A quinoline ligand modified nine-core zirconium-oxygen cluster, a preparation method and application thereof

Abstract

This invention belongs to the field of metal oxide cluster technology, specifically a quinoline ligand-modified nine-nuclear zirconium oxide cluster, its preparation method, and its application. The quinoline ligand-modified nine-nuclear zirconium oxide cluster is prepared according to the following steps: using 8-quinoline carboxylic acid as the ligand, and water and DMF as the solvent, the ligand, solvent, and zirconium sulfate are mixed and subjected to a solvothermal reaction to obtain the quinoline ligand-modified nine-nuclear zirconium oxide cluster; wherein the solvothermal reaction conditions are: holding at 80℃~90℃ for 24h~48h. This invention uses inexpensive ligands as raw materials, and the method has the advantages of simple synthesis conditions, low material cost, short synthesis time, and low synthesis temperature, overcoming the technical defects of existing nine-nuclear zirconium oxide cluster preparation methods.

Description

Technical Field

[0001] This invention belongs to the field of metal oxide cluster technology, specifically a nine-nucleated zirconium oxide cluster modified with quinoline ligands, its preparation method, and its application. Background Technology

[0002] Metal-oxygen clusters are a class of polynuclear inorganic molecular clusters composed of multiple metal centers tightly linked by oxygen bridges (such as μ2-O, μ3-O, μ4-O, etc.) or hydroxyl groups (μ2-OH, μ3-OH). They possess well-defined molecular formulas, definite geometric configurations, and modifiable surface ligand environments, and are frequently applied in catalysis, photoelectromagnetism, and biomedicine. Their research spans multiple fields, including inorganic chemistry, materials science, catalysis chemistry, and radiochemistry.

[0003] In main group and transition metal systems (such as polyacid compounds of V, Mo, W, Fe, and Mn), metal-oxygen clusters have formed mature systems, with typical examples including Keggin-type [PMo] compounds. 12 O 40 ] 3- , Dawson type [NaP2W 18 O 62 ] 6- and Lindqvist type [Mo6O 19 ] 2- It is widely used in fields such as heterogeneous catalysis, proton conduction, magnetic materials and biosimulation.

[0004] Currently, research on zirconium oxide clusters is relatively lagging compared to other transition metals. 4+ Zirconium oxide clusters (ZOCs) possess small radii and high charge numbers, exhibiting strong hydrolytic capabilities, even under strong acid conditions. Therefore, compared to other transition metal oxide clusters, the currently reported ZOCs are fewer in variety and have a lower nucleus number. Among numerous metal clusters, MOCs formed from tetravalent zirconium ions through hydrolysis and condensation reactions, namely zirconium oxide clusters (ZOCs), possess excellent properties such as wide band gaps, high dielectric constants, and high refractive indices. In recent years, metal-organic frameworks (MOFs) constructed using ZOCs, especially hexanuclear zirconium oxide clusters, as nodes have become a research hotspot, offering advantages such as diverse structural types, low toxicity, high thermal stability, and high chemical stability. However, compared to these advantages, research on the zirconium oxide clusters themselves, which serve as their structural units, is relatively limited.

