A molybdenum-tungsten hybrid polyacid cluster material and its preparation method and application, and a preparation method of 1,5-diketone derivatives

Abstract

The present invention discloses a molybdenum-tungsten hybrid polyacid cluster material and its preparation method and application, and a preparation method of 1,5-diketone derivatives. The molybdenum-tungsten hybrid polyacid cluster material has light absorption performance, and combined with the joint action of Mo and W Lewis acids, has a stable solid structure and abundant external Mo-O catalytic sites, so as to have excellent photocatalytic performance and stability. The molybdenum-tungsten hybrid polyacid cluster material can be recycled and reused as a heterogeneous photocatalytic catalyst, and has good recycling stability; the 1,3-diketone conversion rate is above 99.0%, and the product 1,5-diketone selectivity is above 99%. The molybdenum-tungsten hybrid polyacid cluster material is prepared by a bimetallic solution hydrothermal method, the conditions are controllable, and the product can be prepared in large quantities.

Description

Technical Field

[0001] The invention belongs to the technical field of metal inorganic functional materials, and specifically relates to a molybdenum-tungsten hybrid polyacid cluster material and a preparation method and application thereof, and a preparation method of a 1,5-diketone derivative. Background Art

[0002] Polyoxometalates (POMs), also known as polyacids, are discrete metal oxide anion clusters composed of transition metal ions and oxygen in a highly combined state. Polymolybdate clusters are an important branch of polyacid chemistry; as nanoscale mixed-valence polymolybdate compounds, they have adjustable structures and compositions, excellent redox and stability, and have shown broad application prospects in catalysis, energy, medicine and other fields.

[0003] There are still very few heterometallic polymolybdate clusters reported so far, and most of the molybdenum metal in the polymolybdate clusters is mainly hexavalent, and the framework structure is relatively common, which leads to poor structural stability. Among them, high-nuclear dense molybdenum-tungsten hybrid polyacid clusters are still very rare, and the research on their application in organic small molecule photocatalysis is also very limited.

[0004] Currently known polymolybdate metal clusters are mainly synthesized by excess molybdenum salt and reducing agent in water solvent system, which often requires several weeks or even months of static reaction at room temperature to obtain the product, and the reaction temperature is also limited to low temperature. So far, most polymolybdate metal clusters are single metal clusters. Introducing other metal ions is an effective strategy for synthesizing heterometallic polymolybdate clusters, but the addition of multi-reactive components will affect crystallization, making the synthesis more difficult. Summary of the invention

[0005] In order to overcome the shortcomings of the prior art, the first object of the present invention is to provide a molybdenum-tungsten hybrid polyacid cluster material, which is a molybdenum-tungsten hybrid polyacid cluster molecule; it has discrete nano entities and a stable structure, as well as excellent photocatalytic performance.

[0006] The second object of the present invention is to provide a method for preparing the above-mentioned molybdenum-tungsten hybrid polyacid cluster material.

[0007] The third object of the present invention is to provide an application of the above-mentioned molybdenum-tungsten hybrid polyacid cluster material as a heterogeneous catalyst for photocatalytic reactions.

[0008] The fourth object of the present invention is to provide a method for preparing 1,5-diketone derivatives.

[0009] One of the purposes of the present invention can be achieved by adopting the following technical solution:

[0010] A molybdenum-tungsten hybrid polyacid cluster material, the molybdenum-tungsten hybrid polyacid cluster material has Mo 50 W8 Structural unit; each Mo 50 W 8 The structural unit consists of two symmetrical Mo 22 W 4 And connect the two Mo symmetrically 22 W 4 Mo 6 ring;

[0011] A five-pointed star Mo 5 W 1 and two Mo connected at the same angle by one vertex of the five-pointed star 1 CompositionMo 7 W 1 Unit; the five-pointed star Mo 5 W 1 W 1 It has a seven-coordinate, pentagonal bipyramidal coordination configuration;

[0012] Three Mo 7 W 1 The unit is composed of a six-coordinated W 1 unit and a four-coordinated Mo 1 The unit is connected as the core by common edge to form Mo 22 W 4 , forming a dense solid metal cluster structure;

[0013] Mo 6 The ring consists of three Mo with common vertices 2 Each Mo is composed of 22 W 4 Two Mo connected at the same angle on 1 Connect the two Mo 22 W 4 Symmetrical connection in Mo 6 The Mo is formed on both sides of the ring 50 W 8 Structural unit.

