Spherical and spiral supramolecular chiral nano-catalyst as well as preparation method and application thereof

Abstract

The preparation method comprises the following steps: adding sodium hydroxide into a D / L-cysteine ethyl ester hydrochloride aqueous solution to obtain a mixture, carrying out ultrasonic treatment until the solution is clarified to obtain a mixed solution A, and preparing a copper chloride dihydrate aqueous solution for later use; dropwise adding the mixed solution A into a copper chloride dihydrate aqueous solution in a water bath kettle to obtain a mixed solution B, and continuously stirring for reaction; and after the reaction is finished, centrifugally collecting the precipitate, and washing with water and ethanol. A one-pot self-assembly strategy is adopted, self-assembly is driven based on coordination of D / L-Cys.Oet.HCl and Cu < 2 + >, spherical and spiral supramolecular chiral nano-catalysts are constructed, and compared with the spherical and spiral supramolecular chiral nano-catalysts, the spherical and spiral supramolecular chiral nano-catalysts have obvious spatial asymmetry morphology, and have good application prospects. Therefore, the compound has a higher enantioselective catalytic effect on a chiral substrate dopa, and can be used for selectively catalyzing dopa molecules with specific configurations.

Description

Technical Field

[0001] The present invention relates to the technical field of supramolecular chiral self-assembly and asymmetric catalysis, and particularly relates to a spherical and helical supramolecular chiral nanocatalyst, a preparation method thereof, and an application thereof. Background Art

[0002] Due to the chiral characteristics of organisms, chiral compounds have extensive applications in the biomedical field, and their market share increases year by year. Enantioselective catalysis is an important way to synthesize chiral compounds with specific chirality. Currently, although researchers have developed various types of enantioselective catalysts, their enantioselective catalytic efficiency and recycling efficiency still need to be improved. Considering the recyclable characteristics of nanocatalysts, further developing chiral nanocatalysts with high enantioselectivity remains a current research hotspot.

[0003] Enantioselective nanocatalysts have developed rapidly in recent years. The overall design idea is to use chiral molecules as the enantioselective environment and nanomaterials or ions with catalytic ability as the active center. However, limited by the relatively low enantioselectivity of chiral molecules, the enantioselective catalytic efficiency of the obtained catalysts is often not ideal. Therefore, it is crucial to further develop chiral nanocatalysts with high enantioselective catalytic effects.

[0004] Considering the unique chiral environment of organisms and the supramolecular chiral helical morphology and specific enantioselective interactions of functional macromolecules in organisms, such as proteins and DNA, constructing supramolecular chiral nanocatalysts with obvious asymmetric helical morphology is expected to further improve the enantioselective catalytic effect. In addition, to verify the improvement of the enantioselective catalytic effect by the helical morphology, constructing supramolecular chiral nanocatalysts with the same composition but different morphologies and comparing their enantioselective catalytic effects helps to deepen people's understanding of the factors affecting the enantioselective catalytic effect of chiral nanocatalysts and provides theoretical guidance for constructing new and efficient chiral nanocatalysts.

[0005] Based on this, the present invention uses D / L-cysteine ethyl ester hydrochloride (D / L-Cys·Oet·HCl) and copper chloride dihydrate (CuCl 2 ·2H 2 O) as the basic assembly units, and synthesizes two types of supramolecular chiral nanocatalysts with different morphologies, namely spherical and helical, by regulating the pH and assembly temperature. Further enantioselective catalytic research shows that compared with the spherical supramolecular chiral nanocatalyst (D / L-Cys·Oet·HCl-Cu 2+ -1), the helical supramolecular chiral nanocatalyst (D / L-Cys·Oet·HCl-Cu 2+-2) It has a higher enantioselective catalytic effect on the chiral substrate D / L-DOPA, indicating that the construction of an asymmetric helical morphology helps to improve the enantioselective catalytic effect of the chiral catalyst. SUMMARY OF THE INVENTION

[0006] Technical problem to be solved: Aiming at the technical problem that chiral catalysts in the prior art cannot efficiently achieve enantioselective catalysis of chiral substrates, the present invention uses D / L-Cys·Oet·HCl and CuCl 2 ·2H 2 O as the basic assembly unit, and by regulating the pH and assembly temperature, two types of supramolecular chiral nanocatalysts with different morphologies, spherical and helical, are synthesized respectively. A preparation method for spherical and helical supramolecular chiral nanocatalysts is developed, and the higher enantioselective catalytic effect of the helical structure compared to the spherical structure is verified, and an optimization strategy for the enantioselectivity of chiral nanocatalysts is proposed.

