High-density defective polyacid-based metal organic framework catalyst for hydroboration reaction as well as preparation method and application of high-density defective polyacid-based metal organic framework catalyst

Abstract

The invention belongs to the technical field of preparation of catalytic materials, and provides a high-density defective polyacid-based metal organic framework catalyst for hydroboration, a preparation method and application. According to the catalyst, a metal organic framework with defects is constructed by adopting a mixed ligand strategy, a polyacid cluster is introduced in situ on the basis of the metal organic framework, and through weak interaction between a cluster object and a subject framework, regulation and control of an oxidation state of a metal node and regulation and control of a supporting effect of an expanded pore space are realized at the same time; therefore, the problem of unstable structure caused by high defect content is overcome, the polyacid-based metal organic framework catalyst with high-density defects is successfully constructed, the catalyst solves the problems that the existing hydroboration reaction is high in temperature, the catalyst is difficult to recycle and the like, efficient conversion of the alkyne hydroboration reaction can be realized, and the yield of the alkyne hydroboration reaction is increased. Moreover, the structure is still stable after repeated cyclic utilization and use, and can be expanded to various alkyne substrates.

Description

Technical Field

[0001] This invention belongs to the field of catalytic material preparation technology, and relates to a high-density defective polyacid-based metal-organic framework catalyst for hydroboration reaction, its preparation method and application. Background Technology

[0002] Vinyl borate esters are an important class of organic synthetic intermediates, widely used in medicinal chemistry and synthetic chemistry, often participating in various cross-coupling reactions to achieve key steps such as the construction of carbon-carbon single bonds. The hydroboration of alkynes using diboron pinacol esters (B2Pin2), which are relatively stable to water and air, is one of the effective methods for synthesizing these compounds; this process usually requires a copper catalyst. However, currently reported homogeneous copper catalytic systems, in addition to requiring the addition of ligands and bases, also suffer from the problem of difficult catalyst recovery and reuse, which is inconsistent with the development concept of green chemistry. Furthermore, although heterogeneous catalysts such as Cu-MOFs, copper oxides, or copper single atoms have been attempted, these systems often still require relatively high temperatures for the reaction. Therefore, developing a heterogeneous copper-based catalyst that can efficiently catalyze the hydroboration of alkynes with B2Pin2 under mild conditions has significant practical application value.

[0003] Metal-organic frameworks (MOFs) are organic-inorganic porous hybrid materials with designable structures and tunable pore sizes, composed of metal ions / clusters linked to organic ligands via coordination bonds. Due to the tunability of the coordination structure of their metal nodes, MOFs can generate coordination defect structures during preparation by the absence of ligands or metal clusters, leading to various defective MOFs. Among these, coordination-unsaturated metal nodes can form open metal sites, enhancing catalytic and adsorption performance, compared to coordination-saturated metal nodes. Furthermore, defects typically increase porosity and specific surface area, reducing diffusion resistance for reactant molecules to active sites and for product molecules to desorb, thus exhibiting higher catalytic activity. However, the resulting defect structures often lead to structural instability in defective MOFs, thus limiting their practical applications. Therefore, constructing high-density defect sites within MOF structures while maintaining overall structural stability is crucial for the efficient catalytic hydroboration reaction. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a high-density defect polyacid-based metal-organic framework catalyst, so as to achieve efficient alkyne hydroboration reaction under mild conditions.

[0005] To address the aforementioned issues, this invention employs a hybrid ligand strategy to construct defective MOFs. Furthermore, multi-acid clusters are introduced in situ. Through the weak interaction between the cluster guests and the host framework, the oxidation state of the metal nodes and the support effect of the expanded pore space are simultaneously controlled, thereby successfully constructing high-density defect sites in the MOF structure.

[0006] The technical solution of this invention:

[0007] A high-density defect polyacid-based metal-organic framework catalyst for hydroboration reaction, namely the high-density defect D-HKUST-1@PW 12 It is composed of polyacid clusters PW 12 It is composed of a composite with a defective metal-organic framework material, HKUST-1; wherein the defective metal-organic framework material, HKUST-1, is D-HKUST-1@PW. 12 In its solvothermal synthesis process, the tridentate ligand pyromellitic acid is partially replaced with the bidentate ligand isophthalic acid, and PW is introduced in situ. 12 They successfully constructed a metal-organic framework containing a high density of defect sites.