[0014] Furthermore, Mo 50 W 8 The remaining Mo and W atoms in the structural unit are all hexacoordinated octahedral.

[0015] Furthermore, the molybdenum-tungsten hybrid polyacid cluster material crystallizes in the hexagonal P6 3 / m space group; unit cell parameters are: α=β=90°, γ=120°.

[0016] The second purpose of the present invention can be achieved by adopting the following technical solutions:

[0017] A method for preparing a molybdenum-tungsten hybrid polyacid cluster material comprises the following steps:

[0018] Molybdate, tungstate and hydrazine hydrochloride are dissolved in water and mixed, and a hydrothermal reaction is carried out under acidic conditions. After the reaction is completed, the molybdenum-tungsten hybrid polyacid cluster material is obtained.

[0019] Furthermore, the molybdate is sodium molybdate, potassium molybdate or a hydrate thereof.

[0020] Furthermore, the tungstate is sodium tungstate, potassium tungstate or a hydrate thereof.

[0021] Furthermore, the molar ratio of molybdate, tungstate and hydrazine hydrochloride is 5:(0.8-1.2):(4-6).

[0022] Furthermore, the acidic condition is a pH of 0-3.

[0023] Furthermore, the concentration of molybdate dissolved in water to form an aqueous solution is 0.15-0.45 mmol / ml.

[0024] Furthermore, the reaction conditions are: 110-130° C. for 12 h-96 h.

[0025] Further, the reaction is carried out in the presence of acetic acid, and the concentration of acetic acid added to water is 0.8-1.4 mmol / ml.

[0026] Furthermore, the acidic condition is adjusted using hydrochloric acid or sulfuric acid.

[0027] The third object of the present invention can be achieved by adopting the following technical solutions:

[0028] The above molybdenum-tungsten hybrid polyacid cluster material is used as a heterogeneous catalyst for photocatalytic reactions.

[0029] The fourth object of the present invention can be achieved by adopting the following technical solutions:

[0030] A method for preparing a 1,5-diketone derivative, using the molybdenum-tungsten hybrid polyacid cluster material as a catalyst, catalyzing a 1,3-diketone derivative to undergo a photoreaction in the presence of an olefin, to prepare a 1,5-diketone derivative product.

[0031] Furthermore, the 1,3-diketone derivative has a structure shown in Formula I; the olefin has a structure shown in Formula II; and the 1,5-diketone derivative has a structure shown in Formula III:

[0032]

[0033] Among them, R 1 , R 2R3 and R4 are respectively any one of H, aromatic compounds and C4-C9 saturated alkanes.

[0034] Furthermore, the mass molar ratio of the molybdenum-tungsten hybrid polyacid cluster material, olefin and 3-diketone derivative is (10-30) mg: (0.1-0.5) mmol: 0.045 mmol.

[0035] Furthermore, the conditions of the light reaction are: 15-50°C, full light irradiation reaction for 6-48 hours.

[0036] Furthermore, the molybdenum-tungsten hybrid polyacid cluster material is reused after separation, washing and drying.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] 1. A molybdenum-tungsten hybrid polyacid cluster material of the present invention replaces part of the molybdenum atoms with tungsten atoms to form molybdenum-tungsten hybridization, adds tungsten metal active sites on the basis of the original molybdenum metal active sites, and improves the catalytic performance; and the formed molybdenum-tungsten hybrid polyacid cluster material has internally coordinated tungsten atoms, so that the molybdenum-tungsten hybrid polyacid cluster material has a stable solid structure and abundant external Mo-O catalytic sites; the abundant external Mo-O catalytic sites can better contact with the reaction substrate, and the stable solid structure can make the catalytic cycle activity more durable, thereby improving the photocatalytic performance.

