Titanium-based metal organic framework material, and preparation method and application thereof

Abstract

The application provides a titanium-based metal organic framework material and a preparation method and application thereof. The titanium-based metal organic framework material has a chemical formula of Ti8(M 1 )8(M 2 )4, wherein M 1 represents a trivalent anion of a ligand, and M 2 represents a divalent anion of a ligand. The titanium-based metal organic framework has high porosity (for example, 55%) and specific surface area (for example, 544 m 2 / g). The application further provides a preparation method of the titanium-based metal organic framework, and the prepared titanium-based metal organic framework material has a clear single crystal structure.

Description

Technical Field

[0001] This invention belongs to the field of crystal material preparation technology, specifically relating to a titanium-based metal-organic framework material, its preparation method, and its application. Background Technology

[0002] Titanium-based metal-organic frameworks (Ti-MOFs) possess broad application prospects in gas adsorption and separation, catalysis, and drug delivery due to their high hydrothermal stability, porosity, high specific surface area, band structure tunability, easily modifiable pore structure, and abundant host-guest interactions. However, current techniques for synthesizing Ti-MOFs face challenges such as rapid crystallization, easy attainment of crystalline powders, difficulty in structural handling, and difficulty in predicting and controlling the structure. Furthermore, the reported crystal structures of Ti-MOFs are still relatively few. Synthesizing single-crystal structures of Ti-MOFs suitable for X-ray diffraction (XRD) analysis remains challenging. Therefore, the synthesis of novel Ti-MOFs and their single-crystal structures is an urgent priority in this field. Summary of the Invention

[0003] To achieve the above objectives, the present invention provides a titanium-based metal-organic framework material, its preparation method, and its application.

[0004] This invention provides a titanium-based metal-organic framework material, wherein the chemical formula of the titanium-based metal-organic framework material is Ti8(M 1 )8(M 2 )4, where M 1 M represents the trivalent anion of the ligand. 2 The divalent anion representing the ligand;

[0005] The ligand is selected from phenolic hydroxycarboxylic acid ligands, specifically at least one of 2,5-dihydroxyterephthalic acid (H4dobdc), 4,4'-dihydroxy-[1,1'-biphenyl]-3,3'-dicarboxylic acid (H4dobpdc), and 4,4'-dihydroxy-[1,1':4',1'-triphenyl]-3,3'-dicarboxylic acid (H4dotpdc). Further, the phenolic hydroxycarboxylic acid ligand is 4,4'-dihydroxy-[1,1'-biphenyl]-3,3'-dicarboxylic acid (H4dobpdc). The structure of the phenolic hydroxycarboxylic acid ligand is described in detail below. Figure 2 .

[0006] According to an embodiment of the present invention, the molecular formula of the titanium-based metal-organic framework material is, for example, C1. 168 H 88 O 72Ti8, with a chemical formula such as Ti8(Hdobpdc)8(H2dobpdc)4, where Hdobpdc represents the trivalent anion of the ligand 4,4'-dihydroxy-[1,1'-biphenyl]-3,3'-dicarboxylic acid, and H2dobpdc represents the divalent anion of the ligand 4,4'-dihydroxy-[1,1'-biphenyl]-3,3'-dicarboxylic acid.

[0007] According to an embodiment of the present invention, the titanium-based metal-organic framework material is a crystal, preferably a prismatic crystal. Preferably, the crystal is red. Preferably, the crystal is a single crystal.

[0008] According to an embodiment of the present invention, the average length of the titanium-based metal-organic framework material is 50-200 μm, preferably 50-150 μm.

[0009] According to an embodiment of the present invention, the average width of the titanium-based metal-organic framework material is 1-100 μm, preferably 10-50 μm.

[0010] In this invention, the length and width are both numerical values ​​on any plane of the crystal surface.

[0011] According to an embodiment of the present invention, the porosity of the titanium-based metal-organic framework material is not less than 40%, preferably 40%-70%, for example 55%.

[0012] According to an embodiment of the present invention, the specific surface area of ​​the titanium-based metal-organic framework material is not less than 450 m². 2 / g, preferably 450-1000m 2 / g、500-600m 2 / g or 500-550m 2 / g, for example, 544m 2 / g.