[0008] The defective metal-organic framework material HKUST-1 is composed of Cu II A three-dimensional network porous material composed of paddlewheel-shaped secondary structural units formed by connecting dimers and deprotonated pyromellitic acid; when deprotonated isophthalic acid replaces part of the pyromellitic acid ligand, due to the lack of a coordinating carboxyl group, a coordination deficiency will occur in an adjacent Cu2 cluster node, thereby generating a coordination unsaturation defect site at the metal node.

[0009] The polyacid cluster PW 12 It is a Keggin-type saturated polyacid, namely dodecantungstic acid, with the chemical formula H3PW. 12 O 40 abbreviated as PW 12 PW in the material 12 The carrying capacity is 56 wt%; PW 12 It is confined in situ in the HKUST-1 channel in the form of a non-coordinated guest, and its surface oxygen points exactly to the Cu2 cluster node.

[0010] The polyacid cluster PW 12 Polyoxometalates (POMs), also known as polyoxometalates, are nanoscale metal-oxygen cluster compounds formed by former transition metal ions (such as V, Mo, W, Nb, Ta, etc.) and oxygen.

[0011] A method for preparing a high-density defective polyacid-based metal-organic framework catalyst for hydroboration reaction, comprising the following steps:

[0012] Under stirring conditions, copper nitrate trihydrate and dodecantungstic phosphate were dissolved in distilled water to obtain solution A; the molar ratio of copper nitrate trihydrate to dodecantungstic phosphate was 12:1-12:3, and the concentration of copper nitrate trihydrate in solution A was 0.09-0.17 mol / L. Isophthalic acid and trimellitic acid were dissolved sequentially in ethanol to obtain solution B; the molar ratio of isophthalic acid to trimellitic acid was 2:1-3:2, and the concentration of isophthalic acid in solution B was 0.03-0.04 mol / L. Subsequently, solutions A and B were mixed at a volume ratio of 1:1-2:1, sealed and stirred for 5 minutes to ensure homogeneity, and then transferred to a hydrothermal reactor and reacted at 110-140℃ for 6-8 hours. After the reaction, the mixture was cooled to room temperature, and the solid precipitate was collected by centrifugation and washed three times with ethanol. Finally, the obtained product was dried in a vacuum oven at 80℃ for 4 hours to obtain nanocrystalline D-HKUST-1@PW. 12 Material.

[0013] This invention further discloses D-HKUST-1@PW 12 The application of catalysts in the hydroboration of alkynes specifically involves converting alkynes into corresponding alkenylboronic ester compounds. The reaction equation is as follows:

[0014]

[0015] The substrate 1a is replaced with the following compound:

[0016] The substrate 1 was subjected to D-HKUST-1@PW 12 The corresponding products, conversion rates, and selectivity after catalysis:

[0017]

[0018] The beneficial effects of this invention are:

[0019] The D-HKUST-1@PW prepared in this invention 12 Composite materials have the advantages of simple preparation methods, low raw material costs, and short synthesis time. Compared with D-HKUST-1 materials without the introduction of polyacids, their defect content is significantly increased, which can effectively construct high-density defect sites in MOFs while maintaining the stability of the overall MOF structure.

[0020] The D-HKUST-1@PW prepared in this invention 12The composite material was applied to the hydroboration reaction of alkynes. The results showed that the catalyst could achieve a conversion rate of 96.6% for phenylacetylene within 1 hour at a relatively low temperature of 45 degrees Celsius. It also has a wide substrate applicability and can efficiently convert a variety of alkynes. Attached Figure Description

[0021] Figure 1 Powder X-ray diffraction patterns of the defective polyacid-based metal-organic framework material and the comparative sample described in this invention;

[0022] Figure 2 Fourier transform infrared spectra of the defective polyacid-based metal-organic framework material and the comparative sample described in this invention;

[0023] Figure 3 The transmission electron microscope (TEM) image of the defective polyacid-based metal-organic framework material described in this invention;

[0024] Figure 4 The above are the proton NMR spectra of the defective polyacid-based metal-organic framework material and the comparative sample described in this invention, wherein (a) is HKUST-1@PW 12 HKUST-1, D-HKUST-1@PW 12 and the NMR 1H spectrum of D-HKUST-1 after digestion in D2SO4 / DMSO-d6 medium, (b) is an enlarged NMR 1H spectrum of (a) in the range of 7.2–8.4 ppm. The purple rhombus represents the chemical shift of trimesolic acid (BTC: 8.6 ppm); the orange triangle represents the chemical shift of isophthalic acid (IPA: 8.3 ppm, 8 ppm, 7.5 ppm);