[0007] Technical solution: The first object of the present invention is to provide a preparation method for spherical and helical supramolecular chiral nanocatalysts, and the steps are as follows:

[0008] Step 1: Dissolve D / L-cysteine ethyl ester hydrochloride in ultrapure water to obtain an aqueous solution of D / L-cysteine ethyl ester hydrochloride, then add sodium hydroxide to obtain a mixture, and ultrasonicate the mixture until the solution is clear to obtain a mixed solution A. Dissolve copper chloride dihydrate in ultrapure water to obtain an aqueous solution of copper chloride dihydrate for standby.

[0009] Step 2: Dropwise add the mixed solution A into the aqueous solution of copper chloride dihydrate in a water bath to obtain a mixed solution B, and continuously stir and react.

[0010] Step 3: After the reaction is completed, collect the precipitate by centrifugation, wash it with water and ethanol to obtain a highly enantioselective supramolecular chiral nanocatalyst, and the highly enantioselective supramolecular chiral nanocatalyst is a spherical supramolecular chiral nanocatalyst or a helical supramolecular chiral nanocatalyst.

[0011] Preferably, the molar ratio of D / L-cysteine ethyl ester hydrochloride to copper chloride dihydrate is 1.4-1.6:1, the concentration of D / L-cysteine ethyl ester hydrochloride in the mixed solution B is 70-80 mM, and the concentration of copper chloride dihydrate in the mixed solution B is 50 mM.

[0012] Preferably, when the highly enantioselective supramolecular chiral nanocatalyst is a spherical supramolecular chiral nanocatalyst, the ratio of sodium hydroxide to the aqueous solution of D / L-cysteine ethyl ester hydrochloride is 70 - 85 mg : 10 mL; when the highly enantioselective supramolecular chiral nanocatalyst is a helical supramolecular chiral nanocatalyst, the ratio of sodium hydroxide to the aqueous solution of D / L-cysteine ethyl ester hydrochloride is 98 mg : 10 mL.

[0013] Preferably, when the highly enantioselective supramolecular chiral nanocatalyst is a spherical supramolecular chiral nanocatalyst, the temperature of the stirring reaction in step two is 22 - 25 °C, and the reaction time is 6 - 10 min; when the highly enantioselective supramolecular chiral nanocatalyst is a helical supramolecular chiral nanocatalyst, the temperature of the stirring reaction in step two is 7 - 10 °C, and the reaction time is 3 h - 3.5 h.

[0014] Preferably, in step three, the centrifugation conditions are centrifugation at 6000 - 7000 rpm for 5 min.

[0015] Preferably, in step three, washing with water and ethanol is as follows: washing with water 1 - 3 times, and then washing with ethanol 2 - 3 times. The obtained highly enantioselective supramolecular chiral nanocatalyst is dispersed in ethanol and stored for later use.

[0016] The second object of the present invention is to provide a spherical and helical supramolecular chiral nanocatalyst prepared by the above method.

[0017] The third object of the present invention is to provide the application of a spherical and helical supramolecular chiral nanocatalyst based on the above in the enantioselective catalysis of D / L-DOPA.

[0018] Beneficial effects:

[0019] (1) Compared with the existing patent document "A supramolecular chiral nanocatalyst and its preparation method and application (Patent Application No. CN202210014907.8)", the highly enantioselective supramolecular chiral nanocatalyst prepared by the method provided by the present invention, when using D-DOPA and L-DOPA as substrates, the ratio of the absorption values at 475 nm induced is as high as ~2, while for the chiral catalyst provided in the above patent, when using D-DOPA and L-DOPA as substrates, the ratio of the absorption values at 475 nm induced is only ~1.5.