[0013] According to an embodiment of the present invention, the titanium-based metal-organic framework material can have substantially the following characteristics: Figure 1 The morphology shown in Figure a.

[0014] According to an embodiment of the present invention, the crystal system of the titanium-based metal-organic framework material is tetragonal, the space group is I41, and the cell parameters are... It is 30.63±0.02; It is 30.63±0.02. The α[°] is 14.30±0.02, α[°] is 90.00, β[°] is 90.00, and γ[°] is 90.00.

[0015] According to an embodiment of the present invention, the crystals of the titanium-based metal-organic framework material have the crystal parameters shown in Table 1 below, as determined by single-crystal X-ray analysis:

[0016] Table 1

[0017]

[0018] According to an embodiment of the present invention, the titanium-based metal-organic framework material is prepared by a solvothermal reaction of a titanium source and the ligand;

[0019] Preferably, the titanium source is selected from titanium trichloride, titanium tetrachloride, isopropyl titanate, n-butyl titanate, titanium(IV) (triethanolamine) isopropanol, 2-ethyl-1-hexanol titanium, titanium trichlorocerocene, titanium dichlorocerocene, etc., and is preferably at least one of isopropyl titanate, n-butyl titanate, titanium(IV) (triethanolamine) isopropanol and titanium dichlorocerocene.

[0020] According to an embodiment of the present invention, the titanium-based metal-organic framework material can have substantially the following characteristics: Figure 1 The structural diagrams and topology types shown in C and D are shown in the figure.

[0021] According to an embodiment of the present invention, the titanium center of the titanium-based metal-organic framework material is octahedral coordinated, with three ligands coordinated to the titanium center in the form of phenolic hydroxyl and carboxyl oxygen chelates, while the other carboxyl oxygen does not participate in coordination; the titanium center is connected by organic ligands to form a three-dimensional framework with an SRS-type topological network. This framework material has two opposite configurations, each being triple-interpenetrated, and the two types of frameworks interpenetrate each other, ultimately forming a six-fold interpenetrated structure.

[0022] According to embodiments of the present invention, the crystals of the titanium-based metal-organic framework material exhibit solvent stability. For example, the crystals are stable for at least 24 hours in N,N-dimethylformamide (DMF), ethanol (EtOH), ethyl acetate (EA), acetonitrile (CH3CN), 1,4-dioxane, or H2O.

[0023] This invention also provides a method for preparing the above-mentioned titanium-based metal-organic framework material, the method comprising the following steps:

[0024] 1) Using titanium source and ligand as raw materials, a mixture is obtained through a solvothermal reaction after adding a reaction solvent;

[0025] 2) The mixture after the reaction is separated and purified to obtain the titanium-based metal-organic framework material.

[0026] According to an embodiment of the present invention, the titanium source and ligand have the selections shown above.

[0027] According to an embodiment of the present invention, the molar ratio of the titanium source to the ligand is 1:(1-10), preferably 1:(3-6), for example 1:4.

[0028] According to an embodiment of the present invention, the solvent is a mixture of acidic solvents and other types of solvents.

[0029] Preferably, the acid solvent can be formic acid, acetic acid, propionic acid, benzoic acid, hydrochloric acid, etc., with acetic acid being the most preferred.

[0030] Preferably, the other type of solvent can be at least one of 1,4-dioxane, tetrahydrofuran, benzyl alcohol, and N,N-dimethylformamide, and more preferably at least one of tetrahydrofuran and 1,4-dioxane.

[0031] Furthermore, the volume ratio of the other type of solvent to acetic acid is (3-7):1, preferably 4:1 or 5:1.

[0032] According to an embodiment of the present invention, the temperature of the solvothermal reaction can be 120-190°C, preferably 140-180°C, such as 160°C.

[0033] According to an embodiment of the present invention, the solvothermal reaction time can be 5-10 days; more preferably 6-9 days, such as 7 days. For example, the reaction can be carried out at 140°C for 9 days, or at 160°C for 7 days, or at 180°C for 6 days.

