A multi-component mTV-UiO-66 and a method of synthesizing the same

Abstract

This invention provides a multi-component MTV-UiO-66 and its synthesis method, belonging to the field of metal-organic framework (MOF) material synthesis technology. The method involves mixing ZrOCl2·8H2O, terephthalic acid, and a modified ligand in a container. The resulting solution is then added to a solvent, followed by a regulator, and stirred thoroughly to dissolve and form a homogeneous solution. The modified ligand is selected from one or a mixture of 2-aminoterephthalic acid and 2-nitroterephthalic acid. The homogeneous solution is transferred to a reaction vessel, which is then placed in an oven for reaction. After post-treatment, multi-component MTV-UiO-66 is obtained. This invention achieves precise control of the pore microenvironment by introducing one or more different functional groups into the MOF framework, enabling the material to possess diverse active sites and selectively bind specific guest molecules, thus meeting the application requirements for special functional materials in multiple fields such as catalysis, adsorption, and separation.

Description

Technical Field

[0001] This invention belongs to the field of metal-organic framework (MOF) synthesis technology, specifically relating to a multi-component MTV-UiO-66 and its synthesis method. Background Technology

[0002] Metal-organic frameworks (MOFs), also known as metal-organic frameworks, metal-organic skeleton materials, metal-organic complexes, or coordination polymers, are self-assembled from metal ions or ion clusters and multidentate organic ligands, possessing properties common to both organic and inorganic materials. Due to their designable pore structures and tunable functions, MOFs have broad application prospects in catalysis, adsorption, and separation. UiO-66, a classic MOF material, has a framework assembled from Zr6 metal clusters and terephthalic acid ligands. Multi-component MTV-UiO-66 materials can be constructed by introducing ligands with different functional groups.

[0003] Currently, no publicly reported methods exist for synthesizing MTV-UiO-66 containing -H, -NH2, and -NO2 functional groups simultaneously. The -NH2 group possesses hydrophilicity and hydrogen bonding capabilities, while the -NO2 group exhibits strong electron-withdrawing and electrostatic interaction properties. Synergistic modification with one or more of these groups can endow UiO-66 with a unique porous microenvironment, suitable for the selective adsorption and release of complex guest molecules. Summary of the Invention

[0004] The purpose of this invention is to provide a multi-component MTV-UiO-66 and its synthesis method. Utilizing the modifiability of MOF materials, one or more different functional groups are introduced into the MOF framework. The addition of these functional groups alters the microenvironment of the MOF material's pores, enabling precise control over this microenvironment. This results in diverse active sites, allowing for the selective binding of specific guest molecules and meeting the application requirements for specialized functional materials in catalysis, adsorption, separation, and other fields. Through multi-ligand synergistic coordination, the stable coexistence and adjustable proportions of multiple functional groups within the UIO-66 framework are achieved, providing a general technical pathway for the design of functionalized MOF materials. Simultaneously, this method must be able to precisely control the type, proportion, and distribution of functional groups to ensure the controllability and stability of the material's properties.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: This invention first provides a method for synthesizing multi-component MTV-UiO-66, comprising: Step 1: Place ZrOCl2·8H2O, terephthalic acid, and the modified ligand in a container and mix them. Add the mixed solution to the solvent, then add the regulator and stir thoroughly to dissolve and form a homogeneous solution. The modified ligand is selected from one or a mixture of 2-aminoterephthalic acid and 2-nitroterephthalic acid. Step 2: Transfer the homogeneous solution from Step 1 to a reaction vessel, place the reaction vessel in an oven for reaction, and after post-processing, obtain the multi-component MTV-UiO-66, i.e., MTV-UiO-66-(H). x (NH2) y (NO2) z .

[0006] Preferably, the molar ratio (mmol) of ZrOCl2·8H2O in step one to the total molar ratio (mmol) of terephthalic acid and modified ligand is 0.25:0.276.

[0007] Preferably, the solvent in step one is N,N-dimethylformamide.

[0008] Preferably, the regulator mentioned in step one is benzoic acid.

[0009] Preferably, the amount of the regulator added in step one is 300 times the total amount of the ligand.

[0010] Preferably, the reaction temperature in step two is 120 °C and the reaction time is 24 h.

[0011] Preferably, the post-processing in step two is as follows: after the reaction is completed, the reaction vessel is allowed to cool naturally to room temperature, the reaction product is centrifuged to remove the supernatant, and the solid product obtained by centrifugation is washed sequentially with N,N-dimethylformamide and ethanol. The washed product is then dried under vacuum.

