Pyrenyl covalent organic framework material as well as preparation method and application thereof

Abstract

The invention provides a pyrenyl covalent organic framework material as well as a preparation method and application thereof. The pyrenyl covalent organic framework material is constructed by carrying out a Schiff base reaction on a polyamido pyrene monomer and a chiral pyrrole monomer; wherein the chiral pyrrole monomer comprises a compound as shown in a formula I and / or a compound as shown in a formula II, and # imgabs0. The pyrenyl covalent organic framework material has high crystallinity and high specific surface area, is applied to catalysis of asymmetric aldol condensation reaction, and is high in yield, good in stereoselectivity and easy to recycle.

Description

Technical Field

[0001] The invention belongs to the technical field of organic asymmetric catalysis and organic porous materials, and specifically relates to a covalent organic framework material containing a pyrene functional group, a preparation method thereof, and an application thereof in catalyzing an asymmetric aldol condensation reaction. Background Art

[0002] Chiral organic synthesis is an indispensable tool for obtaining highly stereoselective chemicals. It can control the selectivity of various chiral compounds and substances and plays an irreplaceable role in biochemistry, medicine and other fields. Chiral catalysts can directly control the chirality of products and determine the optical purity of products. They are an important component of chiral organic synthesis. How to design and synthesize efficient asymmetric catalysts has become a research focus. In 2000, Benjamin List found that organic chiral small molecule proline can be used as a natural chiral catalyst to achieve direct asymmetric aldol condensation reaction between acetone and various aldehydes, which attracted widespread attention from researchers (DOI: 10.1021 / ja994280y). However, as homogeneous catalysts, organic small molecule catalysts have high loading and difficult separation, which usually limits their large-scale practical application. Compared with homogeneous catalysts, heterogeneous catalysts have higher industrial application potential because they are easy to recycle and quickly reuse.

[0003] Covalent organic frameworks are a class of polymers with high crystallinity and high porosity, with a well-defined pore structure and an easily designed functional group structure. In recent years, covalent organic frameworks have been widely used in the fields of gas adsorption and separation, energy conversion and storage. It is particularly worth mentioning that its insolubility in organic solvents, rich active catalytic sites and developed pore structure give it a unique advantage in heterogeneous catalysis. However, there are few reports on the use of covalent organic frameworks for asymmetric catalysis. Fixing organic small molecule catalysts on the skeleton of rigid covalent organic frameworks can promote product separation and catalyst reuse. It can be foreseen that it will greatly expand the application of organic frameworks in the field of chiral catalysis.

[0004] CN105622579B discloses a method for synthesizing a chiral covalent organic framework and asymmetric catalytic application, including the steps of synthesizing a chiral precursor, condensing the chiral precursor with trimesic acid to obtain a crystallized product, washing and drying to obtain CCOF-LZU22-Boc, and then removing the tert-butyloxycarbonyl group of CCOF-LZU22-Boc at high temperature to obtain the final product CCOF-LZU72. The chiral covalent organic framework CCOF-LZU72 is applied to the Aldol reaction of acetone and p-nitrobenzaldehyde, and the product yield can reach 90%, and the enantiomeric selectivity is 45%; the method has many synthesis steps, resulting in a high catalyst preparation cost.

[0005] CN111138283B discloses a method for preparing chiral aldehyde compounds by asymmetric photocatalysis of a covalent organic framework connected by benzoxazole. The method uses the benzoxazole covalent organic framework LZU90 as a photocatalyst, aldehydes and alkyl bromides as reaction substrates, and additionally adds an imidazolinone chiral catalyst, a solvent and a base. Under the conditions of visible light illumination in an inert gas atmosphere, a target chiral aldehyde compound with a high enantiomeric excess can be synthesized, with a yield of 53%-58% and an enantiomeric excess percentage of 80%-87%. The catalyst prepared by the method is not suitable for catalyzing asymmetric aldol condensation reactions. In addition, the method relies on an additional imidazolinone chiral small molecule catalyst, and there is a homogeneous reaction in the reaction process, and the catalyst is difficult to recycle and reuse.

