Preparation method and application of chiral phosphoric acid intrinsic microporous polymer membrane

Abstract

The invention discloses a preparation method and application of a chiral phosphoric acid intrinsic microporous polymer membrane. In the invention, R / S-1, 1 '-co-2-naphthol and indole-2, 3-dione or a derivative thereof are taken as monomers, and the soluble chiral polymer with an intrinsic microporous structure is prepared through catalytic polymerization. After the polymer forms a film, phosphorylation treatment is carried out, a phosphate group is introduced, and the chiral phosphoric acid intrinsic microporous polymer film is obtained. The membrane has high specific surface area and chiral recognition sites, shows excellent enantiomer selectivity and permeability, can be widely applied to efficient separation of chiral small molecular enantiomers, has important application value and popularization prospect in the field of chiral separation, can simultaneously realize integration of microporous channels, chiral environments and multifunctional phosphate groups, and has broad application prospects. Therefore, breakthrough balance is achieved between chiral selectivity and permeation flux, and a new material platform is provided for chiral membrane separation.

Description

Technical Field

[0001] This invention belongs to the field of membrane separation technology, specifically a method for preparing and applying a chiral phosphoric acid self-porous polymer membrane. Background Technology

[0002] Membrane separation technology, due to its high efficiency, energy saving, and environmental friendliness, has broad application prospects in the separation and purification of gases and liquids. Especially in the preparation of chiral drugs and fine chemicals, the efficient separation of enantiomers is crucial to ensuring drug activity and safety.

[0003] However, existing separation methods such as crystallization and chromatography generally suffer from drawbacks such as high energy consumption, low efficiency, complex operation, and difficulty in scaling up, which limit their industrial application. Microporous polymers, due to their rigid and twisted molecular backbones, can form stable and highly interconnected nanoscale microporous channels, thus possessing high specific surface area and excellent molecular transport properties, making them an important research direction for novel membrane separation materials. The rigid backbone of these polymers also provides an ideal platform for the introduction of functional molecular recognition sites, showing application potential in the field of chiral separation. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a chiral phosphoric acid self-porous polymer membrane and its application in order to solve the problems mentioned above.

[0005] The technical solution adopted in this invention is as follows: a method for preparing a chiral phosphoric acid self-porous polymer membrane and its application, the method comprising the following steps: Step 1, Preparation of chiral self-porous polymer: R / S-1,1'-bi-2-naphthol and a ketone with electron-withdrawing groups are dissolved in dichloromethane. A superacid is added as a catalyst, and the mixture is stirred at room temperature until viscous. Then, a mixed solution of methanol / water or ethanol / water is added to precipitate the polymer. The pH is adjusted to neutral using an alkaline solution. The solid is filtered out and redissolved in N,N-dimethylformamide. Methanol / water or ethanol / water is added again to precipitate the solid. The dissolution-precipitation process is repeated 3 times. The resulting solid is dried to obtain the chiral R / S-BINOL-based self-porous polymer. Step 2, Preparation of chiral polymer film: Dissolve R / S-BINOL-based microporous polymer in N,N-dimethylformamide to form a casting solution with a concentration of 2-5 wt%, and pour it into a petri dish. Place it in an oven and heat at 60-100 ℃ until the solvent evaporates completely. Step 3, Preparation of phosphorylated chiral microporous polymer membrane: Using anhydrous pyridine as solvent, phosphorylate the polymer membrane obtained in step 2 with phosphoric acid. After the reaction is completed, quench the reaction with water. The resulting membrane is then washed with dilute hydrochloric acid, water, ethanol and methanol in sequence.

[0006] In a preferred embodiment, in step S2, the chiral phosphate self-porous polymer has a specific surface area greater than 50 m². 2 It exhibits the characteristic of / g and demonstrates good solvent stability and insolubility.

[0007] In a preferred embodiment, the ketone having an electron-withdrawing group is indole-2,3-dione or its derivatives.

[0008] In a preferred embodiment, the indole-2,3-dione derivative includes, but is not limited to, chloroindole-2,3-dione, fluoroindole-2,3-dione, phenylindole-2,3-dione, methoxyindole-2,3-dione, ethylindole-2,3-dione, etc.

[0009] In a preferred embodiment, the ketone having an electron-withdrawing group is indole-2,3-dione.

