A thorium-based metal-organic framework material containing a hexanuclear nickel cluster and a preparation method and application thereof

Abstract

This invention discloses a thorium-based metal-organic framework material containing a hexanuclear nickel cluster, its preparation method, and its application. Its chemical formula is [Ni6Cl]. 10 [(H₂O)₆Th₆(μ₃-O)₄(μ₃-OH)₄(BPYDC)₆(H₂O)₆·Cl₂]·G₁, where BPYDC is 2,2'-bipyridine-4,4'-dicarboxylate ion and G₁ is a guest molecule; the thorium-based metal-organic framework containing hexanuclear nickel clusters belongs to the cubic crystal system, space group Pa⁻³, and cell parameters α=β=γ=90°. The above-mentioned metal-organic framework is prepared by impregnating a thorium-based metal-organic framework in a diethylene glycol dimethyl ether solution containing NiCl₂·6H₂O and reacting at 90–110 °C. The thorium-based metal-organic framework containing hexanuclear nickel clusters prepared by this invention exhibits good chemical and thermal stability, a simple and mild synthesis process, and good crystallinity, allowing for mass production. It shows promising application prospects in catalysis, magnetic materials, and other fields.

Description

Technical Field

[0001] This invention relates to the field of metal-organic framework materials technology, specifically to a thorium-based metal-organic framework material containing a hexanuclear nickel cluster, its preparation method, and its application. Background Technology

[0002] The development of thorium chemistry has significant theoretical implications for uranium mining, the nuclear fuel cycle, and nuclear waste disposal. However, current research on thorium is limited, especially on its structure and applications. Thorium-based metal-organic frameworks (Th-MOFs) have attracted considerable attention in recent years. Compared to traditional transition metal or rare earth metal MOFs, thorium's rich coordination chemistry and diverse boundary orbitals give thorium-based MOFs abundant secondary building blocks and structural complexity.

[0003] However, to date, no thorium-based MOFs containing polynuclear transition metal clusters have been reported, limiting the development of thorium-based MOFs. Jeffrey R. Long et al. reported that constructing polynuclear nickel clusters into zirconium-based MOFs resulted in different magnetic behaviors, including the elimination of large-spin ground states by eliminating long-range interlayer magnetic order to isolate ferromagnetic coupling (Nature, 2020, 577, 64-68). Furthermore, Luo Feng et al. reported that mononuclear nickel-modified thorium-based MOFs exhibited good electrocatalytic oxygen evolution (OER) performance (ACS Catal. 2022, 12, 9101-9113). Gao Zhi et al. used Ni... 2+ Post-modification into Fe-MIL-53 significantly improved the OER performance of MOF materials (Chem.Eng.J. 2023, 462, 142179). Other reports indicate that the synergistic effect between multiple nickel atoms in multinuclear nickel clusters may further enhance OER performance (Chem.Soc.Rev. 2022, 51, 8923-8956).

[0004] Thorium-based MOFs possess high stability and large single-crystal size, facilitating the characterization of their crystal structure after modification with nickel clusters. Therefore, it is hoped that thorium-based MOFs with multinuclear nickel cluster modification can be prepared, thereby promoting the application of thorium-based MOFs in electrocatalysis and magnetic materials. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a thorium-based metal-organic framework material containing a hexanuclear nickel cluster, its preparation method and application. The thorium-based metal-organic framework material crystal containing a hexanuclear nickel cluster can be prepared by impregnating the thorium-based metal-organic framework material in a specific solvent containing NiCl2·6H2O and reacting. The crystal has good crystallinity and reproducibility, can be prepared in batches, and exhibits outstanding chemical and thermal stability. It has good application prospects in photoelectrocatalysis and magnetic materials.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] The first aspect of this invention provides a thorium-based metal-organic framework material containing a hexanuclear nickel cluster, with the chemical formula [Ni6Cl]. 10 (H2O)6Th6(μ3-O)4(μ3-OH)4(BPYDC)6(H2O)6·Cl2]·G1, where BPYDC is 2,2'-bipyridine-4,4'-dicarboxylate ion and G1 is a guest molecule;

[0008] The thorium-based metal-organic framework material containing hexanuclear nickel clusters belongs to the cubic crystal system, with space group Pa-3 and cell parameters as follows: α=β=γ=90°,

[0009] Further, the guest molecule is diethylene glycol dimethyl ether and water; specifically, in some preferred embodiments of the present invention, G1 is (C6H 14 O3)7(H2O) 36 .