[0006] CN114805832B discloses a chiral covalent organic framework photocatalyst containing transition metals and a preparation method thereof. In this method, under solvent thermal conditions, polyaldehyde and polyamine monomers can prepare a chiral covalent organic framework material with good crystallinity and porosity in the presence of a chiral regulator. The transition metal single atom can be loaded on the framework by an impregnation method to obtain a chiral covalent organic framework material containing a transition metal single atom. The chiral covalent organic framework material can be used as a photocatalyst for visible light decomposition of water to produce hydrogen, which significantly improves the hydrogen production efficiency; the catalyst prepared by this method is not suitable for catalyzing asymmetric aldol condensation reactions.

[0007] "Stable, crystalline, porous, covalent organic frameworks as a platform for chiral organocatalysts, Nature Chemistry, 2015, 7(11): 905-912" reports a series of synthesis methods for mesoporous chiral organic framework materials. This method uses the click reaction between acetylene and azide compounds to successfully integrate chiral pyrrolidine units into mesoporous imine covalent organic frameworks. By adjusting the addition ratio of chiral pyrrole, the content of chiral centers in the covalent organic framework can be finely controlled. The obtained [(S)-Py]x-TPB-DMTP-COFs catalyst can be used in Michael addition reaction to obtain highly stereoselective products; the catalyst prepared by this method is not suitable for catalyzing asymmetric aldol condensation reactions.

[0008] "Multivariate Chiral Covalent Organic Frameworks with Controlled Crystallinity and Stability for Asymmetric Catalysis, Journal of the American Chemical Society, 2017, 139 (24), 8277-8285" reports a multivariate strategy for preparing chiral covalent organic frameworks (CCOFs) with controllable crystallinity and stability. A series of CCOFs were prepared by crystallizing a mixture of triamine monomers, chiral organic catalysts and dialdehyde monomers. The organic catalyst is periodically attached to the channel wall, and its content can be systematically adjusted. The ternary CCOF exhibits relatively high crystallinity and stability. Under harsh conditions, ternary CCOFs can act as efficient heterogeneous catalysts to catalyze a variety of chiral reactions; the catalysts prepared by this method are not suitable for catalyzing asymmetric aldol condensation reactions. Summary of the invention

[0009] In order to solve the above problems, the purpose of the present invention is to provide a pyrene-based covalent organic framework material and a preparation method and application thereof. The pyrene-based covalent organic framework material has high crystallinity and high specific surface area, is used to catalyze asymmetric aldol condensation reactions, has high yield, good stereoselectivity, and is easy to recycle and reuse.

[0010] In order to achieve the above object, the present invention provides a pyrene-based covalent organic framework material, which is constructed by reacting polyaminopyrene monomers with chiral pyrrole monomers via a Schiff base reaction; wherein the chiral pyrrole monomers include the compound shown in formula I and / or the compound shown in formula II,

[0011]

[0012] According to a specific embodiment of the present invention, preferably, the chiral pyrrole monomer comprises a compound represented by formula IV and / or a compound represented by formula V,

[0013]

[0014] According to a specific embodiment of the present invention, preferably, the polyaminopyrene monomer has a structure shown in Formula III,

[0015]

[0016] According to a specific embodiment of the present invention, preferably, the pyrene-based covalent organic framework material is selected from

[0017]

[0018] ( indicates omitted repeating structural unit).

[0019] The present invention also provides a method for preparing the above-mentioned pyrene-based covalent organic framework material, which comprises the following steps:

[0020] (1) preparing a chiral pyrrole monomer with a protecting group;

[0021] (2) Solvothermal crystallization: Solvothermal crystallization of polyaminopyrene monomers and chiral pyrrole monomers with protective groups in the presence of an acid catalyst;

[0022] (3) Preparing a pyrene-based covalent organic framework material: subjecting the product obtained in step (2) to a deprotection treatment to obtain the pyrene-based covalent organic framework material.

[0023] According to a specific embodiment of the present invention, preferably, step (1) comprises the following steps: condensing N-protected proline (e.g., R-proline) with 2,5-dibromoaniline or condensing tert-butyl 2-(aminomethyl)-1-pyrrolidinecarboxylate with 2,5-dibromobenzenesulfonyl chloride, and then reacting with 4-formylphenylboronic acid through Suzuki coupling reaction to obtain a chiral pyrrole monomer with a protective group.

[0024] According to a specific embodiment of the present invention, preferably, in step (2), the temperature of the solvent thermal crystallization is 60 to 150° C., and the time is 12-120 h.

[0025] According to a specific embodiment of the present invention, preferably, in step (2), the molar ratio of the acid catalyst to the chiral pyrrole monomer with a protecting group is 0.05-3.

