A nano metal-organic cage material for catalyzing carbon-oxygen cross-coupling reaction and a preparation method and use thereof

Abstract

The application discloses a nano metal organic cage material for catalyzing carbon-oxygen cross coupling reaction and a preparation method and application thereof. The metal organic cage material comprises a substrate and an exogenous metal, the substrate is a metal organic cage, and the exogenous metal is chimeric in the substrate in the form of ions. The organic cage material can be applied to a visible light promoted cross coupling reaction of aryl halide substrates and alcohols as a photocatalyst, and corresponding aryl ether compounds are obtained.

Description

Technical Field

[0001] This invention relates to the fields of functional materials and organometallic catalysis, and particularly to a nano-organic metal cage material for catalyzing carbon-oxygen cross-coupling reactions, its preparation method, and its applications. Background Technology

[0002] Cross-coupling reactions have important applications in drug preparation and fine chemical synthesis. In recent years, some progress has been made in using light-driven coupling reactions. In photocatalytic cross-coupling reactions, classic photocatalysts generally use dye molecules or semiconductors with light absorption properties, often with first transition metals as the metal center. These reactions do not require strong bases or high temperatures and can be carried out under relatively mild conditions. Photoactive metal-organic frameworks (MOFs), carbon nitrides, and covalent organic frameworks (COFs) have been used to support metal centers for photocatalytic cross-coupling reactions; however, the synthesis conditions of these materials are complex and often require harsh conditions such as high temperatures or deoxygenation.

[0003] Nanoscale metal-organic cages, with their inherent porous structure and discrete properties, possess unique advantages in the construction of metal centers. In recent years, nanoscale metal-organic cages with metal centers have made some progress in areas such as photocatalytic carbon dioxide reduction and photocatalytic water splitting. Summary of the Invention

[0004] The present invention provides a metal-organic cage material, the metal-organic cage material comprising a substrate and an exogenous metal, wherein the substrate is a metal-organic cage, and the exogenous metal is embedded in the substrate in the form of ions.

[0005] According to an embodiment of the present invention, the loading of the exogenous metal can be 0.01-1 wt%, for example 0.1-0.7 wt%, and exemplary 0.66 wt%.

[0006] According to an embodiment of the present invention, the metal-organic cage is a zirconium-based metal cage.

[0007] According to an embodiment of the present invention, the zirconium-based metal cage is prepared by zirconium salt and small molecule ligand.

[0008] Preferably, the small molecule ligand may be selected from at least one or more of terephthalic acid and aminoterephthalic acid.

[0009] Preferably, the zirconium salt may be selected from at least one or more of zirconium dichlorocerocene (Cp2ZrCl2), zirconium hydrocerocene (Cp2ZrClH), Cp2Zr(OTs)2 and Cp2Zr(OTf)2·THF.

[0010] Preferably, the molar ratio of the zirconium salt to the small molecule ligand is (1-20):10, for example (7-20):10, or even 1:10, 5:10, 10:10, 15:10, or 20:10.

[0011] According to an embodiment of the present invention, the metal-organic cage is nanoscale.

[0012] According to an embodiment of the present invention, the exogenous metal is selected from transition metals. Preferably, the transition metal is selected from at least one of nickel, copper, cobalt, iron, and zinc.

[0013] According to an embodiment of the present invention, the exogenous metal and the metal-organic cage are combined through coordination.

[0014] This invention also provides a method for preparing the above-mentioned metal-organic cage material, the method comprising the following steps:

[0015] Step (1): Dissolve the small molecule ligand and zirconium salt in a good solvent to obtain a mixed solution, add a poor solvent dropwise, and hydrolyze at a constant temperature to obtain the substrate;

[0016] Step (2): The substrate obtained in step (1) is reacted with a salt containing an exogenous metal to obtain the metal-organic cage material.

[0017] According to an embodiment of the present invention, in step (1), the small molecule ligand may be selected from at least one or more of terephthalic acid and aminoterephthalic acid.

[0018] According to an embodiment of the present invention, in step (1), the zirconium salt may be selected from at least one or more of zirconium dichlorocerocenium (Cp2ZrCl2), zirconium hydrocerocenium (Cp2ZrClH), Cp2Zr(OTs)2 and Cp2Zr(OTf)2·THF.