[0010] The second aspect of the present invention provides a method for preparing the thorium-based metal-organic framework material containing hexanuclear nickel clusters as described in the first aspect, wherein a single crystal of the thorium-based metal-organic framework material is immersed in a diethylene glycol dimethyl ether solution containing NiCl2·6H2O, and the reaction is carried out to prepare the thorium-based metal-organic framework material containing hexanuclear nickel clusters.

[0011] The thorium-based metal-organic framework material has the chemical formula [Th6(μ3-O)4(μ3-OH)4(BPYDC)6(H2O)6]·G2, where BPYDC is a 2,2'-bipyridine-4,4'-dicarboxylate ion and G2 is a guest molecule; the thorium-based metal-organic framework material belongs to the cubic crystal system with space group Fm-3m and cell parameters as follows: α=β=γ=90°,

[0012] Furthermore, G2 can be (DMF). x (H2O) y, x, y≥0.

[0013] During their experiments, the inventors unexpectedly discovered that immersing single crystals of thorium-based metal-organic frameworks (MOFs) in a diethylene glycol dimethyl ether solution containing NiCl2·6H2O and reacting them under specific temperature conditions could produce thorium-based MOFs containing hexanuclear nickel clusters. However, replacing the diethylene glycol dimethyl ether solvent with methanol, ethanol, tetrahydrofuran, N,N-dimethylformamide, acetonitrile, or other solvents failed to yield the same thorium-based MOF containing hexanuclear nickel clusters. Furthermore, through dozens of verifications, the inventors confirmed that this method can stably prepare the aforementioned thorium-based MOF containing hexanuclear nickel clusters, and the resulting crystals exhibit good crystallinity and reproducibility.

[0014] Furthermore, during the impregnation process, the NiCl2·6H2O in the diethylene glycol dimethyl ether solution containing NiCl2·6H2O remains in a supersaturated state, meaning that undissolved NiCl2·6H2O solids are always present in the solution.

[0015] Furthermore, the reaction temperature is preferably 90–110°C, such as 90°C, 95°C, 100°C, 105°C, 110°C, etc., including but not limited to the temperature values ​​listed above; the reaction time is preferably 30–40 days. Through comparative experiments, the inventors found that if the reaction temperature is lowered to below 90°C, the reaction time is shorter than 30 days, and the post-modified nickel clusters cannot form hexanuclear nickel clusters; if the reaction temperature is set above 110°C, the organic solution becomes overheated, which is not conducive to the reaction under normal pressure, and the reaction glass bottle is very prone to explosion. Therefore, the reaction temperature needs to be controlled within a suitable range, such as 90–110°C.

[0016] Furthermore, the preparation method of the thorium-based metal-organic framework material is as follows: H2BPYDC and Th(NO3)4·6H2O are reacted in the presence of an acidic regulator and an organic solvent to obtain the thorium-based metal-organic framework.

[0017] Further, the molar ratio of H2BPYDC and Th(NO3)4·6H2O is 1:2 to 1:3; the acid regulator is one or more of trifluoroacetic acid, formic acid, or nitric acid; water is added simultaneously with the acid regulator, and the volume ratio of the acid regulator to water is 0.8 to 1.2: 0.3 to 0.5. In the preparation of thorium-based metal-organic framework materials, on the one hand, the addition of an acid regulator slows down the growth of single crystals, resulting in large-size, high-quality single crystals; on the other hand, the addition of a small amount of water to the system controls the crystal size and yield. Without water, the prepared crystals are smaller and the yield is lower.

[0018] Furthermore, the reaction of H2BPYDC and Th(NO3)4·6H2O in the presence of an acidic regulator and an organic solvent takes place at a temperature of 100–120 °C for 3–5 days.

[0019] In some embodiments of the present invention, H2BPYDC and Th(NO3)4·6H2O are dissolved in 5-10 mL of DMF, ultrasonicated until homogeneous, and then 0.8-1.2 mL of trifluoroacetic acid and 0.3-0.5 mL of water are added to obtain a mixture. The mixture is then reacted at 100-120°C for 3-5 days. After the reaction is complete, the mixture is cooled and filtered to obtain the crystals of the thorium-based metal-organic framework material.