[0034] According to an embodiment of the present invention, the pressure of the solvothermal reaction is not specifically limited, and any pressure known in the art can be used, such as atmospheric pressure or high pressure.

[0035] According to an embodiment of the present invention, the solvothermal reaction can be carried out in a pressure vessel known in the art, as long as it has corrosion resistance and pressure resistance, for example, in a polytetrafluoroethylene pressure vessel.

[0036] According to an embodiment of the present invention, the preparation method further includes: step 3) cleaning and drying the titanium-based metal-organic framework material, preferably drying it at room temperature.

[0037] Preferably, the cleaning solvent is selected from at least one of alcohol solvents, ester solvents, amide solvents, ethyl acetate, acetonitrile, and 1,4-dioxane.

[0038] For example, the alcohol solvent is selected from at least one of methanol, ethanol, isopropanol, and n-propanol.

[0039] For example, the amide solvent is selected from at least one of N,N-dimethylformamide (DMF), N,N-dimethylhexamethylene (DMA), N-methylpyrrolidone (NMP), N,N-dimethylpropionamide (DMP), N,N-diethylpropionamide (DEP), or N,N-diethylacetamide (DEA).

[0040] The present invention also provides the application of the above-mentioned titanium-based metal-organic framework materials in the fields of gas adsorption and separation, photoelectrocatalysis, and drug sustained release.

[0041] Beneficial effects

[0042] The preparation method provided by this invention overcomes the problems of conventional Ti-MOF synthesis, such as rapid crystallization, easy acquisition of crystalline powder, difficulty in structural processing, and difficulty in predicting and controlling the structure. The preparation method of this invention can obtain crystals with suitable X-ray diffraction (XRD) analysis. Furthermore, the post-processing method is simple and easy to implement, requiring only washing with an amide solvent and drying at room temperature to obtain the crystalline product. The preparation method of this invention is simple, the crystalline product is easy to separate, and it meets the requirements of green environmental protection.

[0043] The titanium-based metal-organic framework of the present invention has high porosity (e.g., 55%) and specific surface area (e.g., 544 m²). 2 / g).

[0044] The titanium-based metal-organic framework material prepared by the method of the present invention has a well-defined single-crystal structure, which provides a good theoretical model for further explanation of the structure-property relationship in subsequent performance exploration. Attached Figure Description

[0045] Figure 1 (a) Optical microscope image, (b) synthesis route, (c) structure and (d) topology analysis of the Ti-MOFs material of Example 1;

[0046] Figure 2 The structure of the phenolic hydroxycarboxylic acid ligand described in this invention;

[0047] Figure 3 This is a schematic diagram of the powder XRD pattern of the Ti-MOFs material in Example 1;

[0048] Figure 4 Thermogravimetric analysis (TGA) curves of the Ti-MOFs material in Example 1;

[0049] Figure 5 This is an infrared (IR) schematic diagram of the Ti-MOFs material in Example 1;

[0050] Figure 6This is a gas adsorption diagram of CO2 in the Ti-MOFs material of Example 1;

[0051] Figure 7 This is a schematic diagram of the ultraviolet-visible diffuse reflectance spectrum of the Ti-MOFs material in Example 1;

[0052] Figure 8 This is a schematic diagram illustrating the stability of the Ti-MOFs material in Example 1 after immersion in different solvents for 24 hours.

[0053] Figure 9 The light response curve is shown under visible light periodic illumination in Application Example 1. Detailed Implementation

[0054] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0055] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0056] The single-crystal X-ray diffraction data of this invention were collected using Rigaku's XtaLAB Synergy diffractometer.

[0057] The single-crystal structure analysis of this invention was performed using Rigaku's Supernova single-crystal diffractometer from Japan.

[0058] The X-ray powder diffraction pattern of this invention uses Cu-Kα rays as the X-ray source.

