uranium-based metal organic framework materials [(UO2 2+ )3(HL 3- )2(H2O)3·3H2O] n Schematic diagram of the structure.

[0044] Figure 5 Uranium-based metal organic framework materials [(UO2 2+ )(H2L 2- )·2H2O] n Schematic diagram of the structure bond line.

[0045] Figure 6 Uranium-based metal organic framework materials [(UO2 2+ )(H2L 2- )·2H2O] n Schematic diagram of the structure.

[0046] Figure 7 This is a comparison diagram of the uranium-based metal organic framework material prepared in Example 1 and the simulated powder diffraction.

[0047] Figure 8 This is a comparison diagram of the uranium-based metal organic framework material prepared in Example 4 and the simulated powder diffraction.

[0048] Fig. 9 This is a comparison diagram of the uranium-based metal organic framework material prepared in Example 7 and the simulated powder diffraction.

[0049] Fig.10 The actual picture and X-ray imaging picture of the flexible scintillator film prepared from the uranium-based metal-organic framework material prepared in Example 1; wherein (a) is the actual picture and (b) is the X-ray imaging picture.

[0050] Fig.11 This is a graph showing the stability test results of the uranium-based metal organic framework material prepared in Example 1 and previous uranium-based MOF materials for X-ray imaging.

[0051] Fig.12 This is a graph showing the test results of the reusability of the uranium-based metal-organic framework material prepared in Example 1 for X-ray imaging. DETAILED DESCRIPTION

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0053] The first aspect of the present invention provides a uranium-based metal organic framework material, the chemical formula of the uranium-based metal organic framework material is [(UO2 2+ )(H2L 2- )·H2O] n 、[(UO2 2+ )3(HL 3- )2(H2O)3·3H2O] n or [(UO2 2+ )(H2L 2- )·2H2O] n , wherein n is an integer greater than 0, and L is an organic ligand having the following structure:

[0054]

[0055] Uranium-based metal-organic framework materials [(UO2 2+ )(H2L 2- )·H2O] n The structural bond line diagram in the CCDC database is as follows Figure 1 As shown in the crystal visualization drawing software CrystalMaker, the structural schematic diagram is as follows Figure 2 As shown, the polyhedron represents the metal U center and the others are aromatic ring skeletons.

[0056] Uranium-based metal-organic framework materials [(UO2 2+ )3(HL 3- )2(H2O)3·3H2O] n The structural bond line diagram in the CCDC database is as follows Figure 4 As shown in the crystal visualization drawing software CrystalMaker, the structural schematic diagram is as follows Figure 4 As shown, the polyhedron represents the metal U center and the others are aromatic ring skeletons.

[0057] Uranium-based metal-organic framework materials [(UO2 2+ )(H2L 2- )·2H2O] n The structural bond line diagram in the CCDC database is as follows Figure 6As shown in the crystal visualization drawing software CrystalMaker, the structural schematic diagram is as follows Figure 6 As shown, the polyhedron represents the metal U center and the others are aromatic ring skeletons.

[0058] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0059] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods, and the materials, reagents, etc. used are all available from commercial sources unless otherwise specified.

[0060] Example 1

[0061] A method for preparing a uranium-based metal organic framework material comprises the following steps:

[0062] 0.05 mmol 1-(3,5-dicarboxybenzyl)-1H-pyrazole-3,5-dicarboxylic acid and 0.05 mmol uranyl nitrate were weighed and placed in a capped bottle, 4 mL acetonitrile and 2 mL water were added, and 7 drops of nitric acid were dripped with a dropper. The cap was tightly pressed and placed in an oven and heated at 120°C for 1 day. The capped bottle was placed at room temperature to cool for 5 minutes, and then placed in an oven and heated at 120°C for 1 day. After cooling, it was washed twice with acetonitrile and dried at room temperature to obtain pure yellow crystals, i.e., uranium-based metal organic framework material [(UO2 2+ )(H2L 2- )·H2O] n .