[0010] In a preferred embodiment, the molar ratio of R / S-1,1'-bi-2-naphthol to indole-2,3-dione is 1:1-2.

[0011] In a preferred embodiment, the molar ratio of R / S-1,1'-bi-2-naphthol and indole-2,3-dione is 1:1.2.

[0012] In a preferred embodiment, the superacid is one or a mixture of two of trifluoroacetic acid and trifluoromethanesulfonic acid.

[0013] In a preferred embodiment, the superacid is trifluoromethanesulfonic acid.

[0014] In a preferred embodiment, the concentration of the casting solution is 2.5 wt%.

[0015] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: In this invention, a soluble chiral polymer with an intrinsic microporous structure is prepared by catalytic polymerization using R / S-1,1'-bi-2-naphthol and indole-2,3-dione or their derivatives as monomers. After film formation, this polymer is phosphorylated to introduce phosphate groups, resulting in a chiral phosphoric acid self-contained microporous polymer film, the chemical structure of which is as follows: Figure 5 As shown in the figure, this membrane combines high specific surface area with chiral recognition sites, exhibiting excellent enantioselectivity and permeability. It can be widely used for the efficient separation of chiral small molecule enantiomeric compounds, and has significant application value and promising prospects in the field of chiral separation. Attached Figure Description

[0016] Figure 1The carbon dioxide adsorption-desorption curves and pore size distribution diagrams of the chiral self-porous polymer obtained in Example 1 of this invention are shown. Figure 2 The carbon dioxide adsorption-desorption curves and pore size distribution diagrams of the chiral phosphoric acid self-porous polymer membrane obtained in Example 3 of the present invention are shown. Figure 3 This is a SEM image of the chiral phosphoric acid self-porous polymer membrane obtained in Example 3 of the present invention; Figure 4 The images shown are the receiver-side HPLC spectra from Examples 4, 5, 6, and 7 of this invention. Figure 5 The diagram shows the self-porous polymer structure of chiral phosphoric acid in this invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0018] A method for preparing and applying a chiral phosphoric acid self-porous polymer membrane includes the following steps: Step S1: Prepare a microporous polymer precursor of chiral phosphoric acid. Dissolve optically pure 1,1'-bi-2-naphthol and indole-2,3-dione or their derivatives in a solvent, wherein the molar ratio of optically pure 1,1'-bi-2-naphthol to indole-2,3-dione is 1:1.2. Add trifluoromethanesulfonic acid catalyst, stir the reaction until the system becomes viscous, and then add a poor solvent to precipitate the polymer to obtain the chiral polymer. Step S2: Prepare a polymer membrane by dissolving the chiral polymer obtained in step S1 in an organic solvent and casting the membrane using a casting solution with a concentration of 2.5 wt%; and removing the solvent under heating conditions to obtain the polymer membrane. Step S3: Post-modification phosphorylation. The polymer membrane obtained in step S2 is placed in a reaction solvent containing an organophosphorus reagent for phosphorylation reaction. After quenching treatment, a chiral phosphoric acid self-porous polymer membrane insoluble in common solvents is obtained.

[0019] In step S2, the chiral phosphoric acid self-porous polymer has a specific surface area greater than 50 m². 2 It exhibits the characteristic of / g and demonstrates good solvent stability and insolubility.

[0020] In step S1, the derivative includes one or more of chloroindole-2,3-dione, fluoroindole-2,3-dione, phenylindole-2,3-dione, methoxyindole-2,3-dione, and ethylindole-2,3-dione.

[0021] In step S1, the solvent is dichloromethane.

[0022] In step S1, the catalyst is one or a mixture of two of trifluoroacetic acid or trifluoromethanesulfonic acid.

[0023] In step S1, the reaction temperature is room temperature and the reaction time is 1-5 h.

[0024] In step S1, the unsuitable solvent is methanol or a mixture of ethanol and water, with a preferred alcohol / water ratio of 1:1.

[0025] In step S2, the organic solvent is selected from one of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone; The concentration of the casting solution is 2-5 wt%; the oven temperature is 60-100 ℃; and the treatment time is 12-24 h.

[0026] In step S3, the reaction solvent is preferably anhydrous pyridine; the organophosphorus reagent is preferably phosphorus oxychloride; and the quencher is preferably water.