[0020] (2) The method provided by the present invention can simultaneously prepare spherical and helical supramolecular chiral nanocatalysts. Among them, the catalytic effect of the prepared helical supramolecular chiral nanocatalyst is significantly better than that of the spherical supramolecular chiral nanocatalyst. This also provides a basis for the fact that the supramolecular chiral nanocatalyst with an obvious asymmetric helical morphology can further improve the enantioselective catalytic effect. Moreover, through the method provided by the present invention, the constructed nanocatalyst has an obvious and uniform helical morphology.

[0021] (3) The helical supramolecular chiral nanocatalyst D / L-Cys·Oet·HCl-Cu provided by the present invention 2+ -2 can selectively catalyze DOPA molecules with a specific configuration. The supramolecular chiral nanocatalyst D-Cys·Oet·HCl-Cu 2+ -2 has a higher catalytic efficiency for L-DOPA, while the supramolecular chiral nanocatalyst L-Cys·Oet·HCl-Cu 2+ -2 has a higher catalytic efficiency for D-DOPA. Compared with the prior art "A supramolecular chiral nanocatalyst and its preparation method and application (CN202210014907.8)", the helical supramolecular chiral nanocatalyst D / L-Cys·Oet·HCl-Cu 2+ -2 constructed by the present technology has doubled the selective catalytic difference for dopa substrates. Description of the Drawings

[0022] Figure 1 : a and b are respectively the SEM image and TEM image of the spherical supramolecular chiral nanocatalyst D-Cys·Oet·HCl-Cu 2+ -1; c and d are respectively the SEM image and TEM image of the spherical supramolecular chiral nanocatalyst L-Cys·Oet·HCl-Cu 2+ -1; e is the EDX mapping image of D-Cys·Oet·HCl-Cu 2+ -1; f and g are respectively the SEM image and TEM image of the helical supramolecular chiral nanocatalyst D-Cys·Oet·HCl-Cu 2+ -2; h and i are respectively the SEM image and TEM image of the helical supramolecular chiral nanocatalyst L-Cys·Oet·HCl-Cu 2+ -2; j is the EDX mapping image of the helical supramolecular chiral nanocatalyst D-Cys·Oet·HCl-Cu 2 + -2.

[0023] Figure 2 : a and b are respectively the spherical supramolecular chiral nanocatalyst D / L-Cys·Oet·HCl-Cu 2+UV spectra and circular dichroism spectra of -1; c and d are helical supramolecular chiral nanocatalysts D / L-Cys·Oet·HCl-Cu 2+ UV spectra and circular dichroism spectra of -2;

[0024] Figure 3 : a is the spherical supramolecular chiral nanocatalyst D-Cys·Oet·HCl-Cu 2+ UV spectrum of the catalytic oxidation of TMB (0.2 mM) by -1; b is the spherical supramolecular chiral nanocatalyst D-Cys·Oet·HCl-Cu 2+ ESR spectrum of -1; c is the helical supramolecular chiral nanocatalyst D-Cys·Oet·HCl-Cu 2+ UV spectrum of the catalytic oxidation of TMB (0.2 mM) by -2; d is the helical supramolecular chiral nanocatalyst D-Cys·Oet·HCl-Cu 2+ ESR spectrum of -2.

[0025] Figure 4 : a is based on D-Cys·Oet·HCl-Cu 2+ -1 as the catalyst, 0.1 mM D / L-DOPA as the substrate, and the absorbance at 475 nm as the monitored signal kinetic curve; b is based on L-Cys·Oet·HCl-Cu 2+ -1 as the catalyst, 0.1 mM D / L-DOPA as the substrate, and the absorbance at 475 nm as the monitored signal kinetic curve; c is based on D-Cys·Oet·HCl-Cu 2+ -2 as the catalyst, 0.1 mM D / L-DOPA as the substrate, and the absorbance at 475 nm as the monitored signal kinetic curve; d is based on L-Cys·Oet·HCl-Cu 2+ -2 as the catalyst, 0.1 mM D / L-DOPA as the substrate, and the absorbance at 475 nm as the monitored signal kinetic curve.