[0063] Figure 7 This is a comparison chart of the uranium-based metal-organic framework material prepared in Example 1 and the simulated powder diffraction. The black color represents the simulated cluster powder diffraction pattern, and the red color represents the cluster powder diffraction pattern synthesized in Example 1. The correspondence between the simulated and experimental diffraction peaks proves that the cluster structure was successfully synthesized and has a high purity.

[0064] Example 2

[0065] A method for preparing a uranium-based metal organic framework material comprises the following steps:

[0066] 0.03mmol 1-(3,5-dicarboxybenzyl)-1H-pyrazole-3,5-dicarboxylic acid and 0.06mmol uranyl nitrate were weighed and placed in a capped bottle, 3mL DMF and 3mL water were added, and 14 drops of nitric acid were dripped into the bottle with a dropper. The cap was tightly pressed and the bottle was placed in an oven and heated at 100°C for 2 days. The capped bottle was placed at room temperature to cool for 10 minutes, and then placed in an oven and heated at 100°C for 2 days. After cooling, it was washed with acetonitrile 5 times and dried at room temperature to obtain pure yellow crystals, i.e., uranium-based metal organic framework material [(UO22+ )(H2L 2- )·H2O] n .

[0067] Example 3

[0068] A method for preparing a uranium-based metal organic framework material comprises the following steps:

[0069] 0.06mmol 1-(3,5-dicarboxybenzyl)-1H-pyrazole-3,5-dicarboxylic acid and 0.03mmol uranyl nitrate were weighed and placed in a capped bottle, 5mL DMA and 1.5mL water were added, and 10 drops of nitric acid were dripped into the bottle with a dropper. The cap was tightly pressed and the bottle was placed in an oven and heated at 140°C for 3 days. The capped bottle was placed at room temperature to cool for 7 minutes, and then placed in an oven and heated at 140°C for 4 days. After cooling, it was washed with acetonitrile 3 times and dried at room temperature to obtain pure yellow crystals, i.e., uranium-based metal organic framework material [(UO2 2+ )(H2L 2- )·H2O] n .

[0070] After testing, Example 2 and Example 3 also successfully prepared uranium-based metal organic framework materials.

[0071] Example 4

[0072] A method for preparing a uranium-based metal organic framework material comprises the following steps:

[0073] 0.05 mmol 1-(3,5-dicarboxybenzyl)-1H-pyrazole-3,5-dicarboxylic acid and 0.05 mmol uranyl nitrate were weighed and placed in a screw-cap bottle, 1 mL acetonitrile and 5 mL water were added, and then 1 drop of nitric acid was dripped into the bottle with a dropper. The bottle was tightly capped and heated at 100°C in an oven for 1 day. The screw-cap bottle was placed at room temperature to cool for 20 minutes, and then placed in an oven to heat at 100°C for 3 days. After cooling, it was washed twice with acetonitrile and dried at room temperature to obtain pure yellow crystals, i.e., uranium-based metal organic framework material [(UO2 2+ )3(HL 3- )2(H2O)3·3H2O] n .

[0074] Figure 8 This is a comparison chart of the uranium-based metal-organic framework material prepared in Example 4 and the simulated powder diffraction. The black color represents the simulated cluster powder diffraction pattern, and the red color represents the cluster powder diffraction pattern synthesized in Example 4. The correspondence between the simulated and experimental diffraction peaks proves that the cluster structure was successfully synthesized and has a high purity.

[0075] Example 5

[0076] A method for preparing a uranium-based metal organic framework material comprises the following steps:

[0077] 0.05 mmol 1-(3,5-dicarboxybenzyl)-1H-pyrazole-3,5-dicarboxylic acid and 0.1 mmol uranyl nitrate were weighed and placed in a screw cap bottle, 0.5 mL NMP and 6 mL water were added, and 2 drops of nitric acid were dripped with a dropper. The cap was tightened and placed in an oven to heat at 80 ° C for 3 days. The screw cap bottle was placed at room temperature to cool for 20 minutes, and then placed in an oven to heat at 80 ° C for 6 days. After cooling, it was washed with acetonitrile 5 times and dried at room temperature to obtain pure yellow crystals, i.e., uranium-based metal organic framework material [(UO2 2+ )3(HL 3- )2(H2O)3·3H2O] n .

