Preparation method and application of high-nuclear cobalt cluster-based MOFs and derivatives thereof

Abstract

The application provides a preparation method and application of high-nucleus cobalt cluster-based MOFs and derivatives thereof, including Co 16 -MOF-BDC-X, Co 16 -MOF-BPDC, crystallized in a tetragonal system, and a space group is P42 / nmc, wherein Co 16 The cell parameter of the MOF-BDC-X is: alpha=beta=gamma=90°, Co 16 The cell parameter of the MOF-BPDC is: alpha=beta=gamma=90°, the application adopts a strategy of assisted synthesis of double small molecules (azide molecules and formic acid molecules), and successfully constructs a series of novel high-nucleus cobalt cluster-based MOFs, including Co 16 -MOF-BDC, Co 16 -MOF-BDC-X (X=NH2, NO2, OH, Br) and Co 16 -MOF-BPDC, the application realizes a great improvement of solar energy conversion efficiency by regulating functional groups on the MOF ligand and modifying strong absorption photosensitive centers on the MOF metal node, and exhibits application in the field of photocatalysis.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic materials technology, and mainly relates to a method for preparing high-core cobalt cluster-based MOFs and their derivatives and their applications. Background Technology

[0002] Photocatalysis can directly and efficiently convert solar energy into chemical energy. In this process, the application of photocatalysts effectively improves the light energy conversion efficiency. Metal-organic frameworks (MOFs) are a class of porous coordination polymers with well-defined structures, diverse types, and ordered component arrangements, possessing broad application potential. Over the past few decades, based on the tunability of MOF structures, numerous studies have orderly coupled photosensitive centers and catalytic centers into MOF structures to construct composite photocatalysts and apply them to drive various catalytic reactions. Among them, UiO-MOFs (UiO series MOF metal-organic framework materials) have attracted much attention due to their strong stability, simple preparation, and good modifiability.

[0003] To enhance the photocatalytic performance of MOFs, related research mainly employs strategies such as node modification, ligand substitution, and pore encapsulation to directionally functionalize UiO-MOF materials. However, the development of photosensitive cluster nodes in MOFs remains a blank research area. Traditional UiO-MOF nodes are primarily hexanuclear metal-oxygen clusters constructed from metal elements such as Zr, Hf, Eu, and Th. However, these cluster nodes are small in size and lack modifiable functional groups on their surfaces, hindering coupling with other photosensitive centers and limiting the application of UiO-MOF materials in photocatalysis. Therefore, overcoming the limitations of hexanuclear metal-oxygen clusters and developing high-nuclear metal clusters that are easily functionalized is of great significance for further expanding the application range of UiO-MOFs in photocatalysis. Summary of the Invention

[0004] This invention provides methods for preparing and applying a series of high-core cobalt cluster-based MOFs and their derivatives. Addressing the limitations of traditional MOF cluster node development, this invention employs a dual small molecule-assisted strategy to successfully synthesize a series of novel hexadecimal cobalt cluster-based UiO-MOFs. The cobalt clusters of the MOFs (Co...) 16 The cluster exhibits good ligand suitability and unique surface modifiability. The azide molecules in its structure can be covalently bonded to Bodipy (a fluoroboron dipyrrole compound) molecules with strong visible light absorption through the Click reaction to generate MOF photocatalysts with strong visible light absorption.

[0005] The technical solution of this invention is:

[0006] A high-nuclear cobalt cluster-based MOF derivative, including Co16 -MOF-BDC-X, Co 16 -MOF-BPDC, crystallized in the tetragonal crystal system, space group P42 / nmc, wherein Co 16 The unit cell parameters of -MOF-BDC-X are: α=β=γ=90°, Co 16 The unit cell parameters of -MOF-BPDC are: α=β=γ=90°,

[0007] Moreover, the Co 16 -MOF-BDC-X, where X is H, NH2, NO2, OH, or Br.

[0008] Moreover, including Bodipy@Co 16 -MOF-BDC.

