A chiral covalent organic framework composite membrane prepared by in-situ growth method and its application

Abstract

This invention discloses a chiral covalent organic framework composite membrane prepared by in-situ growth and its applications. This invention uses [NALC] as a reference. X -TAPB-DVA COF S As a functionalized material, a chiral covalent organic framework composite membrane was prepared by a secondary in-situ growth method using terephthalaldehyde (PAD) as the linker and 1,3,5-tris(4-aminophenyl)benzene (TAPB) as the nucleation site. This chiral covalent organic framework composite membrane can resolve enantiomers of mandelic acid, warfarin, naproxen, and ibuprofen, exhibiting a wide resolution range and stable resolution performance.

Description

Technical Field

[0001] This invention belongs to the field of chiral membrane separation technology, specifically relating to a chiral covalent organic framework composite membrane prepared by in-situ growth method and its application. Background Technology

[0002] Chiral membrane separation technology utilizes specific chiral recognition sites inside or outside the membrane to separate racemic mixtures. Membrane separation technology offers advantages such as low energy consumption, simple operation, mild separation conditions, large batch processing capacity, and ease of industrial scale-up, making it highly promising for large-scale industrial applications of chiral separation.

[0003] Chiral membrane resolution faces a trade-off between permeability and selectivity, and the key to solving this problem lies in preparing dense membranes with ordered pores and chiral selectants. Different membrane fabrication processes result in significantly different chiral resolution effects. Based on the membrane fabrication process, these methods can be categorized into physical blending, layer-by-layer stacking, interfacial polymerization, and in-situ growth. Physical blending is simple, but the lack of chemical bonds results in discontinuous membranes with poor selectivity. Layer-by-layer stacking makes it difficult to obtain individual thin films, limiting its applications. Interfacial polymerization has a wide range of applications, producing relatively continuous films through chemical bonding, but suffers from low and uneven chiral selectant loading and non-dense membranes. In-situ growth produces continuous, dense films with controllable thickness and a high and uniform chiral selectant loading, giving it certain advantages.

[0004] Traditional chiral materials are unstable in organic solutions, and their high solubility and non-porous nature lead to low permeate flux or poor separation capacity in the prepared membranes. Novel nanoporous materials, due to their inherent high porosity and tunable pore structure, can enable membranes to maintain both high flux and high selectivity, thus mitigating the trade-off between these two factors. Currently used nanoporous materials for chiral membrane preparation include graphene oxide (GO), metal-organic frameworks (MOFs), and covalent organic frameworks (COFs). Compared to other materials, COFs not only possess low density, high porosity, regular pore structure, and large specific surface area, but also exhibit strong resistance to acids, alkalis, and organic solvents, enabling them to adapt to complex membrane separation environments. Therefore, chiral covalent organic frameworks (CCOFs) represent a promising new class of chiral membrane materials with significant application potential. Summary of the Invention

[0005] To address the problems of mutual constraints between permeability and selectivity, and insufficient enantioselectivity in existing chiral membranes, this invention provides a chiral covalent organic framework composite membrane prepared by in-situ growth. This chiral membrane uses a chiral covalent organic framework as a chiral resolving agent and nylon as a base membrane, exhibiting excellent chiral resolving effect and superior acid and alkali resistance, thus expanding the preparation and application of novel chiral membranes.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A chiral covalent organic framework composite membrane is prepared by the following method:

[0008] (1) Mix 0.01-0.06 mmol terephthalaldehyde (PAD), 1.0-4.0 mL 1,4-dioxane and 0.1-0.4 mL 8M acetic acid solution and add it to a nylon membrane. React at room temperature for 0.5-4 h. Wash with 1,4-dioxane and anhydrous ethanol 1-5 times respectively. Dry at 40-80 °C. Then add the obtained nylon membrane to a mixed solution containing 0.01-0.06 mmol 1,3,5-tris(4-aminophenyl)benzene (TAPB), 1.0-4.0 mL acetonitrile and 0.1-0.4 mL 12M acetic acid solution. React at room temperature for 0.5-4.0 h. Wash with acetonitrile and anhydrous ethanol 1-5 times respectively. Dry at 40-80 °C.

