Preparation method of MOF@Pro HNs hollow mesoporous nanomaterials and its products and applications

Abstract

The present invention relates to a preparation method of MOF@Pro HNs hollow mesoporous nanomaterials, its products and applications, and belongs to the technical field of preparation of functional materials. The present invention mainly comprises the following steps: firstly reacting Boc-proline, KOH, anhydrous methanol and DMSO, adding triethylamine and trimethylsilyl trifluoromethanesulfonate in an ice bath to react and obtain proline Pro; then heating proline Pro, a DMSO solution of cobalt acetate tetrahydrate and a DMSO solution of terephthalic acid (H2BDC) in an oxygen-free environment to react and obtain MOF@Pro HNs hollow mesoporous nanomaterials. The present invention uses cobalt acetate tetrahydrate, TEA and H2BDC as raw materials to chelate Boc-proline to prepare MOF@Pro HNs hollow mesoporous nanomaterials with high hydrophilicity, high permeability and high stereoselectivity. The preparation method is simple and has high yield.

Description

Technical Field

[0001] The present invention belongs to the technical field of functional material preparation, and specifically relates to a preparation method of MOF@Pro HNs hollow mesoporous network nanomaterials, as well as products and applications thereof. Background Art

[0002] MOFs, also known as metal-organic frameworks, are a class of structurally ordered porous solid materials based on the interaction between metals and organic ligands. These materials exhibit excellent permeability, uniform pore size, and large specific surface area. Due to their small size and the abundance of organic ligands within their frameworks, MOFs exhibit excellent dispersibility and compatibility. MOFs are highly compatible with water and organic solvents, making them valuable support materials for heterogeneous catalysis.

[0003] There are two main catalysts currently used for the Michael / Michael / aldol tandem reaction: proteases and chiral catalysts combined with Lewis acids. Neither catalyst can be recycled or reused, hindering the promotion of green chemistry. Proteases are expensive, increasing catalytic costs. Conventional supported chiral catalysts, due to structural defects in the support, require high catalyst dosages, trap catalytic sites, and exhibit low catalytic efficiency. However, hollow mesoporous MOF@Pro HNs nanomaterials, in addition to their enormous surface area and pore volume, carry -COOH groups that act as solid acids, enabling bifunctional catalysis.

[0004] Therefore, it is necessary to study a hollow mesoporous MOF@Pro HNs nanomaterial that can be prepared by the non-solvent induced phase separation method in the present invention. Using cinnamaldehyde and benzofuranone as reaction substrates, the catalytic performance of MOF-supported catalysts was systematically studied, providing new ideas and strategies for heterogeneous asymmetric catalysis. Summary of the Invention

[0005] In view of this, one object of the present invention is to provide a method for preparing MOF@Pro HNs hollow mesoporous network nanomaterials; a second object of the present invention is to provide a MOF@Pro HNs hollow mesoporous network nanomaterial; and a third object of the present invention is to provide a use of MOF@Pro HNs hollow mesoporous network nanomaterials as a chiral catalyst in catalyzing Michael / Michael / aldol tandem reactions.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] 1. A method for preparing a MOF@Pro HNs hollow mesoporous nanomaterial, the preparation method comprising the following steps:

[0008] (1) Preparation of Proline Pro: Boc-proline, KOH, anhydrous CH3OH and DMSO were mixed, heated to 60-70°C in an oxygen-free environment, stirred and reacted for 1-3 hours, ice-bathed to 0°C, and then triethylamine or ammonia water was added for alkalization. Trimethylsilyl trifluoromethanesulfonate was added and reacted for 0.5-1 hour. The mixture was moved to room temperature and reacted for 2-4 hours. After that, deionized water was added to quench the reaction. The organic phases were extracted and combined, and then purified by silica gel column chromatography to obtain colorless oily liquid Proline Pro;