[0026] Figure 5 : a is based on D-Cys·Oet·HCl-Cu 2+ -1 as the catalyst, when 0.1 mM L-DOPA is the substrate, the relationship curve of the ln value of the reaction rate with the reciprocal of the reaction temperature; b is based on D-Cys·Oet·HCl-Cu 2+ -1 as the catalyst, when 0.1 mM D-DOPA is the substrate, the relationship curve of the ln value of the reaction rate with the reciprocal of the reaction temperature; c is based on D-Cys·Oet·HCl-Cu 2+-2 as the catalyst, the relationship curve of the ln value of the reaction rate with the reciprocal of the reaction temperature when 0.1 mM L-DOPA is used as the substrate; d is D-Cys·Oet·HCl-Cu 2+ -2 as the catalyst, the relationship curve of the ln value of the reaction rate with the reciprocal of the reaction temperature when 0.1 mM D-DOPA is used as the substrate. Specific embodiments

[0027] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0028] In this specification, " / " represents "or". For example, "D / L-Cys·Oet·HCl" represents "D-Cys·Oet·HCl or L-Cys·Oet·HCl", "D / L-Cys·Oet·HCl-Cu 2+ -1" represents "D-Cys·Oet·HCl-Cu 2+ -1 or L-Cys·Oet·HCl-Cu 2+ -1", "D / L-Cys·Oet·HCl-Cu 2+ -2" represents "D-Cys·Oet·HCl-Cu 2+ -2 or L-Cys·Oet·HCl-Cu 2+ -2", "D / L-DOPA" represents "D-DOPA or L-DOPA";

[0029] The sources of the raw materials in the embodiments of the present invention are as follows:

[0030] D / L-cysteine ethyl ester hydrochloride was purchased from Shanghai Macklin Biochemical Co., Ltd. (Shanghai, China);

[0031] Copper dichloride dihydrate was purchased from Shanghai Macklin Biochemical Co., Ltd. (Shanghai, China);

[0032] Sodium hydroxide was purchased from Sinopharm Chemical Reagent Co., Ltd. (Shanghai);

[0033] D / L-dopa was purchased from Shanghai Aladdin Biochemical Co., Ltd. (Shanghai, China);

[0034] The buffer solution is PBS, and the PBS buffer solution was purchased from Beijing Solarbio Science & Technology Co., Ltd. (Beijing, China).

[0035] Example 1

[0036] This example provides a preparation method for a spherical supramolecular chiral nanocatalyst D / L-Cys·Oet·HCl-Cu 2+ -1, which is specifically as follows:

[0037] Dissolve 1.5 mmol of D / L-Cys·Oet·HCl in 10 mL of ultrapure water. Then add 80 mg of NaOH to the D / L-Cys·Oet·HCl solution (pH = 11.6), and dissolve it by ultrasonic treatment to obtain a mixture. Ultrasonicate the mixture until the solution becomes clear to obtain a mixed solution. Then, dropwise add the mixed solution to the CuCl 2 ·2H 2 O solution (10 mL, 1 mmol). Stir at 25 °C and 1000 rpm for 6 minutes to form the D / L-Cys·Oet·HCl-Cu 2+ -1 spherical supramolecular chiral nanocatalyst. After the reaction, collect the precipitate by centrifugation (7000 rpm, 5 minutes), and wash it with water and ethanol (wash once with water and twice with ethanol). The obtained D / L-Cys·Oet·HCl-Cu 2+ -1 spherical supramolecular chiral nanocatalyst is stored in absolute ethanol for standby.

[0038] As can be seen from Figure 1 (a - e), D / L-Cys·Oet·HCl-Cu 2+ -1 is a spherical nanoparticle with an average diameter of about 200 nm, and elements such as Cu, C, N, O, and S are evenly distributed in the nanoparticle, indicating that the D / L-Cys·Oet·HCl-Cu 2+ -1 spherical nanoparticle is assembled from D / L-Cys·Oet·HCl and Cu 2+ .