[0005] Currently, research on zirconium-oxygen clusters mainly focuses on hexanuclear zirconium-oxygen clusters and dodecenic zirconium-oxygen clusters. The characterized hexanuclear zirconium-oxygen clusters contain various crystal configurations, the most classic of which is the octahedral Zr₆O₃.x (OH) 8-x Most MOFs also use this as a secondary unit; besides the octahedral configuration, a few hexanuclear zirconium oxide clusters exhibit special configurations such as chair, cage, and ring structures. The configuration of dodecenum zirconium oxide clusters is mostly formed by bridging two hexanuclear zirconium oxide cluster units with carboxylic acid ligands. Although this type of zirconium oxide cluster does not affect the rest of the structure except for the bridging portion, researchers have not yet observed the presence of Zr6 monomers and Zr... 12 Transformation between dimers. Compared with hexanuclear zirconium oxo clusters and dodecenic zirconium oxo clusters, reports on zirconium oxo clusters with six to twelve nuclei are few and far between. The earliest report on nonanuclear zirconium oxo clusters appeared in 2015, when C. Artner et al. synthesized the first nonanuclear zirconium oxo cluster in water and n-butanol, published in the literature "New zirconium and zirconium-titanium oxo clustertypes by expansion or metal substitution of the octahedral Zr6O8structuralmotif [J]". It was not until 2024 that Lan Yaqian et al. synthesized the second zirconium oxo cluster in an ethanol-DMF mixed organic solvent, published in the literature "Sulfur atom-directed metal-ligand synergistic catalysis inzirconium / hafnium-oxo clusters for highly efficient amine oxidation [J]".

[0006] However, the synthesis of the first nine-nucleated zirconium oxide cluster took as long as 42 weeks, which affected production efficiency; the ligands for the second nine-nucleated zirconium oxide cluster were expensive, and the reaction had to be carried out at 100°C for 72 hours, which was a harsh reaction condition. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a quinoline ligand-modified nine-nuclear zirconium oxide cluster, its preparation method, and its applications. This invention uses inexpensive ligands as raw materials, mixing the ligands, solvent, and zirconium sulfate, and then conducting a solvothermal reaction at 80℃~90℃ for 24h~48h. This method offers advantages such as simple synthesis conditions, low material cost, short synthesis time, and low synthesis temperature, overcoming the technical deficiencies of existing nine-nuclear zirconium oxide cluster preparation methods.

[0008] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution: This invention protects a method for preparing a nine-nucleated zirconium oxide cluster modified with a quinoline ligand, comprising the following steps: Using 8-quinoline carboxylic acid as a ligand and water and DMF as solvents, the ligand, solvent, and zirconium sulfate were mixed and subjected to a solvothermal reaction to obtain quinoline-ligand-modified nine-nuclear zirconium oxide clusters. The solvothermal reaction conditions were: holding at 80℃~90℃ for 24h~48h. The yield and structural stability of the quinoline-ligand-modified nine-nuclear zirconium oxide clusters obtained by holding at 80℃~90℃ for 48h were basically consistent.

[0009] Preferably, the molar ratio of zirconium sulfate to 8-quinoline carboxylic acid is 1:0.3~1.5.

[0010] Preferably, the volume ratio of water to DMF is 1:0.5~1.

[0011] Preferably, the ligand also includes sulfuric acid, and the addition of sulfuric acid to the ligand improves the yield and product stability.

[0012] Preferably, the molar ratio of zirconium sulfate to sulfuric acid is 1:0~15.

[0013] This invention also protects a quinoline ligand-modified nine-nucleated zirconium oxide cluster, which is prepared using the above-described method.

[0014] Preferably, the molecular formula of the nonanuclear zirconium oxide cluster modified with quinoline ligands is: [Zr9O8(OH)6(8-QA)6(SO4)8] 8- 8-QA is 8-quinoline carboxylic acid, in which SO4 2— Provided by zirconium sulfate; [Zr9O8(OH)6(8-QA)6(SO4)8] 8- All zirconium atoms are 8-coordinated. The zirconium atom at the vertices of the square pyramid is coordinated with two oxygen atoms from two sulfate groups and two oxygen atoms from 8-quinoline carboxylic acid on its periphery, and is connected to two μ3-O atoms and two μ3-OH atoms on its interior. The six zirconium atoms at the four corners of the square pyramid have the same coordination pattern, being coordinated with two oxygen atoms from two sulfate groups and one oxygen atom from 8-quinoline carboxylic acid on its periphery, and connected to three μ3-O atoms and two μ3-OH atoms on its interior.

[0015] This invention also protects the use of quinoline ligand-modified nine-nuclear zirconium oxide clusters as catalysts in the preparation of azobenzene from aniline.