[0009] (2) The nylon membrane obtained in step (1) was added to a mixed solution containing 0.01-0.06 mmol of chiral monomer NALC-DVA, 0.02-0.15 mmol of 1,4-dialdehyde-2,5-divinylbenzene (DVA), 0.3-4.0 mL of 12M acetic acid solution and 1.0-12.0 mL of acetonitrile, and reacted at room temperature for 0.5-2 h. The mixed solution of 0.02-0.12 mmol of 1,3,5-tris(4-aminophenyl)benzene (TAPB), 0.3-4.0 mL of 12M acetic acid solution and 1.0-12.0 mL of acetonitrile was added to the nylon membrane loaded with chiral monomer NALC-DVA and reacted at room temperature for 3-72 h. The membrane was washed 1-5 times with acetonitrile and anhydrous ethanol, and dried at 40-80 °C.

[0010] (3) Secondary reaction of in situ growth of chiral membrane: Repeat the preparation process of step (2) on the membrane obtained in step (2) to obtain the chiral covalent organic framework membrane.

[0011] The preparation process of the chiral monomer NALC-DVA is as follows: 0.03-0.12 mmol of 1,4-dialdehyde-2,5-divinylbenzene and 0.09-0.36 mmol of N-acetyl-L-cysteine ​​are taken, and 0.03-0.15 mmol of initiator azobisisobutyronitrile and 2.0-8.0 mL of solvent are added under a nitrogen atmosphere. The mixture is stirred at 40-80 °C for 12-48 h. After centrifugation, the precipitate is collected to obtain the chiral monomer NALC-DVA.

[0012] Further, the nylon membrane mentioned in step (1) is a pretreated nylon membrane. The pretreatment process is as follows: the nylon membrane is reacted in a 0.5-2M hydrochloric acid solution at 20-60°C for 12-48 hours, washed with water and ethanol 1-5 times, and dried with nitrogen.

[0013] Furthermore, in the preparation of the chiral monomer NALC-DVA, the solvent is a mixed solvent of trifluorotoluene and tetrahydrofuran, with a volume ratio of 1:1.

[0014] The aforementioned chiral covalent organic framework membrane is used to resolve chiral drugs. The chiral drugs are selected from mandelic acid, warfarin, naproxen, and ibuprofen.

[0015] like Figure 1 As shown, the present invention uses [NALC] X -TAPB-DVA COF S The chiral composite membrane was prepared by a secondary in-situ growth method using terephthalaldehyde (PAD) as the linker and 1,3,5-tris(4-aminophenyl)benzene (TAPB) as the nucleation site, as a functionalized material.

[0016] The inventors previously investigated factors affecting membrane separation efficiency, including the presence or absence of connecting arms and nucleation sites, membrane preparation time, monomer ratio, and number of reactions. Specifically:

[0017] 1. When loading the base film with connecting arms and nucleation sites, a seed layer can be provided. Using terephthalaldehyde (PAD) as the connecting arm and 1,3,5-tris(4-aminophenyl)benzene (TAPB) as the nucleation site, the resulting membrane is more continuous and has fewer cracks compared to membranes without connecting arms and nucleation sites. Using racemic mandelic acid as the resolution target, chiral membranes with connecting arms and nucleation sites exhibit better resolution than those without.

[0018] 2. The preparation time of chiral COF membranes affects the resolution effect. Chiral covalent organic framework membranes were prepared at five time points (6h, 12h, 24h, 36h, and 48h) using an in-situ growth method. Racemic mandelic acid was used as the resolution target. The shorter preparation times of 6h and 12h resulted in relatively discontinuous and dense chiral membranes with poor resolution. However, there was no significant difference in the resolution effect at the 24h, 36h, and 48h time points.

[0019] 3. The separation performance of chiral covalent organic framework membranes prepared by the in-situ growth method varies significantly depending on the ratio of chiral monomers (NALC-DVA:DVA). Four chiral covalent organic framework membranes with different NALC-DVA:DVA(n:n) ratios were prepared by the in-situ growth method, namely NALC-DVA:DVA(n:n) = 1:5, 1:2, 1:1, and 2:1. The separation effect was optimal when the NALC-DVA:DVA(n:n) ratio was 1:2.