[0026] According to a specific embodiment of the present invention, preferably, in step (2), the acid catalyst comprises an inorganic acid and / or an organic acid, more preferably comprises one or a combination of two or more of scandium trifluoromethanesulfonate, formic acid, acetic acid, trifluoroacetic acid, trifluoromethanesulfonic acid, and p-toluenesulfonic acid.

[0027] According to a specific embodiment of the present invention, preferably, in step (2), the molar ratio of the polyaminopyrene monomer to the chiral pyrrole monomer with a protecting group is 1:(1-4), more preferably 1:(1.5-2.5).

[0028] According to a specific embodiment of the present invention, preferably, the solvent used for solvent thermal crystallization includes one or a combination of two or more of 1,4-dioxane, n-butanol, benzyl alcohol, o-dichlorobenzene, mesitylene, N,N-dimethylformamide, tetrahydrofuran, and dimethyl sulfoxide, and more preferably one or a combination of two or more of 1,4-dioxane, n-butanol, benzyl alcohol, o-dichlorobenzene, and mesitylene, for example, a mixed solvent selected from 1,4-dioxane + mesitylene, a mixed solvent of o-dichlorobenzene + n-butanol, or a mixed solvent of mesitylene + benzyl alcohol.

[0029] According to a specific embodiment of the present invention, the above preparation method comprises the following specific steps:

[0030] (1) Preparation of chiral pyrrole monomer with protecting group:

[0031] N-protected R-proline is condensed with 2,5-dibromoaniline, and then reacted with 4-formylphenylboronic acid through Suzuki coupling reaction to obtain a chiral pyrrole monomer with a protective group; wherein the conditions of the first step condensation reaction are: temperature -20 to 30°C, time 6-24h; the conditions of the second step coupling reaction are: temperature 60 to 120°C, time 12-72h; the product is extracted, concentrated, purified, dried and then used;

[0032] (2) Solvothermal crystallization:

[0033] The polyaminopyrene monomer and the chiral pyrrole monomer with a protective group are subjected to solvent thermal crystallization in the presence of an acid catalyst. The solvent thermal crystallization conditions are: temperature 60 to 150°C, time 12-120h, and the molar ratio of the acid catalyst to the chiral pyrrole monomer with a protective group is 0.05-3. The product is centrifuged, washed, and dried to obtain a highly crystalline pyrene-based covalent framework material, but the covalent framework material does not have catalytic activity at this time; the reaction temperature and time of this step depend on the amount of raw materials, monomers, catalysts and the type of solvent;

[0034] (3) Preparation of pyrene-based covalent organic framework materials:

[0035] The pyrene-based covalent framework material obtained in step (2) is treated with acid under the following reaction conditions: acid concentration 0.1-1 g / mL, temperature -20 to 60° C., and time 2-24 h. The product is filtered, washed, and dried to obtain a pyrene-based covalent organic framework material with catalytic activity. More preferably, the acid used in the acid treatment process may be an inorganic acid and / or an organic acid, such as one or a combination of two or more of hydrochloric acid, sulfuric acid, hydrofluoric acid, trifluoroacetic acid, and trifluoromethanesulfonic acid.

[0036] The present invention also provides a method for catalyzing an asymmetric aldol condensation reaction, which uses the pyrene-based covalent organic framework material as a catalyst.

[0037] According to a specific embodiment of the present invention, preferably, the method for catalyzing an asymmetric aldol condensation reaction comprises the following steps: mixing an aromatic aldehyde, a ketone compound, an acid catalyst, a solvent and the pyrene-based covalent organic framework material, and reacting at -20 to 30°C for 4-72 hours.

[0038] According to a specific embodiment of the present invention, preferably, after the reaction is completed, the pyrene-based covalent organic framework material is recovered.

[0039] According to a specific embodiment of the present invention, preferably, the aromatic aldehyde includes one or a combination of two or more of p-nitrobenzaldehyde, p-bromobenzaldehyde, p-trifluoromethylbenzaldehyde, and p-cyanobenzaldehyde; the ketone compound includes one or a combination of two or more of acetone, cyclopentanone, and cyclohexanone.

[0040] According to a specific embodiment of the present invention, preferably, in the method for catalyzing an asymmetric aldol condensation reaction, the acid catalyst is one or a combination of two or more of p-nitrobenzoic acid, benzoic acid, o-nitrobenzoic acid, and trifluoroacetic acid.