[0019] According to an embodiment of the present invention, in step (1), the concentration of the small molecule ligand in the mixed solution is 0.01-0.2 mol / L, for example 0.015-0.04 mol / L, 0.01-0.5 mol / L, or for example 0.01 mol / L, 0.02 mol / L, 0.03 mol / L, 0.04 mol / L, 0.05 mol / L, 0.1 mol / L, 0.15 mol / L, or 0.2 mol / L.

[0020] According to an embodiment of the present invention, in step (1), the molar ratio of the zirconium salt to the small molecule ligand is (1-20):10, for example (7-20):10, or for example 1:10, 5:10, 10:10, 15:10, or 20:10.

[0021] According to an embodiment of the present invention, in step (1), the good solvent may be selected from at least one or more of N,N-diethylformamide, N,N-dimethylformamide and N,N-dimethylacetamide.

[0022] According to an embodiment of the present invention, in step (1), the undesirable solvent is selected from water.

[0023] According to an embodiment of the present invention, in step (1), the volume ratio of the good solvent to the bad solvent is 10:(10-1), for example, 10:(1-3).

[0024] According to an embodiment of the present invention, in step (1), the conditions for isothermal hydrolysis include: a reaction temperature of 25-80℃, for example 25-60℃, or for example 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃; and a reaction time of 1-24h, for example 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h.

[0025] According to an embodiment of the present invention, after obtaining the substrate by isothermal hydrolysis, the substrate is further subjected to post-processing.

[0026] According to an embodiment of the present invention, the post-processing may be performed using methods known in the art, such as cleaning and / or vacuum drying.

[0027] Preferably, the cleaning specifically includes cleaning with the good solvent and / or ethanol, for example, cleaning with the good solvent and ethanol sequentially several times, such as cleaning once, twice, three times, four times, and five times. Preferably, the present invention does not specifically limit the vacuum drying, as long as the substrate can be dried. For example, the vacuum drying time can be 1-24 hours, for example, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, 22 hours, and 24 hours.

[0028] According to an embodiment of the present invention, in step (2), the salt containing exogenous metal can be a transition metal salt, such as one or more of nickel salt, copper salt, cobalt salt, iron salt and zinc salt.

[0029] According to an embodiment of the present invention, in step (2), the reaction is carried out in an organic solvent. Preferably, the organic solvent is a polar organic solvent, for example, it may be selected from at least one or more of methanol, ethanol, acetone or chloroform.

[0030] According to an embodiment of the present invention, in step (2), the concentration of the salt containing the exogenous metal in the polar organic solvent is 1-100 mmol / L, for example 10-80 mmol / L, or for example 10 mmol / L, 30 mmol / L, 50 mmol / L, or 80 mmol / L.

[0031] According to an embodiment of the present invention, in step (2), the concentration of the substrate in the polar organic solvent is 0.5-20 g / L, for example, 5 g / L, 10 g / L, 15 g / L, or 20 g / L.

[0032] According to an embodiment of the present invention, in step (2), the molar mass ratio of the salt containing the exogenous metal to the substrate is 1-100 mmol: 5-20 g, for example 10-80 mmol: 5-20 g, or for example 10 mmol: 5-20 g, 20 mmol: 5-20 g, 30 mmol: 5-20 g, 40 mmol: 5-20 g, 50 mmol: 5-20 g, 60 mmol: 5-20 g, 70 mmol: 5-20 g, or 80 mmol: 5-20 g.

[0033] According to an embodiment of the present invention, in step (2), the reaction time can be 1-48h, for example 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h, 30h, 40h, 48h.

[0034] According to an embodiment of the present invention, in step (2), after the reaction, the process further includes washing with the polar organic solvent, preferably at least twice.

[0035] According to an embodiment of the present invention, drying can be performed after cleaning, for example, for 1-24 hours.

[0036] The present invention also provides a photocatalyst comprising the above-mentioned metal-organic cage material.

[0037] The present invention also provides the use of the above-mentioned metal-organic cage material and / or photocatalyst, preferably for carbon-oxygen cross-coupling reactions.