[0027] Applications of methods for preparing chiral phosphoric acid self-porous polymer membranes include their use as selective membranes for the membrane separation of chiral enantiomers. Reference Figure 1-5 , Example 1: Preparation of chiral self-porous polymers: The specific steps are as follows: In a round-bottom flask, add R-1,1'-bi-2-naphthol (286 mg), indole-2,3-dione (176 mg), and dichloromethane (1.5 mL). After stirring for 30 min, add 0.3 mL of trifluoromethanesulfonic acid. Continue stirring at room temperature until the liquid becomes viscous. Pour in a 50 mL mixture of methanol and water (1:1 volume ratio) to precipitate the solid, and add a small amount of ammonia to adjust the pH to neutral. After filtration, dissolve the solid using 3 mL of N,N-dimethylformamide, and again add the methanol and water mixture to precipitate the solid. Repeat the dissolution-precipitation process three times. Dry the final solid in an oven at 100 °C for 12 h to obtain the R-chiral self-microporous polymer (R-PIM).

[0028] S-chiral self-contained microporous polymers (S-PIM) were prepared using the same steps, replacing R-1,1'-bi-2-naphthol with S-1,1'-bi-2-naphthol.

[0029] Example 2: Preparation of chiral self-porous polymer membranes The specific steps are as follows: Weigh 50 mg of R-PIM and dissolve it in 2 g of N,N-dimethylformamide to prepare a 2.5 wt% casting solution. Pour the casting solution into a 4 cm diameter polytetrafluoroethylene petri dish and place it in an oven at 80 ℃ until the solvent has completely evaporated. Peel the prepared film off the petri dish to obtain the R-PIM film.

[0030] S-PIM membranes were prepared using the same steps, replacing R-1,1'-bi-2-naphthol with S-1,1'-bi-2-naphthol.

[0031] Example 3: Preparation of phosphorylated chiral self-porous polymer membranes The specific steps are as follows: Place a prepared R-PIM membrane in a round-bottom flask, and add 5 mL of anhydrous pyridine and 10 μL of phosphorus oxychloride under nitrogen protection. After reacting at 80 ℃ for 10 h, cool the reaction flask to room temperature, and then slowly add 5 mL of water to quench the reaction. Remove the obtained membrane and wash it sequentially with dilute hydrochloric acid, water, ethanol, and methanol to obtain a phosphorylated chiral self-contained microporous polymer membrane (RP-PIM membrane). Immerse the cleaned RP-PIM membrane in a methanol solution for subsequent experiments.

[0032] SP-PIM membranes were prepared using the same steps as R-PIM membranes, replacing R-PIM membranes.

[0033] Example 4: Selective osmosis experiment: The specific steps are as follows: The RP-PIM membrane prepared in Example 1 was sandwiched in the middle of a self-made horizontal diffusion cell. 9.5 mL of a 0.005 mol / L racemic methanol solution of 1,1'-bi-2-naphthol was added to the left feed side, and 9.5 mL of methanol was added to the right receiving side. After standing for 30 min, the concentration of R / S-BINOL on the receiving side was detected using high-performance liquid chromatography (HPLC), and the enantiomeric excess value (ee%) was calculated.

[0034] ee% is calculated from the peak area (A) of the R and S enantiomers on the receiving side, ee% = |(A) R -A S )| / (A R +A S )% HPLC detection method: Column: Daicel CHIRALPAK IG column; Mobile phase: n-hexane / ethanol = 85 / 15; Flow rate: 1 mL / min; Detection wavelength: 245 nm; Column oven temperature: 35 ℃.

[0035] Example 5 differs from Example 4 in that it uses an SP-PIM membrane.

[0036] Example 6 differs from Example 4 in that 9.5 mL of a 0.005 mol / L racemic 6,6'-dibromo-1,1'-bi-2-naphthol solution is added to the feed side.

[0037] Example 7 differs from Example 6 in that it uses an SP-PIM membrane.

[0038] The following table shows the ee% calculated for Examples 4, 5, 6, and 7: ee% Example 4 24.27 Example 5 33.63 Example 6 63.96 Example 7 61.11 From the above, we can conclude that: In this invention, introducing groups with highly directional recognition capabilities is crucial for achieving efficient separation of chiral molecules. 1,1'-bi-2-naphthol, as a classic axial chiral framework, possesses a stable chiral configuration and modifiability, and has been widely used in the field of chiral recognition. Introducing the 1,1'-bi-2-naphthol group into the PIMs framework can construct a microporous network with a defined chiral environment, thereby improving the separation selectivity and permeation flux of chiral molecules. Furthermore, phosphorylation modification of the 3,3'-hydroxyl group on the 1,1'-bi-2-naphthol group introduces a high-density phosphate group into the polymer channels. This group can enhance intermolecular interactions through hydrogen bonding, electrostatics, and ionic interactions, thereby significantly improving the recognition ability of chiral molecules.