[0039] 2. The preparation method of the molybdenum-tungsten hybrid polyacid cluster material of the present invention is to prepare it by hydrothermal synthesis of a bimetallic solution; and to obtain a molybdenum-tungsten hybrid polyacid cluster material with controllable composition and structure by controlling the pH range.

[0040] 3. Application of the molybdenum-tungsten hybrid polyacid cluster material of the present invention. The molybdenum-tungsten hybrid polyacid cluster material is an inorganic metal catalyst having discrete nano entities, and thus can be used as a heterogeneous catalyst and in a photocatalytic reaction.

[0041] 4. The preparation method of a 1,5-diketone derivative of the present invention performs heterogeneous photocatalysis, and the catalyst molybdenum-tungsten hybrid polyacid cluster material can be recycled and reused, and has good recycling stability; the conversion rate of 1,3-diketone derivatives is high, and the product 1,5-diketone derivatives has high selectivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 Schematic diagram of the structure of the molybdenum-tungsten hybrid polyacid cluster material of the present invention;

[0043] Figure 2 This is a crystal photo of the molybdenum-tungsten hybrid polyacid cluster material of the present invention;

[0044] Figure 3 is an X-ray powder diffraction pattern of the molybdenum-tungsten hybrid polyacid cluster material of the present invention;

[0045] Figure 4 An infrared spectrum of an X-ray powder diffraction pattern of the molybdenum-tungsten hybrid polyacid cluster material of the present invention;

[0046] Figure 5 It is a thermal gravimetric curve of the molybdenum-tungsten hybrid polyacid cluster material of the present invention;

[0047] Figure 6 This is the nuclear magnetic hydrogen spectrum of the product of the first catalytic conversion of 1,3-diphenyl-1,3-propanedione by the molybdenum-tungsten hybrid polyacid cluster material of the present invention;

[0048] Figure 7 The carbon spectrum of the product of the first catalytic conversion of 1,3-diphenyl-1,3-propanedione by the molybdenum-tungsten hybrid polyacid cluster material of the present invention;

[0049] Figure 8-12 This is the H NMR spectrum of the products after different substrates were catalyzed by molybdenum-tungsten hybrid polyacid cluster materials. DETAILED DESCRIPTION

[0050] The technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only partial embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0051] Polyoxometalates are discrete metal oxide anion clusters composed of pre-transition metal elements in a highly combined state. The octahedral structure [MO 6 ](M=Mo, W, V, Nb or Ta) is the basic building block, which is connected to each other by sharing edges, corners or faces, producing polyacid anions with different structures and functional properties. The diversity of polyacid structures gives it unique physical and chemical properties. They have special thermal stability, high negative charge, significant redox ability, unique vacancy polyacid ligand properties, etc. These properties combine to make polyacids have a variety of applications from catalysis, medicine, electrochemistry, photochromism to magnetism.

[0052] Molybdenum polyacid clusters are an important branch of polyacid chemistry. As nanoscale mixed-valence polymolybdate compounds, they have adjustable structures and compositions, excellent redox and stability, and have shown broad application prospects in catalysis, energy, medicine and other fields. Currently known polymolybdate metal clusters are mainly synthesized by static reaction of excess molybdenum salts and reducing agents in a water solvent system at room temperature for several weeks or even months, and the reaction temperature selection is also limited to low temperatures.

[0053] The composition and structure of polymolybdate metal clusters can be controlled by the type of molybdenum salt and the ratio with acid; if other metals are doped in polymolybdenum metal oxoates, the metal active sites can be increased and the catalytic performance can be improved. However, to date, most polymolybdate metal clusters are still single metal clusters. Few bimetallic polymolybdate clusters have been reported, and the application research of their catalytic performance in small organic molecules is also very limited.

[0054] Therefore, the present invention provides a molybdenum-tungsten hybrid polyacid cluster material and a preparation method thereof, and a preparation method of a 1,5-diketone derivative.