[0025] Figure 5 For the defective polyacid-based metal-organic framework material and comparative samples described in this invention, the Fourier transform k 2 Weighted spectrum;

[0026] Figure 6 X-ray photoelectron spectra of the defective polyacid-based metal-organic framework material and the comparative sample described in this invention;

[0027] Figure 7 The results of the hydroboration of alkynes catalyzed by the defective metal-organic framework catalyst of this invention are shown, where * represents the conversion rate of the catalyst for this reaction when the temperature is increased to 45 degrees Celsius.

[0028] Figure 8 The defective polyacid-based metal-organic framework catalyst D-HKUST-1@PW of this invention 12 Test results of five cycles of catalytic hydroboration of phenylacetylene;

[0029] Figure 9 The defective polyacid-based metal-organic framework catalyst D-HKUST-1@PW of this invention 12 XRD pattern of the sample after five cycles of catalytic hydroboration of phenylacetylene. Detailed Implementation

[0030] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0031] Example 1

[0032] 0.33 g (1.74 mmol) of copper nitrate trihydrate was dissolved in 10 mL of distilled water. After complete dissolution, 0.42 g (0.15 mmol) of dodecantungstic acid was added, and this solution was designated as solution A. 0.12 g (0.70 mmol) of isophthalic acid was dissolved in 20 mL of ethanol. After complete dissolution, 0.09 g (0.46 mmol) of trimesic acid was added, and this solution was designated as solution B. At room temperature, solution B was added to solution A and stirring was continued for 5 min. The mixture was then transferred to a reaction vessel and reacted at 110 °C for 8 h to obtain a solid product. After thorough washing with ethanol and drying in a vacuum oven at 80 °C for 4 hours, a defective polyacid-based metal-organic framework material was obtained, designated as D-HKUST-1@PW. 12 .

[0033] Comparative Example 1

[0034] 0.33 g (1.74 mmol) of copper nitrate trihydrate was dissolved in 10 mL of distilled water. After complete dissolution, 0.42 g (0.15 mmol) of dodecantungstic acid was added, and this solution was designated as solution A. 0.22 g (1.16 mmol) of trimesic acid was dissolved in 20 mL of ethanol, and this solution was designated as solution B. At room temperature, solution B was added to solution A and stirring was continued for 5 min. The mixture was then transferred to a reaction vessel and reacted at 110 °C for 8 h to obtain a solid product. After thorough washing with ethanol and drying in a vacuum oven at 80 °C for 4 hours, a defective polyacid-based metal-organic framework material was obtained, designated as HKUST-1@PW. 12 .

[0035] Comparative Example 2

[0036] 0.33 g (1.74 mmol) of copper nitrate trihydrate was dissolved in 10 mL of distilled water, denoted as solution A. 0.22 g (1.16 mmol) of trimesic acid was dissolved in 20 mL of ethanol, denoted as solution B. At room temperature, solution B was added to solution A and stirring was continued for 5 min. The mixture was then transferred to a reaction vessel and reacted at 110 °C for 8 h to obtain a solid product. After thorough washing with ethanol and drying in a vacuum oven at 80 °C for 4 hours, a defective polyacid-based metal-organic framework material, denoted as HKUST-1, was obtained.

[0037] Comparative Example 3

[0038] 0.33 g (1.74 mmol) of copper nitrate trihydrate was dissolved in 10 mL of distilled water, denoted as solution A. 0.12 g (0.70 mmol) of isophthalic acid was dissolved in 20 mL of ethanol. After complete dissolution, 0.09 g (0.46 mmol) of trimesic acid was added, denoted as solution B. At room temperature, solution B was added to solution A and stirring was continued for 5 min. The mixture was transferred to a reaction vessel and reacted at 110 °C for 8 h to obtain a solid product. After thorough washing with ethanol and drying in a vacuum oven at 80 °C for 4 hours, a defect-containing polyacid-based metal-organic framework material was obtained, denoted as D-HKUST-1.