[0059] Example 1

[0060] like Figure 1 The route shown in (b) involves placing a mixture of isopropyl titanate (0.065 mmol, 20 μL), 4,4′-dihydroxy-[1,1′-biphenyl]-3,3′-dicarboxylic acid (H4dobpdc, 0.25 mmol, 70 mg), 1,4-dioxane (5 mL), and acetic acid (HOAc, 1 mL) into a 25 mL polytetrafluoroethylene-lined stainless steel autoclave. The mixture was heated at 160 °C for 7 days and then cooled to room temperature. The collected solid product was washed with N,N-dimethylformamide (DMF) and dried at room temperature to obtain Ti-MOFs material with the chemical formula Ti8(Hdobpdc)8(H2dobpdc)4.

[0061] Figure 1(a) is an optical microscope image of the Ti-MOFs material in Example 1, which can be seen to be red prismatic. Figure 1 Figures (c) and (d) show the structural and topological analysis of the material, respectively. As can be seen from the figures, each titanium atom is octahedral coordinated, with the six oxygen atoms originating from the phenolic hydroxyl and carboxylate groups on three ligands. The three dobpdc ligands are all in a cis configuration coordinated to two adjacent titanium centers. Each TiO6 octahedron is connected by three dobpdc ligands, forming a three-dimensional (3D) chiral framework with an SRS topology. It also contains an SRS network with opposite configurations, with three sets of each configuration. Each identical configuration interweaves with others, and different configurations interweave with each other, ultimately forming a six-fold interweaving framework.

[0062] Figure 3 This is a schematic diagram of the powder XRD pattern of the Ti-MOFs material in Example 1 (the "experimental values" in the figure represent the Ti-MOFs material in Example 1). Figure 3 It can be seen from this that Ti-MOFs materials have good crystallinity.

[0063] Single-crystal X-ray diffraction revealed the following crystal parameters for Ti-MOFs materials, as shown in Table 1:

[0064] Table 1

[0065]

[0066] Figure 4 The thermogravimetric analysis (TGA) curves of the Ti-MOFs material in Example 1 are shown below. "Experimental values" represent the TGA tests performed on the Ti-MOFs material of Example 1, while "after activation" represents the TGA test performed after the Ti-MOFs material of Example 1 underwent vacuum treatment at 100°C to remove solvent molecules from its pores (referred to as activation treatment). Comparing the experimental values ​​and the activated TGA curves, it can be seen that the plateau in the activated TGA curve from 25°C to 230°C indicates that the activation treatment effectively removed solvent molecules from the material; from... Figure 4 The experimental curves show that the material loses approximately 8% of its weight within the temperature range of 25℃ to 120℃, corresponding to the weight loss of solvent molecules. The plateau from 120℃ to 230℃ indicates that the material has good thermal stability and porosity.

[0067] Figure 5 This is an infrared (IR) schematic diagram of the Ti-MOFs material in Example 1; from Figure 5 The results show that the material is effective at wavelengths of 3439, 3025, 1609, 1577, 1458, and 832 cm⁻¹. -1The absorption peaks at these locations correspond to the characteristic functional groups on the ligand carboxyl group and benzene ring, proving the successful preparation of Ti-MOF materials.

[0068] Figure 6 This is a schematic diagram of CO2 adsorption of the Ti-MOFs material in Example 1 at 195 K; from Figure 6 This indicates that the material possesses permanent porosity. Calculations show that the porosity of the Ti-MOFs material is 55%, and its BET surface area is 544 m². 2 g -1 .

[0069] Figure 7 The image shows the UV-Vis diffuse reflectance spectrum of the Ti-MOFs material in Example 1; from Figure 7 It can be seen that the material has strong absorption over a wide visible light range, and its band gap is calculated to be 1.87 eV according to the Tauc equation.

[0070] Test Example 1

[0071] Solvent stability test

[0072] The Ti-MOFs crystals from Example 1 were immersed in DMF, ethanol (EtOH), ethyl acetate (EA), acetonitrile (CH3CN), 1,4-dioxane, and H2O for 24 hours, respectively, and then X-ray powder diffraction tests were performed. (See attached diagram.) Figure 8 .from Figure 8 It can be seen that the diffraction peaks of the Ti-MOFs crystals after immersion are consistent with those before immersion, proving that their structure has not been destroyed. This demonstrates that the Ti-MOFs crystals of Example 1 exhibit good stability in different solvents.