[0055] A molybdenum-tungsten hybrid polyacid cluster material, the molybdenum-tungsten hybrid polyacid cluster material has Mo 50 W 8 Structural unit; each Mo 50 W 8 The structural unit consists of two symmetrical Mo 22 W 4 And connect the two Mo symmetrically 22 W 4 Mo 6 ring;

[0056] A five-pointed star Mo 5 W 1 and two Mo connected at the same angle by one vertex of the five-pointed star 1 CompositionMo 7 W 1 Unit; the five-pointed star Mo 5 W 1 W 1 It has a seven-coordinate, pentagonal bipyramidal coordination configuration;

[0057] Three Mo 7 W 1 The unit is composed of a six-coordinated W 1 unit and a four-coordinated Mo 1 The unit is connected as the core by common edge to form Mo 22 W 4 , forming a dense solid metal cluster structure;

[0058] Mo 6 The ring consists of three Mo with common vertices 2 Each Mo is composed of 22 W 4 Two Mo connected at the same angle on 1 Connect the two Mo 22 W 4 Symmetrical connection in Mo 6 The Mo is formed on both sides of the ring 50 W 8 Structural unit. Among them, Mo50 W 8 The remaining Mo and W atoms in the structural unit are all hexacoordinated octahedral.

[0059] Molybdenum-tungsten hybridization makes the whole structure different from other hollow structure polyacids. 7 W 1 The unit is composed of a six-coordinated W 1 unit and a four-coordinated Mo 1 The unit is connected as the core by common edge to form Mo 22 W 4 , forming a dense solid metal cluster structure; the dense solid structure makes it more stable, can complete the catalytic reaction in a more harsh environment, and has better performance. The present invention replaces part of the molybdenum atoms with tungsten atoms, maintains the original building unit of molybdenum polyacid, makes it have the catalytic performance of molybdenum, adds metal tungsten active sites on the molybdenum pentagram, and improves the catalytic performance. The structural diagram is shown in Figure 1 shown.

[0060] As one embodiment, the molybdenum-tungsten hybrid polyacid cluster material is crystallized in the hexagonal P6 3 / m space group; unit cell parameters are: α=β=90°, γ=120°.

[0061] The present invention also provides a method for preparing a molybdenum-tungsten hybrid polyacid cluster material, comprising the following steps:

[0062] Molybdate, tungstate and hydrazine hydrochloride are dissolved in water and mixed, and a hydrothermal reaction is carried out under acidic conditions. After the reaction is completed, the molybdenum-tungsten hybrid polyacid cluster material is obtained.

[0063] As one embodiment, the molybdate is sodium molybdate, potassium molybdate or a hydrate thereof.

[0064] As one embodiment, the tungstate is sodium tungstate, potassium tungstate or a hydrate thereof.

[0065] As one embodiment thereof, the molar ratio of molybdate, tungstate and hydrazine hydrochloride is 5:(0.8-1.2):(4-6).

[0066] As one embodiment, the concentration of molybdate dissolved in water to form an aqueous solution is 0.15-0.45 mmol / ml.

[0067] As one embodiment, the solvent is deionized water with a conductivity of less than 18.25 MΩ·cm to prevent other impurity ions in the water from affecting the reaction.

[0068] The bimetallic solution formed by dissolving molybdate and tungstate in water undergoes a hydrothermal reaction in the presence of a reducing agent.

[0069] As one embodiment, the reaction is carried out in the presence of acetic acid, and the concentration of acetic acid added to water is 0.8-1.4mmol / ml. Acetic acid, as a configuration regulator, can make the structure of the molybdenum-tungsten hybrid polyacid cluster material more regular, and the catalyst stability and catalytic performance are better.

[0070] As one embodiment, the acidic condition is a pH of 0-3. The present invention performs a hydrothermal reaction under acidic conditions to achieve the formation of the composition and structure of the molybdenum-tungsten hybrid polyacid cluster material, and limits the pH range to 0-3, so that the composition and structure of the molybdenum-tungsten hybrid polyacid cluster material can be controlled.

[0071] As one embodiment, the acidic condition is adjusted using hydrochloric acid or sulfuric acid. In this embodiment, sulfuric acid and hydrochloric acid can be used simultaneously to adjust the pH; when sulfuric acid and hydrochloric acid are used simultaneously, the addition of hydrochloric acid and sulfuric acid can be in a certain order or added simultaneously. The hydrochloric acid is preferably concentrated hydrochloric acid, and the sulfuric acid is preferably dilute sulfuric acid; further preferably, the volume fraction of the dilute sulfuric acid is 25%.