[0009] The preparation method of the aforementioned high-core cobalt cluster-based MOFs comprises the following steps:

[0010] (1) Add a mixture of H2BDC-X (X = H, NH2, NO2, OH or Br) or H2BPDC, cobalt sulfate heptahydrate, dysprosium nitrate hexahydrate, sodium azide and formic acid to a high-pressure reactor, add N,N-dimethylformamide (DMF) and methanol, and stir slowly at room temperature for 3 minutes.

[0011] (2) Seal the mixture from step (1) and place it in an oven, heat it to 140°C and keep it warm for 72 hours;

[0012] (3) After step (2) is completed, the reaction mixture is cooled to room temperature, and the solid and liquid are separated. The separated solids are washed with N,N-dimethylformamide (DMF) and ethanol, respectively. Then, red crystals are screened under a microscope, which are the target products. The products corresponding to reactants H2BDC-X (X = H, NH2, NO2, OH or Br) or H2BPDC are as follows:

[0013] When the reactant is H₂BDC-H, the product is Co. 16 -MOF-BDC;

[0014] When the reactant is H₂BDC-NH₂, the product is Co. 16 -MOF-BDC-NH2;

[0015] When the reactant is H2BDC-NO2, the product is Co. 16 -MOF-BDC-NO2;

[0016] When the reactant is H₂BDC-OH, the product is Co. 16 -MOF-BDC-OH;

[0017] When the reactant is H2BDC-Br, the product is Co. 16 -MOF-BDC-Br;

[0018] When the reactant is H2BPDC, the product is Co. 16 -MOF-BPDC.

[0019] Moreover, the volume ratio of DMF to methanol in step (1) is 1:1.

[0020] Moreover, the cooling rate of the cooling process described in step (3) is 5°C / h.

[0021] Moreover, the Bodipy@Co 16 -MOF-BDC by Co 16 -MOF-BPDC and Bodipy molecules were prepared via a Click reaction.

[0022] This invention also provides an application of high-core cobalt cluster-based MOFs in the field of photocatalysis, wherein the Co... 16 -MOF-BDC-X (X = H, NH2, NO2, OH, or Br) or the Bodipy@Co 16 MOF-BDC was used as a photocatalyst for the photo-oxidation of benzylamine to N-benzylenediamine. The procedure was as follows: High-core cobalt cluster-based MOFs were added to a mixed solution of dichloromethane and acetonitrile in air and stirred for 30 minutes to ensure uniform dispersion of the MOFs. Then, benzylamine was added to the reaction system, and stirring continued for 5 minutes. The reaction system was then irradiated with a xenon lamp. After the reaction was complete, the solution was centrifuged to remove excess solvent, and the conversion rate of benzylamine was determined by 1H NMR spectroscopy.

[0023] Furthermore, the volume ratio of the dichloromethane and acetonitrile solvents is 1:1, and the photocatalytic reaction is carried out under irradiation by a 300W xenon lamp (λ>400nm) with a light intensity of 100mW / cm². 2 The photocatalytic reaction is carried out in an environment with a temperature of 20-30°C for 3 hours.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) This invention employs a dual small molecule (azide molecule and formic acid molecule) assisted synthesis strategy to successfully construct a series of novel high-core cobalt cluster-based MOFs, including Co 16 -MOF-BDC, Co 16-MOF-BDC-X (X = NH2, NO2, OH, Br) and Co 16 -MOF-BPDC, this invention achieves a significant improvement in solar energy conversion efficiency by regulating the functional groups on MOF ligands and modifying the MOF metal nodes with strong absorption photosensitive centers, and demonstrates its application in the field of photocatalysis.

[0026] (2) This invention utilizes Co 16 The unique surface-modifiable nature of clusters allowed for the successful and precise modification of the strongly visible-light-absorbing Bodipy molecules onto the surface of metal clusters via a Click reaction, resulting in MOF materials with enhanced photocatalytic performance, such as Bodipy@Co. 16 -MOF-BDC, the MOF and Co 16 -MOF-BDC-X has the same topology.

[0027] (3) Co of this series of MOFs 16 Clusters are the largest secondary structural units known in UiO-MOFs, and can provide more room for the functionalization of materials.