[0009] (2) Preparation of nanosphere MOF@Pro HNs hollow mesoporous network nanomaterials: Co(CH3COO)2·4H2O was dissolved in anhydrous DMSO and ultrasonicated for 10 to 50 minutes as solution A, triethanolamine (TEA) and terephthalic acid (H2BDC) were dissolved in DMSO and ultrasonicated for 10 to 50 minutes as solution B, the proline pro, solution A and anhydrous DMSO described in step (1) were heated to 60 to 70°C in an oxygen-free environment and stirred for reaction for 0.5 to 2 hours, during which solution B was added dropwise, and the mixture was cooled to room temperature and reacted for 4 to 6 hours. The solid component was collected by centrifugation, washed with DMSO, and then centrifuged to collect the pink solid, which was the MOF@Pro HNs hollow mesoporous network nanomaterial, which was dispersed in DMSO solvent and stored for use.

[0010] Preferably, in step (1), the alkalization is carried out using triethylamine or aqueous ammonia;

[0011] When triethylamine is used for alkalization, the mass volume ratio of the Boc-proline, KOH, anhydrous CH3OH, and DMSO is 1.0-2.0:2.0-3.2:20-30:60-80, g:g:mL:mL;

[0012] When alkalization is performed using 25% ammonia water, the mass volume ratio of the Boc-proline, KOH, anhydrous CH3OH, and DMSO is 1.0-2.0:1.0-1.6:40-60:90-120, g:g:mL:mL.

[0013] Preferably, in step (1), the mass ratio of Boc-proline, triethylamine and trimethylsilyl trifluoromethanesulfonate is 1.0-2.0:1.4-2.8:0.4-0.8; the mass ratio of Boc-proline, ammonia water with a mass concentration of 25% and trimethylsilyl trifluoromethanesulfonate is 1.0-2.0:0.7-1.4:0.4-0.8.

[0014] Preferably, in step (1), the extraction is performed using any one of chloroform, dichloromethane or toluene.

[0015] Preferably, in step (2), the dropwise addition rate of the solution B is 1 to 2 drops per second.

[0016] Preferably, in step (2), the mass volume ratio of Co(CH3COO)2·4H2O and anhydrous DMSO in the solution is 4.4-8.8:100-200, g:mL;

[0017] The mass volume ratio of triethanolamine (TEA), terephthalic acid (H2BDC) and DMSO in the solution B is 2.2-4.4:1.2-2.4:100-200, g:g:mL.

[0018] Preferably, in step (2), the molar volume ratio of proline pro, solution A, solution B and anhydrous DMSO is 2:50:64:35, mmol:mL:mL:mL.

[0019] Preferably, in step (2), the heating to 60-70° C. is performed in a water bath.

[0020] 2. MOF@Pro HNs hollow mesoporous nanomaterials prepared according to the above preparation method.

[0021] 3. Application of the above-mentioned MOF@Pro HNs hollow mesoporous nanomaterials as chiral catalysts in catalyzing Michael / Michael / aldol tandem reactions.

[0022] The beneficial effects of the present invention are:

[0023] 1. The present invention discloses a method for preparing a MOF@Pro HNs hollow mesoporous nanomaterial. The method comprises first reacting Boc-proline, KOH, anhydrous CH3OH, and DMSO, followed by the addition of triethylamine and trimethylsilyl trifluoromethanesulfonate in an ice bath to produce Pro. Pro, a DMSO solution of Co(CH3COO)2·4H2O, and a DMSO solution of terephthalic acid (H2BDC) are then heated in an oxygen-free environment to produce the MOF@Pro HNs hollow mesoporous nanomaterial. This method addresses the issues of poor hydrophilicity and low supported catalytic efficiency of organic chiral catalysts. By using a non-solvent-induced phase separation method, Co(CH3COO)2·4H2O, TEA, and H2BDC as raw materials, and complexing Boc-proline, the resulting MOF@Pro HNs hollow mesoporous nanomaterial exhibits high hydrophilicity, high permeability, and high stereoselectivity. This method is simple and provides high yield.

[0024] 2. The present invention also discloses a MOF@Pro HNs hollow mesoporous network nanomaterial, which has high hydrophilicity, high permeability and high stereoselectivity, has a good catalytic effect on catalyzing Michael / Michael / aldol tandem reactions (91-95% yield, ee of 98-99.5%), and is easy to recycle and can be reused (11 times). Therefore, the MOF@Pro HNs hollow mesoporous network nanomaterial prepared by the present invention has good application prospects as a chiral catalyst in catalyzing asymmetric Michael / Michael / aldol tandem reactions.