[0072] As one embodiment, molybdate, tungstate, acetic acid, hydrochloric acid and hydrazine hydrochloride are fully mixed and stirred in water to react to obtain an initial reaction solution; then sulfuric acid is added to the initial reaction solution to adjust the pH and then a hydrothermal reaction is carried out.

[0073] As one embodiment, the reaction conditions are: 110-130° C. for 12 h to 96 h. The reaction temperature is higher than the boiling point of the solvent water.

[0074] As one embodiment, after the reaction is completed, the material is cooled and allowed to stand to obtain the molybdenum-tungsten hybrid polyacid cluster material. The material can be placed in a cool place to cool naturally, or cooled by additional auxiliary cooling, such as air cooling.

[0075] The present invention also provides an application of a molybdenum-tungsten hybrid polyacid cluster material as a heterogeneous catalyst for a photocatalytic reaction.

[0076] A method for preparing a 1,5-diketone derivative, using the molybdenum-tungsten hybrid polyacid cluster material as a catalyst, catalyzing a 1,3-diketone derivative to undergo a photoreaction in the presence of an olefin, to prepare a 1,5-diketone derivative product.

[0077] Under the catalytic action of the molybdenum-tungsten hybrid polyacid cluster material, the olefin is connected to the carbon chain between the two keto groups of the 1,3-diketone derivative through a double bond, so that the carbon chain grows to form the corresponding 1,5-diketone derivative.

[0078] As one embodiment, the 1,3-diketone derivative has a structure shown in Formula I; the olefin has a structure shown in Formula II; and the 1,5-diketone derivative has a structure shown in Formula III:

[0079]

[0080] Among them, R 1 , R 2 are any one of aromatic compounds and C1-C5 saturated alkanes; R 3 , R 4 They are any one of H, aromatic compounds, and C4-C9 saturated alkanes.

[0081] As one embodiment, R 1 , R 2 R is any one of H, phenyl, substituted phenyl, and C1-C5 saturated alkane; 3 , R 4 They are any one of H, benzene, substituted phenyl, and C4-C9 saturated alkane.

[0082] As one embodiment, the molar ratio of the molybdenum-tungsten hybrid polyacid cluster material, olefin and 3-diketone derivative is (10-30) mg: (0.1-0.5) mmol: 0.045 mmol.

[0083] Furthermore, as one embodiment, the conditions of the light reaction are: 15-50° C., full light irradiation reaction for 6-48 hours.

[0084] As one implementation method, the molybdenum-tungsten hybrid polyacid cluster material is reused after separation, washing and drying.

[0085] The following is a further description of a specific implementation method.

[0086] Example 1

[0087] Weigh 16 mmol of sodium molybdate dihydrate (Na 2 MoO 4 ·2H 2 O), 3mmol sodium tungstate (Na 2 WO 4 ) Add 50ml of water (H 2 O) stirring to dissolve, to obtain a molybdenum-tungsten mixed solution, add 8mL 2mol / L N 2 H 4 ·2HCl (16 mmol) solution, stirred for 10 min, then 66 mmol acetic acid (CH 3COOH), 2mL concentrated hydrochloric acid (HCl), added to the above solution, and then adjusted the pH value to 1.5 with sulfuric acid with a volume ratio of 3:1 to obtain a reaction pre-solution; then hydrothermally reacted at 120°C for 72h; after the reaction was completed, it was placed in a cool place, the precipitated solid was collected, and the solid was washed five times with saturated sodium chloride solution (5×10ml) until the solution was colorless and transparent and there were only hexagonal crystals in the precipitated solid, and then naturally dried to obtain a molybdenum-tungsten hybrid polyacid cluster material, denoted as Mo50W8, and the crystal photo is shown in Figure 2 shown.