[0078] Example 6

[0079] A method for preparing a uranium-based metal organic framework material comprises the following steps:

[0080] 0.1mmol 1-(3,5-dicarboxybenzyl)-1H-pyrazole-3,5-dicarboxylic acid and 0.1mmol uranyl nitrate were weighed and placed in a screw-cap bottle, 2mL DEF and 3mL water were added, and 2 drops of nitric acid were dripped with a dropper. The cap was tightened and placed in an oven for heating at 100°C for 2 days. The screw-cap bottle was placed at room temperature for cooling for 15 minutes, and then placed in an oven for heating at 100°C for 4 days. After cooling, it was washed with acetonitrile 3 times and dried at room temperature to obtain pure yellow crystals, i.e., uranium-based metal organic framework material [(UO2 2+ )3(HL 3- )2(H2O)3·3H2O] n .

[0081] After testing, Example 5 and Example 6 also successfully prepared uranium-based metal organic framework materials.

[0082] Example 7

[0083] A method for preparing a uranium-based metal organic framework material comprises the following steps:

[0084] 0.05mmol 1-(3,5-dicarboxybenzyl)-1H-pyrazole-3,5-dicarboxylic acid and 0.05mmol uranyl nitrate were weighed and placed in a screw-cap bottle, 1mL acetonitrile and 5mL water were added, and 6 drops of nitric acid were dripped with a dropper. The lid was tightened and the mixture was placed in an oven and heated at 100°C for 1 day. The reaction mixture was placed at room temperature to cool for 20 minutes, and then placed in an oven and heated at 100°C for 3 days. The mixture was taken out and cooled for more than 1 hour, and then continued to be placed in an oven at 100°C for 5 days until crystals appeared. After cooling at room temperature, the mixture was washed twice with acetonitrile and dried at room temperature to obtain pure yellow crystals, i.e., uranium-based metal organic framework material [(UO2 2+ )(H2L2- )·2H2O] n .

[0085] Fig. 9 This is a comparison chart of the uranium-based metal-organic framework material prepared in Example 7 and the simulated powder diffraction. The black color represents the simulated cluster powder diffraction pattern, and the red color represents the cluster powder diffraction pattern synthesized in Example 7. The correspondence between the simulated and experimental diffraction peaks proves that the cluster structure was successfully synthesized and has a high purity.

[0086] Example 8

[0087] A method for preparing a uranium-based metal organic framework material comprises the following steps:

[0088] Weigh 0.1mmol 1-(3,5-dicarboxybenzyl)-1H-pyrazole-3,5-dicarboxylic acid and 0.05mmol uranyl nitrate into a screw cap bottle, add 0.5mL acetonitrile and 3mL water, and then use a dropper to drip 7 drops of nitric acid, tighten the lid and place in an oven to heat at 90°C for 2 days, place the reaction at room temperature to cool for 20 minutes, then place in an oven to heat at 90°C for 5 days, then take out and cool for more than 1 hour, and then continue to place in an oven at 90°C for 4 days until crystals appear. After cooling at room temperature, wash with acetonitrile 3 times, and dry at room temperature to obtain pure yellow crystals, i.e., uranium-based metal organic framework material [(UO2 2+ )(H2L 2- )·2H2O] n .