[0039] As can be seen from Figure 2 (a) of the UV-Vis spectrum, D-Cys·Oet·HCl-Cu 2+ -1 and L-Cys·Oet·HCl-Cu 2+ -1 have absorption peaks at 190 nm and 220 nm, and the UV-Vis spectra almost overlap, indicating that they have the same molecular and supramolecular assembly structures. As can be seen from Figure 2 (b) of the CD spectrum, D-Cys·Oet·HCl-Cu 2+ -1 shows a positive Cotton effect at 230 nm, while L-Cys·Oet·HCl-Cu 2+ -1 shows a negative Cotton effect at 230 nm, indicating that they have opposite chiral characteristics.

[0040] Example 2

[0041] This example provides a method for preparing a helical supramolecular chiral nanocatalyst D / L-Cys·Oet·HCl-Cu 2+ -2:

[0042] Dissolve 1.5 mmol of D / L-Cys·Oet·HCl in 10 mL of ultrapure water. Then add 98 mg of NaOH to the D / L-Cys·Oet·HCl solution (pH = 12.3), and dissolve it by ultrasonic treatment to obtain a mixture. Ultrasonically treat the mixture until the solution becomes clear to obtain a mixed solution. Then, add the mixed solution dropwise to the CuCl 2 ·2H 2 O solution (10 mL, 1 mmol), and stir at 8 °C and 1000 rpm for 3 hours to form the D / L-Cys·Oet·HCl-Cu 2+ -2 helical supramolecular chiral nanocatalyst. After the reaction, collect the precipitate by centrifugation (7000 rpm, 5 minutes), and wash it with water and ethanol (wash once with water and twice with ethanol). The obtained D / L-Cys·Oet·HCl-Cu 2+ -2 helical supramolecular chiral nanocatalyst is stored in absolute ethanol.

[0043] It can be seen from Figure 1 (f-j) that D / L-Cys·Oet·HCl-Cu 2+ -2 is a helical nanosheet with a length of ~1 μm and a width of ~500 nm, and elements such as Cu, C, N, O, and S are evenly distributed in the helical nanosheet, indicating that the D / L-Cys·Oet·HCl-Cu 2+ -2 helical nanoparticles are assembled from D / L-Cys·Oet·HCl and Cu 2+ . In addition, the helical directions of the D / L-Cys·Oet·HCl-Cu 2+ -2 nanosheets are significantly different. D-Cys·Oet·HCl-Cu 2+ -2 shows a right-handed helix, while L-Cys·Oet·HCl-Cu 2+ -2 shows a left-handed helix.

[0044] Figure 2 It can be seen from the UV-Vis spectrum of (c) that D-Cys·Oet·HCl-Cu 2+ -2 and L-Cys·Oet·HCl-Cu 2+ -2 have absorption peaks at 250 nm and 290 nm, and the UV-Vis spectra almost overlap, indicating that they have the same molecular and supramolecular assembly structures. Figure 2 It can be seen from (d) that D-Cys·Oet·HCl-Cu 2+ -2 shows a negative circular dichroism signal at 280 nm and a positive circular dichroism signal at 300 nm. While L-Cys·Oet·HCl-Cu 2+-2 exhibits a positive circular dichroism signal at 280 nm and a negative circular dichroism signal at 300 nm, indicating that the two have opposite chiral characteristics.

[0045] Example 3

[0046] This example provides a preparation method of a spherical supramolecular chiral nanocatalyst D / L-Cys·Oet·HCl-Cu 2+ -1, which is specifically as follows:

[0047] Step 1: Dissolve D / L-cysteine ethyl ester hydrochloride in ultrapure water to obtain an aqueous solution of D / L-cysteine ethyl ester hydrochloride, then add sodium hydroxide to obtain a mixture, ultrasonicate the mixture until the solution becomes clear to obtain a mixed solution A, and dissolve copper chloride dihydrate in ultrapure water to obtain an aqueous solution of copper chloride dihydrate for standby;

[0048] Step 2: Dropwise add the mixed solution A into the aqueous solution of copper chloride dihydrate in a water bath to obtain a mixed solution B, and continuously stir and react;

[0049] Step 3: After the reaction is completed, collect the precipitate by centrifugation, wash it with water and ethanol to obtain a highly enantioselective supramolecular chiral nanocatalyst.

