A modular, dual-ligand metal-organic framework material and its preparation method

Abstract

This invention discloses a modular, dual-ligand metal-organic framework material and its preparation method, belonging to the technical field of dual-ligand metal-organic framework materials. The invention first dissolves divalent metal nitrates, halides, or carboxylates of Zn, Ni, Cu, Fe, Mn, and Co with bidentate or polydentate ligands in a solvent. The solution is stirred and dissolved at room temperature, then placed in a sealed container and reacted at 60-300°C for 0.1-720 h. After cooling, the product is separated by centrifugation, washed with solvent, and dried to obtain the final material. The resulting material consists of polyhedral and granular particles as modular building blocks, which are assembled in multiple dimensions through coordination, covalent bonding, or supramolecular bonding to form a multi-level structure with complex morphologies. The modular, dual-ligand metal-organic framework material of this invention possesses rich morphological scalability and is expected to play a role in adsorption, surface wetting, electrochemistry, and separation.

Description

Technical Field

[0001] This invention belongs to the technical field of dual-ligand metal-organic framework materials, specifically relating to a modular dual-ligand metal-organic framework material and its preparation method. Background Technology

[0002] Materials with complex hierarchical structures and surface morphologies (such as serrated, stepped, and corrugated shapes) play a crucial role in adsorption, superwetting, electrochemistry, separation, and numerous biomimetic applications. The construction of these structures and morphologies typically begins with simple building blocks, which are then assembled in multiple dimensions through coordination, covalent bonding, or supramolecular bonding to form complex aggregates. This modular approach is an effective strategy for material expansion. Metal-organic frameworks (MOFs) are a class of porous materials composed of metal ions or ion clusters coordinated with organic ligands. Introducing tridentate and tetradentate ligands into the traditional single bidentate ligand configuration holds promise for regulating the coordination units, enriching the linkages and interaction sites, and enabling the expansion and linkage of single building blocks in different dimensions to form materials with multi-level structures and complex morphologies. Summary of the Invention

[0003] The purpose of this invention is to provide modular dual-ligand metal-organic framework materials with unique microstructures and their preparation methods. The prepared modular dual-ligand metal-organic framework materials have rich surface morphologies and are expected to play an important role in adsorption, surface wetting, electrochemistry, separation and other fields.

[0004] The objective of this invention is achieved through the following technical solution:

[0005] This invention provides a method for preparing a modular metal-organic framework material, comprising the following steps:

[0006] (1) Dissolve divalent metal nitrates, halides or carboxylates of Zn, Ni, Cu, Fe, Mn and Co with bidentate ligands or polydentate ligands in a solvent and stir to dissolve at room temperature;

[0007] (2) The mixed solution obtained in step (1) is placed in a sealed container and reacted at 60-300℃ for 0.1-720h:

[0008] (3) Cool, centrifuge to separate the product, wash with solvent and dry to obtain the final product.

[0009] Based on the above technical solution, further, the bidentate ligand mentioned in step (1) is imidazole and its derivatives or terephthalic acid and its derivatives, including but not limited to 2-methylimidazolium, 2-ethylimidazolium, benzimidazole, 3,5-diaminotriazole, 3,4-diaminotriazole, 2-chloroimidazolium, terephthalic acid, and 2,5-dihydroxyterephthalic acid.

[0010] Based on the above technical solution, further, the multidentate ligand mentioned in step (1) is a tridentate or tetradentate ligand, including but not limited to 1,2,3-triazole, 1,2,4-triazole, 2-methyl-1,2,4-triazole, isobenzoic acid, and 1,2,4,5-benzenetetracarboxylic acid.

[0011] Based on the above technical solution, further, the solvent mentioned in step (1) is methanol, water, N,N-dimethylformamide, ethanol, or N,N-dimethylacetamide.

[0012] Based on the above technical solution, further, in step (1), the molar ratio of metal, total ligand and solvent is 1:0.1~15:500~30000.

[0013] Based on the above technical solution, further, in step (1), the molar ratio of bidentate ligand to polydentate ligand is 1:49 to 49:1.

[0014] Based on the above technical solution, further, the reaction temperature in step (2) is 80-200℃ and the reaction time is 1-48h.

[0015] Based on the above technical solution, further, the reaction in step (2) is specifically heated in an oven or in a microwave oven.

[0016] In another aspect, the present invention provides a modular metal-organic framework material prepared by the above-mentioned preparation method, which is a multi-level structured metal-organic framework material with complex morphology achieved by multi-dimensional splicing and assembly of polyhedral and granular particles as building block units through coordination, covalent or supramolecular bonding.