[0020] 4. The number of reactions in the in-situ growth method has a significant impact on the membrane's resolution performance. The resolution effect of chiral membranes is related to both the membrane's density and the amount of chiral selective agent. In the single-stage in-situ growth method, the chiral membrane has cracks and the amount of chiral selective agent is insufficient, resulting in a less than ideal resolution effect. However, the secondary growth method can compensate for the cracks and insufficient amount of chiral selective agent present in the first stage, making the prepared chiral COF membrane continuous and dense, and significantly improving the resolution effect.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. Constructing novel chiral systems using a bottom-up approach [NALC] X -TAPB-DVA COF S The material, by introducing chiral selectors from the bottom up, allows for control over the amount of chiral selectors. The introduction of carboxyl groups not only improves the dispersibility of the material but also increases its hydrophilicity compared to achiral covalent organic frameworks.

[0023] 2. Chiral covalent organic framework membrane fabrication conditions are mild and the process is relatively simple. Commercially available nylon membranes are used as the base membrane material, and nanoporous N-acetyl-L-cysteine ​​covalent organic framework membranes ([NALC)) are employed. X -TAPB-DVA COF S As a chiral resolving agent, it can be used to prepare high-performance chiral membranes through a secondary in-situ growth method, solving the problems of insufficient adhesion between chiral COF materials and substrates and insufficient membrane density, while effectively alleviating the limiting relationship between selectivity and permeation flux of traditional chiral membranes.

[0024] 3. Chiral covalent organic framework membranes can resolve enantiomers of mandelic acid, warfarin, naproxen, and ibuprofen, exhibiting a wide resolution range and stable resolution performance.

[0025] 4. Chiral covalent organic framework membranes have excellent acid and alkali resistance, with a pH tolerance range of 3 to 11. Attached Figure Description

[0026] Figure 1 This invention relates to the secondary in-situ growth method for preparing chiral [NALC]. X -TAPB-DVA COFS A schematic diagram of the process principle of / nylon membrane.

[0027] Figure 2 In the diagram, (a) represents [NALC]. 1 / 3 -Infrared spectrum of TAPB-DVA COF, (b) is [NALC] 1 / 3 PXRD plot of TAPB-DVACOF.

[0028] Figure 3 In the diagram, (a) represents [NALC]. 1 / 3 Infrared spectrum of the TAPB-DVA COF / nylon film, (b) is [NALC]. 1 / 3 XRD pattern of TAPB-DVA COF / nylon membrane.

[0029] Figure 4 In the middle, the left image is a surface electron microscope (SEM) image of a nylon-based film; the middle image is a surface SEM image of a non-chiral covalent organic framework (TAPB-DVA COF / nylon) film; and the right image is a [NALC] image. 1 / 3 -Surface electron microscope image of TAPB-DVA COF / nylon film.

[0030] Figure 5 In the image, (a) is a cross-sectional electron microscope (TEM) image of the nylon-based film, (b) is a cross-sectional TEM image of the achiral covalent organic framework (TAPB-DVA COF / nylon) film, and (c) is a [NALC] image. 1 / 3 Cross-sectional electron micrograph of a TAPB-DVA COF / nylon membrane.

[0031] Figure 6 Comparison of the separation effects of different types of membranes.

[0032] Figure 7 For [NALC] 1 / 3 - Acid and alkali resistance of TAPB-DVA COF / nylon membrane.

[0033] Figure 8 For [NALC] 1 / 3 Enantiomer separation results of different chiral drugs using TAPB-DVA COF / nylon membrane. Detailed Implementation

[0034] The preferred embodiments of the present invention will now be described in detail with reference to specific examples. It should be understood that the following examples are given for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art can make various modifications and substitutions to the present invention without departing from its spirit and essence.

[0035] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0036] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0037] Example 1

[0038] I. N-acetyl-L-cysteine ​​covalent organic framework ([NALC)) 1 / 3 Preparation of TAPB-DVA COF:

[0039] (1) Preparation of chiral monomer NALC-DVA: Chiral functional monomer NALC-DVA was synthesized by using DVA and NALC via a "thiol-ene" click reaction. 1,4-dialdehyde-2,5-divinylbenzene (DVA, 0.045 mmol) and N-acetyl-L-cysteine ​​(NALC, 0.135 mmol) were added at room temperature and under N2 atmosphere. The mixture was stirred at 60 °C for 24 h, and the product was collected by centrifugation and dried under high vacuum at 60 °C for 24 h.