[0050] Wherein the molar ratio of D / L-cysteine ethyl ester hydrochloride to copper chloride dihydrate is 1.5:1, the concentration of D / L-cysteine ethyl ester hydrochloride in the mixed solution B is 70 mM, and the concentration of copper chloride dihydrate in the mixed solution B is 50 mM.

[0051] The ratio of the sodium hydroxide to the aqueous solution of D / L-cysteine ethyl ester hydrochloride is 70 mg:10 mL.

[0052] The temperature of the stirring reaction in Step 2 is 22 °C, and the reaction time is 10 min.

[0053] The centrifugation conditions in Step 3 are centrifugation at 6000 rpm for 5 min, washing once with water, and then washing twice with ethanol.

[0054] Example 4

[0055] This example provides a preparation method of a spherical supramolecular chiral nanocatalyst D / L-Cys·Oet·HCl-Cu 2+ -1, which is specifically as follows:

[0056] Step 1: Dissolve D / L-cysteine ethyl ester hydrochloride in ultrapure water to obtain an aqueous solution of D / L-cysteine ethyl ester hydrochloride, then add sodium hydroxide to obtain a mixture, ultrasonicate the mixture until the solution becomes clear to obtain a mixed solution A, and dissolve copper chloride dihydrate in ultrapure water to obtain an aqueous solution of copper chloride dihydrate for standby;

[0057] Step 2: Slowly add the mixed solution A drop by drop into the aqueous solution of copper(II) chloride dihydrate in a water bath to obtain a mixed solution B, and continuously stir the reaction.

[0058] Step 3: After the reaction is completed, collect the precipitate by centrifugation, wash it with water and ethanol to obtain a highly enantioselective supramolecular chiral nanocatalyst.

[0059] The molar ratio of D / L-cysteine ethyl ester hydrochloride to copper(II) chloride dihydrate is 1.5:1. The concentration of D / L-cysteine ethyl ester hydrochloride in the mixed solution B is 80 mM, and the concentration of copper(II) chloride dihydrate in the mixed solution B is 50 mM.

[0060] The ratio of sodium hydroxide to the aqueous solution of D / L-cysteine ethyl ester hydrochloride is 85 mg: 10 mL.

[0061] The temperature of the stirring reaction in Step 2 is 25 °C, and the reaction time is 6 min.

[0062] The conditions for centrifugation in Step 3 are centrifugation at 7000 rpm for 5 min, washing once with water, and then washing twice with ethanol.

[0063] Example 5

[0064] This example provides a preparation method of a helical supramolecular chiral nanocatalyst D / L-Cys·Oet·HCl-Cu 2+ -2, which is as follows:

[0065] Step 1: Dissolve D / L-cysteine ethyl ester hydrochloride in ultrapure water to obtain an aqueous solution of D / L-cysteine ethyl ester hydrochloride, then add sodium hydroxide to obtain a mixture, ultrasonicate the mixture until the solution becomes clear to obtain a mixed solution A, and dissolve copper(II) chloride dihydrate in ultrapure water to obtain an aqueous solution of copper(II) chloride dihydrate for standby.

[0066] Step 2: Slowly add the mixed solution A drop by drop into the aqueous solution of copper(II) chloride dihydrate in a water bath to obtain a mixed solution B, and continuously stir the reaction.

[0067] Step 3: After the reaction is completed, collect the precipitate by centrifugation, wash it with water and ethanol to obtain a highly enantioselective supramolecular chiral nanocatalyst.

[0068] The molar ratio of D / L-cysteine ethyl ester hydrochloride to copper(II) chloride dihydrate is 1.4:1. The concentration of D / L-cysteine ethyl ester hydrochloride in the mixed solution B is 70 mM, and the concentration of copper(II) chloride dihydrate in the mixed solution B is 50 mM.