[0012] The present invention also provides a multi-component MTV-UiO-66 obtained by the above preparation method, the structural formula of which is MTV-UiO-66-(H). x (NH2) y (NO2) z The material is defined as follows: x, y, and z represent the proportions of -H, -NH2, and -NO2 groups in the material ligands, respectively, and x+y+z=1, 0≤x≤1, 0≤y≤1, and 0≤z≤1.

[0013] Preferably, the structural formula of the multi-component MTV-UiO-66 is MTV-UiO-66-(H). 0.9 (NH2) 0.1 MTV-UiO-66-(H) 0.7 (NH2) 0.3MTV-UiO-66-(H) 0.5 (NH2) 0.5 MTV-UiO-66-(H) 0.5 (NO2) 0.5 .

[0014] Beneficial effects of the present invention This invention provides a multi-component MTV-UiO-66 and its synthesis method. The method uses ZrOCl2·8H2O as the metal source, terephthalic acid as the basic ligand, and introduces 2-aminoterephthalic acid and 2-nitroterephthalic acid as modifying ligands, achieving the precise introduction of -H, -NH2, and -NO2 functional groups into the UIO-66 framework. The unique chemical properties of these functional groups produce synergistic effects. The hydrogen bond donor capability of -NH2 and the strong electron-withdrawing and electrostatic interaction characteristics of -NO2 enable the porous microenvironment of the material to possess multiple interaction modes, allowing for specific binding with different types of guest molecules. By precisely controlling the ligand ratio, MTV-UiO-66 materials with unique porous microenvironments and multifunctional active sites can be constructed. This material exhibits a multi-functional group synergistic effect and has broad application prospects in catalysis, adsorption, and separation. This synthesis method has the advantages of being simple to operate and highly reproducible. The prepared MTV-UiO-66 material has good stability, providing new ideas and methods for the functionalization and practical application of metal-organic framework materials. Attached Figure Description

[0015] Figure 1 The MTV-UiO-66-(H) prepared in this invention x (NH2) y Powder X-ray diffraction pattern of the sample.

[0016] Figure 2 The UiO-66 and MTV-UiO-66-(H) prepared in this invention 0.9 (NH2) 0.1 N2 adsorption curves of UiO-66-NH2 sample.

[0017] Figure 3 The MTV-UiO-66-(H) prepared in this invention x (NH2) y Scanning electron microscope image of the sample.

[0018] Figure 4 The MTV-UiO-66-(H) prepared in this invention x (NH2) y NMR spectrum of the sample.

[0019] Figure 5 The MTV-UiO-66-(H) prepared in this invention x (NO2) y Powder X-ray diffraction pattern of the sample. Detailed Implementation

[0020] This invention first provides a method for synthesizing multi-component MTV-UiO-66, comprising: Step 1: Mix ZrOCl2·8H2O, terephthalic acid, and the modified ligand in a container. Add the mixed solution to a solvent, preferably N,N-dimethylformamide (DMF), to dissolve the raw materials and promote the reaction. Then add a regulator, preferably benzoic acid, and stir thoroughly to dissolve the metal source and ligand, forming a homogeneous solution. The modified ligand is selected from one or a mixture of 2-aminoterephthalic acid and 2-nitroterephthalic acid. The molar ratio (mmol) of ZrOCl2·8H2O to the total molar ratio (mmol) of terephthalic acid and the modified ligand is 0.25:0.276. The amount of regulator added is preferably 300 times the total amount of the ligand.

[0021] Step 2: Transfer the homogeneous solution from Step 1 to a reaction vessel, seal the reaction vessel, and place the reaction vessel in an oven for reaction. The preferred reaction temperature is 120 ℃, and the preferred reaction time is 24 h. During the reaction, the ligands and metal ions undergo coordination reactions to gradually form an MTV-UiO-66 crystal structure. After post-processing, multi-component MTV-UiO-66 is obtained.

[0022] According to the present invention, ZrOCl2·8H2O is selected as the metal source, terephthalic acid is used as the basic ligand, and one or a mixture of 2-aminoterephthalic acid and 2-nitroterephthalic acid are used as the modifying ligand; 2-aminoterephthalic acid is used to introduce -NH2 group, and 2-nitroterephthalic acid is used to introduce -NO2 group.