[0089] Example 9

[0090] A method for preparing a uranium-based metal organic framework material comprises the following steps:

[0091] 0.08mmol 1-(3,5-dicarboxybenzyl)-1H-pyrazole-3,5-dicarboxylic acid and 0.04mmol uranyl nitrate were weighed and placed in a screw-cap bottle, 2mL acetonitrile and 6mL water were added, and 8 drops of nitric acid were dripped with a dropper. The lid was tightened and the mixture was placed in an oven and heated at 80°C for 3 days. The reaction mixture was placed at room temperature to cool for 20 minutes, and then placed in an oven and heated at 80°C for 6 days. The mixture was taken out and cooled for more than 1 hour, and then placed in an oven and heated at 80°C for 3 days until crystals appeared. After cooling at room temperature, the mixture was washed with acetonitrile 5 times and dried at room temperature to obtain pure yellow crystals, i.e., uranium-based metal organic framework material [(UO2 2+ )(H2L 2- )·2H2O] n .

[0092] After testing, Example 8 and Example 9 also successfully prepared uranium-based metal-organic framework materials.

[0093] Comparative Example 1

[0094] A method for preparing a uranium-based metal organic framework material is basically the same as that of Example 1, except that nitric acid is replaced by hydrochloric acid.

[0095] Comparative Example 2

[0096] A method for preparing a uranium-based metal organic framework material is basically the same as that of Example 1, except that nitric acid is replaced by sulfuric acid.

[0097] Comparative Example 3

[0098] A method for preparing a uranium-based metal organic framework material is basically the same as that of Example 1, except that nitric acid is replaced by trifluoroacetic acid (TFA).

[0099] Comparative Example 4

[0100] A method for preparing a uranium-based metal organic framework material is basically the same as that of Example 1, except that nitric acid is replaced by acetic acid.

[0101] Comparative Example 5

[0102] A method for preparing a uranium-based metal organic framework material is basically the same as that of Example 1, except that nitric acid is replaced by formic acid.

[0103] Comparative Example 6

[0104] A method for preparing a uranium-based metal organic framework material is basically the same as Example 4, except that 1-(3,5-dicarboxybenzyl)-1H-pyrazole-3,5-dicarboxylic acid is replaced by 1-(4-carboxybenzyl)-1H-pyrazole-3,5-dicarboxylic acid.

[0105] Comparative Example 7

[0106] A method for preparing a uranium-based metal organic framework material is basically the same as that of Example 7, except that acetonitrile is replaced by tetrahydrofuran (THF).

[0107] No yellow crystals were precipitated in Comparative Examples 1-7, indicating that the uranium-based metal-organic framework material of the present invention was not prepared.

[0108] Application Examples

[0109] The uranium-based metal organic framework material prepared in Example 1 is used for X-ray imaging. The specific method is as follows: SYLGARD 184 silicone elastomer and curing agent are fully mixed, stirred at a ratio of 10:1, and a 40% loading of the uranium-based metal organic framework material powder prepared in Example 1 after sifting is added, and stirred vigorously. Then the mixed solution is poured on the vacuum-treated polyethylene terephthalate (PET) substrate and evenly applied with a scraper. Finally, it is heated at 80°C for 24 hours to form a flexible scintillator film.

[0110] The above-mentioned flexible scintillator film is used for X-ray imaging (Moxtek TUB00154-W06), the X-ray source is placed in front of the imaging object, the flexible scintillator film is closely attached to the back of the imaging object, and then a digital camera is used to capture the X-ray imaging image on the flexible scintillator film.

[0111] The test results are as follows Fig.10 As shown, from Fig.10 As can be seen from (a), the flexible scintillator film prepared from the uranium-based metal organic framework material prepared in Example 1 has good flexibility, is yellow under natural light, and exhibits a bright green fluorescent film under the excitation of ultraviolet rays and X-rays; Fig.10 As can be seen in (b), the imaging resolution of the card under X-ray using this film can reach 4 line pairs (lp·mm -1 ) or higher resolution.

[0112] Test Example 1

[0113] The stability of the uranium-based metal-organic framework material prepared in Test Example 1 for X-ray imaging was tested by using an X-RAD SmART system and a NOVA spectrometer (ideaoptics, China) with a W Kα radiation source to test the X-ray excited luminescence (XEL) spectrum. The dose rate was controlled by adjusting the X-ray source current. A spectrometer embedded in a laboratory X-ray source (Bruker D8 advance, with Cu Kα radiation) was used to record the XEL data.