[0069] The ratio of sodium hydroxide to the aqueous solution of D / L-cysteine ethyl ester hydrochloride is 98 mg: 10 mL.

[0070] In the second step, the temperature of the stirring reaction is 7 °C and the reaction time is 3.5 h.

[0071] In the third step, the centrifugation conditions are centrifugation at 6000 rpm for 5 min, washing 3 times with water, and then washing 3 times with ethanol.

[0072] Example 6

[0073] This example provides a preparation method of a helical supramolecular chiral nanocatalyst D / L-Cys·Oet·HCl-Cu 2+ -2, which is as follows:

[0074] Step 1: Dissolve D / L-cysteine ethyl ester hydrochloride in ultrapure water to obtain an aqueous solution of D / L-cysteine ethyl ester hydrochloride, then add sodium hydroxide to obtain a mixture, and ultrasonicate the mixture until the solution becomes clear to obtain a mixed solution A. Dissolve copper chloride dihydrate in ultrapure water to obtain an aqueous solution of copper chloride dihydrate for standby.

[0075] Step 2: Slowly add the mixed solution A dropwise to the aqueous solution of copper chloride dihydrate in a water bath to obtain a mixed solution B, and continuously stir and react.

[0076] Step 3: After the reaction is completed, collect the precipitate by centrifugation, wash it with water and ethanol to obtain a highly enantioselective supramolecular chiral nanocatalyst.

[0077] Among them, the molar ratio of D / L-cysteine ethyl ester hydrochloride to copper chloride dihydrate is 1.6:1, the concentration of D / L-cysteine ethyl ester hydrochloride in the mixed solution B is 80 mM, and the concentration of copper chloride dihydrate in the mixed solution B is 50 mM.

[0078] The ratio of the sodium hydroxide to the aqueous solution of D / L-cysteine ethyl ester hydrochloride is 98 mg:10 mL.

[0079] In the second step, the temperature of the stirring reaction is 10 °C and the reaction time is 3 h.

[0080] In the third step, the centrifugation conditions are centrifugation at 7000 rpm for 5 min, washing 1 time with water, and then washing 2 times with ethanol.

[0081] Application Example

[0082] The supramolecular chiral nanocatalysts D-Cys·Oet·HCl-Cu 2+ -1 and L-Cys·Oet·HCl-Cu 2+ -1 prepared in Example 1 and D-Cys·Oet·HCl-Cu 2+ -2 and L-Cys·Oet·HCl-Cu prepared in Example 22+ -2 was studied for its catalytic properties and enantioselective catalysis of D / L-DOPA as follows:

[0083] (1) In the presence of H 2 O 2 The catalytic effect of the prepared chiral catalyst was evaluated by monitoring the absorbance change of TMB over time. The experimental reaction volume was 3 mL of buffer solution (pH = 7), the reaction temperature was 25 °C, and the concentrations of D-Cys·Oet·HCl-Cu 2+ -1, L-Cys·Oet·HCl-Cu 2+ -1, D-Cys·Oet·HCl-Cu 2+ -2 and L-Cys·Oet·HCl-Cu 2+ -2 catalysts were 0.005 mg / mL, the concentration of TMB was 0.1 mM, and the H 2 O 2 concentration was 50 mM.