[0016] Preferably, the application method is as follows: using methanol as solvent, aniline as substrate, 30% hydrogen peroxide as oxidant, and [Zr9O8(OH)6(8-QA)6(SO4)8] as the solvent. 8- Using it as a catalyst, aniline is oxidized at room temperature to prepare azobenzene.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention provides a highly reproducible method for synthesizing nine-nuclear zirconium oxide clusters. The nine-nuclear zirconium oxide clusters are prepared by mixing 8-quinoline carboxylic acid as a ligand with water and DMF as solvents, and then carrying out a solvothermal reaction. Under solvothermal conditions, sulfuric acid, 8-quinoline carboxylic acid, and zirconium(IV) undergo self-assembly. Compared with the synthesis method of C. Artner et al., the method of this invention requires only 1-2 days, significantly shortening the preparation time. Compared with the Lan Yaqian synthesis method, firstly, the unit price of the ligand in the Lan Yaqian synthesis method is 100 yuan / 250mg, while the unit price of the ligand in this invention is 23 yuan / 100mg, achieving a significant cost reduction and facilitating long-term research on nine-nuclear zirconium oxide clusters. Secondly, compared with the synthesis conditions of 100℃ and 72h, the product of this invention can be stably synthesized at 80℃~90℃ for 24h~48h. Furthermore, the product of this invention also exhibits similar catalytic performance to the product synthesized by Lan Yaqian.

[0018] 2. This invention provides the cluster compound [Zr9O8(OH)6(8-QA)6(SO4)8] 8- Regarding the limited research on zirconium oxide clusters (especially those with hexanuclear to dodecenic numbers), this invention explores and discovers a novel zirconium oxide cluster compound with novel structure and properties. The new cluster compound is [Zr9O8(OH)6(8-QA)6(SO4)8]. 8- The 8-quinoline carboxylic acid ligand, [Zr9O8(OH)6(8-QA)6(SO4)8], was introduced. 8- In aniline catalysis, it exhibits excellent efficacy in the catalytic formation of azobenzene oxide. The catalytic mechanism is as follows: aniline molecules are adsorbed onto ligands, H₂O₂ is adsorbed onto Zr sites and activated to generate HOO·, subsequently reacting with HOO· to ​​form Ph-NHOH. Ph-NHOH is easily oxidized to form Ph-NO, and Ph-NO condenses with Ph-NHOH to form azobenzene oxide. The technical route is as follows: Figure 10 As shown.

[0019] 3. The synthesis method of the present invention has the advantages of simple experimental operation and low cost of experimental raw materials. It is a reproducible method for synthesizing nine-core zirconium oxide clusters with a simple synthetic route. It has important scientific significance and technical value for enriching the coordination chemistry of Zr(IV), exploring the assembly rules of group IV transition metal oxide clusters, and promoting the research of functional MOFs materials. Attached Figure Description

[0020] Figure 1 The cluster compound of Example 1 is [Zr9O8(OH)6(8-QA)6(SO4)8]. 8- Optical microscope image.

[0021] Figure 2The cluster compound of Example 1 is [Zr9O8(OH)6(8-QA)6(SO4)8]. 8- The structural diagram shows that Zr is blue, C is black, N is cyan, O is red, and S is yellow.

[0022] Figure 3 The cluster compound of Example 1 is [Zr9O8(OH)6(8-QA)6(SO4)8]. 8- The bidentate coordination diagram of sulfuric acid, with the bidentate sulfuric acid coordination mode: Zr-blue, O-red, S-yellow.

[0023] Figure 4 The cluster compound of Example 1 is [Zr9O8(OH)6(8-QA)6(SO4)8]. 8- Tridentate coordination diagram of sulfuric acid, tridentate sulfuric acid coordination mode: Zr-blue, O-red, S-yellow.