[0028] (4) Co of this series of MOFs 16 Clusters can assemble with different linear dicarboxylic acid ligands to generate UiO-MOFs with different sizes and functions.

[0029] (5)Bodipy@Co 16 In the -MOF-BDC structure, the azide molecule is covalently linked to the Bodipy molecule, which has strong visible light absorption. This bonding mechanism exhibits good stability and, through the Click reaction, in Co... 16 -MOF-BDC Co 16 Precise modification of clusters with Bodipy molecules that have strong visible light absorption enhances the visible light absorption capacity of MOFs and significantly improves their photocatalytic performance.

[0030] (6) This invention significantly improves the photocatalytic performance of MOFs by regulating the functional groups on MOF ligands and modifying MOF metal nodes with strong absorption photosensitive centers. Using Co... 16 -MOF-BDC-X (X = H, NH2, NO2, OH, or Br) is a photocatalyst used for the photo-oxidation of benzylamine coupling reaction. Co... 16 -MOF-BDC-NH2 exhibits the best photocatalytic performance. Co... 16 -MOF-BDC and Bodipy@Co 16 -MOF-BDC is a photocatalyst used in the photo-oxidation of benzylamine coupling reaction. Compared to Co... 16The introduction of Bodipy molecules into MOF-BDC significantly enhances the light absorption capacity of MOFs in the visible light region. During photocatalysis, Bodipy molecules can effectively absorb light energy and subsequently transfer photogenerated electrons to the Co atoms of the MOF. 16 On the cluster, O2 is then sensitized into superoxide radicals (O2 free radicals) with strong oxidizing power. ·- Meanwhile, MOF's Co 16 Clusters absorb light energy, sensitizing O2 into singlet oxygen with strong oxidizing power. 1 O2). Ultimately, O2 ·- and 1 O2 synergistically oxidizes and couples benzylamine to generate N-benzylbutane. Attached Figure Description

[0031] Figure 1 a) Co provided by the present invention 16 Zr6 and Co in MOF-BDC 16 Cluster structure diagram (above), Co 16 -MOF-BDC Co II The central coordination environment (below);

[0032] Figure 1 b) Co provided by the present invention 16 -MOF-BDC's UiO-type 3D frame structure;

[0033] Figure 1 c) Co provided by the present invention 16 -Octahedral cage structure of MOF-BDC;

[0034] Figure 1 d) Co provided by the present invention 16 -Octahedral cage structure of MOF-BPDC.

[0035] Figure 2 a) Co provided by the present invention 16 Co in MOF-BPDC 16 A ball-and-stick and polyhedral view of the cluster along the b-axis (left) and c-axis (right);

[0036] Figure 2 b) Co provided by the present invention 16 -MOF-BDC 3D structure and polyhedral view along the b-axis (top) and c-axis (bottom) directions.

[0037] Figure 3 Co provided by the present invention 16 The structure of -MOF-BPDC along the b-axis (left) and c-axis (middle) and Co 16-Three-dimensional porous structure of MOF-BPDC and fcu topology (right).

[0038] Figure 4 The Bodipy@Co provided by this invention 16 A schematic diagram of the synthesis of MOF-BDC.

[0039] Figure 5 Co provided by the present invention 16 Optical microscopic images of MOFs.

[0040] Figure 6 Co provided by the present invention 16 PXRD patterns of MOFs in experiments and simulations.

[0041] Figure 7 Co provided by the present invention 16 Fourier transform infrared (FT-IR) spectra of MOFs.

[0042] Figure 8 a) Co provided by the present invention 16 PXRD patterns of MOF-BDC after soaking in different organic solvents for 72 hours;

[0043] Figure 8 b) Co provided by the present invention 16 PXRD patterns of -MOF-BDC after soaking in different organic solvents for one month.

[0044] Figure 9 Co provided by the present invention 16 -MOF-BDC and Bodipy@Co 16 UV-Vis absorption spectrum of MOF-BDC.