[0017] The present invention also provides the application of the above-mentioned modular metal-organic framework material in the preparation of adsorbents, proton conduction membranes, and gas separation membranes.

[0018] Compared with the prior art, the advantages of the present invention are:

[0019] (1) The modular dual-ligand metal-organic framework material of the present invention has a simple and rapid preparation process; the obtained modular dual-ligand metal-organic framework material has rich surface morphology and is expected to play an important role in adsorption, surface wetting, electrochemistry, separation and other fields.

[0020] (2) This invention obtains a unique serrated step metal-organic framework material with anisotropy through simple solvothermal synthesis, which is of great significance to the research on MOF material growth and preparation. Attached Figure Description

[0021] To more clearly illustrate the embodiments of the present invention, the accompanying drawings involved in the embodiments will be briefly described below.

[0022] Figure 1 The X-ray diffraction pattern of the modular metal-organic framework material and ZIF-8 in Example 1 is shown.

[0023] Figure 2 It is the modular metal-organic framework material in Example 1. 1 H NMR spectrum.

[0024] Figure 3 These are SEM images of the modular metal-organic framework material (a) and the ZIF-8 material (b) from Example 1.

[0025] Figure 4 These are SEM images of the modular metal-organic framework (MOF) and the room-temperature dual-ligand MOF (MOF) prepared by microwave method in Example 2.

[0026] Figure 5 The X-ray diffraction patterns are those of the cluster polyhedron-dual ligand MOF and ZIF-8 in Example 3.

[0027] Figure 6 This is a SEM image of the cluster polyhedron-dual ligand MOF in Example 3. Detailed Implementation

[0028] The following specific embodiments further illustrate the present invention and should not be construed as limiting the present invention in any way.

[0029] Example 1: Hydrothermal Preparation of Modular Metal-Organic Framework Materials

[0030] The synthetic metal raw material is zinc nitrate hexahydrate (Zn). 2+ The ligands 2-methylimidazolium (MIM) and 3-methyl-1,2,4-triazole (MTZ) are dissolved in methanol, with the molar ratio of Zn... 2+The mixture of :mim:mtz:CH3OH = 1:3.2:0.8:1000 was thoroughly mixed at room temperature, and a milky white turbidity was immediately formed in the mixed solution. The mixture was placed in a reaction vessel and heated to 110°C in an oven for 6 hours. After natural cooling, the product was collected by centrifugation (15000 rpm, 10 min). The product was washed twice with methanol to remove unreacted metal ions and ligands, and then dried in an oven to obtain the dual-ligand MOF material.

[0031] For comparison, ZIF-8 material was also prepared. The preparation method is as follows: ZIF-8 synthesis raw material zinc nitrate hexahydrate (Zn) was prepared... 2+ ), 2-methylimidazole (mim) are dissolved in CH3OH solvent, with the molar ratio of each substance being Zn. 2+ The mixture of :mim:CH3OH = 1:4:1000 was thoroughly mixed at room temperature, and a milky white product was immediately formed in the solution. The mixture was placed in a reaction vessel and heated to 150°C in an oven for 12 hours. After natural cooling, the product was collected by centrifugation (15000 rpm, 10 min). The product was washed with methanol to remove unreacted metal ions and ligands, and then dried in an oven to obtain ZIF-8 material.

[0032] Figure 1 The X-ray diffraction patterns of the dual-ligand MOF and ZIF-8 are shown. Since mtz and mim have similar molecular structures, the dual-ligand MOF containing a relatively small amount of mtz ligands has the same diffraction peaks as ZIF-8, that is, the material has the same topological structure as ZIF-8.

[0033] Figure 2 For dual-ligand MOFs 1 H NMR spectrum, 1 1H NMR results indicate that 2-methylimidazole and 3-methyl-1,2,4-triazole were simultaneously introduced into the material.

[0034] Figure 3 The images show SEM images of the dual-ligand MOF and ZIF-8. SEM results indicate that the experimentally synthesized dual-ligand MOF material possesses a unique cube-like structure with regular serrated steps on the grain surface, and each vertex of the polyhedron has a different shape, demonstrating anisotropic growth. In contrast, the ZIF-8 material obtained under high-temperature conditions can only form a smooth and isotropic polyhedral structure.