[0023] According to the present invention, the post-processing is specifically as follows: after the reaction is completed, the reaction vessel is allowed to cool naturally to room temperature, the reaction product is centrifuged to remove the supernatant, and the solid product obtained by centrifugation is washed three times with N,N-dimethylformamide and ethanol in sequence to thoroughly remove unreacted ligands, metal sources and impurities generated during the reaction. The washed product is dried in a vacuum environment for 24 hours to obtain pure multi-component MTV-UiO-66 material.

[0024] According to this invention, different application requirements can be controlled by adjusting the types and proportions of functional groups in MOF materials. For example, in catalytic applications, if it is necessary to enhance the adsorption capacity of the material for positively charged substrates, the proportion of 2-nitroterephthalic acid can be appropriately increased; if the focus is on utilizing hydrogen bonding, the proportion of 2-aminoterephthalic acid can be increased.

[0025] The present invention also provides a multi-component MTV-UiO-66 obtained by the above preparation method, the structural formula of which is MTV-UiO-66-(H). x (NH2) y (NO2) z The material, wherein x, y, and z represent the proportions of -H, -NH2, and -NO2 groups in the material ligands, respectively, and x + y + z = 1, 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, and 0 ≤ z ≤ 1. Preferably, the structural formula of the multi-component MTV-UiO-66 is MTV-UiO-66-(H). 0.9 (NH2) 0.1 MTV-UiO-66-(H) 0.7 (NH2) 0.3 MTV-UiO-66-(H) 0.5 (NH2) 0.5 MTV-UiO-66-(H) 0.5 (NO2) 0.5 .

[0026] The present invention will be further described in detail below with reference to specific embodiments. All raw materials involved in the embodiments are commercially available.

[0027] Example 1 0.25 mmol ZrOCl2·8H2O, 0.2484 mmol terephthalic acid, and 0.0276 mmol 2-aminoterephthalic acid were added to 5 ml of N,N-dimethylformamide. 1.25 g benzoic acid was added as a regulator. The mixture was stirred thoroughly to dissolve the precipitate. The reaction vessel was then heated and placed in an oven for 24 h at 120 °C. After the reaction, the vessel was allowed to cool naturally to room temperature. The reaction product was centrifuged, and the supernatant was removed. The solid product obtained by centrifugation was washed three times, successively with N,N-dimethylformamide and ethanol, to thoroughly remove unreacted ligands, metal sources, and impurities generated during the reaction. The washed product was dried under vacuum for 24 h to obtain UiO-66-(H). 0.9 (NH2) 0.1 sample.

[0028] Example 2 0.193 mmol of terephthalic acid and 0.0828 mmol of 2-aminoterephthalic acid were added together with 0.25 mmol of ZrOCl2·8H2O to 5 ml of N,N-dimethylformamide. 1.25 g of benzoic acid was added as a regulator. The mixture was stirred thoroughly to dissolve the terephthalic acid, and then heated in a reaction vessel. The reaction vessel was placed in an oven for 24 h at 120 °C. After the reaction, the reaction vessel was allowed to cool naturally to room temperature. The reaction product was centrifuged, and the supernatant was removed. The solid product obtained by centrifugation was washed three times, successively with N,N-dimethylformamide and ethanol, to thoroughly remove unreacted ligands, metal sources, and impurities generated during the reaction. The washed product was dried under vacuum for 24 h to obtain UiO-66-(H). 0.7 (NH2) 0.3 The sample is defined as follows: x represents the proportion of terephthalic acid in the MOF material ligand, and y represents the proportion of 2-nitroterephthalic acid in the MOF material ligand.

[0029] Example 3 0.138 mmol of terephthalic acid and 0.138 mmol of 2-aminoterephthalic acid were added together with 0.25 mmol of ZrOCl2·8H2O to 5 ml of N,N-dimethylformamide. 1.25 g of benzoic acid was added as a regulator. The mixture was stirred thoroughly to dissolve the terephthalic acid, and then heated in a reaction vessel. The reaction vessel was placed in an oven for 24 h at 120 °C. After the reaction, the reaction vessel was allowed to cool naturally to room temperature. The reaction product was centrifuged, and the supernatant was removed. The solid product obtained by centrifugation was washed three times, successively with N,N-dimethylformamide and ethanol, to thoroughly remove unreacted ligands, metal sources, and impurities generated during the reaction. The washed product was dried under vacuum for 24 h to obtain UiO-66-(H). 0.5 (NH2) 0.5 sample.