[0088] Example 2

[0089] Weigh 16 mmol of sodium molybdate (Na 2 MoO 4 )、3.84mmol sodium tungstate dihydrate (Na 2 WO 4 ) Add 94 ml of water (H 2 O) stirring to dissolve, to obtain a molybdenum-tungsten mixed solution, add 12.8mL 1mol / L N 2 H 4 ·2HCl (10mmol) solution, stirred for 10min, then 85mmol acetic acid (CH 3 COOH) was added to the above solution, and the pH value was adjusted to 0 with concentrated hydrochloric acid to obtain a reaction pre-solution, and then the reaction was hydrothermally reacted at 110°C for 96 hours; after the reaction was completed, it was placed in a cool place, the precipitated solid was collected, and the solid was washed five times with a saturated sodium chloride solution (5×10 ml) until the solution was colorless and transparent and only hexagonal crystals were found in the precipitated solid, and then it was naturally dried to obtain a molybdenum-tungsten hybrid polyacid cluster material, denoted as Mo 50 W 8 , crystal photos such as Figure 2 shown.

[0090] Example 3

[0091] Weigh 16 mmol of sodium molybdate dihydrate (Na 2 MoO 4 ·2H 2 O), 2.56mmol sodium tungstate (Na 2 WO 4 ) Add 16 ml of water (H 2 O) stirring to dissolve, to obtain a molybdenum-tungsten mixed solution, add 19mL 1mol / L N 2 H 4 ·2HCl (10 mmol) solution, stirred for 10 min, then 78 mmol acetic acid (CH 3COOH) was added to the above solution, and the pH value was directly adjusted to 3.0 with sulfuric acid in a volume ratio of 3:1 to obtain a reaction pre-solution, and then hydrothermally reacted at 130°C for 12 hours; after the reaction, it was placed in a cool place, the precipitated solid was collected, and the solid was washed five times with a saturated sodium chloride solution (5×10 ml) until the solution was colorless and transparent and only hexagonal crystals were found in the precipitated solid, and then naturally dried to obtain a molybdenum-tungsten hybrid polyacid cluster material, denoted as Mo 50 W 8 , crystal photos such as Figure 2 shown.

[0092] Test example:

[0093] (1) The molybdenum-tungsten hybrid polyacid cluster material Mo prepared in Example 1 was 50 W 8 X-ray powder diffraction test was performed. Figure 3 Shown; Mo 50 W 8 The crystallographic data and results are shown in Table 1.

[0094] Table 1:Mo 50 W 8 Crystallographic data and results

[0095]

[0096]

[0097] The data and results in Table 1, Mo 50 W 8 The molecular formula is H 215 Mo 50 Na 6 O 260 W 8 , crystallized in hexagonal P6 3 / m space group; unit cell parameters are: α=β=90°, γ=120°.

[0098] from Figure 3 The results of X-ray powder diffraction test show that the synthesized Mo 50 W 8 The peak positions of the diffraction spectrum and the simulated diffraction spectrum are highly consistent, indicating that the synthesized Mo 50 W 8 The crystallinity is good.

[0099] (2) The molybdenum-tungsten hybrid polyacid cluster material Mo prepared in Example 1 50 W 8 Perform Fourier transform-infrared spectroscopy test, the infrared spectrum is as follows Figure 4 shown.

[0100] from Figure 4 It can be clearly observed from the infrared spectrum that Mo 50 W 8 The infrared spectrum of -1 Multiple characteristic peaks of Mo-O bonds and WO bonds appeared at the site, proving that both Mo and W exist in the sample.

[0101] (3) The molybdenum-tungsten hybrid polyacid cluster material Mo prepared in Example 1 50 W 8 Thermogravimetric analysis test was carried out in an oxygen atmosphere. The thermogravimetric analysis test diagram is shown in the figure below. Figure 5 shown.

[0102] from Figure 5 Thermogravimetric analysis shows that Mo 50 W 8 There is a small amount of weight loss at 50-100℃, mainly due to the loss of guest molecules in the pores, such as water molecules; at around 750℃, Mo 50 W 8 There is a small amount of weight loss at the beginning, mainly due to the decomposition of the crystals in the oxygen atmosphere, indicating that Mo 50 W 8 The thermal stability of Mo is around 750℃; there is almost no weight loss at 100-750℃, and the final residual mass at 800℃ is 80%. Thermogravimetric analysis shows that Mo 50 W 8 Has good thermal stability.