[0039] like Figure 1 As shown, the X-ray diffraction pattern of the synthesized sample after the introduction of isophthalic acid is similar to that of the parent compound HKUST-1@PW. 12 The basic consistency indicates that the crystal structure has been preserved; Figure 2 The infrared spectrum shows that in the range of 700~1000 cm⁻¹ -1 PW appeared within the range 12 The characteristic absorption peaks of PW prove that 12 It has been successfully encapsulated in the HKUST-1 framework; Figure 3 The transmission microscopy pattern further indicates that PW 12 The introduction did not cause significant cluster aggregation; such as Figure 4 In the 1H NMR spectrum, characteristic chemical shifts of isophthalic acid appeared at 8.3 ppm, 8 ppm and 7.5 ppm, directly confirming that the isophthalic acid ligand has been introduced; compared with the control sample D-HKUST-1, its signal peaks were significantly enhanced, indicating that the presence of polyacids promoted the introduction of more isophthalic acid; Figure 5 The extended X-ray absorption fine structure spectrum shows that the main peak is located at ~1.5 Å, which is related to the Cu-O coordination bond; D-HKUST-1@PW 12 The peak intensity was significantly lower than that of fully coordinated HKUST-1@PW 12This confirms the presence of unsaturated defects in the metal nodes; and compared to D-HKUST-1, D-HKUST-1@PW 12 The decrease in coordination number of Cu is more significant, reflecting a further increase in defect density; Figure 6 X-ray photoelectron spectroscopy showed that Cu appeared in the sample at 932.7 eV. I The characteristic peaks, and D-HKUST-1@PW 12 Cu in I The peak area is significantly higher than that of HKUST-1. Combined analysis of proton NMR spectroscopy, synchrotron radiation near-edge absorption, and X-ray photoelectron spectroscopy consistently confirms the prepared D-HKUST-1@PW 12 The defect content in the material is significantly higher than that in D-HKUST-1 without the introduction of polyacids.

[0040] like Figure 1 As shown, the control sample D-HKUST-1, which did not introduce polyacids, can still maintain a crystal structure that is basically the same as the parent HKUST-1 after the addition of isophthalic acid. Figure 4 The proton NMR spectrum showed that although the signal of isophthalic acid could be observed at 8.3 ppm, 8 ppm and 7.5 ppm, its intensity was significantly lower than that of D-HKUST-1@PW. 12 The materials indicate that the amount of phthalic acid introduced into this sample is relatively small; Figure 5 Extended X-ray absorption fine structure spectroscopy analysis showed that, compared with D-HKUST-1@PW 12 In comparison, the decrease in Cu coordination number in the D-HKUST-1 sample was relatively small, indicating that the degree of ligand loss at its metal nodes was weak and the number of defects was small. Figure 6 In the X-ray photoelectron spectroscopy, Cu appeared in the sample at 932.7 eV. I Characteristic peaks; and Cu in D-HKUST-1 I The peak area is significantly smaller than that of D-HKUST-1@PW 12 Cu in I Peak area; the above results collectively confirm that the defect content formed in the D-HKUST-1 sample without the introduction of polyacids is significantly lower than that in the D-HKUST-1@PW sample containing polyacids. 12 Material.

[0041] The above results demonstrate that the sample D-HKUST-1@PW prepared in this invention... 12 It contains a high density of defective active sites.

[0042] Example 2

[0043] 0.33 g (1.74 mmol) of copper nitrate trihydrate was dissolved in 10 mL of distilled water. After complete dissolution, 0.84 g (0.45 mmol) of dodecantungstic acid was added, and this solution was designated as solution A. 0.12 g (0.70 mmol) of isophthalic acid was dissolved in 20 mL of ethanol. After complete dissolution, 0.09 g (0.46 mmol) of trimesic acid was added, and this solution was designated as solution B. At room temperature, solution B was added to solution A and stirring was continued for 5 min. The mixture was then transferred to a reaction vessel and reacted at 110 °C for 8 h to obtain a solid product. After thorough washing with ethanol and drying in a vacuum oven at 80 °C for 4 hours, a defective polyacid-based metal-organic framework material was obtained, designated as D1-HKUST-1@PW. 12 .

[0044] Example 3

[0045] 0.33 g (1.74 mmol) of copper nitrate trihydrate was dissolved in 10 mL of distilled water. After complete dissolution, 0.42 g (0.15 mmol) of dodecantungstic acid was added, and this solution was designated as solution A. 0.12 g (0.7 mmol) of isophthalic acid was dissolved in 20 mL of ethanol. After complete dissolution, 0.09 g (0.46 mmol) of trimesic acid was added, and this solution was designated as solution B. At room temperature, solution B was added to solution A and stirring was continued for 5 min. The mixture was then transferred to a reaction vessel and reacted at 140 °C for 6 h to obtain a solid product. After thorough washing with ethanol and drying in a vacuum oven at 80 °C for 4 hours, a defective polyacid-based metal-organic framework material was obtained, designated as D2-HKUST-1@PW. 12 .