[0020] The third aspect of this invention provides the application of the thorium-based metal-organic framework material containing hexanuclear nickel clusters described in the first aspect in catalysis and magnetic materials.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] 1. This invention provides a novel thorium-based metal-organic framework material containing hexanuclear nickel clusters. It is synthesized in one step from a thorium-based metal-organic framework material (Th-MOF) with a specific crystal structure in a specific solvent (diethylene glycol dimethyl ether) containing NiCl2·6H2O. This synthesis method features mild reaction conditions and can rapidly modify thorium-based metal-organic framework materials with nickel ions to form a single thorium-based metal-organic framework material containing hexanuclear nickel clusters. The single crystal morphology remains essentially unchanged after nickel cluster modification, with only the single crystal color changing from colorless to grayish-green. The prepared crystals exhibit good crystallinity, and the Th content can be precisely controlled. 4+ and Ni 2+ The ratio is well-reproducible and can be mass-produced.

[0023] 2. The thorium-based metal-organic framework material containing a hexanuclear nickel cluster prepared in this invention contains one thorium ion and two nickel ions, Th1 and BPYDC from four ligands. 2- The carboxylic acid O atom coordinates with two μ3-O atoms, two μ3-OH atoms, and one water molecule's O atom to form the Th6(μ3-O)4(μ3-OH)4(H2O)6(-CO2)6 secondary building unit; Ni1 coordinates with a ligand BPYDC 2- The two pyridine N atoms, two μ2-Cl and one μ3-Cl Cl atom, and one O atom of a coordinated water molecule are coordinated with Ni2, forming a hexanuclear nickel cluster of Ni6(μ3-Cl)4(μ2-Cl)6(H2O)6. Further, this secondary building block, the hexanuclear nickel cluster, and BPYDC... 2-The ligands are linked to form a three-dimensional framework, and free chloride ions exist in the channels to maintain the charge balance of the structure. The material has a porosity of 47.2%, excellent chemical and thermal stability, and can be used under extreme conditions such as acids, alkalis, and high temperatures. Compared with thorium-based metal-organic frameworks, it has better acid resistance, and the presence of polynuclear nickel clusters in the material makes it promising for applications in catalysis and magnetic materials. Attached Figure Description

[0024] Figure 1 This is a crystal structure diagram of the thorium-based metal-organic framework material containing a hexanuclear nickel cluster prepared in Example 1 of the present invention;

[0025] Figure 2 The image shows the crystal structure of the hexanuclear nickel cluster in the thorium-based metal-organic framework material containing the hexanuclear nickel cluster prepared in Example 1 of this invention.

[0026] Figure 3 X-ray powder diffraction (PXRD) pattern of the thorium-based metal-organic framework material containing a hexanuclear nickel cluster prepared in Example 1 of this invention;

[0027] Figure 4 The infrared spectrum of the thorium-based metal-organic framework material containing a hexanuclear nickel cluster prepared in Example 1 of this invention;

[0028] Figure 5 Thermogravimetric analysis diagram of the thorium-based metal-organic framework material containing hexanuclear nickel clusters prepared in Example 1 of the present invention;

[0029] Figure 6 Nitrogen adsorption curve of the thorium-based metal-organic framework material containing a hexanuclear nickel cluster prepared in Example 1 of the present invention;

[0030] Figure 7 PXRD overlay images of the thorium-based metal-organic framework material containing hexanuclear nickel clusters prepared in Example 1 of this invention after being immersed in aqueous solutions of different pH (1-12) for 24 h;

[0031] Figure 8 The image shows the PXRD overlay images of the thorium-based metal-organic framework material prepared in Example 1 of this invention after being immersed in aqueous solutions of different pH values ​​(1-12) for 24 hours. Detailed Implementation

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0034] The test equipment and parameters involved in the following embodiments are as follows:

[0035] X-ray powder diffraction characterization: X-ray powder diffraction data were collected on a Bruker D8 Advance diffractometer, operating at 40 kV and 40 mA, using a graphite-monochromatized copper target X-ray (CuKα, The scanning was completed continuously within the range of 3° to 40°.

[0036] X-ray single-crystal diffraction characterization and structural analysis: A single crystal of appropriate size was selected under a microscope, and its structure was analyzed using a Mo-Kα single-crystal diffractometer on a Bruker D8 VENTURE CMOS photon 100diffractometer with a Helios MX Multilayer spectrometer. During the 120K radiation collection, all crystal data were corrected for Lp factor and empirical absorption correction. The absorption correction was performed using the SADABS program, and the structure was resolved using the direct method. Then, the anisotropic correction was performed on all non-hydrogen atoms on the framework using the full matrix least squares method. The coordinates of hydrogen atoms on all carbon atoms were obtained by theoretical hydrogenation, and then the hydrogen atoms were corrected for isotropic correction.

