Metal organic framework material HP-UiO-66-F4 as well as room-temperature rapid preparation method and application thereof

Abstract

The invention relates to a layered mesoporous metal organic framework material HP-UiO-66-F4 and a room-temperature rapid preparation method and application thereof, and the preparation method comprises the following steps: (1) respectively dissolving a zirconium source and an organic ligand in deionized water, adding a proper amount of acetic acid, uniformly mixing, stirring at room temperature, centrifuging, and discarding supernate to obtain an intermediate product; and (2) carrying out vacuum drying on the intermediate product obtained in the step (1) to obtain the layered mesoporous metal organic framework material HP-UiO-66-F4. Compared with the prior art, the method has the advantages that toxic organic solvents such as N, N-dimethylformamide in a traditional solvothermal method are not used, the HP-UiO-66-F4 can be synthesized only by stirring in the deionized water at room temperature and drying, the condition is mild, the yield is higher, the synthesis time is greatly shortened, the product purity is extremely high, the step of activating the product can be omitted, and the method is suitable for industrial production. The large-scale synthesis of the metal organic framework material becomes great possible; immobilization of dextranase is successfully achieved, and the method can be applied to immobilization of large-size enzyme.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal organic framework materials, particularly a layered mesoporous metal organic framework material HP-UiO-66-F4, and in particular relates to a layered mesoporous metal organic framework material HP-UiO-66-F4, a rapid room temperature preparation method thereof, and an application of immobilized dextranase. Background Art

[0002] Hierarchical porous metal-organic frameworks (HP-MOFs) have attracted much attention due to their significant advantages in catalysis, adsorption and other fields due to their multi-level pore structures. Although traditional synthetic strategies (such as ligand extension, template assistance and defect engineering) can construct mesopores, the precise control of the mesopore size (2-50nm) is still challenging. This parameter is crucial for selective catalysis and adsorption performance. In the template-free method, water and monocarboxylic acids, as competitive modulators, exhibit a unique regulation mechanism: water accelerates nucleation by hydrolyzing metal salts and dicarboxylic acid ligands, reducing the grain size and inducing aggregated mesopores; monocarboxylic acids inhibit nucleation through competitive coordination and promote the formation of large single crystals. The antagonistic effect of the two on the nucleation rate indicates that the synergistic regulation of the ratio of the two modulators can achieve the directional design of crystal size and pore structure. This discovery provides a new idea for the rational synthesis of HP-MOF.

[0003] UiO-66(Zr) is a metal-organic framework (MOF) composed of the inorganic metal unit Zr6O4(OH)4 and twelve terephthalic acid ligands, forming a tetrahedral and octahedral cage. Each octahedral cage has eight faces connected to a tetrahedral cage, forming a three-dimensional structure. This makes it a MOF with higher structural strength and better tolerance to extreme external conditions (such as pH and temperature) among existing MOF materials, making it a very promising potential support for enzyme immobilization.

[0004] The following literature reports the synthesis of UiO-66.

[0005] The open literature Advanced Functional Materials, 31(30) reported a method for synthesizing hierarchical mesoporous UiO-66(Zr), wherein BDC and ZrCl4 dissolved in a mixed solvent of N,N-dimethylformamide / acetic acid / deionized water were placed in a polytetrafluoroethylene autoclave and heated at 123°C for 24 hours. The isolated white microcrystalline powder was soaked in anhydrous methanol at room temperature for 3 days. During this period, the extract was decanted and fresh methanol was added every day. The sample was then treated with anhydrous dichloromethane for 3 days. The sample was dried under dynamic vacuum at 80°C for 12 hours to obtain the final product HP-UiO-66(Zr). This method requires the consumption of a large amount of N,N-dimethylformamide, the process is cumbersome and the synthesis time is long.

[0006] The open literature Inorganic Chemistry, 54(10), 4862-4868 reports a method for synthesizing a mild green UiO-66(Zr). The organic ligand and Zr(NO3)4 are suspended in 50 mL of a water / acetic acid mixed solvent in different proportions. The reaction mixture is heated under reflux for 24 hours to obtain a powder product. The product is soaked in anhydrous methanol at room temperature for 3 days. During this period, the extract is decanted and fresh methanol is added every day. The sample is then treated with anhydrous dichloromethane for 3 days. This process is performed to wash away residual reagents in the pores. After removing dichloromethane by decantation, the sample is dried under dynamic vacuum at 120°C for 24 hours to obtain the final product. The UiO-66(Zr) synthesized by this method has better crystallinity, but the reaction time is longer.

[0007] Publication Dalton Transactions, 2015, 44(31): 14019-14026 reports a microwave-assisted synthesis method for UiO-66(Zr). ZrCl4 and terephthalic acid are dissolved in N,N-dimethylformamide solvent, acetic acid and water are added as auxiliary agents, and microwave heating is performed at 120°C for 15 minutes. After cooling to room temperature, the solid is collected by centrifugation, washed with N,N-dimethylformamide and acetone in sequence, and dried at 60°C to obtain UiO-66(Zr) powder. This method is relatively time-consuming, but requires the addition of acetic acid and water as auxiliary agents. Moreover, microwave-assisted heating is difficult to scale up experimentally and achieve industrial production.