[0038] The present invention also provides a carbon-oxygen cross-coupling reaction, which includes: reacting a haloalkane with an alcohol to prepare an aryl ether compound in the presence of the above-mentioned metal-organic cage material and / or photocatalyst.

[0039] According to an embodiment of the present invention, the halogenated hydrocarbon is a halogenated aromatic compound, such as at least one of p-bromoacetophenone, p-bromotrifluorotoluene, p-bromobenzonitrile, p-bromobenzaldehyde, ethyl p-bromobenzoate, m-bromoacetophenone, 4-methylbenzophenone, 5-bromo-2-cyanopyridine, p-chlorobenzonitrile, p-iodobenzonitrile, and bromobenzene.

[0040] According to an embodiment of the present invention, the alcohol is a short-chain alcohol. Preferably, the short-chain alcohol is selected from monohydric alcohols with fewer than 10 carbon atoms, such as at least one of methanol, ethanol, isopropanol, and n-butanol.

[0041] According to an embodiment of the present invention, the carbon-oxygen cross-coupling reaction specifically includes the following steps:

[0042] The metal-organic cage material and / or photocatalyst, halogenated aromatic compound, and organic base are dissolved in the alcohol and reacted under light conditions to obtain aryl ether compounds.

[0043] According to embodiments of the present invention, the reaction can be carried out in equipment known in the art, such as a photoreactor. Exemplarily, the photoreactor is preferably a light-transmitting reactor. Furthermore, the photoreactor also needs to be sealed for deoxygenation.

[0044] According to an embodiment of the present invention, the illumination conditions may be those known in the art, such as irradiation with 400nm blue light.

[0045] According to an embodiment of the present invention, the organic base is selected from triethylamine, triethanolamine, quinine ring, 1,4-diazabicyclo[2.2.2]octane, N,N-diisopropylethylamine, for example, triethylamine.

[0046] According to an embodiment of the present invention, the concentration of the metal-organic cage material and / or photocatalyst in the reaction system is 0.1-1 g / L, for example, 0.1 g / L, 0.2 g / L, 0.3 g / L, 0.4 g / L, 0.5 g / L, 0.6 g / L, 0.7 g / L, 0.8 g / L, 0.9 g / L, or 1 g / L.

[0047] According to an embodiment of the present invention, the concentration of the halogenated aromatic compound in the reaction system is 0.002-0.1 mol / L, for example, 0.01 mol / L.

[0048] According to an embodiment of the present invention, the volume of the alcohol in the reaction system is 5-10 mL, for example, 10 mL.

[0049] According to an embodiment of the present invention, in the reaction system, the molar ratio of the halogenated aromatic compound to the organic base can be 1:0.5-15, for example, 1:2.

[0050] According to an embodiment of the present invention, the reaction temperature can be 10-40°C, for example 25°C; the reaction time can be 4 hours or more, for example 6 hours, 8 hours, or 12 hours.

[0051] According to an embodiment of the present invention, the reaction is carried out under stirring.

[0052] Beneficial effects

[0053] This invention utilizes the amino and carboxyl groups of ligands in zirconium-based metal-organic cages to coordinate with exogenous metals, synthesizing a metal-organic cage material. The photoactive metal-organic cage is linked to the exogenous metal through coordination bonds, promoting electron transfer between the two and activation of the exogenous metal.

[0054] The organic cage material of this invention, as a photocatalyst, can be applied to the visible light-promoted cross-coupling reaction of aryl halide substrates with alcohols to obtain aryl ether compounds. Using the organic cage material of this invention as a photocatalyst, the coupling of electron-deficient halogenated aromatic compounds with alcohols can be efficiently achieved under mild conditions. Furthermore, the selected metal-organic cage substrate allows for mild synthesis conditions, ease of operation, and a wide range of applicable substrates. Attached Figure Description

[0055] Figure 1 The image shows a high-resolution electrospray ionization-Fourier-mass spectrum of the catalyst prepared in Example 1.

[0056] Figure 2 The absorption spectra of the catalyst and metal-organic cage prepared in Example 1 show obvious visible light absorption.