[0046] Example 4

[0047] 0.33 g (1.74 mmol) of copper nitrate trihydrate was dissolved in 10 mL of distilled water. After complete dissolution, 0.42 g (0.15 mmol) of dodecantungstic acid was added, and this solution was designated as solution A. 0.12 g (0.70 mmol) of isophthalic acid was dissolved in 10 mL of ethanol. After complete dissolution, 0.09 g (0.46 mmol) of trimesic acid was added, and this solution was designated as solution B. At room temperature, solution B was added to solution A and stirring was continued for 5 min. The mixture was then transferred to a reaction vessel and reacted at 110 °C for 6 h to obtain a solid product. After thorough washing with ethanol and drying in a vacuum oven at 80 °C for 4 hours, a defective polyacid-based metal-organic framework material was obtained, designated as D3-HKUST-1@PW. 12 .

[0048] Example 5

[0049] 0.33 g (1.74 mmol) of copper nitrate trihydrate was dissolved in 20 mL of distilled water. After complete dissolution, 0.42 g (0.15 mmol) of dodecantungstic acid was added, and this solution was designated as solution A. 0.12 g (0.70 mmol) of isophthalic acid was dissolved in 40 mL of ethanol. After complete dissolution, 0.09 g (0.46 mmol) of trimesic acid was added, and this solution was designated as solution B. At room temperature, solution B was added to solution A and stirring was continued for 5 min. The mixture was then transferred to a reaction vessel and reacted at 110 °C for 8 h to obtain a solid product. After thorough washing with ethanol and drying in a vacuum oven at 80 °C for 4 hours, a defective polyacid-based metal-organic framework material was obtained, designated as D3-HKUST-1@PW. 12 .

[0050] Application Example 1

[0051] phenylacetylene borohydride reaction

[0052] Phenylacetylene (0.5 mmol), bis(pinacol borate) diboron (B2Pin2, 0.7 mmol, 177.76 mg), sodium ethoxide (0.15 mmol), dodecane (50 μL), and catalyst (0.35 mol%) were sequentially added to a 10 mL Sinville reaction tube containing 2 mL of ethanol. The reaction tube was evacuated using a double-row tube and filled with nitrogen gas at a volume concentration of 99.99%, repeated three times. The resulting mixture was then ultrasonically vibrated to form a homogeneous suspension and stirred at 35 °C / 45 °C for 1 hour under a nitrogen atmosphere. After the reaction was completed, the reaction solution was centrifuged. The reaction mixture was analyzed by gas chromatography-mass spectrometry (GC-MS) to determine the selectivity of the target product E-vinylboronic acid ester (3). At the same time, the alkyne conversion rate or the yield of product 3a was determined by gas chromatography using dodecane as an internal standard. In the cyclic experiment, the catalyst was separated from the reaction mixture and could be used directly in the next cycle without any treatment.

[0053] During application testing, Examples 1, 1, 2, and 3 were used, along with PW. 12 The catalytic performance results of the four catalysts physically blended with Comparative Example 2 are as follows: Figure 7 As shown.

[0054] The experimental test results show that the D-HKUST-1@PW prepared in this invention... 12 (Example 1) Compared with Comparative Example 1, Comparative Example 2, Comparative Example 3, and PW 12 Four catalysts physically blended with Comparative Example 2 exhibited superior catalytic activity; such as Figure 7-9 As shown, the catalyst D-HKUST-1@PW 12At 45°C for 1 hour, the conversion rate of phenylacetylene reached 96.6%, and it maintained high catalytic efficiency even after five recycling cycles. No significant change was observed in the crystal structure of the catalyst after cycling. Furthermore, D-HKUST-1@PW 12 It exhibits good substrate versatility, efficiently catalyzing the conversion of various alkyne substrates to obtain the corresponding vinylboronic esters. Specifically, when the substrate is extended from phenylacetylene to arylalkynes, sterically hindered alkylalkynes, and internal alkynes containing electron-donating or electron-withdrawing substituents, high product yields can be obtained.