[0025] Other advantages, objects, and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art upon examination of the following description or may be learned from practice of the present invention. The objects and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings, in which:

[0027] Figure 1 This is a flow chart for the preparation of MOF@Pro HNs hollow mesoporous nanomaterials of the present invention;

[0028] Figure 2 This is the SEM image of the MOF@Pro HNs hollow mesoporous nanomaterial prepared in Example 1;

[0029] Figure 3 TEM image of the MOF@Pro HNs hollow mesoporous nanomaterial prepared in Example 1;

[0030] Figure 4 This is the HTEM image of the MOF@Pro HNs hollow mesoporous nanomaterial prepared in Example 1;

[0031] Figure 5 Comparison of the specific surface area (a) and pore size distribution (b) of the MOF@Pro HNs hollow mesoporous nanomaterial and the polymer catalyst prepared in Example 1;

[0032] Figure 6 This is the XRD pattern of the MOF@Pro HNs hollow mesoporous nanomaterial prepared in Example 1;

[0033] Figure 7 This is a comparison chart of the water contact angle test of the MOF@Pro HNs hollow mesoporous nanomaterial and the polymer catalyst prepared in Example 1;

[0034] Figure 8 This is the infrared spectrum of the MOF@Pro HNs hollow mesoporous nanomaterial prepared in Example 1;

[0035] Figure 9 This is the HPLC chart of the asymmetric Michael / Michael / aldol tandem reaction catalyzed by the MOF@Pro HNs hollow mesoporous nanomaterial prepared in Example 1. DETAILED DESCRIPTION

[0036] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. The details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other unless they conflict.

[0037] Example 1

[0038] A MOF@Pro HNs hollow mesoporous nanomaterial, the specific preparation method is as follows:

[0039] (1) Preparation of Proline Pro: A 100 mL three-necked flask was replaced with vacuum nitrogen three times, and Boc-proline (2 g, 9.28 mmol), KOH (3.2 g, 52 mmol), 20 mL of anhydrous CH3OH and 60 mL of DMSO were added. The mixture was reacted in a water bath at 65°C for 2 h. After ice cubes were added to the water bath to stabilize at 0°C, triethylamine (1.4 g, 1.4 mmol) and trimethylsilyl trifluoromethanesulfonate (0.4 g, 1.4 mmol) were added. The mixture was reacted for 0.5 h and then moved to room temperature for 3 h. The reaction was quenched by adding 20 mL of deionized water, and the mixture was extracted three times with 20 mL of chloroform. The organic phases were combined and purified by silica gel column to obtain 0.22 g of colorless oily liquid, which was Proline Pro, with a yield of 97%.

[0040] (2) Preparation of MOF@Pro HNs hollow mesoporous nanomaterials: First, 4.4 g Co(CH3COO)2·4H2O was dissolved in 100 mL anhydrous DMSO and ultrasonicated for 30 min until completely dissolved as solution A; secondly, 2.2 g triethanolamine (TEA) and 1.2 g terephthalic acid (H2BDC) were dissolved in 100 mL DMSO and ultrasonicated for 30 min until completely dissolved as solution B; then, a 250 mL three-necked flask containing 2 mmol proline pro prepared in the above step (1) was evacuated three times under argon protection, 50 mL of solution A was dropped into it, 35 mL of anhydrous DMSO was injected into it by syringe, and ultrasonicated again for 15 min until the solution became clear, then heated in a water bath to 65 ° C for 1 h, and 64 mL of solution B was added dropwise at a rate of 1 drop / s during the reaction. After removing the heating device, the reaction was cooled to room temperature for 5 h; the solid components were collected by centrifugation, washed 3 times with 20 mL DMSO, and soaked in 50 mL After stirring in DMSO for 24 h, the pink solid product was collected by centrifugation, which was the MOF@Pro HNs hollow mesoporous nanomaterial, and dispersed into 100 mL of DMSO solvent and stored for later use.