[0024] Figure 5 The cluster compound of Example 1 is [Zr9O8(OH)6(8-QA)6(SO4)8]. 8- The bidentate coordination diagram of 8-quinoline carboxylic acid, 8-QA bidentate coordination mode: Zr-blue, O-red, N-cyan, C-black.

[0025] Figure 6 The cluster compound of Example 1 is [Zr9O8(OH)6(8-QA)6(SO4)8]. 8- The laser Raman spectrum.

[0026] Figure 7 The cluster compound of Example 1 is [Zr9O8(OH)6(8-QA)6(SO4)8]. 8- SEM-EDS plot.

[0027] Figure 8 The cluster compound of Example 1 is [Zr9O8(OH)6(8-QA)6(SO4)8]. 8- TG / DTG graph.

[0028] Figure 9 The cluster compound [Zr9O8(OH)6(8-QA)6(SO4)8] used in Example 1 was employed. 8- A catalytic coupling diagram of aniline was constructed.

[0029] Figure 10 It is a cluster compound [Zr9O8(OH)6(8-QA)6(SO4)8] 8- Technical roadmap for aniline-coupled catalysis. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Currently, among the reported zirconium-oxygen clusters, hexanuclear zirconium clusters are dominant. Hexanuclear zirconium-oxygen clusters typically exhibit a typical tetragonal bipyramidal octahedral configuration, with 6 Zr atoms. 4+ The ions are located at the vertices of the octahedron, with four μ3-O and four μ3-OH groups staggeredly covering the octahedral surface, and the periphery is capped by formic acid, benzoic acid, methacrylic acid, or glycolic acid ligands. The configuration of the first decanuclear zirconium cluster can be regarded as an extension of Zr5 in two directions, with the extended zirconium atoms forming a tetrahedron; the nine-nuclear zirconium-oxygen cluster synthesized by Lan Yaqian et al. has the same configuration as the zirconium-oxygen cluster in this invention.

[0032] This invention provides a novel cluster compound [Zr9O8(OH)6(8-QA)6(SO4)8] 8- [Zr9O8(OH)6(8-QA)6(SO4)8] 8- The differences between this invention and previously reported zirconium oxide clusters are as follows: 1) This invention uses zirconium sulfate as a raw material, where sulfate ions coordinate with zirconium ions; 2) The growth environment of this invention differs from that of existing clusters. The [Zr9O8(OH)6(8-QA)6(SO4)8] of this invention... 8- Growth was carried out in a water-DMF mixed solvent system at 80℃~90℃; 3) This invention [Zr9O8(OH)6(8-QA)6(SO4)8] 8- The ligands differ from those of previously reported nine-nuclear zirconium oxide clusters; the cluster compound is [Zr9O8(OH)6(8-QA)6(SO4)8]. 8- The ligands used are 8-quinoline carboxylic acid and / or sulfuric acid. 8-quinoline carboxylic acid ligands have the advantage of being inexpensive.

[0033] This invention employs 8-quinoline carboxylic acid and sulfate ligands for end-capping to passivate the surface of hydrolysis products, and uses a water-organic mixed solvent system, controlling Zr content by adjusting different solvent ratios. 4+ The hydrolysis behavior occurs through a competitive-cooperative coordination mechanism of organic ligands under solvothermal conditions, forming a molecular formula [Zr9O8(OH)6(8-QA)6(SO4)8]. 8- The nine-core zirconium oxide cluster. Compared with existing technologies, the preparation cost of this invention is low, the reproducibility is high, and the synthesis process is more economical and efficient.

[0034] The technical solution of the present invention will be studied using the following embodiments, as detailed below: Example 1 The preparation method of quinoline ligand-modified nonanuclear zirconium oxide clusters includes the following steps: Add 20 mg of 8-quinoline carboxylic acid to a 7 mL glass reaction flask, then add 200 μL of DMF using a pipette. Shake the glass reaction flask until the 8-quinoline carboxylic acid is evenly dispersed. Continue to add 200 μL of 0.5 mol / L zirconium sulfate solution, shake the flask to evenly disperse the suspension in the flask, and finally add 100 μL of 5 mol / L sulfuric acid solution. Shake the flask until the solution in the flask is pale yellow and clear.