[0114] The normalized comparison of the initial XEL intensity of the uranium-based metal organic framework material prepared in Example 1 and the previous uranium-based MOF material with the increase of 90Gy X-ray irradiation dose is shown in the figure Fig.11 shown.

[0115] Test Example 2

[0116] The reusability of the uranium-based metal organic framework material prepared in Example 1 for X-ray imaging was tested by exposing 30 mg of the uranium-based metal organic framework material prepared in Example 1 to 42.3 mGy / s X-ray radiation, with a 20-second pause after every 20 seconds of radiation. During the entire 30 intermittent radiation cycles, the peak fluorescence intensity at 513 nm was recorded every second.

[0117] The test results are as follows Fig.12 As shown, it is proved that the uranium-based metal organic framework material prepared by the present invention has the ability to be reused multiple times.

[0118] Obviously, the above embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art should understand that other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A uranium-based metal-organic framework material, characterized in that: The chemical formula of the uranium-based metal organic framework material is [(UO2 2+ )(H2L 2- )·H2O] n 、[(UO2 2+ )3(HL 3- )2(H2O)3·3H2O] n or [(UO2 2+ )(H2L 2- )·2H2O] n , wherein n is an integer greater than 0, and L is an organic ligand having the following structure:

2. A method for preparing a uranium-based metal-organic framework material, characterized in that: The following steps are involved: At 80-140° C., aromatic tetracarboxylic acid and uranyl nitrate are dissolved in a mixed solvent of an organic solvent and water, and after adding nitric acid, a coordination reaction occurs to obtain the uranium-based metal organic framework material; the organic solvent is selected from one of acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone and N,N-diethylformamide.

3. The preparation method according to claim 2, characterized in that: The aromatic tetracarboxylic acid is 1-(3,5-dicarboxybenzyl)-1H-pyrazole-3,5-dicarboxylic acid.

4. The preparation method according to claim 2, characterized in that: The molar ratio of the aromatic tetracarboxylic acid to uranyl nitrate is (0.5-2):

1.

5. The preparation method according to claim 2, characterized in that: The volume ratio of the organic solvent to water is (0.5-5):(1.5-6).

6. The preparation method according to claim 2, characterized in that: The volume ratio of the organic solvent to nitric acid is (0.5-5):(0.02-0.7).

7. The preparation method according to claim 2, characterized in that: At 100-140° C., aromatic tetracarboxylic acid and uranyl nitrate are dissolved in a mixed solvent of an organic solvent and water. After nitric acid is added, the volume ratio of the organic solvent, water and nitric acid is (3-5):(1.5-3):(0.14-0.7). After a coordination reaction occurs for 2-7 days, the uranium-based metal organic framework material is obtained.

8. The preparation method according to claim 2, characterized in that: At 80-110° C., aromatic tetracarboxylic acid and uranyl nitrate are dissolved in a mixed solvent of an organic solvent and water. After nitric acid is added, the volume ratio of the organic solvent, water and nitric acid is (0.5-2):(3-6):(0.02-0.1). After a coordination reaction occurs for 4-10 days, the uranium-based metal organic framework material is obtained.

9. The preparation method according to claim 2, characterized in that: At 80-100° C., aromatic tetracarboxylic acid and uranyl nitrate are dissolved in a mixed solvent of an organic solvent and water. After nitric acid is added, the volume ratio of the organic solvent, water and nitric acid is (0.5-2):(3-6):(0.12-0.4). After the coordination reaction occurs for 7-14 days, the uranium-based metal organic framework material is obtained.

10. Use of the uranium-based metal organic framework material according to claim 1 or the uranium-based metal organic framework material prepared by the method according to claims 2 to 9 in the field of X-ray imaging.

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