[0045] Figure 10 Co provided by the present invention 16 Catalytic activity of the MOF-BDC-X-ray photo-oxidation of benzylamine coupling reaction.

[0046] Figure 11 Co provided by the present invention 16 -MOF-BDC and Bodipy@Co 16 Catalytic activity of the MOF-BDC photo-oxidation of benzylamine coupling reaction.

[0047] Figure 12 The Bodipy@Co provided by this invention 16 -Photocatalytic cycling performance of MOF-BDC.

[0048] Figure 13 The Bodipy@Co photocatalytic reaction before and after the present invention is provided16 PXRD pattern of MOF-BDC. Detailed Implementation

[0049] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0050] This invention synthesizes a series of high-nuclearity transition metal cluster-based UiO-MOFs, including Co. 16 -MOF-BDC-X(X=H,NH2,NO2,OH,Br),Co 16 -MOF-BPDC and Bodipy@Co 16 -MOF-BDC.

[0051] This invention employs a dual small molecule (azide molecule and formic acid molecule) assisted synthesis strategy to successfully construct a series of novel hexadecimal cobalt cluster-based UiO-MOFs, including Co 16 -MOF-BDC-X (X = H, NH2, NO2, OH, or Br) and Co 16 -MOF-BPDC. Co 16 The molecular formula of -MOF-BDC-X is [NH2(CH3)2]6[Co 16 (μ -1,1 -N3) 10 (μ -1,1,1 [-N3)4(HCOO)8(BDC-X)8], where H2BDC is terephthalic acid, MOFs are crystallized in a tetragonal crystal system with space group P42 / nmc, and the unit cell parameters are: α=β=γ=90°, Co 16 The molecular formula of -MOF-BPDC is [NH2(CH3)2]6[Co 16 (μ -1,1 -N3) 10 (μ -1,1,1 [-N3)4(HCOO)8(BPDC)8], where H2BPDC is 4,4'-biphenyl dicarboxylic acid. This MOF crystallizes in a tetragonal crystal system with space group P42 / nmc and cell parameters as follows: α=β=γ=90°,

[0052] like Figure 1 As shown, Co 16 The length of the cluster is Width is Much larger than traditional Zr6 clusters It is the largest known secondary structural unit in UiO-MOFs, providing more room for material functionalization. Co in MOF materials 16 The cluster consists of 16 Co 2+ 14 N3 - and 8 HCOO - The cobalt cluster is further connected outward through 16 linear dicarboxylic acid ligands, forming a classic fcu topology. 16 The azide molecules in the cluster have two different coordination modes (μ -1,1,1 and μ -1,1 (Mode). Furthermore, three types of Co exist in MOF. II Both are related to two N3 - Two HCOO - Co coordinates with two linear carboxylic acid ligands. 16 The dimensions of the octahedral cage in MOF-BDC are: Co 16 The dimensions of the octahedral cage in MOF-BPDC are:

[0053] Co 16 -MOF-BDC and various Co 16 The preparation methods for MOF-BDC derivatives are shown in Examples 1 to 7, respectively:

[0054] Example 1--Co 16 Preparation of MOF-BDC

[0055] A mixture of terephthalic acid (H₂BDC, 11.9 mg, 0.072 mmol), cobalt sulfate heptahydrate (56.2 mg, 0.2 mmol), dysprosium nitrate hexahydrate (45.6 mg, 0.1 mmol), and sodium azide (11.7 mg, 0.18 mmol) was added to a high-pressure reactor, along with 5.0 mL of DMF and 5.0 mL of methanol. The mixture was slowly stirred at room temperature for 3 minutes, sealed, and transferred to an oven. The oven was heated to 140 °C and maintained at this temperature for 72 hours. After the reaction was complete, the reaction system was cooled to room temperature at a rate of 5 °C / h. The solid was separated by filtration and washed with DMF and ethanol, respectively. The red polyhedral crystals in the solid were screened using a microscope, yielding the target product at approximately 45.4% (calculated based on the ligand H₂BDC).