[0035] The glass reaction flask was sealed and placed in an oven, heated to 90°C, and kept at that temperature for 48 hours to obtain a nine-nuclear zirconium oxide cluster modified with quinoline ligands, denoted as [Zr9O8(OH)6(8-QA)6(SO4)8]. 8- .

[0036] Example 2 The preparation method of quinoline ligand-modified nonanuclear zirconium oxide clusters includes the following steps: Add 5 mg of 8-quinoline carboxylic acid to a 7 mL glass reaction flask, then add 200 μL of DMF using a pipette. Shake the glass reaction flask until the 8-quinoline carboxylic acid is evenly dispersed. Continue to add 200 μL of 0.5 mol / L zirconium sulfate solution and shake the flask until the solution in the flask is pale yellow and clear.

[0037] The glass reaction flask was sealed and placed in an oven, heated to 90°C, and kept at that temperature for 48 hours to obtain a nine-nuclear zirconium oxide cluster modified with quinoline ligands, denoted as [Zr9O8(OH)6(8-QA)6(SO4)8]. 8- In a solution without sulfuric acid, only a few crystals are present.

[0038] Example 3 The preparation method of quinoline ligand-modified nonanuclear zirconium oxide clusters includes the following steps: Add 20 mg of 8-quinoline carboxylic acid to a 7 mL glass reaction flask, then add 200 μL of DMF using a pipette. Shake the glass reaction flask until the 8-quinoline carboxylic acid is evenly dispersed. Continue to add 200 μL of 0.5 mol / L zirconium sulfate solution, shake the flask to evenly disperse the suspension in the flask, and finally add 180 μL of 5 mol / L sulfuric acid solution. Shake the flask until the solution in the flask is pale yellow and clear.

[0039] The glass reaction flask was sealed and placed in an oven at 90°C for 48 hours. After cooling, the flask was placed back in the oven and heated to 90°C for 24 hours to obtain a quinoline-ligand-modified nine-nuclear zirconium oxide cluster. Both the synthetic routes in Examples 1 and 3 stably yielded the cluster compound [Zr9O8(OH)6(8-QA)6(SO4)8]. 8- Crystal.

[0040] The following example uses the cluster compound [Zr9O8(OH)6(8-QA)6(SO4)8] from Example 1. 8- Taking [Zr9O8(OH)6(8-QA)6(SO4)8] as an example, the crystal structure of the cluster compound was tested using a single-crystal X-ray diffractometer under liquid nitrogen purging. Based on the collected data, the unit cell parameters of the crystal were calculated using APEX4 software, and the crystal structure was determined. Laser Raman spectroscopy, scanning electron microscopy, and thermogravimetric analysis were used to test [Zr9O8(OH)6(8-QA)6(SO4)8]. 8- . Cluster compound [Zr9O8(OH)6(8-QA)6(SO4)8] 8- The unit cell parameters of the crystal are shown in Table 1:

[0041] Table 1. Cluster compound [Zr9O8(OH)6(8-QA)6(SO4)8] 8- Main crystallographic parameters table 1. [Zr9O8(OH)6(8-QA)6(SO4)8] 8- Structure: Based on single-crystal X-ray diffraction data, the structure of the yellow-brown crystal can be determined, such as... Figure 2 As shown. In the cluster compound [Zr9O8(OH)6(8-QA)6(SO4)8] 8- It contains nine independent zirconium metal centers. Based on its coordination mode, it is described in three parts: (1) In the structure, the coordination mode of the six sulfate ligands is a bidentate bridging, such as Figure 3 As shown; two are three-tooth bridges, as... Figure 4 As shown; the structure contains six 8-quinoline carboxylic acid structural units, all of which are bidental bridged, as... Figure 5As shown; (2) All oxygen atoms in the structure are in a bridging mode, of which 8 are μ3-O and 6 are μ3-OH; (3) All zirconium atoms in the cluster are 8-coordinated, of which the zirconium atom at the vertices of the quadrangular pyramid is coordinated with 2 oxygen atoms from 2 sulfuric acid atoms and 2 oxygen atoms from 8-quinoline carboxylic acid atoms on the periphery, and is connected to 2 μ3-O atoms and 2 μ3-OH atoms on the inside; the coordination mode of the remaining 6 zirconium atoms at the four corners of the quadrangular pyramid is the same, with the periphery coordinated with 2 oxygen atoms from 2 sulfuric acid atoms and 1 oxygen atom from 1 8-quinoline carboxylic acid atoms, and is connected to 3 μ3-O atoms and 2 μ3-OH atoms on the inside.