[0040] (2) N-acetyl-L-cysteine ​​chiral covalent organic framework: NALC-DVA (0.03 mmol), 1,3,5-tris(4-aminophenyl)benzene (TAPB, 0.06 mmol), and 1,4-dialdehyde-2,5-divinylbenzene (DVA, 0.06 mmol) were added to 7.5 mL of acetonitrile and 1.05 mL of 12 M AcOH, vortexed for 10 s, and allowed to stand at room temperature for 72 h. After washing, the precipitate was collected by centrifugation and dried under high vacuum at 60 °C for 24 h to obtain the N-acetyl-L-cysteine ​​covalent organic framework ([NALC-DVA]). 1 / 3 -TAPB-DVA COF).

[0041] II. Preparation of TAPB-DVA COF:

[0042] 7.5 mL of acetonitrile and 1.05 mL of 12 M AcOH were added to 1,3,5-tris(4-aminophenyl)benzene (TAPB, 0.06 mmol) and 1,4-dialdehyde-2,5-divinylbenzene (DVA, 0.09 mmol), vortexed for 10 s, and allowed to stand at room temperature for 72 h. The mixture was washed, and the precipitate was collected by centrifugation and dried under high vacuum at 60 °C for 24 h to obtain the achiral skeleton.

[0043] Figure 2 (a) is [NALC]1 / 3 The Fourier transform infrared (IR) spectrum of the TAPB-DVA COF shows [NALC]. 1 / 3 -TAPB-DVA COF at 3300cm -1 The peak at 1612 cm⁻¹ is attributed to -OH. -1 A new peak appeared, attributed to the stretching vibration of the imine bond C=N, indicating the successful synthesis of chiral [NALC]. 1 / 3 -TAPB-DVA COF; (b) is [NALC] 1 / 3 The powder X-ray diffraction (PXRD) pattern of TAPB-DVA COF shows diffraction peaks at 2.73°, 4.78°, 5.52°, 7.35°, 9.73°, and 25.29°. Compared with TAPB-DVA COF without chiral selector modification, all of its diffraction peaks correspond to those of TAPB-DVA COF, indicating that it has a superior crystal form.

[0044] Example 2

[0045] A method for preparing a chiral covalent organic framework membrane includes the following steps:

[0046] (1) Base membrane pretreatment: The base membrane was pretreated by reacting the nylon membrane in HCl (1M) at 40℃ for 24h, washing it three times with water and anhydrous ethanol respectively, and drying it with nitrogen. A mixed solution of terephthalaldehyde (PAD, 0.04mmol), 1,4-dioxane (2.5mL), and 0.215mL AcOH (8M) for the connecting arm was added to the pretreated nylon membrane and reacted at room temperature for 2h, washing it three times with 1,4-dioxane and anhydrous ethanol respectively, and drying it at 60℃ for 5min. A mixed solution of 1,3,5-tris(4-aminophenyl)benzene (TAPB, 0.03mmol), 2.5mL acetonitrile, and 0.2mL AcOH (12M) for the nucleation site was added to the nylon membrane with the supporting connecting arm and reacted at room temperature for 2h, washing it three times with acetonitrile and anhydrous ethanol respectively, and drying it at 60℃ for 5min.

[0047] (2) Chiral membrane in situ growth method: The chiral monomer NALC-DVA (0.03 mmol), 1,4-dialdehyde-2,5-divinylbenzene (DVA, 0.06 mmol), 0.5 mL AcOH (12 M), and 5.0 mL acetonitrile were added to the nylon membrane loaded with nucleation sites and reacted at room temperature for 0.5 h; the 1,3,5-tris(4-aminophenyl)benzene (TAPB, 0.06 mmol), 0.55 mL AcOH (12 M), and 2.5 mL acetonitrile were added to the nylon membrane loaded with chiral monomer NALC-DVA and reacted at room temperature for 24 h. The membrane was washed three times with acetonitrile and anhydrous ethanol, and dried at 60 °C for 10 min to obtain the final product.