[0057] Figure 3 The image shows the gas spectrum of the product from the coupling reaction of p-bromobenzonitrile and methanol in Application Example 1. Detailed Implementation

[0058] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0059] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0060] Example 1

[0061] The preparation method of nickel-centered metal-organic cage (Ni-MOC) nanomaterials is as follows:

[0062] (1) Dissolve 350 mg of zirconium dichloropentazo and 108 mg of aminoterephthalic acid in 20 mL of N,N-diethylformamide, add 6 mL of water, and then evenly disperse them in 20 glass bottles. Heat at 60 °C for 6 h to obtain yellow cubic crystals. Wash the crystals with N,N-diethylformamide and ethanol 2-5 times in sequence and then vacuum dry for 1 h to obtain zirconium-based metal organic cage (MOC).

[0063] (2) Disperse 200 mg of the metal-organic cage prepared in step (1) in 10 mL of 0.17 mol / L NiCl2·6H2O methanol solution. After reacting for 24 h, centrifuge and wash twice (wash with methanol). After vacuum drying for 1 h, a yellow solid is obtained, which is the nano-metal-organic cage material with nickel center (Ni-MOC).

[0064] like Figure 1 and Figure 2 As shown in the figure, the Ni loading in Ni-MOC is 0.66 wt%. Ni binds to MOC through coordination with the metal-organic cage.

[0065] Examples 2-5

[0066] The preparation method of the nickel-centered nano-metal-organic cage material (Ni-MOC) in this embodiment is basically the same as that in Example 1, except that...

[0067] In Example 2, NiCl2·6H2O in step (2) was replaced with CuCl2·6H2O to prepare Cu-MOC nanomaterials with copper centers.

[0068] In Example 3, NiCl2·6H2O in step (2) was replaced with CoCl2·6H2O to prepare Co-MOC nanomaterials with cobalt centers.

[0069] In Example 4, NiCl2·6H2O in step (2) was replaced with FeCl2·6H2O to prepare Fe-MOC nanomaterials with iron centers.

[0070] In Example 5, NiCl2·6H2O in step (2) was replaced with ZnCl2·6H2O to prepare Zn-MOC nanomaterials with zinc centers.

[0071] In the nano-metal-organic cage materials prepared in Examples 2-5, the binding mode of the exogenous metal (copper, cobalt, iron or zinc) with the MOC is basically the same as that of Ni-MOC, that is, the metal-organic cage and the exogenous metal (copper, cobalt, iron or zinc) are bound together through coordination.

[0072] Comparative Example 1

[0073] The preparation method of the nickel-centered nano-metal-organic cage material (Ni-MOC) in this comparative example is basically the same as that in Example 1, except that the reaction time in step (2) is 1 h.

[0074] Tests show that the Ni loading in the Ni-MOC of this comparative example is 0.143 wt%.

[0075] Application Example 1

[0076] The photocatalytic carbon-oxygen cross-coupling reaction is as follows:

[0077] 10 mg of Ni-MOC prepared in Example 1, 0.2 mmol of triethylamine, 0.1 mmol of p-bromobenzonitrile, and 10 mL of methanol were added to the photoreactor. The reaction mixture was then purged with argon gas for at least 15 minutes under magnetic stirring to remove oxygen. The photocatalytic reaction was carried out under irradiation with a 400 nm LED lamp. The reaction temperature was maintained at 25 °C with circulating water cooling. After irradiation for 8 hours, the product p-methoxybenzonitrile was obtained in 93% yield. The gas chromatography spectrum of the product from the coupling reaction of p-bromobenzonitrile and methanol is shown below. Figure 3 As shown, by Figure 3 It can be seen that after 8 hours of reaction, the p-bromobenzonitrile in the reaction system, which includes the reaction mixture and reaction products, has been completely converted, and the coupling product p-methoxybenzonitrile is present in the reaction system.

[0078] When the nano-metal-organic cage materials of Examples 2-5 are used for photocatalytic carbon-oxygen cross-coupling reactions, the coupling reaction and the products obtained are basically the same as in Application Example 1.