[0041] Example 2

[0042] A MOF@Pro HNs hollow mesoporous nanomaterial, the specific preparation method is as follows:

[0043] (1) Preparation of Proline Pro: A 100 mL three-necked flask was replaced with vacuum nitrogen three times, and Boc-proline (2 g, 9.28 mmol), KOH (2.0 g, 32.5 mmol), 20 mL of anhydrous CH3OH and 60 mL of DMSO were added. The mixture was reacted in a 60°C water bath for 3 h. After ice cubes were added to the water bath to stabilize at 0°C, triethylamine (1.4 g, 1.4 mmol) and trimethylsilyl trifluoromethanesulfonate (0.4 g, 1.4 mmol) were added. The mixture was reacted for 0.5 h and then moved to room temperature for 2 h. The reaction was quenched by adding 20 mL of deionized water, and extracted three times with 20 mL of chloroform. The organic phases were combined and purified by silica gel column to obtain 0.205 g of colorless oily liquid, which was Proline Pro, with a yield of 91%.

[0044] (2) Preparation of MOF@Pro HNs hollow mesoporous nanomaterials: First, 4.4 g Co(CH3COO)2·4H2O was dissolved in 200 mL anhydrous DMSO and ultrasonicated for 10 min until completely dissolved as solution A; secondly, 2.2 g triethanolamine (TEA) and 1.2 g terephthalic acid (H2BDC) were dissolved in 200 mL DMSO and ultrasonicated for 10 min until completely dissolved as solution B; then, a 250 mL three-necked flask containing 2 mmol of proline pro prepared in the above step (1) was evacuated three times under argon protection, 50 mL of solution A was dropped into it, 35 mL of anhydrous DMSO was injected into it by syringe, and ultrasonicated again for 15 min until the solution became clear, then heated in a water bath to 60 ° C for 2 h, and 64 mL of solution B was added dropwise at a rate of 1 drop / s during the reaction. After removing the heating device, the reaction was cooled to room temperature for 4 h; the solid components were collected by centrifugation, washed 3 times with 20 mL DMSO, and soaked in 50 mL After stirring in DMSO for 24 h, the pink solid product was collected by centrifugation, which was the MOF@Pro HNs hollow mesoporous nanomaterial, and dispersed into 100 mL of DMSO solvent and stored for later use.

[0045] Example 3

[0046] A MOF@Pro HNs hollow mesoporous nanomaterial, the specific preparation method is as follows:

[0047] (1) Preparation of Proline Pro: A 100 mL three-necked flask was replaced with vacuum nitrogen three times, and Boc-proline (1 g, 9.28 mmol), KOH (3.2 g, 52 mmol), 30 mL of anhydrous CH3OH and 80 mL of DMSO were added. The mixture was reacted in a 70°C water bath for 1 h. After ice cubes were added to the water bath to stabilize at 0°C, triethylamine (2.8 g, 1.4 mmol) and trimethylsilyl trifluoromethanesulfonate (0.8 g, 1.4 mmol) were added. After the reaction was continued for 1 h, the mixture was moved to room temperature and reacted for 4 h. 20 mL of deionized water was added to quench the reaction. The mixture was extracted three times with 20 mL of chloroform. The organic phases were combined and purified using a silica gel column to obtain 0.197 g of a colorless oily liquid, which was Proline Pro, with a yield of 88%.

[0048] (2) Preparation of MOF@Pro HNs hollow mesoporous nanomaterials: First, 8.8 g Co(CH3COO)2·4H2O was dissolved in 100 mL anhydrous DMSO and ultrasonicated for 50 min until completely dissolved as solution A; secondly, 4.4 g triethanolamine (TEA) and 1.2 g terephthalic acid (H2BDC) were dissolved in 100 mL DMSO and ultrasonicated for 50 min until completely dissolved as solution B; then, a 250 mL three-necked flask containing 2 mmol of proline pro prepared in the above step (1) was evacuated three times under argon protection, 50 mL of solution A was dropped into it, 35 mL of anhydrous DMSO was injected into it by syringe, and ultrasonicated for 15 min again until the solution became clear, then heated in a water bath to 70 ° C for reaction for 0.5 h, and 64 mL of solution B was added dropwise at a rate of 1 drop / s during the reaction. After removing the heating device, the reaction was cooled to room temperature for 6 h; the solid components were collected by centrifugation, washed 3 times with 20 mL DMSO, and soaked in 50 mL After stirring in DMSO for 24 h, the pink solid product was collected by centrifugation, which was the MOF@Pro HNs hollow mesoporous nanomaterial, and dispersed into 100 mL of DMSO solvent and stored for later use.