[0073] The photoconductivity of the Ti-MOFs crystal from Example 1 was tested under visible light conditions (>420nm, 300W). The material was exposed to light for 4 minutes or blocked for 5 minutes using a cardboard, and the current data was recorded in real time using a Keithley 2602B source meter. The photoconductivity curve is shown below. Figure 9 .from Figure 9 The light response curves in the figure show that the Ti-MOFs crystal of Example 1 has visible light activity under visible light irradiation.

[0074] Therefore, it can be seen that the Ti-MOFs crystals of Example 1 have the characteristics of permanent porosity, excellent chemical stability and visible light activity, which provide great potential for their application in gas recognition sensing and as visible light active MOF catalysts.

[0075] The exemplary embodiments of the present invention have been described above. However, the scope of protection of this application is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a titanium-based metal-organic framework material, characterized in that, The preparation method includes the following steps: 1) Using titanium source and ligand as raw materials, a mixture is obtained through a solvothermal reaction after adding a reaction solvent; 2) The mixture after the reaction is separated and purified to obtain the titanium-based metal-organic framework material; The molar ratio of the titanium source to the ligand is 1:1-10; The solvent is a mixture of acidic solvents and other types of solvents; the acidic solvent is acetic acid; the other types of solvents are at least one of 1,4-dioxane, tetrahydrofuran, benzyl alcohol, and N,N-dimethylformamide; the volume ratio of the other types of solvents to acetic acid is 3-7:

1. The molecular formula of the titanium-based metal-organic framework material is C 168 H 88 O 72 Ti8 has the chemical formula Ti8(Hdobpdc)8(H2dobpdc)4; where Hdobpdc represents the trivalent anion of the ligand 4,4'-dihydroxy-[1,1'-biphenyl]-3,3'-dicarboxylic acid, and H2dobpdc represents the divalent anion of the ligand 4,4'-dihydroxy-[1,1'-biphenyl]-3,3'-dicarboxylic acid; The crystal system of the titanium-based metal-organic framework material is tetragonal, and the space group is [space group number missing]. I 41, cell parameters a [Å] are 30.63±0.02; b [Å] are 30.63±0.02; c [Å] are 14.30±0.02; α [°] is 90.00; β [°] is 90.00; γ [°] is 90.

00. The titanium-based metal-organic framework material has an average length of 50-200 μm and an average width of 1-100 μm.

2. The production method according to claim 1, characterized by, The titanium-based metal-organic framework material is a prismatic crystal, the crystal is red, and the crystal is a single crystal.

3. The preparation method according to claim 1, characterized in that, The porosity of the titanium-based metal-organic framework material is not less than 40%; The specific surface area of the titanium-based metal organic framework material is not less than 450 m 2 / g.

4. The method of claim 1, wherein, The crystals of the titanium-based metal-organic framework material exhibit solvent stability.

5. The preparation method according to claim 1, characterized in that, The titanium source is selected from at least one of titanium trichloride, titanium tetrachloride, isopropyl titanate, n-butyl titanate, titanium(IV) (triethanolamine) isopropanol, 2-ethyl-1-hexanol titanium, titanium trichlorocerocene, and titanium dichlorocerocene. The ligand is selected from phenolic hydroxycarboxylic acid ligands, and the phenolic hydroxycarboxylic acid ligand is selected from 4,4'-dihydroxy-[1,1'-biphenyl]-3,3'-dicarboxylic acid.

6. The method of claim 1, wherein, The molar ratio of the titanium source to the ligand is 1:3-6; The volume ratio of the other types of solvents to acetic acid is 4:1 or 5:

1.

7. The preparation method according to claim 1, characterized in that, The temperature of the solvothermal reaction is 120-190℃; The solvothermal reaction takes 5-10 days.

8. The method of claim 1, wherein, The preparation method further includes: step 3) cleaning and drying the titanium-based metal-organic framework material.

9. The application of the titanium-based metal-organic framework material obtained by the preparation method according to any one of claims 1-8 in the fields of gas adsorption and separation, photoelectrocatalysis, and drug sustained release.

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