[0042] 2. [Zr9O8(OH)6(8-QA)6(SO4)8] 8- The representation of: The sample was tested using a Renishaw in Via Qontor laser Raman spectrometer, and the obtained spectra are shown below. Figure 6 As shown. Located at 1200cm -1 ~1600cm -1 The peaks between these peaks correspond to the stretching vibrations of C, CN, and CO on the ligand molecules; 617 cm⁻¹ -1 The peak at that point belongs to free SO4. 2- Bending vibration of the OSO bond in the middle; 476cm -1 The nearby peak represents the vibration of the Zr-OH-Zr bond, 10¹³ cm⁻¹. -1 948cm -1 The peaks at these locations are all attributed to characteristic vibrations resulting from the coordination of sulfate and zirconium ions.

[0043] The synthesized cluster compound [Zr9O8(OH)6(8-QA)6(SO4)8] 8- Scanning electron microscopy (SEM) was performed, such as... Figure 1 As shown, the cluster exhibits a regular blocky crystal morphology with a size of approximately 100 μm, a smooth surface, and no obvious agglomeration or breakage, indicating that the crystals grow well and have a stable structure. Figure 7 EDS analysis detected five characteristic peaks in the cluster: C, N, O, S, and Zr. The C peak mainly originated from the carbon skeleton of 8-quinoline carboxylic acid, the N peak mainly originated from the nitrate group and the quinoline skeleton, the characteristic peaks of C and O in the quinoline skeleton originated from μ2-O, μ3-O, sulfate group and water of crystallization in the crystal structure, and S originated from the sulfate group. The Zr peak confirmed the presence of Zr element in the crystal structure, verifying the consistency between the chemical composition and crystal structure of the cluster at the elemental level.

[0044] For the cluster compound [Zr9O8(OH)6(8-QA)6(SO4)8] 8- The crystal underwent TG-DTG testing, and the test results are as follows: Figure 8 As shown. The sample exhibited continuous weight loss from room temperature. By 120℃, the cumulative weight loss was 5%, corresponding to small amounts of crystal water, adsorbed water, and residual solvent. These components were gradually removed during heating and released as gases. In the temperature range of 120℃ to 380℃, the sample underwent its first decomposition weight loss, reaching 21.5%, corresponding to the fragmentation of the crystal structure. Subsequently, a second decomposition weight loss occurred in the range of 380℃ to 600℃, with a weight loss of 44.2%, reflecting further decomposition. The DTG curve showed characteristic peaks at 342.6℃ and 540.7℃, corresponding to the decomposition of the 8-QA organic framework and the formation of zirconium oxide, respectively. At 800℃, the cumulative total weight loss was 70.7%, with the remaining residue being zirconium oxide, which should be ZrO2.