[0049] Example 4

[0050] A MOF@Pro HNs hollow mesoporous nanomaterial, the specific preparation method is as follows:

[0051] (1) Preparation of Proline Pro: A 100 mL three-necked flask was replaced with vacuum nitrogen three times, and Boc-proline (2 g, 9.28 mmol), KOH (1.0 g, 16.25 mmol), 40 mL of anhydrous CH3OH and 90 mL of DMSO were added. The mixture was reacted in a water bath at 60°C for 3 h. After ice cubes were added to the water bath to stabilize at 0°C, 25% ammonia water (the mass of ammonia water was 0.7 g) and trimethylsilyl trifluoromethanesulfonate (0.4 g, 1.4 mmol) were added. The mixture was reacted for 0.5 h and then moved to room temperature for 2 h. The reaction was quenched by adding 20 mL of deionized water, and the mixture was extracted three times with 20 mL of chloroform. The organic phases were combined and purified by silica gel column to obtain 0.194 g of colorless oily liquid, which was Proline Pro, with a yield of 85%.

[0052] (2) Preparation of MOF@Pro HNs hollow mesoporous nanomaterials: First, 4.4 g Co(CH3COO)2·4H2O was dissolved in 200 mL anhydrous DMSO and ultrasonicated for 10 min until completely dissolved as solution A; secondly, 2.2 g triethanolamine (TEA) and 1.2 g terephthalic acid (H2BDC) were dissolved in 200 mL DMSO and ultrasonicated for 10 min until completely dissolved as solution B; then, a 250 mL three-necked flask containing 2 mmol of proline pro prepared in the above step (1) was evacuated three times under argon protection, 50 mL of solution A was dropped into it, 35 mL of anhydrous DMSO was injected into it by syringe, and ultrasonicated again for 15 min until the solution became clear, then heated in a water bath to 60 ° C for 2 h, and 64 mL of solution B was added dropwise at a rate of 1 drop / s during the reaction. After removing the heating device, the reaction was cooled to room temperature for 4 h; the solid components were collected by centrifugation, washed 3 times with 20 mL DMSO, and soaked in 50 mL After stirring in DMSO for 24 h, the pink solid product was collected by centrifugation, which was the MOF@Pro HNs hollow mesoporous nanomaterial, and dispersed into 100 mL of DMSO solvent and stored for later use.

[0053] Example 5

[0054] A MOF@Pro HNs hollow mesoporous nanomaterial, the specific preparation method is as follows:

[0055] (1) Preparation of Proline Pro: A 100 mL three-necked flask was replaced with vacuum nitrogen three times, and Boc-proline (1 g, 9.28 mmol), KOH (1.6 g, 26 mmol), 60 mL of anhydrous CH3OH and 120 mL of DMSO were added. The mixture was reacted in a 70°C water bath for 1 h. After ice cubes were added to the water bath to stabilize at 0°C, 25% ammonia water (the mass of ammonia water was 1.4 g) and trimethylsilyl trifluoromethanesulfonate (0.8 g, 1.4 mmol) were added. After the reaction was continued for 1 h, the mixture was moved to room temperature and reacted for 4 h. 20 mL of deionized water was added to quench the reaction. The mixture was extracted three times with 20 mL of chloroform. The organic phases were combined and purified using a silica gel column to obtain 0.189 g of a colorless oily liquid, which was Proline Pro, with a yield of 83%.