[0055] Application Example 2

[0056] p-Methoxyphenylacetylene (0.5 mmol), bis(pinacol borate) diboron (B2Pin2, 0.7 mmol, 177.76 mg), sodium ethoxide (0.15 mmol), dodecane (50 μL), and catalyst (0.35 mol%) were sequentially added to a 10 mL Sinville reaction tube containing 2 mL of ethanol. The reaction tube was evacuated using a double-row tube and then filled with nitrogen gas at a volume concentration of 99.99%, repeated three times. The resulting mixture was then ultrasonically vibrated to form a homogeneous suspension and stirred at 45 °C for 1 hour under a nitrogen atmosphere. After the reaction was completed, the reaction solution was centrifuged. The reaction mixture was analyzed by gas chromatography-mass spectrometry (GC-MS) to determine the selectivity of the target product E-vinylboronic acid ester (3). At the same time, the alkyne conversion rate or the yield of product 3b was determined by gas chromatography using dodecane as an internal standard. In the cyclic experiment, the catalyst was separated from the reaction mixture and could be used directly in the next cycle without any treatment.

[0057] Application Example 3

[0058] p-Chlorophenylacetylene (0.5 mmol), bis(pinacol borate) diboron (B2Pin2, 0.7 mmol, 177.76 mg), sodium ethoxide (0.15 mmol), dodecane (50 μL), and catalyst (0.35 mol%) were sequentially added to a 10 mL Sinville reaction tube containing 2 mL of ethanol. The reaction tube was evacuated using a double-row tube and then filled with nitrogen gas at a volume concentration of 99.99%, repeated three times. The resulting mixture was then ultrasonically vibrated to form a homogeneous suspension and stirred at 35 °C for 1 hour under a nitrogen atmosphere. After the reaction was completed, the reaction solution was centrifuged. The reaction mixture was analyzed by gas chromatography-mass spectrometry (GC-MS) to determine the selectivity of the target product E-vinylboronic acid ester (3). At the same time, the alkyne conversion rate or the yield of product 3c was determined by gas chromatography using dodecane as an internal standard. In the cyclic experiment, the catalyst was separated from the reaction mixture and could be directly used in the next cycle without any treatment.

[0059] Application Example 4

[0060] p-Nitrophenylacetylene (0.5 mmol), bis(pinacol borate) diboron (B2Pin2, 0.7 mmol, 177.76 mg), sodium ethoxide (0.15 mmol), dodecane (50 μL), and catalyst (0.35 mol%) were sequentially added to a 10 mL Sinville reaction tube containing 6 mL of ethanol. The reaction tube was evacuated using a double-row tube and then filled with nitrogen gas at a volume concentration of 99.99%, repeated three times. The resulting mixture was then ultrasonically vibrated to form a homogeneous suspension and stirred at 45 °C for 1 hour under a nitrogen atmosphere. After the reaction was completed, the reaction solution was centrifuged. The reaction mixture was analyzed by gas chromatography-mass spectrometry (GC-MS) to determine the selectivity of the target product E-vinylboronic acid ester (3). At the same time, the alkyne conversion rate or the yield of the product 3d was determined by gas chromatography using dodecane as an internal standard. In the cyclic experiment, the catalyst could be directly used in the next cycle after being separated from the reaction mixture without any treatment.

[0061] Application Example 5

[0062] 1-Octyne (0.5 mmol), bis(pinacol borate) diboron (B2Pin2, 0.7 mmol, 177.76 mg), sodium ethoxide (0.15 mmol), dodecane (50 μL), and catalyst (0.35 mol%) were sequentially added to a 10 mL Sinville reaction tube containing 2 mL of ethanol. The reaction tube was evacuated using a double-row tube and purged with 99.99% nitrogen by volume, repeated three times. The resulting mixture was then ultrasonically vibrated to form a homogeneous suspension and stirred at 45 °C for 2 hours under a nitrogen atmosphere. After the reaction was completed, the reaction solution was centrifuged. The reaction mixture was analyzed by gas chromatography-mass spectrometry (GC-MS) to determine the selectivity of the target product E-vinylboronic acid ester (3). At the same time, the alkyne conversion rate or the yield of product 3e was determined by gas chromatography using dodecane as an internal standard. In the cyclic experiment, the catalyst was separated from the reaction mixture and could be directly used in the next cycle without any treatment.