[0045] 3. [Zr9O8(OH)6(8-QA)6(SO4)8] 8- Catalytic ability: For the cluster compound [Zr9O8(OH)6(8-QA)6(SO4)8] 8- GC-MS testing was performed using a Triple quadrupole GC-MS / MS instrument. This was to test the cluster compound [Zr9O8(OH)6(8-QA)6(SO4)8]. 8- The catalytic activity of aniline was assessed using 1 mL methanol as solvent, 10 μL aniline as substrate, 200 μL 30% hydrogen peroxide as oxidant, and 10 mg [Zr9O8(OH)6(8-QA)6(SO4)8] as oxidant. 8- Aniline catalysis was performed using crystals as a catalyst, with 15.3 μL of mesitylene as an internal standard. The reaction temperature was room temperature, and the reaction time was 12 h. Figure 9 As shown, the characteristic peak of the substrate aniline completely disappeared, proving that the conversion rate of aniline was 100%. When the time reached approximately 11.3 min, a more obvious characteristic peak appeared, corresponding to the catalytic reaction product azobenzene oxide, whose yield was calculated to be approximately 24%. In this catalytic reaction, the cluster [Zr9O8(OH)6(8-QA)6(SO4)8]... 8- This demonstrates its high selectivity and high activity.

[0046] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for preparing a nine-nuclear zirconium oxide cluster modified with a quinoline ligand, characterized in that, Includes the following steps: Using 8-quinoline carboxylic acid as a ligand and water and DMF as solvents, the ligand, solvent and zirconium sulfate were mixed and subjected to a solvothermal reaction to obtain a non-nuclear zirconium oxide cluster modified with quinoline ligands; The conditions for the solvothermal reaction are: to maintain the temperature at 80℃~90℃ for 24h~48h.

2. The method for preparing the nonanuclear zirconium oxide cluster modified with quinoline ligands according to claim 1, characterized in that, The molar ratio of zirconium sulfate to 8-quinoline carboxylic acid is 1:0.3~1.

5.

3. The method for preparing the nonanuclear zirconium oxide cluster modified with quinoline ligands according to claim 1, characterized in that, The volume ratio of water to DMF is 1:0.5~1.

4. The method for preparing the nonanuclear zirconium oxide cluster modified with quinoline ligands according to claim 1, characterized in that, The ligands also include sulfuric acid.

5. The method for preparing the nonanuclear zirconium oxide cluster modified with quinoline ligands according to claim 4, characterized in that, The molar ratio of zirconium sulfate to sulfuric acid is 1:0~15.

6. A nine-nuclear zirconium oxide cluster modified with a quinoline ligand, characterized in that, It is prepared by any one of the preparation methods described in claims 1 to 5.

7. The nonanuclear zirconium oxide cluster modified with quinoline ligands according to claim 6, characterized in that, The molecular formula of the quinoline ligand modified nine-nuclear zirconium-oxygen cluster is: [Zr9O8(OH)6(8-QA)6(SO4)8] 8- , 8-QA is 8-quinoline carboxylic acid; [Zr9O8(OH)6(8-QA)6(SO4)8] 8- In [Zr9O8(OH)6(8-QA)6(SO4)8], all the zirconium atoms are 8-coordinated, wherein the zirconium atom as the vertex of the tetragonal pyramid is respectively coordinated with 2 oxygen atoms from 2 sulfate groups and 2 oxygen atoms from 8-quinoline carboxylic acid on the periphery, and is connected with 2 μ3-O and 2 μ3-OH on the inside, the coordination mode of the 6 zirconium atoms at the four corners of the tetragonal pyramid is the same, which is respectively coordinated with 2 oxygen atoms from 2 sulfate groups and 1 oxygen atom from 8-quinoline carboxylic acid on the periphery, and is connected with 3 μ3-O and 2 μ3-OH on the inside.

8. The application of the quinoline ligand-modified nine-nuclear zirconium oxide cluster of claim 6 as a catalyst for the preparation of azobenzene oxide from aniline.

9. The application according to claim 8, characterized in that, The application method is as follows: using methanol as solvent, aniline as substrate, 30% hydrogen peroxide as oxidant, and [Zr9O8(OH)6(8-QA)6(SO4)8] as the solvent. 8- Using it as a catalyst, aniline is oxidized at room temperature to prepare azobenzene.

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