[0041] According to a specific embodiment of the present invention, preferably, in the method of catalyzing an asymmetric aldol condensation reaction, the amount of the pyrene-based covalent organic framework material added is 5%-50% of the mass of the aldehyde-based substrate (aromatic aldehyde), more preferably 10%-30%.

[0042] According to a specific embodiment of the present invention, the method for catalyzing an asymmetric aldol condensation reaction comprises the following specific steps:

[0043] (1) Aromatic aldehyde, ketone compound, acid catalyst, solvent and the prepared pyrene-based covalent organic framework material are mixed and stirred in a certain proportion, and the reaction conditions are: temperature -20 to 30°C, time 4-72h. After the reaction, the mixture is centrifuged and washed to recover the solid pyrene-based covalent organic framework material, and the solution is concentrated and purified to obtain the target product;

[0044] (2) After the purified target product is weighed, the yield can be calculated based on the amount of aromatic aldehyde fed. The target product can be tested by high performance liquid chromatography (HPLC) to obtain the enantiomeric excess value of the product.

[0045] The present invention has the following beneficial effects:

[0046] 1. The pyrene-based covalent organic framework material of the present invention has high crystallinity and high specific surface area, and its skeleton contains abundant periodically arranged chiral pyrrole groups, which can be used as active sites for the Aldol condensation reaction of ketones and aldehydes, and the catalyst is easy to recycle and reuse, and obtains the Aldol condensation reaction product with high yield and good stereoselectivity, and has a very broad application prospect in the field of chiral molecule synthesis as a heterogeneous catalyst;

[0047] 2. The prepared chiral covalent organic framework material has a periodic rhombus pore structure and uniform pore size distribution. It is an ideal chiral organic porous material with high product stereoselectivity and is expected to be used in biology, medicine and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 Schematic diagram of the structure of pyrene-based covalent organic framework materials COF-PRI1-Boc and COF-PRI1;

[0049] Figure 2 Schematic diagram of the structure of pyrene-based covalent organic framework materials COF-PRI2-Boc and COF-PRI2;

[0050] Figure 3 X-ray diffraction spectra of pyrene-based covalent organic framework materials COF-PRI1-Boc (a) and COF-PRI1 (b);

[0051] Figure 4 X-ray diffraction spectra of pyrene-based covalent organic framework materials COF-PRI2-Boc (a) and COF-PRI2 (b);

[0052] Figure 5 The nitrogen adsorption-desorption curves of pyrene-based covalent organic framework materials COF-PRI1-Boc (a) and COF-PRI1 (b);

[0053] Figure 6 These are the nitrogen adsorption and desorption curves of pyrene-based covalent organic framework materials COF-PRI2-Boc (a) and COF-PRI2 (b). DETAILED DESCRIPTION

[0054] In order to have a clearer understanding of the technical features, purposes and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below, but it should not be construed as limiting the applicable scope of the present invention.

[0055] The raw materials used in the examples are:

[0056] Organic raw materials: N-tert-butyloxycarbonyl-R-proline (purity 98%), isobutyl chloroformate (purity 99%), 2,5-dibromoaniline (purity 98%), tetrakis(triphenylphosphine)palladium(0) (purity 99%), 4-formylphenylboronic acid purity (98%), tert-butyl 2-(aminomethyl)-1-pyrrolidinecarboxylate (purity 98%), 2,5-dibromobenzenesulfonyl chloride (purity 98%), 1,3,6,8-tetrakis(4-aminophenyl)pyrene (purity 97%), p-nitrobenzaldehyde (purity 99%), o-nitrobenzoic acid (purity 99%).

[0057] Inorganic salts: sodium chloride (purity 99%), sodium carbonate (99%), anhydrous magnesium sulfate (99%).

[0058] Solvent: dichloromethane (purity 99%), triethylamine (purity 98%), tetrahydrofuran (purity 99%), o-dichlorobenzene (purity 99%), n-butanol (purity 99%), 1,4-dioxane (purity 99%), acetone (purity 99%), ethyl acetate (purity 99%), acetic acid (purity 98%), trifluoroacetic acid (purity 99%), n-hexane (purity 99%), deionized water.