[0056] (2) Preparation of MOF@Pro HNs hollow mesoporous nanomaterials: First, 8.8 g Co(CH3COO)2·4H2O was dissolved in 100 mL anhydrous DMSO and ultrasonicated for 50 min until completely dissolved as solution A; secondly, 4.4 g triethanolamine (TEA) and 1.2 g terephthalic acid (H2BDC) were dissolved in 100 mL DMSO and ultrasonicated for 50 min until completely dissolved as solution B; then, a 250 mL three-necked flask containing 2 mmol of proline pro prepared in the above step (1) was evacuated three times under argon protection, 50 mL of solution A was dropped into it, 35 mL of anhydrous DMSO was injected into it by syringe, and ultrasonicated again for 15 min until the solution became clear, then heated in a water bath to 70 ° C for reaction for 0.5 h, and 64 mL of solution B was added dropwise at a rate of 1 drop / s during the reaction. After removing the heating device, the reaction was cooled to room temperature for 6 h; the solid components were collected by centrifugation, washed 3 times with 20 mL DMSO, and soaked in 50 mL After stirring in DMSO for 24 h, the pink solid product was collected by centrifugation, which was the MOF@Pro HNs hollow mesoporous nanomaterial, and dispersed into 100 mL of DMSO solvent and stored for later use.

[0057] Performance Testing

[0058] 1. Physical property tests of various products in the examples

[0059] Figure 1 This is a flow chart for the preparation of MOF@Pro HNs hollow mesoporous nanomaterials of the present invention.

[0060] Figure 2 This is the SEM image of the MOF@Pro HNs hollow mesoporous nanomaterial prepared in Example 1. Figure 2 It can be seen from the spectrum that the MOF@Pro HNs hollow mesoporous network nanomaterial prepared in Example 1 is a mesoporous microsphere with a size distribution of 236±19 nm.

[0061] Figure 3 TEM image of the MOF@Pro HNs hollow mesoporous nanomaterial prepared in Example 1. Figure 3 As can be seen from the graph in, the MOF@Pro HNs hollow mesoporous network nanomaterial prepared in Example 1 is hollow mesoporous microspheres.

[0062] Figure 4 This is the HTEM image of the MOF@Pro HNs hollow mesoporous nanomaterial prepared in Example 1. Figure 4 As can be seen in the graph, the hollow mesoporous shell of the MOF@Pro HNs hollow mesoporous network nanomaterial prepared in Example 1 is covered with 1-3 nm cavities, which is beneficial for the entry and exit of catalytic raw materials and products and is beneficial for increasing the specific surface area of ​​the carrier.

[0063] Figure 5 The figure is a comparison of the specific surface area (a) and pore size distribution (b) of the MOF@Pro HNs hollow mesoporous network nanomaterial and the polymer catalyst prepared in Example 1. Figure 5 As can be seen from the graph in Example 1, the mesopores of the hollow mesoporous network nanomaterial and the polymer catalyst prepared in Example 1 are distributed between 1 and 10 nm and have a higher absorption, while the mesopores of the polymer catalyst are distributed between 1 and 6 nm and have a lower absorption. The specific surface area of ​​the polymer catalyst is 40.8 m 2 g -1 Specific surface area of ​​hollow mesoporous chiral catalyst: 965.3m 2 g -1 , indicating that MOF materials can provide larger three-dimensional space and sufficient contact specific surface area.

[0064] Figure 6 The XRD pattern of the MOF@Pro HNs hollow mesoporous nanostructured material prepared in Example 1 is shown. Compared with the MOF-74 standard card, the (111), (220), (311), and (222) crystal planes corresponding to 2θ6.8°, 9.7°, 13.6°, and 15.4° are consistent with the XRD characteristic peak positions of the standard MOF-74, indicating that the preparation method of the present invention has successfully synthesized the MOF-74 crystal material.

[0065] Figure 7 This is a comparison chart of the water contact angle test of the MOF@Pro HNs hollow mesoporous nanomaterial and the polymer catalyst prepared in Example 1. Figure 7 It can be seen that the MOF@Pro HNs hollow mesoporous chiral catalyst and the polymer catalyst were pressed into tablets, and the static water contact angle of the MOF@Pro HNs hollow mesoporous chiral catalyst was measured to be 44.6°, and the static water contact angle of the polymer catalyst was 61.4°. It can be seen that compared with the polymer catalyst, the MOF@Pro HNs hollow mesoporous chiral catalyst has better hydrophilicity.