[0063] Application Example 6

[0064] Diphenylacetylene (0.5 mmol), bis(pinacol borate) diboron (B2Pin2, 0.7 mmol, 177.76 mg), sodium ethoxide (0.15 mmol), dodecane (50 μL), and catalyst (0.35 mol%) were sequentially added to a 10 mL Sinville reaction tube containing 2 mL of ethanol. The reaction tube was evacuated using a double-row tube and then filled with nitrogen gas at a volume concentration of 99.99%, repeated three times. The resulting mixture was then ultrasonically vibrated to form a homogeneous suspension and stirred at 45 °C for 1 hour under a nitrogen atmosphere. After the reaction was completed, the reaction solution was centrifuged. The reaction mixture was analyzed by gas chromatography-mass spectrometry (GC-MS) to determine the selectivity of the target product E-vinylboronic acid ester (3). At the same time, the alkyne conversion rate or the yield of product 3f was determined by gas chromatography using dodecane as an internal standard. In the cyclic experiment, the catalyst was separated from the reaction mixture and could be used directly in the next cycle without any treatment.

[0065] The above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A high-density defect-based polyacid metal-organic framework catalyst for hydroboration reactions, characterized in that, This high-density defect polyacid-based metal-organic framework catalyst is a high-density defect D-HKUST-1@PW catalyst. 12 It is composed of polyacid clusters PW 12 It is composed of a composite with a defective metal-organic framework material, HKUST-1; wherein the defective metal-organic framework material, HKUST-1, is D-HKUST-1@PW. 12 .

2. The high-density defect-based polyacid metal-organic framework catalyst for hydroboration reaction according to claim 1, characterized in that, The defective metal-organic framework material HKUST-1 is composed of Cu II A three-dimensional network porous material composed of paddlewheel-shaped secondary structural units formed by connecting dimers with deprotonated pyromellitic acid.

3. The high-density defect-based polyacid metal-organic framework catalyst for hydroboration reaction according to claim 1, characterized in that, The polyacid cluster PW 12 It is a Keggin-type saturated polyacid, namely dodecantungstic acid, with the chemical formula H3PW. 12 O 40 abbreviated as PW 12 PW in the material 12 The carrying capacity is 56 wt%; PW 12 It is confined in situ in the HKUST-1 channel in the form of a non-coordinated guest, with its surface oxygen pointing towards the Cu2 cluster node.

4. The high-density defect-based polyacid metal-organic framework catalyst for hydroboration reaction according to claim 1, characterized in that, The polyacid cluster PW 12 It is a nanoscale metal-oxygen cluster compound formed by a former transition metal ion and oxygen; wherein the former transition metal ion is V, Mo, W, Nb or Ta.

5. A method for preparing a high-density defect-based polyacid-based metal-organic framework catalyst for hydroboration reaction, characterized in that, The steps are as follows: Under stirring conditions, copper nitrate trihydrate and dodecantungstic phosphate were dissolved in distilled water to obtain solution A; isophthalic acid and trimesic acid were dissolved sequentially in ethanol to obtain solution B; then, solutions A and B were mixed at a volume ratio of 1:1-2:1, sealed and stirred for 5 minutes to ensure homogeneity, and then transferred to a hydrothermal reactor and reacted at 110-140℃ for 6-8 hours; after the reaction was completed, the mixture was cooled to room temperature, the solid precipitate was collected by centrifugation and washed three times with ethanol; finally, the obtained product was dried in a vacuum oven at 80℃ for 4 hours to obtain D-HKUST-1@PW with high-density defects. 12 , is a high-density defective polyacid-based metal-organic framework catalyst for hydroboration reactions.

6. The preparation method according to claim 5, characterized in that, The molar ratio of copper nitrate trihydrate to dodecantungstic phosphoric acid is 12:1-12:3, and the concentration of copper nitrate trihydrate in solution A is 0.09-0.17 mol / L.

7. The preparation method according to claim 5, characterized in that, The molar ratio of isophthalic acid and trimesic acid is 2:1-3:2, and the concentration of isophthalic acid in solution B is 0.03-0.04 mol / L.

8. The application of the high-density defect polyacid-based metal-organic framework catalyst according to any one of claims 1-4 in the catalytic hydroboration reaction of alkynes, wherein the reaction equation is as follows: 。 9. The application according to claim 8, characterized in that, Substrate 1a can be replaced with the following compounds: 。

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