[0059] Preparation Example 1

[0060] This preparation example provides a pyrene-based covalent organic framework material COF-PRI1, which is prepared by the following steps:

[0061] 1. Synthesis of chiral monomer 1, as shown in the following reaction formula:

[0062]

[0063] (1) Synthesis of compound 4: N-tert-butyloxycarbonyl-R-proline (2.50 g, 11.6 mmol) was placed in a round-bottom flask and 40 mL of dichloromethane was added, followed by isobutyl chloroformate (1.67 mL, 12.8 mmol) and triethylamine (1.80 mL, 12.8 mmol) in sequence. After stirring at 0°C for 20 minutes, 2,5-dibromoaniline (3.21 g, 12.8 mmol) was added, and the reaction was heated to room temperature and stirred overnight. The reactants were washed with 1 M potassium sulfate aqueous solution, saturated sodium bicarbonate aqueous solution and saturated sodium chloride aqueous solution in sequence, and the organic layer was dried over anhydrous sodium sulfate and concentrated to obtain a light brown solid. The crude solid was ultrasonically dispersed in hexane, cooled to 0°C and filtered to obtain a light yellow solid. The white powder was separated by column chromatography using petroleum ether / EtOAc (v / v=10:1) with a yield of 87%.

[0064] (2) Synthesis of chiral monomer 1: Compound 4 (0.82 mmol, 0.37 g), 4-formylphenylboronic acid (2.46 mmol, 0.37 g), sodium carbonate (6.2 mmol, 1.1 g), tetrakis(triphenylphosphine)palladium(0) (0.06 mmol, 0.12 g) and tetrahydrofuran / water (50 mL, v / v=4 / 1) were placed in a Schlenk tube under a nitrogen atmosphere, and then heated under reflux for 24 hours; after cooling to room temperature, the mixture was filtered using diatomaceous earth, and the filtrate was poured into water, and a white solid powder was obtained after suction filtration. The crude product was purified by silica gel column chromatography using dichloromethane as an eluent to obtain a white powder with a yield of 90%. 1H NMR(400MHz, CDCl3)δ=10.10(2H),7.96–8.02(4H),7.75–7.85(3H),7.60(2H),7.55( 1H),7.39(1H),4.35(1H),3.10–3.29(3H),1.65–1.98(4H),1.35(9H).HRMS(ESI),m / z calcd for[C 30 H 30 N2O5+H] + 499.2228, found 499.2223.

[0065] 2. Synthesis of pyrene-based covalent organic framework material COF-PRI1, as shown in the following reaction formula:

[0066]

[0067] (1) Synthesis of pyrene-based covalent organic framework material COF-PRI1-Boc: 28.3 mg 1,3,6,8-tetrakis(4-aminophenyl)pyrene, 50 mg chiral monomer 1, and 3 mL o-dichlorobenzene / n-butanol (2:1) mixed solution were added to a 10 mL pressure tube in sequence. After ultrasonic treatment for 5 min to obtain a uniform suspension, 0.2 mL 6 M acetic acid aqueous solution was added and ultrasonic treatment was performed for 5 min. After three freeze-thaw cycles, the pressure tube was sealed and heated at 120°C for 3 days. After the reaction, the solid product was washed by centrifugation with 1,4-dioxane, tetrahydrofuran, and n-hexane, and the obtained solid was dried in a vacuum oven at 120°C for 12 hours to obtain 67 mg of yellow powder, named COF-PRI1-Boc.

[0068] (2) Synthesis of pyrene-based covalent organic framework material COF-PRI1: 50 mg of COF-PRI1-Boc powder was ultrasonically dispersed in a beaker containing 20 mL of anhydrous dichloromethane, and then 0.2 mL of trifluoroacetic acid was added. The reaction was stirred at room temperature for 12 h. The suspension after the reaction was filtered and the filter cake was washed with tetrahydrofuran and n-hexane. The solid was placed in a vacuum oven at 120 °C and dried for 12 h to obtain 45 mg of yellow powder, named COF-PRI1.