[0030] Figure 1 The MTV-UiO-66-(H) prepared in this invention 0.9 (NH2) 0.1 MTV-UiO-66-(H) 0.7 (NH2) 0.3 MTV-UiO-66-(H) 0.5 (NH2) 0.5 The powder X-ray diffraction pattern of the sample. As can be seen from the figure, the diffraction peak positions of the sample are consistent with the standard UiO-66 pattern, indicating that after introducing different amounts of -NH2 groups, the material still maintains the typical crystal structure of UiO-66 and no framework collapse occurs, proving that 2-aminoterephthalic acid has successfully coordinated with the Zr6 metal cluster and incorporated into the framework.

[0031] Figure 2 The UiO-66 and MTV-UiO-66-(H) prepared in this invention 0.9 (NH2) 0.1 The N2 adsorption curves of the UiO-66-NH2 sample are shown in the figure. It can be seen from the figure that all three samples exhibit typical type IV adsorption-desorption curves, indicating that the material has a mesoporous structure; MTV-UiO-66-(H) 0.9 (NH2) 0.1 The specific surface area is between that of UiO-66 and UiO-66-NH2, indicating that functional group modification has a regulatory effect on the pore structure of the material. Furthermore, the hysteresis loop shape of the desorption curve and the adsorption curve are similar, proving that the pore structure of the material is stable.

[0032] Figure 3 The MTV-UiO-66-(H) prepared in this invention x (NH2) y Scanning electron microscope image of the sample. The image shows that the sample exhibits a regular octahedral morphology, consistent with the traditional morphology of UiO-66. With the increase of the proportion of 2-aminoterephthalic acid, the crystal morphology remains intact, without obvious agglomeration or morphological distortion, indicating that the introduction of the modified ligand did not disrupt the crystal growth pattern and the material has good dispersion.

[0033] Figure 4 The MTV-UiO-66-(H) prepared in this invention x (NH2) y The NMR spectrum of the sample shows that characteristic hydrogen peaks on the benzene ring of the ligand appear in the range of 7.0–7.8 ppm. As the proportion of 2-aminoterephthalic acid (y value) increases, the intensity of the characteristic peaks corresponding to the ortho, meta, and para hydrogens of -NH2 gradually changes, and the peak shapes are symmetrical without impurity peaks, proving that the ligand is uniformly distributed in the framework and no local aggregation occurs. At the same time, the actual ratio of x and y can be calculated by integrating the characteristic peak area, which is basically consistent with the feed ratio, verifying the controllability of the functional group ratio.

[0034] Example 4 0.138 mmol of terephthalic acid and 0.138 mmol of 2-nitroterephthalic acid were added together with 0.25 mmol of ZrOCl2·8H2O to 5 ml of N,N-dimethylformamide. 1.25 g of benzoic acid was added as a regulator. The mixture was stirred thoroughly to dissolve the terephthalic acid, and then heated in a reaction vessel. The reaction vessel was placed in an oven for 24 h at 120 °C. After the reaction, the reaction vessel was allowed to cool naturally to room temperature. The reaction product was centrifuged, and the supernatant was removed. The solid product obtained by centrifugation was washed three times, successively with N,N-dimethylformamide and ethanol, to thoroughly remove unreacted ligands, metal sources, and impurities generated during the reaction. The washed product was dried under vacuum for 24 h to obtain UiO-66-(H). 0.5 (NO2) 0.5 sample.

[0035] Figure 5 The MTV-UiO-66-(H) prepared in this invention 0.5 (NO2) 0.5 The powder X-ray diffraction pattern of the sample. As can be seen from the figure, the diffraction peak positions of the sample are consistent with the standard UiO-66 pattern, indicating that after introducing different amounts of -NO2 groups, the material still maintains the typical crystal structure of UiO-66 and no framework collapse occurs, proving that 2-nitroterephthalic acid has successfully coordinated with the Zr6 metal cluster and incorporated into the framework.

[0036] Similarly, MOF materials with any one or more functional groups such as -NH2, -NO2, -Cl2, -F, -OR, and -COOH can be prepared.

[0037] This synthetic method successfully introduces various functional groups (such as -H, -NH2, and -NO2) into the UIO-66 framework. The unique properties of these functional groups produce synergistic effects, enabling the microenvironment of the material's pores to exhibit multiple interaction modes. By precisely adjusting the proportions of different functional groups, the strength of the interaction between the material and guest molecules can be accurately controlled at the microscopic level, thereby achieving precise control over the material's properties at the macroscopic level. In the field of adsorption, the adsorption selectivity and adsorption capacity of the material can be customized according to the characteristics of the guest molecules; in catalytic reactions, different functional groups synergistically provide diverse active sites for the reaction, improving catalytic efficiency and selectivity.