[0035] Example 2: Microwave fabrication of modular metal-organic framework materials

[0036] The synthetic metal raw material is zinc nitrate hexahydrate (Zn). 2+The ligands 2-methylimidazolium (MIM) and 3-methyl-1,2,4-triazole (MTZ) are dissolved in methanol, with the molar ratio of Zn... 2+ The mixture of :mim:mtz:CH3OH = 1:3.2:0.8:1000 was thoroughly mixed at room temperature, and a milky white turbidity was immediately formed in the mixed solution. The mixture was placed in a reaction vessel and heated to 110°C in a microwave reactor for 1 hour. After cooling, the product was collected by centrifugation (15000 rpm, 10 min). The product was washed twice with methanol to remove unreacted metal ions and ligands, and then dried in an oven to obtain the dual-ligand MOF material.

[0037] For comparison, dual-ligand MOF materials were prepared at room temperature. The preparation method is as follows: zinc nitrate hexahydrate (Zn) was used as the synthetic metal raw material. 2+ The ligands 2-methylimidazolium (MIM) and 3-methyl-1,2,4-triazole (MTZ) are dissolved in methanol, with the molar ratio of Zn... 2+ The mixture of :mim:mtz:CH3OH = 1:3.2:0.8:1000 was thoroughly mixed at room temperature, and a milky white product was immediately generated in the mixed solution. The mixture was stirred at room temperature for 0.5 h, centrifuged (15000 rpm, 10 min) to collect the product, washed with methanol to remove unreacted metal ions and ligands, and then dried in an oven to obtain room temperature dual-ligand MOF material.

[0038] Figure 4 The images show SEM images of microwave-synthesized dual-ligand MOFs and room-temperature dual-ligand MOFs. SEM results indicate that the microwave-synthesized dual-ligand MOF also possesses a unique cube-like structure, but its surface is relatively smooth, and amorphous micron-sized particles are generated as byproducts. In contrast, the room-temperature product consists only of amorphous nanoparticles, demonstrating the crucial influence of temperature on the material morphology.

[0039] Example 3: Hydrothermal Preparation of Cluster Polyhedral Morphology Dual-Ligand MOF Materials

[0040] This embodiment is similar to Example 1, with the total proportion of ligands remaining unchanged, but the relative contents of the two ligands being changed, and bimetallic MOF materials are prepared using the same method.

[0041] The synthetic metal raw material is zinc nitrate hexahydrate (Zn). 2+ The ligands 2-methylimidazolium (MIM) and 3-methyl-1,2,4-triazole (MTZ) are dissolved in methanol, with the molar ratio of Zn... 2+The mixture of :mim:mtz:CH3OH = 1:3.6:0.4:1000 was thoroughly mixed at room temperature, and a milky white turbidity immediately formed in the mixed solution. The mixture was placed in a reaction vessel and heated to 110°C in an oven for 6 hours. After natural cooling, the product was collected by centrifugation (15000 rpm, 10 min). The product was washed twice with methanol to remove unreacted metal ions and ligands, and then dried in an oven to obtain the clustered polyhedral-double ligand MOF material.

[0042] Figure 5 The X-ray diffraction patterns of the polyhedral-dual-ligand MOF and ZIF-8 are shown. Since the relative content of mtz is still low, it has the same diffraction peak as ZIF-8, which means that the material has the same topological structure as ZIF-8.

[0043] Figure 6 The image shows the SEM image of the polyhedral-double ligand MOF of this cluster. The SEM test results show that the material morphology is still quite different from ZIF-8 in Example 1. The grain size varies greatly, and the grains agglomerate and tend to merge.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; modifications or equivalent substitutions may be made to the technical solutions described in the foregoing embodiments, and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a modular metal-organic framework material, characterized in that, Includes the following steps: (1) Dissolve the divalent metal nitrate, halide or carboxylate of Zn with bidentate or polydentate ligands in a solvent and stir to dissolve; (2) The mixed solution obtained in step (1) is placed in a sealed container and reacted at 110°C for 1-6 h: (3) Cool, centrifuge to separate the product, wash with solvent and dry to obtain the final product; The bidentate ligand mentioned in step (1) is 2-methylimidazole; The polydentate ligand mentioned in step (1) is 3-methyl-1,2,4-triazole; The solvent mentioned in step (1) is methanol; In step (1), the molar ratio of metal, total ligand, and solvent is 1:4:1000; In step (1), the molar ratio of bidentate ligand to polydentate ligand is 4:

1.

2. The preparation method according to claim 1, characterized in that, The reaction in step (2) is specifically heated in an oven or in a microwave.

3. The modular metal-organic framework material prepared by the preparation method according to any one of claims 1-2.

4. The application of the modular metal-organic framework material as described in claim 3 in the preparation of adsorbents, proton conduction membranes, and gas separation membranes.

Images