[0048] (3) Secondary reaction of in-situ chiral membrane growth: Repeat the reaction of step (2) with the membrane obtained in step (2) to obtain a chiral covalent organic framework membrane ([NALC)). 1 / 3 -TAPB-DVA COF / nylon).

[0049] Comparative Example 1

[0050] A method for preparing a non-chiral covalent organic framework membrane includes the following steps:

[0051] (1) Base membrane pretreatment: The base membrane was pretreated by reacting the nylon membrane in HCl (1M) at 40℃ for 24h, washing it three times with water and anhydrous ethanol respectively, and drying it with nitrogen. A mixed solution of terephthalaldehyde (PAD, 0.04mmol), 1,4-dioxane (2.5mL), and 0.215mL AcOH (8M) for the connecting arm was added to the pretreated nylon membrane and reacted at room temperature for 2h, washing it three times with 1,4-dioxane and anhydrous ethanol respectively, and drying it at 60℃ for 5min. A mixed solution of 1,3,5-tris(4-aminophenyl)benzene (TAPB, 0.03mmol), 2.5mL acetonitrile, and 0.2mL AcOH (12M) for the nucleation site was added to the nylon membrane with the supporting connecting arm and reacted at room temperature for 2h, washing it three times with acetonitrile and anhydrous ethanol respectively, and drying it at 60℃ for 5min.

[0052] (2) In-situ non-chiral membrane growth method: A mixed solution of 1,4-dialdehyde-2,5-divinylbenzene (DVA, 0.09 mmol), 0.5 mL AcOH (12 M), and 5.0 mL acetonitrile was added to the nylon membrane loaded with nucleation sites and reacted at room temperature for 2 h; a mixed solution of 1,3,5-tris(4-aminophenyl)benzene (TAPB, 0.06 mmol), 0.55 mL AcOH (12 M), and 2.5 mL acetonitrile was added to the nylon membrane loaded with monomer 1,4-dialdehyde-2,5-divinylbenzene (DVA) and reacted at room temperature for 24 h. The membrane was washed three times with acetonitrile and anhydrous ethanol, and dried at 60 °C for 10 min to obtain the final product.

[0053] (3) Secondary reaction of in situ growth of achiral membrane: Repeat the reaction of step (2) on the membrane obtained in step (2) to obtain achiral covalent organic framework membrane (TAPB-DVA COF / nylon).

[0054] Figure 3 (a) is [NALC] 1 / 3 The Fourier transform infrared (IR) spectrum of the TAPB-DVA COF / nylon film shows [NALC]. 1 / 3 -TAPB-DVA COF / nylon membrane at 3300cm -1 The peak is attributed to -OH, compared to the peak without [NALC]. 1 / 3 -TAPB-DVA COF nylon base film, [NALC] 1 / 3 -TAPB-DVA COF / nylon membrane at 1612cm -1 A new peak appeared at this point, attributed to the stretching vibration of the imine bond C=N, which indicates [NALC]. 1 / 3 -TAPB-DVA COF / nylon membrane successfully prepared; (b) for [NALC] 1 / 3 The X-ray diffraction (XRD) pattern of the TAPB-DVA COF / nylon film shows that, compared to films without [NALC], [the following is observed]. 1 / 3 -TAPB-DVA COF nylon base film, [NALC] 1 / 3 The -TAPB-DVA COF / nylon film exhibits diffraction peaks at 2.76°, 4.78°, 5.57°, 7.35°, and 9.72°, indicating that [NALC]... 1 / 3 -TAPB-DVA COF / nylon membrane successfully prepared.

[0055] SEM was used to observe nylon-based membranes, achiral covalent organic framework (TAPB-DVA COF / nylon) membranes, and [NALC]. 1 / 3 The surface of the TAPB-DVA COF / nylon film is magnified 10,000 times. Figure 4 The left image shows a surface electron microscope (SEM) image of the nylon base film, revealing an interwoven network of macroporous structures. The middle image shows a surface SEM image of the achiral covalent organic framework (TAPB-DVA COF / nylon), exhibiting a nano-flower-like morphology that fills the network of macroporous pores on the nylon base film surface. The right image shows a chiral COF film with secondary reactions ([NALC)). 1 / 3The surface electron microscope image of the TAPB-DVA COF / nylon film shows a tentacle-like spherical morphology that fills the large mesh-like pores on the nylon base film surface, without obvious holes or cracks. Compared with the nylon base film, this indicates that the [NALC] was successfully prepared. 1 / 3 -TAPB-DVA COF / nylon membrane.