[0056] Example 2--Co 16 Preparation of -MOF-BDC-NH2

[0057] A mixture of 2-aminoterephthalic acid (H₂BDC-NH₂, 13.0 mg, 0.072 mmol), cobalt sulfate heptahydrate (56.2 mg, 0.2 mmol), dysprosium nitrate hexahydrate (45.6 mg, 0.1 mmol), and sodium azide (11.7 mg, 0.18 mmol) was added to a high-pressure reactor, along with 5.0 mL of DMF and 5.0 mL of methanol. The mixture was slowly stirred at room temperature for 3 minutes, sealed, and transferred to an oven. The oven temperature was raised to 140 °C and maintained at this temperature for 72 hours. After the reaction was complete, the reaction system was cooled to room temperature at a rate of 5 °C / h. The solid was separated by filtration and washed with DMF and ethanol, respectively. The dark red polyhedral crystal blocks in the solid were screened by microscopy, yielding the target product at a yield of approximately 42.5% (calculated based on the ligand H₂BDC-NH₂).

[0058] Example 3--Co 16 Preparation of -MOF-BDC-NO2

[0059] A mixture of 2-nitroterephthalic acid (H₂BDC-NO₂, 15.2 mg, 0.072 mmol), cobalt sulfate heptahydrate (56.2 mg, 0.2 mmol), dysprosium nitrate hexahydrate (45.6 mg, 0.1 mmol), sodium azide (11.7 mg, 0.18 mmol), and formic acid (7.5 μL) was added to a high-pressure reactor, along with 5.0 mL of DMF and 5.0 mL of methanol. The mixture was slowly stirred at room temperature for 3 minutes, sealed, and transferred to an oven. The oven temperature was raised to 140 °C and maintained at this temperature for 72 hours. After the reaction was complete, the reaction system was cooled to room temperature at a rate of 5 °C / h. The solid was separated by filtration and washed with DMF and ethanol, respectively. The red polyhedral crystals in the solid were screened by microscopy to obtain the target product, with a yield of approximately 35.2% (calculated based on the ligand H₂BDC-NO₂).

[0060] Example 4--Co 16 Preparation of -MOF-BDC-OH

[0061] A mixture of 2-hydroxyterephthalic acid (H₂BDC-OH, 13.1 mg, 0.072 mmol), cobalt sulfate heptahydrate (56.2 mg, 0.2 mmol), dysprosium nitrate hexahydrate (45.6 mg, 0.1 mmol), sodium azide (11.7 mg, 0.18 mmol), and formic acid (35.0 μL) was added to a high-pressure reactor, along with 5.0 mL of DMF and 5.0 mL of methanol. The mixture was slowly stirred at room temperature for 3 minutes, sealed, and transferred to an oven. The oven temperature was raised to 140 °C and maintained at this temperature for 72 hours. After the reaction was complete, the reaction mixture was cooled to room temperature at a rate of 5 °C / h. The solid was separated by filtration and washed with DMF and ethanol, respectively. The red polyhedral crystals in the solid were screened using a microscope, yielding the target product at approximately 15.4% (calculated based on the ligand H₂BDC-OH).

[0062] Example 5--Co 16 Preparation of -MOF-BDC-Br

[0063] A mixture of 2-bromoterephthalic acid (H₂BDC-Br, 17.5 mg, 0.072 mmol), cobalt sulfate heptahydrate (56.2 mg, 0.2 mmol), dysprosium nitrate hexahydrate (45.6 mg, 0.1 mmol), sodium azide (11.7 mg, 0.18 mmol), and formic acid (50.0 μL) was added to a high-pressure reactor, along with 5.0 mL of DMF and 5.0 mL of methanol. The mixture was slowly stirred at room temperature for 3 minutes, sealed, and transferred to an oven. The oven temperature was raised to 140 °C and maintained at this temperature for 72 hours. After the reaction was complete, the reaction system was cooled to room temperature at a rate of 5 °C / h. The solid was separated by filtration and washed with DMF and ethanol, respectively. The red polyhedral crystals in the solid were screened using a microscope, yielding the target product at approximately 12.5% ​​(calculated based on the ligand H₂BDC-Br).