[0039] Therefore, in this invention, a chiral polymer framework with an intrinsic microporous structure is obtained by polymerizing 1,1'-bi-2-naphthol with indole-dione or its derivatives, and then further modified by phosphorylation of its hydroxyl sites. This method can simultaneously achieve the integration of microporous channels, a chiral environment, and multifunctional phosphate groups, thereby achieving a breakthrough balance between chiral selectivity and permeation flux, providing a new material platform for chiral membrane separation.

[0040] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the term "comprising" or any other variations thereof is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0041] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a chiral phosphoric acid self-porous polymer membrane and its application, characterized in that: The method includes the following steps: Step S1: Prepare a chiral phosphoric acid self-porous polymer precursor by dissolving optically pure 1,1'-bi-2-naphthol and indole-2,3-dione or their derivatives in a solvent, wherein the molar ratio of optically pure 1,1'-bi-2-naphthol and indole-2,3-dione is 1:1.2; add trifluoromethanesulfonic acid catalyst, stir the reaction until the system becomes viscous, and then add a poor solvent to precipitate the polymer to obtain a chiral polymer; Step S2: Prepare a polymer membrane by dissolving the chiral polymer obtained in Step S1 in an organic solvent and casting the membrane using a casting solution concentration of 2.5 wt%; and removing the solvent under heating conditions to obtain a polymer membrane; Step S3: Post-modification phosphorylation by placing the polymer membrane obtained in Step S2 in a reaction solvent containing an organophosphorus reagent for phosphorylation reaction, and after quenching treatment, obtain a chiral phosphoric acid self-porous polymer membrane insoluble in common solvents.

2. The preparation method and application of a chiral phosphoric acid self-porous polymer membrane as described in claim 1, characterized in that: In step S2, the chiral phosphate self-porous polymer has a specific surface area greater than 50 m². 2 It has a concentration of / g and exhibits good solvent stability and insolubility.

3. The preparation method and application of a chiral phosphoric acid self-porous polymer membrane as described in claim 1, characterized in that: In step S1, the derivative includes one or more of chloroindole-2,3-dione, fluoroindole-2,3-dione, phenylindole-2,3-dione, methoxyindole-2,3-dione, and ethylindole-2,3-dione.

4. The preparation method and application of a chiral phosphoric acid self-porous polymer membrane as described in claim 1, characterized in that: In step S1, the solvent is dichloromethane.

5. The preparation method and application of a chiral phosphoric acid self-porous polymer membrane as described in claim 1, characterized in that: In step S1, the catalyst is one or a mixture of two of trifluoroacetic acid or trifluoromethanesulfonic acid.

6. The method for preparing a chiral phosphoric acid self-porous polymer membrane as described in claim 1 and its application, characterized in that: In step S1, the reaction temperature is room temperature and the reaction time is 1-5 h.

7. The preparation method and application of a chiral phosphoric acid self-porous polymer membrane as described in claim 1, characterized in that: In step S1, the unsuitable solvent is methanol or a mixture of ethanol and water, with a preferred alcohol / water ratio of 1:

1.

8. The method for preparing a chiral phosphoric acid self-porous polymer membrane as described in claim 1 and its application, characterized in that: In step S2, the organic solvent is selected from one of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone. The concentration of the casting solution is 2-5 wt%; the oven temperature is 60-100 ℃, and the processing time is 12-24 h.

9. The preparation method and application of a chiral phosphoric acid self-porous polymer membrane as described in claim 1, characterized in that: In step S3, the reaction solvent is preferably anhydrous pyridine; the organophosphorus reagent is preferably phosphorus oxychloride; and the quenching agent is preferably water.

10. The application of a method for preparing a chiral phosphoric acid self-porous polymer membrane according to any one of claims 1 to 9, characterized in that: The applications include using it as a selective diaphragm for the membrane separation of chiral enantiomers.

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