[0103] Example 4

[0104] Weigh the Mo of the present invention 50 W 8 10mg was added to a 10ml photocatalytic reaction tube, 1ml chloroform solvent was added, argon was passed for 15min, 0.025mmol substrate 1,3-propanedione derivative and 0.05mmol olefin were added, and the reaction was carried out at room temperature under full light conditions for 24h; the reaction was filtered and dried overnight, separated and purified by silica gel plate, and detected by nuclear magnetic hydrogen spectrum. The reaction process is as follows:

[0105]

[0106] The reaction conversion rates and selectivities of different substrates are shown in Table 2.

[0107]

[0108] It can be seen from the catalytic oxidation results in Table 2 that the Mo 50 W 8As a catalyst, 1,3-propanedione derivatives can be prepared into corresponding 1,5-diketone products through photocatalytic reaction under mild conditions. The conversion rates of 1,3-diphenyl-1,3-propanedione, styrene and diphenylethylene are over 99%, and the conversion rates of other substrates such as 1-phenyl-1,3-propanedione are all higher than 75%, and no by-products are produced, showing high conversion rate and selectivity, and the yield of 1,5-diketone is high. Figure 7 This is the H-NMR spectrum of the reaction product of 1,3-diphenyl-1,3-propanedione and styrene.

[0109] The molybdenum-tungsten hybrid polyacid cluster material Mo 50 W 8 Contains 2 symmetrical Mo 22 W 4 and Mo as a connection 6 Ring structure; among them, Mo 22 W 4 By 3 Mo 7 W 1 The unit is composed of a six-coordinated W 1 unit and a four-coordinated Mo 1 The units are connected as cores through common edge method to form a dense solid metal cluster structure; Mo 6 The ring consists of three Mo with common vertices 2 Composition, while connecting both sides of Mo 22 W 4 Mo 7 W 1 The unit consists of a five-pointed star Mo 5 W 1 and two Mo connected at the same angle 1 Composition; among them, the five-pointed star Mo 5 W 1 The W in the structure is a seven-coordinate, pentagonal bipyramidal coordination configuration; the remaining Mo and W atoms in the structure are all six-coordinate octahedral. All of the above basic units together constitute {Mo 50 W 8 Molybdenum-tungsten hybrid polyacid cluster material. Molybdenum-tungsten polyacid doping is beneficial to expose more metal sites of molybdenum and tungsten, and can catalyze organic reactions more efficiently.

[0110] The reaction solution after the reaction in Example 4 was filtered and separated, and the solid residue was the molybdenum-tungsten hybrid polyacid cluster material Mo of the present invention. 50 W 8, use chloroform to wash (5×10ml) the solid residue, and dry it naturally to obtain the recovered molybdenum-tungsten hybrid polyacid cluster material. The recovered molybdenum-tungsten hybrid polyacid cluster material is further subjected to catalytic reaction according to the method of Example 4. The conversion rate of 1,3-diphenyl-1,3-propanedione and styrene, diphenylene is still more than 99%, and the conversion rate of other substrates such as 1-phenyl-1,3-propanedione is higher than 75%, and no by-products are produced. After 5 cycles, the conversion rate remains basically unchanged. The molybdenum-tungsten hybrid polyacid cluster material Mo 50 W 8 It exhibits excellent stability and catalytic performance.

[0111] In summary, the present invention synthesizes the molybdenum-tungsten hybrid polyacid cluster material Mo by hydrothermal reaction of molybdate, tungstate, acetic acid and hydrazine hydrochloride under acidic conditions. 50 W 8 ; It has discrete nano-entities and a stable solid structure as well as increased metal reaction sites and reaction stability time. It can serve as a heterogeneous catalyst for photoreactions, catalyzing the efficient conversion of 1,3-diketone and its derivatives into 1,5-diketone derivatives; and the molybdenum-tungsten hybrid polyacid cluster catalyst can be recycled.