[0064] Example 6--Co 16 Preparation of MOF-BPDC

[0065] A mixture of 4,4'-biphenyl dicarboxylic acid (H₂BPDC, 34.8 mg, 0.144 mmol), cobalt sulfate heptahydrate (56.2 mg, 0.2 mmol), dysprosium nitrate hexahydrate (45.6 mg, 0.1 mmol), sodium azide (11.7 mg, 0.18 mmol), and formic acid (600.0 μL) was added to a high-pressure reactor, along with 5.0 mL of DMF and 5.0 mL of methanol. The mixture was slowly stirred at room temperature for 3 minutes, sealed, and transferred to an oven. The oven temperature was raised to 140 °C and maintained at this temperature for 72 hours. After the reaction was complete, the reaction mixture was cooled to room temperature at a rate of 5 °C / h. The solid was separated by filtration and washed with DMF and ethanol, respectively. The red polyhedral crystals in the solid were screened using a microscope, yielding the target product at approximately 22.5% (calculated based on the ligand H₂BPDC).

[0066] Example 7 -- Bodiy@Co 16 Preparation of MOF-BDC

[0067] This invention utilizes Co 16 The cluster's unique surface-modifiable capabilities enabled the precise modification of strongly visible-light-absorbing Bodipy molecules onto Co using a Click reaction. 16 -MOF-BDC metal cluster surface, to obtain Bodipy@Co 16 -MOF-BDC. This MOF is related to Co. 16 -MOF-BDC-X has the same topology. For example... Figure 4 As shown, through the Click reaction, Co 16 The azide molecules on the -MOF-BDC metal nodes are covalently linked to the Bodipy molecules.

[0068] The Co prepared in Example 1 16 MOF-BDC (34.8 mg, 0.01 mmol), Bodipy molecules (15.2 mg, 0.04 mmol), copper sulfate pentahydrate (5.0 mg, 0.02 mmol), and sodium ascorbate (11.8 mg, 0.06 mmol) were dissolved in a mixture of 4.0 mL DMF and 1.0 mL methanol. The mixture was heated to 65 °C and reacted for 48 hours. After the reaction, the reaction system was cooled to room temperature, and the solid was separated by centrifugation. The solid was washed with DMF and dichloromethane until the supernatant was colorless, and dried under vacuum for 3 hours to obtain Bodipy@Co 16 -MOF-BDC.

[0069] like Figure 2 and 3 As shown, Co 16 -MOF-BDC and Co16 The -MOF-BPDC all have a three-dimensional porous structure.

[0070] As Figure 5 shown, Co 16 -MOFs are polyhedral block-shaped crystals with uniform size.

[0071] As Figure 6 shown, the XRD data of the experimentally obtained Co 16 -MOFs and the simulated XRD results exhibit consistent peak shapes and peak positions, proving the successful preparation of the material.

[0072] Co 16 -MOFs' Fourier transform infrared spectrum (FT-IR) is as Figure 7 and shown. There is a strong and sharp signal peak at approximately 2100 cm -1 for MOFs, proving the presence of azide groups in MOFs. In addition, the signal peak of Co 16 -MOF-BDC-OH at 1188 cm -1 is attributed to the stretching vibration of C-O, proving the presence of OH functional groups in this MOF. The signal peak of Co 16 -MOF-BDC-Br at 592 cm -1 proves the presence of C-Br in this MOF. The signal peak of Co 16 -MOF-BDC-NO2 at 1562 cm -1 indicates that this MOF contains NO2 functional groups. Compared with the FT-IR spectrum of Co 16 -MOF-BDC, Co 16 -MOF-BDC-NH2 shows obvious doublets at 3436 cm -1 and 3364 cm -1 , which are caused by the asymmetric and symmetric stretching vibrations of the amino group. In the low-frequency region, the signal peaks at 1658 cm -1 and 1258 cm -1 correspond to the N-H bending vibration and C-N stretching vibration of aromatic amines respectively, proving the presence of amino groups in this MOF.

[0073] As Figure 8 shown, Co 16 -MOF-BDC can exist stably in various organic solvents for a long time, proving that the MOF has excellent chemical stability.