[0066] Figure 8 This is the infrared spectrum of the MOF@Pro HNs hollow mesoporous nanomaterial prepared in Example 1. Figure 8 It can be seen that at 3700~3270cm -1 A wide absorption peak appears in the range of 3434cm -1 The stretching vibration absorption peak of the NH bond is at 701 cm -1 NH non-planar rocking vibration absorption peak; 2951cm -1 The absorption peak of CH stretching vibration of benzene ring is at 1728cm -1There is a strong and sharp absorption peak at 1603cm, which is the stretching vibration absorption peak of the C=O double bond; -1 、1494cm -1 and 1453cm -1 C=C vibration of benzene ring skeleton; 1162cm -1 It can be seen from this that the catalyst in the MOF@Pro HNs hollow mesoporous nanomaterial prepared in Example 1 of the present invention is completely bound to the MOF skeleton.

[0067] This shows that the product prepared in Example 1 indeed conforms to the hollow, mesoporous, large specific surface area and hydrophilic nanosphere structure.

[0068] Similarly, the above various performance tests were performed on the MOF@Pro HNs hollow mesoporous network nanomaterials prepared in other examples, and the results were similar to the performance of the MOF@Pro HNs hollow mesoporous network nanomaterials prepared in Example 1 above.

[0069] 2. Catalysis of asymmetric Michael / Michael / aldol tandem reactions

[0070] 10 mg of the MOF@Pro HNs hollow mesoporous nanostructured material prepared in Example 1 and 1 mL of deionized water were added to a 25 mL catalytic test tube. After stirring and dispersing for 5 minutes, 19.7 mg of cinnamaldehyde and 15.8 mg of 3-methylcyclohexenylpropylenenitrile were added and the mixture was allowed to react at room temperature for 48 hours. The heterogeneous catalyst was separated by centrifugation, and the supernatants were combined and concentrated under reduced pressure. The crude product was purified by silica gel column (V 石油醚 / V 乙酸乙酯 =7:1) to obtain a yellow solid product (91% yield), and its corresponding selectivity was detected by high performance liquid chromatography (HPLC).

[0071] The reaction formula in the above catalytic reaction is:

[0072] In this reaction, the reaction solvent was deionized water (1 mL), the reaction temperature was 40° C., and the amount of the heterogeneous catalyst MOF@Pro HNs was 10 mg.

[0073] Figure 9 The HPLC chart of the asymmetric Michael / Michael / aldol tandem reaction catalyzed by the MOF@Pro HNs hollow mesoporous nanomaterial prepared in Example 1. Figure 9It can be seen that the ee% of the product obtained by catalysis of the MOF@Pro HNs hollow mesoporous network nanomaterial prepared in Example 1 is close to 100%, indicating that the MOF@Pro HNs hollow mesoporous network nanomaterial as a chiral catalyst has good stereoselectivity due to its huge specific surface area, pores that can connect the inside and outside, and good hydrophilicity.

[0074] Similarly, the MOF@Pro HNs prepared in the other examples above catalyzed the above asymmetric Michael / Michael / aldo 1 tandem reaction, wherein the ee% of the obtained products was above 98%.