[0079] Comparative Application Example 1

[0080] The photocatalytic carbon-oxygen cross-coupling reaction is as follows:

[0081] 10 mg of Ni-MOC prepared in Example 1, 0.2 mmol of organic base, 0.1 mmol of p-bromobenzonitrile, and 10 mL of methanol were added to the reactor. The reaction mixture was then purged with argon gas for at least 15 minutes under magnetic stirring to remove oxygen. The reaction temperature was maintained at 25 °C with circulating water cooling. After 8 hours of reaction without light irradiation, no reactant conversion and no formation of p-methoxybenzonitrile were observed.

[0082] Comparative Application Example 2

[0083] The photocatalytic carbon-oxygen cross-coupling reaction is as follows:

[0084] 0.2 mmol of organic base, 0.1 mmol of p-bromobenzonitrile, and 10 mL of methanol were added to the reactor. The reaction mixture was then purged with argon gas for at least 15 minutes under magnetic stirring to remove oxygen. The photoreaction was carried out under irradiation with a 400 nm LED lamp. The reaction temperature was maintained at 25 °C using circulating water cooling. After 8 hours of irradiation, no reactant conversion was observed, and no p-methoxybenzonitrile was formed.

[0085] Comparative Application Example 3

[0086] The photocatalytic carbon-oxygen cross-coupling reaction in this comparative application example is basically the same as in application example 1, except that Ni-MOC from comparative example 1 is used.

[0087] The product obtained from the reaction was p-methoxybenzonitrile, with a yield of 33%. The decrease in yield may be due to the reduction in the content of Ni active sites.

[0088] The exemplary embodiments of the present invention have been described above. However, the scope of protection of this application is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A metal-organic cage material for carbon-oxygen cross-coupling reactions, characterized in that, The metal-organic cage material includes a substrate and an exogenous metal, wherein the substrate is a metal-organic cage and the exogenous metal is embedded in the substrate in the form of ions; the exogenous metal is at least one of nickel, copper, cobalt, iron and zinc; The loading of the exogenous metal was 0.66 wt%; The metal-organic cage is a zirconium-based metal cage, which is prepared by zirconium salt and small molecule ligand, wherein the small molecule ligand is aminoterephthalic acid and the zirconium salt is zirconium dichlorocerocene. The molar ratio of the zirconium salt to the small molecule ligand is 15-20:10; the exogenous metal is combined with the amino and carboxyl groups of the ligand in the metal-organic cage through coordination.

2. The method for preparing the metal-organic cage material according to claim 1, characterized in that, The preparation method includes the following steps: Step (1): Dissolve the small molecule ligand and zirconium salt in a good solvent to obtain a mixed solution, add a poor solvent dropwise, and hydrolyze at a constant temperature to obtain the substrate; the small molecule ligand is aminoterephthalic acid, and the zirconium salt is zirconium dichloroethylene; Step (2): The substrate obtained in step (1) is reacted with a salt containing an exogenous metal to obtain the metal-organic cage material.

3. The preparation method according to claim 2, characterized in that, In step (1), the concentration of the small molecule ligand in the mixed solution is 0.01-0.2 mol / L; In step (1), the molar ratio of the zirconium salt to the small molecule ligand is 15-20:

10.

4. The preparation method according to claim 2, characterized in that, In step (1), the good solvent is selected from at least one of N,N-diethylformamide, N,N-dimethylformamide and N,N-dimethylacetamide; In step (1), the undesirable solvent is selected from water; In step (1), the volume ratio of the good solvent to the bad solvent is 10:10-1.

5. The preparation method according to claim 2, characterized in that, In step (1), the conditions for isothermal hydrolysis include: a reaction temperature of 25-80 ℃; The process of obtaining the substrate by isothermal hydrolysis also includes post-processing of the substrate.

6. The preparation method according to claim 2, characterized in that, In step (2), the reaction is carried out in an organic solvent; In step (2), the reaction time is 1-48 h.

7. A photocatalyst, characterized in that, The photocatalyst comprises the metal-organic cage material as described in claim 1.

8. A carbon-oxygen cross-coupling reaction, characterized in that, The carbon-oxygen cross-coupling reaction includes: preparing aryl ether compounds by reacting haloalkanes and alcohols in the presence of the metal-organic cage material of claim 1 and / or the photocatalyst of claim 7.

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