[0069] Preparation Example 2

[0070] This preparation example provides a pyrene-based covalent organic framework material COF-PRI2, which is prepared by the following steps:

[0071] 1. Synthesis of chiral monomer 2, as shown in the following reaction formula:

[0072]

[0073] (1) Synthesis of compound 6: 2-(aminomethyl)-1-pyrrolidinecarboxylic acid tert-butyl ester (2 g, 10 mmol) and triethylamine (2.1 mL, 15 mmol) were added to a round-bottom flask containing 50 mL of dichloromethane, and then 2,5-dibromobenzenesulfonyl chloride (3.7 g, 11 mmol) was added. After the resulting mixture was stirred at room temperature for 3 hours, the mixture was diluted with ethyl acetate and washed with 1 M aqueous hydrochloric acid solution, deionized water and saturated aqueous sodium chloride solution in sequence. The organic extract was dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The residue was purified by column chromatography (petroleum ether / ethyl acetate = 10:1, v / v) to obtain a white powder solid with a yield of 88%;

[0074] (2) Synthesis of chiral monomer 2: Compound 6 (0.82 mmol, 0.41 g), 4-formylphenylboronic acid (2.46 mmol, 0.37 g), sodium carbonate (6.2 mmol, 1.1 g), tetrakis(triphenylphosphine)palladium(0) (0.06 mmol, 0.12 g) and tetrahydrofuran / water (50 mL, v / v=4 / 1) were placed in a Schlenk tube under a nitrogen atmosphere, and then heated under reflux for 24 hours; after cooling to room temperature, the mixture was filtered using diatomaceous earth, and the filtrate was poured into water, and a white solid powder was obtained after suction filtration. The crude product was purified by silica gel column chromatography using dichloromethane as an eluent to obtain a white powder with a yield of 84%. 1 H NMR(400MHz, CDCl3)δ=10.18(2H),8.02–8.10(4H),7.80–7.92(4H),7.68(2H),7.43(1H) ,3.75(1H),3.12–3.20(3H),2.85–3.10(2H),1.55–1.73(4H),1.42(9H).HRMS(ESI),m / z calcdfor[C 30 H 32 N2O6S+H] + 549.2054, found 549.2045.

[0075] 2. Synthesis of pyrene-based covalent organic framework material COF-PRI2, as shown in the following reaction formula:

[0076]

[0077] (1) Synthesis of pyrene-based covalent organic framework material COF-PRI2-Boc: 28.3 mg 1,3,6,8-tetrakis(4-aminophenyl)pyrene, 55 mg chiral monomer 2, and 3 mL o-dichlorobenzene / n-butanol (2:1) mixed solution were added to a 10 mL pressure tube in sequence. After ultrasonic treatment for 5 min to obtain a uniform suspension, 0.2 mL 6 M acetic acid aqueous solution was added and ultrasonic treatment was performed for 5 min. After three freeze-thaw cycles, the pressure tube was sealed and heated at 120°C for 3 days. After the reaction, the solid product was washed by centrifugation with 1,4-dioxane, tetrahydrofuran and n-hexane respectively. The obtained solid was placed in a vacuum oven at 120°C and dried for 12 hours to obtain 72 mg of yellow powder, named COF-PRI2-Boc.

[0078] (2) Synthesis of pyrene-based covalent organic framework material COF-PRI2: 50 mg of COF-PRI2-Boc powder was ultrasonically dispersed in a beaker containing 20 mL of anhydrous dichloromethane, and then 0.2 mL of trifluoroacetic acid was added. The reaction was stirred at room temperature for 12 h. The suspension after the reaction was filtered and the filter cake was washed with tetrahydrofuran and n-hexane. The solid was placed in a vacuum oven at 120 °C and dried for 12 h to obtain 44 mg of yellow powder, named COF-PRI2.

[0079] The chiral pyrene-based covalent organic framework materials obtained in Preparation Example 1 and Preparation Example 2 were characterized accordingly. Figure 1 The schematic diagram of the structure of pyrene-based covalent organic framework materials COF-PRI1-Boc and COF-PRI1. Figure 2 Schematic diagram of the structure of pyrene-based covalent organic framework materials COF-PRI2-Boc and COF-PRI2, both of which have regular diamond-shaped pore structures. Figure 3 and Figure 4 is the X-ray diffraction pattern, where Figure 3 (a) corresponds to COF-PRI1-Boc, Figure 3 (b) corresponds to COF-PRI1, Figure 4 (a) corresponds to COF-PRI2-Boc, Figure 4 (b) corresponds to COF-PRI2, both of which have high crystallinity, which indicates that the present invention has successfully synthesized two new pyrene-based covalent organic framework materials. Figure 5 and Figure 6 is the nitrogen isothermal adsorption-desorption curve, where Figure 5 (a) corresponds to COF-PRI1-Boc, Figure 5 (b) corresponds to COF-PRI1, Figure 6 (a) corresponds to COF-PRI2-Boc, Figure 6 (b) corresponds to COF-PRI2, both of which have higher specific surface areas.