[0074] Example 8 - Using the Co 16 -MOF-BDC-X (X = H, NH2, NO2, OH or Br) prepared in Examples 1-5 as a catalyst, carry out the photooxidative benzylamine coupling reaction.

[0075] In an air atmosphere, 5.0 mg of MOF was added to 2 mL of a mixed solution of dichloromethane and acetonitrile (volume ratio of the two solvents: 1:1), and stirred for 30 minutes to ensure uniform dispersion of the MOF in the solution. Subsequently, 0.02 mmol of benzylamine was added to the reaction system, and stirring was continued for 5 minutes. Then, a 300 W xenon lamp (λ > 400 nm, light intensity 100 mW / cm²) was used for illumination. 2 The reaction system was irradiated with light for 3 hours. After the reaction, the solution was centrifuged to remove excess solvent, and the conversion rate of benzylamine was determined by 1H NMR spectroscopy. The photocatalyst can be reused after centrifugation following the aforementioned method.

[0076] Example 9 – Co prepared in Examples 1 and 7 16 -MOF-BDC and Bodioy@Co 16 -MOF-BDC was used as a catalyst to carry out the photo-oxidation of benzylamine coupling reaction.

[0077] In an air atmosphere, 5.0 mg of MOF was added to 2 mL of a mixed solution of dichloromethane and acetonitrile (volume ratio of the two solvents: 1:1), and stirred for 30 minutes to ensure uniform dispersion of the MOF in the solution. Then, 0.05 mmol of benzylamine was added to the reaction system, and stirring was continued for 5 minutes. Finally, a 300 W xenon lamp (λ > 400 nm, light intensity 100 mW / cm²) was used for illumination. 2 The reaction system was irradiated with light for 3 hours. After the reaction, the solution was centrifuged to remove excess solvent, and the conversion rate of benzylamine was determined by 1H NMR spectroscopy. The photocatalyst can be reused after centrifugation following the aforementioned method.

[0078] The 1H N-benzylbutane spectrum of the product: 1 H NMR (400MHz, CDCl3) δ8.40(s,1H),7.78-7.75(m,2H),7.43-7.36(m,3H),7.33(d,4H),7.28-7.21(m,2H),4.80(s,2H).

[0079] Figure 9 For Co 16 -MOF-BDC and Bodipy@Co 16 -UV-Vis absorption spectrum of MOF-BDC. Compared to Co 16 The introduction of the -MOF-BDC Bodipy molecule significantly improves the light absorption capacity of MOF in the visible light region.

[0080] With Co 16-MOF-BDC-X (X = H, NH2, NO2, OH, or Br) is used as a catalyst for the photo-oxidation coupling reaction of benzylamine. For example... Figure 10 As shown, under the same reaction conditions, Co 16 -MOF-BDC-NH2 exhibits the best photocatalytic performance.

[0081] With Co 16 -MOF-BDC and Bodipy@Co 16 -MOF-BDC is used as a catalyst for the photo-oxidation of benzylamine coupling reaction. For example... Figure 11 As shown, under the same reaction conditions, compared to Co 16 -MOF-BDC, with Bodipy@Co having a strongly absorbing photosensitive center 16 The photocatalytic performance of MOF-BDC is significantly improved, with the conversion rate of benzylamine increasing from 31.5% to 100%.

[0082] like Figure 12 and 13 As shown, Bodipy@Co 16- After five consecutive cycles of experiments, the catalytic activity of MOF-BDC did not decrease significantly, and its crystallinity remained good, indicating that Co in MOF... 16 The covalent bond between the cluster and the Bodipy molecule exhibits good stability.