[0008] All reported UiO-66(Zr) synthesis methods require heating or pretreatment of the reactants, resulting in complex, demanding processes and long reaction times exceeding 24 hours. These processes also require the use of toxic organic solvents such as N,N-dimethylformamide. Furthermore, the washing and activation processes are cumbersome, costly, and difficult to scale up for production. Summary of the Invention

[0009] The present invention aims to overcome the shortcomings of the prior art by providing a layered mesoporous metal-organic framework (HP-UiO-66-F4) and its rapid room-temperature preparation method and applications. Through rapid, efficient, and simple synthesis, the layered mesoporous metal-organic framework (HP-UiO-66-F4) is prepared in a green solvent system, enabling the industrial production and application of this novel material.

[0010] The purpose of the present invention can be achieved by the following technical solutions:

[0011] The first aspect of the present invention provides a layered mesoporous metal-organic framework material HP-UiO-66-F4 and a rapid preparation method thereof at room temperature, comprising the following steps:

[0012] (1) Dissolve the zirconium source and the organic ligand in deionized water, add an appropriate amount of acetic acid and mix well, place at room temperature and stir, centrifuge and discard the supernatant to obtain an intermediate product;

[0013] (2) vacuum drying the intermediate product obtained in step (1) to obtain the layered mesoporous metal-organic framework material HP-UiO-66-F4.

[0014] As a preferred technical solution, the zirconium source is zirconyl nitrate.

[0015] As a preferred technical solution, the organic ligand is tetrafluoroterephthalic acid.

[0016] As a preferred technical solution, the molar ratio of the zirconium source and the organic ligand is (1-2): (2-1).

[0017] As a preferred technical solution, in step (1), the mass ratio of the mixture of the zirconium source and the organic ligand to water is 1:(10-100).

[0018] As a preferred technical solution, in step (1), the volume ratio of acetic acid to water is 1:3.

[0019] As a preferred technical solution, in step (1), the stirring time is 1 hour.

[0020] In the present invention, during the stirring process of step (1), the solution gradually changes from transparent to a white emulsion, the organic ligand completes the deprotonation process, and the zirconium atom in the zirconyl nitrate forms a Zr-O bond with the oxygen atom in the organic ligand. Both reactions are necessary for the formation of UiO-66.

[0021] As a preferred technical solution, in step (2), the heating and drying temperature is 80°C.

[0022] As a preferred technical solution, in step (2), the heating and drying time is 4 hours.

[0023] Compared with existing technologies, this method achieves ultrafast synthesis of nanosized HP-UiO-66-F4 under mild conditions, significantly shortening the synthesis time and simplifying the process. It also avoids the use of high temperatures and toxic organic solvents such as N,N-dimethylformamide, reducing synthesis costs and overcoming the low yields associated with traditional methods. The resulting high-quality layered mesoporous metal-organic framework (MOF) material, HP-UiO-66-F4, makes large-scale MOF synthesis possible.

[0024] The second aspect of the present invention provides a layered mesoporous metal-organic framework material HP-UiO-66-F4, which is obtained by the preparation method.

[0025] The third aspect of the present invention provides an application of the layered mesoporous metal-organic framework material HP-UiO-66-F4, wherein the layered mesoporous metal-organic framework material HP-UiO-66-F4 is used to immobilize dextranase.

[0026] The application includes the following steps: taking a certain amount of the layered mesoporous metal-organic framework material HP-UiO-66-F4, adding a certain amount of dextranase solution of different concentrations, shaking and fixing at room temperature for 12 hours, and then centrifuging to separate the solid. The obtained solid product is washed several times with deionized water, and finally obtained by vacuum freeze-drying to obtain dextranase @HP-UiO-66-F4, and stored at 4°C. The results show that compared with UIO-66 (Zr) synthesized by conventional solvothermal method, the layered mesoporous metal-organic framework material HP-UiO-66-F4 of the present invention has more structural defects, can expose more active sites, and also has a multi-level pore structure such as micro / mesopores, which is conducive to the adsorption and binding of enzymes. Therefore, the layered mesoporous metal-organic framework material HP-UiO-66-F4 obtained by the present invention has a better effect on immobilizing enzymes. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is the XRD pattern of the HP-UiO-66-F4 sample synthesized in Example 1;

[0028] Figure 2 is the XRD pattern of the HP-UiO-66-F4 sample synthesized in Example 2;

[0029] Figure 3 is the XRD pattern of the HP-UiO-66-F4 sample synthesized in Example 3;

[0030] Figure 4 This is a curve diagram showing the effect of different dextranase concentrations on the immobilized amount of dextranase@HP-UiO-66-F4 in Example 4. DETAILED DESCRIPTION

[0031] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] Example 1

[0033] Weigh 0.714g of tetrafluoroterephthalic acid and 0.693g of zirconium oxynitrate respectively, add 25ml of water to dissolve, mix well, add 17ml of acetic acid and stir under magnetic stirring conditions at 500rpm for 1h. After the reaction is completed, the white emulsion obtained after stirring is centrifuged and the supernatant is discarded to obtain a white intermediate product. The intermediate product is transferred to a vacuum drying oven and heated and dried at 80℃ for 4h to obtain the final product. XRD characterization analysis ( Figure 1), indicating that the product synthesized in this embodiment is a layered mesoporous metal-organic framework material HP-UiO-66-F4 with good crystallinity.