[0056] SEM was used to observe nylon-based membranes, achiral covalent organic framework (TAPB-DVA COF / nylon) membranes, and [NALC]. 1 / 3 The cross-sections of the TAPB-DVA COF / nylon membranes are all magnified by 5000 times. Figure 5 (a) Cross-sectional electron micrograph of the nylon-based membrane. The image shows an interwoven network of macroporous structures. (b) Cross-sectional electron micrograph of the achiral covalent organic framework (TAPB-DVA COF / nylon). The TAPB-DVA COF membrane exhibits a spherical nanoparticle morphology, growing along the nylon-based membrane framework and simultaneously filling the network of macroporous pores. (c) Chiral COF membrane with secondary reaction ([NALC)). 1 / 3 A cross-sectional electron micrograph of the TAPB-DVA COF / nylon film shows a tentacle-like spherical morphology. The obvious spherical structure in the upper layer may be the reaction and deposition of [NALC] on the film surface. 1 / 3 -TAPB-DVACOF. [NALC] 1 / 3 Compared to nylon-based membranes and TAPB-DVA COF / nylon membranes, NALC (Non-Nano Liposome Array) membranes are more porous. 1 / 3 The presence of -TAPB-DVA COF provides more solvent transport channels, while [NALC] 1 / 3 -TAPB-DVA COF endows the membrane with chiral resolution capabilities, thus enabling the in-situ growth method to prepare [NALC]. 1 / 3 -TAPB-DVA COF / nylon membranes simultaneously improve the selectivity and permeation flux of nylon-based membranes.

[0057] Mandelic acid was selected as the separation target. The stock solution concentration was 0.05 g / L, and the solvent was pure water. The solution was filtered under constant pressure of 0.1 MPa membrane for 5 hours. The collector was changed every 1 hour to collect the filtrate. The ee of the filtrate and the stock solution was determined by HPLC.

[0058] The HPLC conditions are as follows:

[0059]

[0060] The results are as follows Figure 6As shown, the nylon-based membrane and the achiral covalent organic framework have almost no resolving effect, while the chiral covalent organic framework membrane has an ee% of 31.7%, and its resolving effect is significantly better than that of the nylon-based membrane and the achiral covalent organic framework. This indicates that the in-situ growth method can successfully prepare chiral covalent organic framework membranes with good resolving effect.

[0061] Test Example 1

[0062] Stability study of chiral COF membranes

[0063] Pure water with pH values ​​of 1, 3, 5, 7, 9, 11, and 13 was selected as the hydrolysis solution for [NALC] prepared by the secondary in-situ growth method. 1 / 3 The TAPB-DVA COF / nylon membrane was placed in the above solution, with a blank control group included. Both the experimental and blank groups were simultaneously placed in a constant-temperature shaker and shaken at 125 rpm for 12 hours. The total carbon content (TC) of the experimental and blank groups was then measured. The TC values ​​of the experimental and blank groups were compared to determine the hydrolysis of the membrane at different pH values. Figure 7 It can be seen that the prepared [NALC] 1 / 3 -TAPB-DVA COF / nylon membranes are stable within a pH range of 3 to 11 for 12 hours.

[0064] Test Example 2

[0065] Investigation on the effect of in-situ growth method on the separation of chiral substances in chiral COF membranes

[0066] A chiral covalent organic framework was successfully immobilized onto a nylon-based membrane using a secondary in-situ growth method at room temperature, and then subjected to chiral [NALC]. 1 / 3 -TAPB-DVA COF / nylon membrane. The prepared chiral covalent organic framework membrane can resolve the enantiomers of warfarin, naproxen, and ibuprofen with good resolution. The enantiomer stock solution concentration was selected as 0.05 g / L, the solvent was pure water, and the membrane was filtered at a constant pressure of 0.1 MPa for 5 h. The filtrate was collected by changing the collector every 1 h, and the ee% of the filtrate and stock solution was determined by HPLC.