[0037] Simulation and conversion of X-ray powder diffraction patterns of single-crystal structures: Mercury software.

[0038] Infrared spectroscopy (IR) was performed using a Thermo Nicolet 6700FTIR spectrometer equipped with a diamond attenuated total reflectance (ATR) accessory, with a test range of 400-4000 cm⁻¹. -1 .

[0039] Thermogravimetric analysis (TGA) was performed using a NETZSCH STA449 F3 in a nitrogen atmosphere at a heating rate of 10 °C / min and at a test temperature ranging from 30 °C to 800 °C.

[0040] Nitrogen adsorption was tested using a Micron ASAP 2020 surface area and porosity analyzer, and the N2 adsorption isotherm was measured at 77 K.

[0041] Example

[0042] This embodiment relates to the preparation of a thorium-based metal-organic framework (Th-MOF) and a thorium-based metal-organic framework containing a hexanuclear nickel cluster (ThNi-MOF-1), and the specific operations are as follows:

[0043] Preparation of Th-MOF: The preparation method is the same as Example 1 of patent CN115490872A, as follows:

[0044] (1) Dissolve H2BPYDC (19.5 mg, 0.08 mmol) and Th(NO3)4·6H2O (94 mg, 0.16 mmol) in 5 mL of N,N-dimethylformamide (DMF), sonicate until homogeneous, add 0.8 mL of trifluoroacetic acid and 0.3 mL of water to the solution, and sonicate to obtain a mixture.

[0045] (2) Place the above mixture in a reaction vessel and react at 120°C for 5 days. After cooling, filter to obtain crystals and filtrate. Collect the crystals, wash them three times with DMF, and then wash them three times with ethanol to obtain thorium-based metal-organic framework, named Th-MOF.

[0046] Preparation of ThNi-MOF-1:

[0047] The thorium-based metal-organic framework (Th-MOF) prepared above was immersed in a diethylene glycol dimethyl ether solution containing NiCl2·6H2O and reacted at 100°C for 30 days. After cooling, it was filtered to obtain gray-green octahedral single crystals and filtrate. The crystals were washed and dried with acetone to obtain a thorium-based metal-organic framework containing hexanuclear nickel clusters, named ThNi-MOF-1.

[0048] The prepared ThNi-MOF-1 was characterized by X-ray single-crystal diffraction. The corresponding crystallographic diffraction point data and some parameters for structural refinement are shown in Table 1.

[0049] Table 1. Parameters of ThNi-MOF-1 single crystal

[0050]

[0051]

[0052] The crystal structure analysis results of ThNi-MOF-1 prepared in this embodiment are as follows: ThNi-MOF-1 contains one thorium ion and two nickel ions, and its crystal structure is as follows. Figure 1 As shown, Th1 interacts with four ligands BPYDC 2- The carboxylic acid O atom coordinates with two μ3-O atoms, two μ3-OH atoms, and one water molecule's O atom to form the Th6(μ3-O)4(μ3-OH)4(H2O)6(-CO2)6 secondary building unit; Ni1 coordinates with a ligand BPYDC 2-The two pyridine N atoms, two μ2-Cl and one μ3-Cl Cl atom, and one O atom of a coordinated water molecule are coordinated with Ni2, forming a hexanuclear nickel cluster Ni6(μ3-Cl)4(μ2-Cl)6(H2O)6. Figure 2 Further, this secondary building block, the six-core nickel cluster, and BPYDC... 2- The ligands are linked into a three-dimensional framework, and free chloride ions exist within the pores to maintain the charge balance of the structure. The porosity of this material is 47.2%. Figure 3 As shown, the X-ray powder diffraction pattern obtained from single-crystal data simulation and the PXRD pattern actually measured by ThNi-MOF-1 are compared. Figure 1 This indicates that the crystal structure of the synthesized ThNi-MOF-1 matches the resolved structure.

[0053] The infrared spectrum of the ThNi-MOF-1 material prepared in this embodiment is as follows: Figure 4 As shown, Figure 5 The thermogravimetric analysis (TGA) curve shows that the ThNi-MOF-1 material prepared in this embodiment has good thermal stability up to 400℃. Figure 6 The figure shows the nitrogen adsorption isotherm of ThNi-MOF-1 at 77 K. As can be seen from the figure, this is a Type I adsorption curve, indicating that it has a microporous structure and a specific surface area of ​​51.8 m². 2 / g, has promising applications in catalysis and adsorption materials.