[0080] Asymmetric catalytic properties of pyrene-based covalent organic frameworks

[0081] The Aldol reaction of p-nitrobenzaldehyde and acetone was used as a model reaction to investigate the asymmetric catalytic activity of two pyrene-based covalent organic framework materials, COF-PRI1 and COF-PRI2. After the purified target product was weighed, the yield was calculated based on the amount of aromatic aldehyde fed. The target product was tested by Agilent 1260 HPLC (equipped with a Daicel OD-H chiral column, a detection wavelength of 240 nm, a mobile phase of n-hexane / isopropanol = 9 / 1, and a flow rate of 1 mL / min) to obtain the enantiomeric excess (ee) value of the product (i.e., the "enantiomeric selectivity" described below). The ee value calculation method is:

[0082]

[0083] Where t is the retention time and S is the peak area of ​​the compound at the retention time.

[0084] Example 1

[0085] 30.2 mg of p-nitrobenzaldehyde, 3.3 mg of o-nitrobenzoic acid and 5 mg of COF-PRI1 material were added to the reaction bottle, followed by 3 mL of acetone and ultrasonication for 5 min, and the reaction was continued under stirring at room temperature for 12 h. After the reaction was completed, the solid catalyst (COF-PRI1 material) was recovered by centrifugal washing, the collected liquid was removed from the solvent by a rotary evaporator, and the residual solid was purified by silica gel column chromatography (petroleum ether / ethyl acetate = 5 / 1, v / v) to obtain the corresponding target product with a yield of 89% and an enantiomeric selectivity of 58%. The results are shown in Table 1.

[0086] Example 2

[0087] 30.2 mg of p-nitrobenzaldehyde, 3.3 mg of o-nitrobenzoic acid and 5 mg of COF-PRI2 material were added to the reaction bottle, followed by 3 mL of acetone and ultrasonication for 5 min, and the reaction was continued under stirring at room temperature for 12 h. After the reaction was completed, the solid catalyst (COF-PRI2 material) was recovered by centrifugal washing, the collected liquid was removed from the solvent by a rotary evaporator, and the residual solid was purified by silica gel column chromatography (petroleum ether / ethyl acetate = 5 / 1, v / v) to obtain the corresponding target product with a yield of 92% and an enantiomeric selectivity of 66%. The results are shown in Table 1.

[0088] Example 3

[0089] 30.2 mg of p-nitrobenzaldehyde, 3.3 mg of o-nitrobenzoic acid and 2.5 mg of COF-PRI1 material were added to the reaction bottle, followed by 3 mL of acetone and ultrasonication for 5 min, and the reaction was continued under stirring at room temperature for 12 h. After the reaction was completed, the solid catalyst (COF-PRI1 material) was recovered by centrifugal washing, the collected liquid was removed from the solvent by a rotary evaporator, and the residual solid was purified by silica gel column chromatography (petroleum ether / ethyl acetate = 5 / 1, v / v) to obtain the corresponding target product with a yield of 82% and an enantiomeric selectivity of 57%. The results are shown in Table 1.

[0090] Example 4

[0091] 30.2 mg of p-nitrobenzaldehyde, 3.3 mg of o-nitrobenzoic acid and 2.5 mg of COF-PRI2 material were added to the reaction bottle, followed by 3 mL of acetone and ultrasonication for 5 min, and the reaction was continued under stirring at room temperature for 12 h. After the reaction was completed, the solid catalyst (COF-PRI2 material) was recovered by centrifugal washing, the collected liquid was removed from the solvent by a rotary evaporator, and the residual solid was purified by silica gel column chromatography (petroleum ether / ethyl acetate = 5 / 1, v / v) to obtain the corresponding target product with a yield of 85% and an enantiomeric selectivity of 65%. The results are shown in Table 1.

[0092] Comparative Example 1

[0093] CCOF-LZU72 (13.2 mg, disclosed in CN105622579A), o-nitrobenzoic acid (5.0 mg), and acetone (1.0 mL) were added to a reaction tube and stirred at room temperature for 5 min. Then p-nitrobenzaldehyde (45.3 mg) was added and stirred at room temperature for 4 h. After the reaction was completed, the liquid was collected by centrifugation or filtration and washing, and the solvent was removed under reduced pressure. The residue was purified by column chromatography (petroleum ether: ethyl acetate = 3:1, V / V) to obtain the target product with a yield of 90% and an enantiomeric selectivity of 45%. The results are shown in Table 1.