[0067] The results are as follows Figure 8 As shown, the chiral COF membrane achieved a resolution of naproxen with an ee% of 9.3% and a Js of 2.65 nmol·cm⁻¹. -2 ·h -1 The fractional ee% of warfarin was 12.0%, and Js was 2.02 nmol·cm⁻¹. -2 ·h -1 The fractional fraction of ibuprofen was ee% 16.6% and Js 3.53 nmol·cm⁻¹. -2 ·h -1Chiral COFs are immobilized on nylon-based membranes, thereby improving both membrane permeability and selectivity.

Claims

1. A chiral covalent organic framework composite membrane, characterized in that, It is prepared by the following method: (1) Mix 0.01~0.06 mmol terephthalaldehyde, 1.0~4.0 mL 1,4-dioxane and 0.1~0.4 mL 8 M acetic acid solution and add it to a nylon membrane. React at room temperature for 0.5~4 h. Wash with 1,4-dioxane and anhydrous ethanol respectively. Dry at 40~80℃. Then add the obtained nylon membrane to a mixed solution containing 0.01~0.06 mmol 1,3,5-tris(4-aminophenyl)benzene, 1.0~4.0 mL acetonitrile and 0.1~0.4 mL 12 M acetic acid solution. React at room temperature for 0.5~4.0 h. Wash with acetonitrile and anhydrous ethanol respectively. Dry at 40~80℃. (2) The nylon membrane obtained in step (1) was added to a mixed solution containing 0.01~0.06 mmol of chiral monomer NALC-DVA, 0.02~0.15 mmol of 1,4-dialdehyde-2,5-divinylbenzene, 0.3~4.0 mL of 12 M acetic acid solution and 1.0~12.0 mL of acetonitrile, and reacted at room temperature for 0.5~2 h. The mixed solution of 0.02~0.12 mmol of 1,3,5-tris(4-aminophenyl)benzene, 0.3~4.0 mL of 12 M acetic acid solution and 1.0~12.0 mL of acetonitrile was added to the nylon membrane loaded with chiral monomer NALC-DVA and reacted at room temperature for 3~72 h. The membrane was washed with acetonitrile and anhydrous ethanol respectively and dried at 40~80℃. The chiral monomer NALC-DVA is synthesized using 1,4-dialdehyde-2,5-divinylbenzene and N-acetyl-L-cysteine ​​via a "thiol-ene" click reaction. (3) Secondary reaction of in situ growth of chiral membrane: Repeat the preparation process of step (2) on the membrane obtained in step (2) to obtain the chiral covalent organic framework composite membrane.

2. The chiral covalent organic framework composite membrane according to claim 1, characterized in that, The preparation process of the chiral monomer NALC-DVA is as follows: 0.03~0.12 mmol of 1,4-dialdehyde-2,5-divinylbenzene and 0.09~0.36 mmol of N-acetyl-L-cysteine ​​are taken, and 0.03~0.15 mmol of initiator azobisisobutyronitrile and 2.0~8.0 mL of solvent are added under a nitrogen atmosphere. The mixture is stirred at 40~80℃ for 12~48 h. After centrifugation, the precipitate is collected to obtain the chiral monomer NALC-DVA.

3. The chiral covalent organic framework composite membrane according to claim 2, characterized in that, In the preparation of the chiral monomer NALC-DVA, the solvent is a mixture of trifluorotoluene and tetrahydrofuran in a volume ratio of 1:

1.

4. The chiral covalent organic framework composite membrane according to claim 1, characterized in that, The nylon membrane mentioned in step (1) is a pretreated nylon membrane. The pretreatment process is as follows: the nylon membrane is reacted in 0.5~2 M hydrochloric acid solution at 20~60℃ for 12~48 h, washed with water and ethanol 1~5 times, and dried with nitrogen.

5. The application of the chiral covalent organic framework composite membrane according to claim 1 in the resolution of chiral drugs.

6. The application according to claim 5, characterized in that, The chiral drug is selected from mandelic acid, warfarin, naproxen, or ibuprofen.

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