[0112] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A molybdenum-tungsten hybrid polyacid cluster material, characterized in that: The molybdenum-tungsten hybrid polyacid cluster material has Mo 50 W8 structural unit; each Mo 50 The W8 structural unit consists of two symmetrical Mo 22 W4 and two Mo connected symmetrically 22 Mo6 ring of W4; A pentagonal star Mo5W1 and two Mo1s connected at the same angle at one vertex of the pentagonal star form a Mo7W1 unit; the W1 of the pentagonal star Mo5W1 has a seven-coordinate, pentagonal bipyramidal coordination configuration; Three Mo7W1 units are connected by edge-sharing to form Mo with a six-coordinated W1 unit and a four-coordinated Mo1 unit as the core. 22 W4, forming a dense solid metal cluster structure; The Mo6 ring is composed of three Mo2 with the same vertices. Each Mo is connected to Mo 22 Connect the two Mo1s on W4 that are connected at the same angle. 22 W4 is symmetrically connected on both sides of the Mo6 ring to form the Mo 50 W8 structural unit.

2. The molybdenum-tungsten hybrid polyacid cluster material according to claim 1, characterized in that: The molybdenum-tungsten hybrid polyacid cluster material crystallizes in the hexagonal P63 / m space group; the unit cell parameters are: a=19.8353(17) Å, b=19.8353(17) Å, c=41.589(6) Å, α=β=90º, γ=120º.

3. A method for preparing the molybdenum-tungsten hybrid polyacid cluster material according to claim 1 or 2, characterized in that: The following steps are involved: Dissolving molybdate, tungstate and hydrazine hydrochloride in water and mixing them, and performing a hydrothermal reaction under acidic conditions, and completing the reaction to obtain the molybdenum-tungsten hybrid polyacid cluster material; The molybdate is sodium molybdate, potassium molybdate or a hydrate thereof; the tungstate is sodium tungstate, potassium tungstate or a hydrate thereof; The molar ratio of molybdate, tungstate and hydrazine hydrochloride is 5:(0.8-1.2):(4-6); Acidic conditions are pH 0-3; The concentration of molybdate dissolved in water to form an aqueous solution is 0.15-0.45 mmol / ml; The reaction conditions are: 110-130°C for 12h-96h; The reaction is carried out in the presence of acetic acid, and the concentration of acetic acid added to water is 0.8-1.4mmol / ml; Acidic conditions are adjusted using hydrochloric acid and / or sulfuric acid.

4. Use of the molybdenum-tungsten hybrid polyacid cluster material according to claim 1 or 2 as a heterogeneous catalyst for photocatalytic reactions.

5. A method for preparing a 1,5-diketone derivative, characterized in that: The molybdenum-tungsten hybrid polyacid cluster material prepared by the molybdenum-tungsten hybrid polyacid cluster material according to claim 1 or 2 or the molybdenum-tungsten hybrid polyacid cluster material prepared by the preparation method of the molybdenum-tungsten hybrid polyacid cluster material according to claim 3 is used as a catalyst to catalyze a photoreaction of a 1,3-diketone derivative in the presence of an olefin to prepare a 1,5-diketone derivative product.

6. The method for preparing a 1,5-diketone derivative according to claim 5, characterized in that: The 1,3-diketone derivative has a structure shown in Formula I; the olefin has a structure shown in Formula II; and the 1,5-diketone derivative has a structure shown in Formula III: Wherein, R1 and R2 are respectively any one of an aromatic compound and a C1-C5 saturated alkane; R3 and R4 are respectively any one of H, an aromatic compound and a C4-C9 saturated alkane.

7. The method for preparing a 1,5-diketone derivative according to claim 5, characterized in that: The mass molar ratio of the molybdenum-tungsten hybrid polyacid cluster material, the olefin and the 3-diketone derivative is (10-30) mg: (0.1-0.5) mmol: 0.045 mmol; The conditions for the light reaction are: 15-50°C, full light irradiation for 6-48 hours.

8. The method for preparing a 1,5-diketone derivative according to claim 5, characterized in that: The molybdenum-tungsten hybrid polyacid cluster material is reused after separation, washing and drying.

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