[0075] In summary, the present invention discloses a method for preparing a MOF@Pro HNs hollow mesoporous chiral catalyst. To address the problems of poor hydrophilicity and low supported catalytic efficiency of organic chiral catalysts, a non-solvent-induced phase separation method is first used to prepare a MOF@Pro HNs hollow mesoporous chiral catalyst with high hydrophilicity, high permeability, and high stereoselectivity using Co(CH3COO)2·4H2O, TEA, and H2BDC as raw materials through complexation with Boc-proline. This preparation method is simple and has high yield. It has good catalytic effect on catalyzing Michael / Michael / aldol tandem reactions (91-95% yield, ee of 98-99.5%) and is easily recovered and can be reused (11 times). Therefore, the MOF@Pro HNs hollow mesoporous chiral catalyst prepared by the present invention has good application prospects in catalyzing asymmetric Michael / Michael / aldol tandem reactions.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for preparing MOF@Pro HNs hollow mesoporous nanomaterials, characterized in that: The preparation method comprises the following steps: (1) Preparation of Proline Pro: Boc-proline, KOH, anhydrous CH3OH and DMSO were mixed, heated to 60-70°C in an oxygen-free environment, stirred and reacted for 1-3 hours, ice-bathed to 0°C, and triethylamine or ammonia water was added for alkalization. Trimethylsilyl trifluoromethanesulfonate was added and reacted for 0.5-1 hour. The mixture was moved to room temperature and reacted for 2-4 hours. Deionized water was added to quench the reaction. The organic phases were extracted and combined, and then purified by silica gel column chromatography to obtain colorless oily liquid Proline Pro; (2) Preparation of nanosphere MOF@Pro HNs hollow mesoporous network nanomaterials: Co(CH3COO)2·4H2O was dissolved in anhydrous DMSO and ultrasonicated for 10 to 50 minutes as solution A, triethanolamine and terephthalic acid were dissolved in DMSO and ultrasonicated for 10 to 50 minutes as solution B, the proline pro, solution A and anhydrous DMSO described in step (1) were heated to 60 to 70°C in an oxygen-free environment and stirred for reaction for 0.5 to 2 hours, during which solution B was added dropwise, and the mixture was cooled to room temperature and reacted for 4 to 6 hours. The solid component was collected by centrifugation, washed with DMSO, and then centrifuged to collect the pink solid, which was the MOF@Pro HNs hollow mesoporous network nanomaterial, which was dispersed in DMSO solvent and stored for use.

2. The preparation method according to claim 1, characterized in that In step (1), triethylamine or aqueous ammonia is used for alkalization; When triethylamine is used for alkalization, the mass volume ratio of the Boc-proline, KOH, anhydrous CH3OH, and DMSO is 1.0-2.0:2.0-3.2:20-30:60-80, g:g:mL:mL; When alkalization is performed using 25% ammonia water, the mass volume ratio of the Boc-proline, KOH, anhydrous CH3OH, and DMSO is 1.0-2.0:1.0-1.6:40-60:90-120, g:g:mL:mL.

3. The preparation method according to claim 1, characterized in that In step (1), the mass ratio of the Boc-proline, triethylamine and trimethylsilyl trifluoromethanesulfonate is 1.0-2.0:1.4-2.8:0.4-0.8; the mass ratio of the Boc-proline, ammonia water with a mass concentration of 25% and trimethylsilyl trifluoromethanesulfonate is 1.0-2.0:0.7-1.4:0.4-0.

8.

4. The preparation method according to claim 1, characterized in that In step (1), the extraction is performed using any one of chloroform, dichloromethane or toluene.

5. The preparation method according to claim 1, characterized in that In step (2), the dropwise addition rate of the solution B is 1 to 2 drops per second.

6. The preparation method according to claim 1, characterized in that In step (2), the mass volume ratio of Co(CH3COO)2·4H2O and anhydrous DMSO in the solution A is 4.4-8.8:100-200, g:mL; The mass volume ratio of triethanolamine, terephthalic acid and DMSO in the solution B is 2.2-4.4:1.2-2.4:100-200, g:g:mL.

7. The preparation method according to claim 1, characterized in that In step (2), the molar volume ratio of proline pro, solution A, solution B and anhydrous DMSO is 2:50:64:35, mmol:mL:mL:mL.

8. The preparation method according to claim 1, characterized in that In step (2), the heating to 60-70° C. is performed using a water bath.

9. The MOF@Pro HNs hollow mesoporous nanomaterial prepared according to the preparation method according to any one of claims 1 to 8.

10. Use of the MOF@Pro HNs hollow mesoporous nanomaterial according to claim 9 as a chiral catalyst in catalyzing Michael / Michael / aldol tandem reactions.

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