[0094] Table 1

[0095]

[0096] As can be seen from Table 1, the pyrene-based covalent organic framework material of the present invention is applied to catalyze asymmetric aldol condensation reaction with high yield and good stereoselectivity.

[0097] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, technicians familiar with the field may make several modifications and improvements to the form and details according to the present invention, but these corresponding changes and deformations should all fall within the scope of protection of the present invention.

Claims

1. A pyrene-based covalent organic framework material, which is constructed by reacting a polyaminopyrene monomer with a chiral pyrrole monomer via a Schiff base reaction; in, The chiral pyrrole monomer includes a compound shown in formula I and / or a compound shown in formula II, Preferably, the polyaminopyrene monomer has a structure shown in Formula III, 2. The pyrene-based covalent organic framework material according to claim 1, wherein: The pyrene-based covalent organic framework material is selected from and / or 3. The method for preparing the pyrene-based covalent organic framework material according to claim 1 or 2, comprising the following steps: (1) preparing a chiral pyrrole monomer with a protecting group; (2) Solvothermal crystallization: Solvothermal crystallization of polyaminopyrene monomers and chiral pyrrole monomers with protective groups in the presence of an acid catalyst; (3) Preparing a pyrene-based covalent organic framework material: subjecting the product obtained in step (2) to a deprotection treatment to obtain the pyrene-based covalent organic framework material.

4. The preparation method according to claim 3, wherein Step (1) comprises the following steps: N-protected proline is condensed with 2,5-dibromoaniline or tert-butyl 2-(aminomethyl)-1-pyrrolidinecarboxylate is condensed with 2,5-dibromobenzenesulfonyl chloride, and then reacted with 4-formylphenylboronic acid through Suzuki coupling reaction to obtain a chiral pyrrole monomer with a protective group.

5. The preparation method according to claim 3, wherein: In step (2), the temperature of the solvent thermal crystallization is 60 to 150° C. and the time is 12 to 120 h; Preferably, the molar ratio of the acid catalyst to the chiral pyrrole monomer with a protecting group is 0.05-3.

6. The preparation method according to claim 3, wherein: In step (2), the acid catalyst comprises an inorganic acid and / or an organic acid, preferably comprises one or a combination of two or more of scandium trifluoromethanesulfonate, formic acid, acetic acid, trifluoroacetic acid, trifluoromethanesulfonic acid, and p-toluenesulfonic acid.

7. The preparation method according to claim 3, wherein: In step (2), the molar ratio of the polyaminopyrene monomer to the chiral pyrrole monomer with a protecting group is 1:(1-4), more preferably 1:(1.5-2.5); Preferably, the solvent used for solvent thermal crystallization includes one or a combination of two or more of 1,4-dioxane, n-butanol, benzyl alcohol, o-dichlorobenzene, mesitylene, N,N-dimethylformamide, tetrahydrofuran, and dimethyl sulfoxide, and more preferably one or a combination of two or more of 1,4-dioxane, n-butanol, benzyl alcohol, o-dichlorobenzene, and mesitylene.

8. A method for catalyzing an asymmetric aldol condensation reaction, which uses the pyrene-based covalent organic framework material according to claim 1 or 2 as a catalyst.

9. The method according to claim 8, wherein: The method for catalyzing an asymmetric aldol condensation reaction comprises the following steps: Mixing an aromatic aldehyde, a ketone compound, an acid catalyst, a solvent and the pyrene-based covalent organic framework material, and reacting at -20 to 30° C. for 4 to 72 hours; Preferably, after the reaction is completed, the pyrene-based covalent organic framework material is recovered; Preferably, the aromatic aldehyde includes one or a combination of two or more of p-nitrobenzaldehyde, p-bromobenzaldehyde, p-trifluoromethylbenzaldehyde, and p-cyanobenzaldehyde; and the ketone compound includes one or a combination of two or more of acetone, cyclopentanone, and cyclohexanone.

10. The method according to claim 9, wherein: The acid catalyst is one or a combination of two or more of p-nitrobenzoic acid, benzoic acid, o-nitrobenzoic acid, and trifluoroacetic acid; Preferably, the amount of the pyrene-based covalent organic framework material added is 5%-50% of the amount of the aldehyde-based material, more preferably 10%-30%.

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