[0034] Example 2

[0035] 1.428g of tetrafluoroterephthalic acid and 0.693g of zirconium oxynitrate were weighed and dissolved in 50ml of water respectively. After mixing, 34ml of acetic acid was added and stirred at 500rpm under magnetic stirring for 1h. After the reaction was completed, the white emulsion obtained after stirring was centrifuged and the supernatant was discarded to obtain a white intermediate product. The intermediate product was transferred to a vacuum drying oven and heated and dried at 80℃ for 4h to obtain the final product. XRD characterization analysis ( Figure 2 ), indicating that the product synthesized in this embodiment is a layered mesoporous metal-organic framework material HP-UiO-66-F4 with good crystallinity.

[0036] Example 3

[0037] Weigh 0.714g of tetrafluoroterephthalic acid and 1.386g of zirconium oxynitrate respectively, add 50ml of water to dissolve, mix well, add 34ml of acetic acid and stir under magnetic stirring at 500rpm for 1h. After the reaction is completed, the white emulsion obtained after stirring is centrifuged and the supernatant is discarded to obtain a white intermediate product. The intermediate product is transferred to a vacuum drying oven and heated and dried at 80℃ for 4h to obtain the final product. XRD characterization analysis ( Figure 3 ), indicating that the product synthesized in this embodiment is a layered mesoporous metal-organic framework material HP-UiO-66-F4 with good crystallinity.

[0038] Example 4

[0039] Dextranase solutions of different concentrations were prepared using 0.02M acetate buffer solution, pH = 5.0. 20 mg of HP-UiO-66-F4 synthesized in Example 1 was added and shaken at room temperature for 12 hours. The solid was then centrifuged and washed three times with water. The supernatant was collected and the protein content of the supernatant was determined by PBS method to calculate the immobilized capacity. The effect curve of different dextranase concentrations on the immobilized capacity of dextranase@HP-UiO-66-F4 is shown in Figure 2. Figure 4 The enzyme@HP-UiO-66-F4 of the present invention exhibits excellent immobilized enzyme capability.

[0040] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A method for rapid preparation of a layered mesoporous metal-organic framework material HP-UiO-66-F4 at room temperature, characterized in that: The following steps are involved: (1) Dissolve the zirconium source and the organic ligand in deionized water, add an appropriate amount of acetic acid and mix well, place at room temperature and stir, centrifuge and discard the supernatant to obtain an intermediate product; (2) vacuum drying the intermediate product obtained in step (1) to obtain the layered mesoporous metal-organic framework material HP-UiO-66-F4.

2. The room temperature rapid preparation method of the layered mesoporous metal-organic framework material HP-UiO-66-F4 according to claim 1, characterized in that: The zirconium source is zirconyl nitrate.

3. The room temperature rapid preparation method of the layered mesoporous metal-organic framework material HP-UiO-66-F4 according to claim 1, characterized in that: The organic ligand is tetrafluoroterephthalic acid.

4. The room temperature rapid preparation method of the layered mesoporous metal organic framework material HP-UiO-66-F4 according to any one of claims 1 to 3, characterized in that: The molar ratio of the zirconium source and the organic ligand is (1-2): (2-1).

5. The room temperature rapid preparation method of the layered mesoporous metal-organic framework material HP-UiO-66-F4 according to claim 1, characterized in that: In step (1), the volume ratio of acetic acid to water is 1:

3.

6. The room temperature rapid preparation method of the layered mesoporous metal-organic framework material HP-UiO-66-F4 according to claim 1, characterized in that: In step (1), the stirring time is 1 h.

7. The room temperature rapid preparation method of the layered mesoporous metal-organic framework material HP-UiO-66-F4 according to claim 1, characterized in that: In step (2), the vacuum drying temperature is 80°C.

8. The room temperature rapid preparation method of the layered mesoporous metal-organic framework material HP-UiO-66-F4 according to claim 1, characterized in that: In step (2), the heating and drying time is 4 hours.

9. A layered mesoporous metal-organic framework material HP-UiO-66-F4, characterized in that The method is as described in any one of claims 1 to 8.

10. The use of the layered mesoporous metal-organic framework material HP-UiO-66-F4 according to claim 9, characterized in that: The layered mesoporous metal-organic framework material HP-UiO-66-F4 was used to immobilize dextranase.

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