[0038] This synthetic method is simple and highly reproducible. The raw materials are common and readily available, such as ZrOCl₂·8H₂O, terephthalic acid, 2-aminoterephthalic acid, and 2-nitroterephthalic acid. The preparation process and post-treatment steps are relatively simple to operate, with undemanding requirements for experimental equipment, which is beneficial for large-scale production. The washing and drying steps in the post-treatment process effectively remove impurities, ensuring the purity and stability of the material. Furthermore, the process is highly reproducible, yielding materials with similar properties in each preparation.

[0039] The MTV-UiO-66 material synthesized by this method exhibits good stability. Post-processing further enhances this stability by repeatedly washing to remove unreacted raw materials and impurities, preventing their impact on the material's structure and properties. Vacuum drying ensures the material's structure remains intact, enabling it to maintain stable performance in various application environments and extending its service life.

[0040] The MTV-UiO-66 material prepared by this synthesis method has a wide range of applications. In gas adsorption and separation, it can efficiently separate mixed gases by utilizing the specific interactions between different functional groups and gas molecules. In the field of catalysis, its abundant active sites and tunable microenvironment provide an excellent catalytic platform for various chemical reactions. Furthermore, this synthesis method provides a reference for the synthesis of other multifunctional MOF materials, contributing to expanding the application of the entire MOF material family in more fields.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for synthesizing multi-component MTV-UiO-66, characterized in that, include: Step 1: Place ZrOCl2·8H2O, terephthalic acid, and the modified ligand in a container and mix them. Add the mixed solution to the solvent, then add the regulator and stir thoroughly to dissolve and form a homogeneous solution. The modified ligand is selected from one or a mixture of 2-aminoterephthalic acid and 2-nitroterephthalic acid. Step 2: Transfer the homogeneous solution from Step 1 to a reaction vessel, place the reaction vessel in an oven for reaction, and after post-processing, obtain the multi-component MTV-UiO-66, i.e., MTV-UiO-66-(H). x (NH2) y (NO2) z .

2. The method for synthesizing a multi-component MTV-UiO-66 according to claim 1, characterized in that, The molar ratio (mmol) of ZrOCl2·8H2O mentioned in step one is 0.25 mmol to the total molar ratio (mmol) of terephthalic acid and modified ligand.

3. The method for synthesizing a multi-component MTV-UiO-66 according to claim 1, characterized in that, The solvent mentioned in step one is N,N-dimethylformamide.

4. The method for synthesizing a multi-component MTV-UiO-66 according to claim 1, characterized in that, The regulator mentioned in step one is benzoic acid.

5. The method for synthesizing a multi-component MTV-UiO-66 according to claim 1, characterized in that, The amount of regulator added in step one is 300 times the total amount of ligand.

6. The method for synthesizing a multi-component MTV-UiO-66 according to claim 1, characterized in that, The reaction temperature in step two is 120 °C, and the reaction time is 24 h.

7. The method for synthesizing a multi-component MTV-UiO-66 according to claim 1, characterized in that, The post-processing described in step two is as follows: After the reaction is completed, the reaction vessel is allowed to cool naturally to room temperature. The reaction product is then centrifuged to remove the supernatant. The solid product obtained by centrifugation is washed sequentially with N,N-dimethylformamide and ethanol. The washed product is then dried under vacuum.

8. The multi-component MTV-UiO-66 obtained by the preparation method according to claim 1, characterized in that, Its structural formula is MTV-UiO-66-(H). x (NH2) y (NO2) z The material is defined as follows: x, y, and z represent the proportions of -H, -NH2, and -NO2 groups in the material ligands, respectively, and x+y+z=1, 0≤x≤1, 0≤y≤1, and 0≤z≤1.

9. The multi-component MTV-UiO-66 according to claim 8, characterized in that, Its structural formula is MTV-UiO-66-(H). 0.9 (NH2) 0.1 MTV-UiO-66-(H) 0.7 (NH2) 0.3 MTV-UiO-66-(H) 0.5 (NH2) 0.5 MTV-UiO-66-(H) 0.5 (NO2) 0.5 .

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