[0083] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments and drawings. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A high-nuclear-nucleus transition cobalt cluster-based MOF, characterized in that: Including Co 16 -MOF-BDC-X and Co 16 -MOF-BPDC, the Co 16 The molecular formula of -MOF-BDC-X is [NH2(CH3)2]6[Co 16 (μ -1,1 -N3) 10 (μ -1,1,1 -N3)4(HCOO)8(BDC-X)8], where BDC-X is a phthalic acid derivative and X is H 、 NH2, NO2, OH or Br, BPDC is biphenyl dicarboxylic acid, MOFs are crystallized in the tetragonal crystal system, space group P42 / nmc, with the following cell parameters: a = b = 17.095(6) Å, c = 32.316(15) Å, α = β = γ = 90°, V = 9445.3(8) Å 3 The Co 16 The molecular formula of -MOF-BPDC is [NH2(CH3)2]6[Co 16 (μ -1,1 -N3) 10 (μ -1,1,1 [-N3)4(HCOO)8(BPDC)8], where H2BPDC is 4,4'-biphenyl dicarboxylic acid. This MOF crystallizes in the tetragonal crystal system with space group P42 / nmc. The cell parameters are: a = b = 21.228(5) Å, c = 38.409(16) Å, α = β = γ = 90°, V = 17309.4(10) Å. 3 .

2. A method for preparing high-core transition cobalt cluster-based MOFs as described in claim 1, characterized in that: (1) Add the mixture of H2BPDC-X or H2BPDC, cobalt sulfate heptahydrate, dysprosium nitrate hexahydrate, sodium azide and formic acid to a high-pressure reactor, add N,N-dimethylformamide and methanol, stir at room temperature for 3 minutes, and stir slowly at room temperature for 3 minutes. (2) Seal the mixture from step (1) and place it in an oven, heat it to 140 °C, and keep it warm for 72 hours; (3) After step (2) is completed, the reaction mixture is cooled to room temperature, and the solid and liquid are separated. The separated solids are washed with N,N-dimethylformamide and ethanol, respectively. Then, red crystals are screened under a microscope, which are the target products. The products corresponding to reactants H2BPDC-X or H2BPDC are as follows: When the reactant is H2BPDC-H, the product is Co. 16 -MOF-BDC; When the reactant is H2BPDC-NH2, the product is Co. 16 -MOF-BDC-NH2; When the reactant is H2BPDC-NO2, the product is Co. 16 -MOF-BDC-NO2; When the reactant is H₂BPDC-OH, the product is Co. 16 -MOF-BDC-OH; When the reactant is H2BPDC-Br, the product is Co. 16 -MOF-BDC-Br; When the reactant is H2BPDC, the product is Co. 16 -MOF-BPDC.

3. The method for preparing high-core transition cobalt cluster-based MOFs according to claim 2, characterized in that: The volume ratio of N,N-dimethylformamide to methanol in step (1) is 1:

1.

4. The method for preparing high-core transition cobalt cluster-based MOFs according to claim 2, characterized in that: The cooling rate described in step (3) is 5 °C / h.

5. An application of a high-nuclear-core transition cobalt cluster-based MOF in the field of photocatalysis, characterized in that: The high-nuclear transition cobalt cluster-based MOFs described in claim 1 are used for photo-oxidation of benzylamine to generate N-benzylbutane.

6. The application of the high-nuclear-core transition cobalt cluster-based MOFs according to claim 5 in the field of photocatalysis, characterized in that: The operation steps are as follows: In an air atmosphere, the high-nuclear transition cobalt cluster-based MOF derivatives are added to a mixed solution of dichloromethane and acetonitrile and stirred for 30 minutes to uniformly disperse the MOFs in the solution. Then, benzylamine is added to the reaction system and stirring is continued for 5 minutes. The reaction system is then irradiated with a xenon lamp. After the reaction is completed, the solution is centrifuged to remove excess solvent, and then the conversion rate of benzylamine is determined by 1H NMR spectroscopy.

7. The application of the high-core transition cobalt cluster-based MOF derivative according to claim 6 in the field of photocatalysis, characterized in that: The volume ratio of dichloromethane and acetonitrile solvents is 1:

1. The photocatalytic reaction is carried out under irradiation with a 300 W xenon lamp, a wavelength λ > 400 nm, and a light intensity of 100 mW / cm². 2 The photocatalytic reaction is carried out in an environment with a temperature of 20-30°C for 3 hours.

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