[0054] In addition, this invention further investigated the chemical resistance of ThNi-MOF-1 and the starting material Th-MOF. Equal amounts of the two single crystals were placed in aqueous solutions with different pH values ​​(pH = 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12) and immersed for 24 hours, and then taken out to test PXRD.

[0055] The chemical resistance test results of ThNi-MOF-1 and the starting material Th-MOF are as follows: Figure 7 , 8As shown, the diffraction peak positions of ThNi-MOF-1 after treatment with aqueous solutions at different pH values ​​all belong to the initial ThNi-MOF-1 crystal form, that is, the crystal form has not changed, and the intensity of the characteristic diffraction peaks has not changed significantly. This phenomenon indicates that the ThNi-MOF-1 prepared in this invention has good structural stability under acidic or alkaline conditions of pH = 1 to 12. However, the Th-MOF without nickel cluster modification can maintain its original crystal structure under acidic or alkaline conditions of pH = 2 to 12. But after being immersed in acidic conditions of pH = 1 for 24 hours, the diffraction peaks of Th-MOF disappear, that is, the crystal structure of Th-MOF collapses. Therefore, it can be seen that the acid resistance of MOF is further improved after Th-MOF is modified with nickel cluster.

[0056] The performance results above show that the ThNi-MOF-1 prepared by this invention has a high specific surface area, good chemical stability and thermal stability, and has good application prospects in the fields of catalysis and adsorption materials. Furthermore, due to the modification of polynuclear nickel clusters, MOF materials have certain application prospects in the field of magnetic materials.

[0057] The above-described embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims.

Claims

1. A thorium-based metal-organic framework material containing a hexanuclear nickel cluster, characterized in that, Its chemical formula is [Ni6Cl] 10 (H2O)6Th6(μ3-O)4(μ3-OH)4(BPYDC)6(H2O)6·Cl2]·G1, where BPYDC is 2,2'-bipyridine-4,4'-dicarboxylate ion and G1 is a guest molecule; The thorium-based metal organic framework material containing the hexanuclear nickel cluster belongs to a cubic system, a space group is Pa-3, and a unit cell parameter is: α = β = γ = 90°, 2. The thorium-based metal-organic framework material containing hexanuclear nickel clusters according to claim 1, characterized in that, The guest molecules are diethylene glycol dimethyl ether and water.

3. The thorium-based metal-organic framework material containing hexanickel clusters of claim 1, wherein, said G1is (C6H 14 O3)7(H2O) 36 .

4. A method for preparing the thorium-based metal-organic framework material containing hexanickel clusters according to any one of claims 1 to 3, characterized in that, The thorium-based metal-organic framework material was prepared by impregnating a single crystal of the thorium-based metal-organic framework material in a diethylene glycol dimethyl ether solution containing NiCl2·6H2O. The thorium-based metal-organic framework material has the chemical formula [Th6(μ3-O)4(μ3-OH)4(BPYDC)6(H2O)6]·G2, where BPYDC is a 2,2'-bipyridine-4,4'-dicarboxylate ion and G2 is a guest molecule; the thorium-based metal-organic framework material belongs to the cubic crystal system with space group Fm-3m and cell parameters as follows: α=β=γ=90°, 5. The production method according to claim 4, characterized by, During the impregnation process, the NiCl2·6H2O in the diethylene glycol dimethyl ether solution containing NiCl2·6H2O remains in a supersaturated state.

6. The preparation method according to claim 4, characterized in that, The reaction temperature is 90–110°C, and the reaction time is 30–40 days.

7. The preparation method according to claim 4, characterized in that, The thorium-based metal-organic framework material is prepared by reacting H2BPYDC and Th(NO3)4·6H2O in the presence of an acidic regulator and an organic solvent to obtain the thorium-based metal-organic framework.

8. The preparation method according to claim 7, characterized in that, The molar ratio of H2BPYDC and Th(NO3)4·6H2O is 1:2 to 1:3; the acid regulator is one or more of trifluoroacetic acid, formic acid, or nitric acid; water is added at the same time as the acid regulator, and the volume ratio of the acid regulator to water is 0.8 to 1.2: 0.3 to 0.

5.

9. The preparation method according to claim 7, characterized in that, The reaction of H2BPYDC and Th(NO3)4·6H2O in the presence of an acidic regulator and an organic solvent takes place at a temperature of 100–120 °C for 3–5 days.

10. The application of a thorium-based metal-organic framework material containing a hexanuclear nickel cluster as described in any one of claims 1-3 in catalysis and magnetic materials.

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