[0084] From Figure 3 (a)'s UV-Vis spectrum, it can be seen that neither pure TMB nor TMB + H 2 O 2 solution showed an absorption peak at 652 nm. However, for the D-Cys·Oet·HCl-Cu 2+ -1 + TMB + H 2 O 2 mixed solution, after reacting for 1 minute in the cuvette, a significant absorption enhancement was measured at 652 nm, indicating that D-Cys·Oet·HCl-Cu 2+ -1 can catalyze H 2 O 2 to generate free radicals and further oxidize TMB. From Figure 3 (b)'s ESR spectrum, it can be seen that D-Cys·Oet·HCl-Cu 2+ -1 + H 2 O 2 produced four signal peaks with a signal intensity ratio of 1:2:2:1, indicating that D-Cys·Oet·HCl-Cu 2+ -1 can decompose H 2 O 2 into hydroxyl radicals and has peroxidase-like catalytic activity. From Figure 3 (c)'s UV-Vis spectrum, it can be seen that neither pure TMB nor TMB + H 2 O 2 solution showed an absorption peak at 652 nm. However, for the D-Cys·Oet·HCl-Cu 2+ -2 + TMB + H 2 O2 The mixed solution showed a significant absorption enhancement at 652 nm after reacting for 1 minute, indicating that D-Cys·Oet·HCl-Cu 2+ -2 can catalyze H 2 O 2 to generate free radicals and further oxidize TMB. As can be seen from the ESR spectrum of Figure 3 (d), D-Cys·Oet·HCl-Cu 2+ -2 + H 2 O 2 can produce four signal peaks with a signal intensity ratio of 1:2:2:1, indicating that D-Cys·Oet·HCl-Cu 2+ -2 can decompose H 2 O 2 into hydroxyl radicals and has peroxidase-like catalytic activity.

[0085] (2) In the presence of H 2 O 2 , the enantioselective catalytic efficiency of different chiral catalysts on D / L-DOPA was evaluated by monitoring the absorbance change of D / L-DOPA at 475 nm over reaction time. The experimental reaction volume was 3 mL, the reaction temperature was 25 °C, the concentrations of D-Cys·Oet·HCl-Cu 2+ -1, L-D-Cys·Oet·HCl-Cu 2+ -1, D-Cys·Oet·HCl-Cu 2+ -2 and L-Cys·Oet·HCl-Cu 2+ -2 catalysts were 0.005 mg / mL, the concentration of D / L-DOPA substrate was 0.1 mM, and the H 2 O 2 concentration was 50 mM.

[0086] As can be seen from Figure 4 (a), the catalytic rate of D-Cys·Oet·HCl-Cu 2+ -1 on L-DOPA is better than that on D-DOPA. As can be seen from Figure 4 (b), the catalytic rate of L-Cys·Oet·HCl-Cu 2+ -1 on D-DOPA is better than that on L-DOPA. As can be seen from Figure 4 (c), under the same conditions, the catalytic rate of D-Cys·Oet·HCl-Cu 2+ -2 on L-DOPA is faster than that on D-DOPA, and the induced enantioselective catalytic difference is greater than that of D-Cys·Oet·HCl-Cu 2+ -1. As can be seen from Figure 4(d) It can be seen that under the same conditions, the catalytic rate of L-Cys·Oet·HCl-Cu 2+ -2 for D-DOPA is faster than that for L-DOPA, and the induced enantioselective catalytic difference is greater than that of L-Cys·Oet·HCl-Cu 2+ -1. The above results indicate that the helical morphology is beneficial to the improvement of the enantioselective catalytic performance of the catalyst.

[0087] (3) In the presence of H 2 O 2 , by monitoring the absorbance change of D / L-DOPA at 475 nm over time at different temperatures, the catalytic efficiency of different catalysts for D / L-DOPA can be evaluated, and the activation energy of different catalytic processes can be further calculated. The experimental reaction volume is 3 mL of buffer solution (pH = 7), and the concentrations of D-Cys·Oet·HCl-Cu 2+ -1 and D-Cys·Oet·HCl-Cu 2+ -2 catalysts are 0.005 mg / mL, the concentration of the D / L-DOPA substrate is 0.1 mM, and the concentration of H 2 O 2 is 50 mM.

[0088] It can be seen from Figure 5 (a) and (b) that the activation energy of D-Cys·Oet·HCl-Cu 2+ -1 for catalyzing D-DOPA is higher than that for catalyzing L-DOPA, which is consistent with the catalytic difference of D-Cys·Oet·HCl-Cu 2+ -1 for D / L-DOPA. It can be seen from Figure 5 (c) and (d) that the activation energy of D-Cys·Oet·HCl-Cu 2+ -2 for catalyzing D-DOPA is higher than that for catalyzing L-DOPA, which is consistent with the catalytic difference of D-Cys·Oet·HCl-Cu 2+ -2 for D / L-DOPA. And the activation energy difference of D-Cys·Oet·HCl-Cu 2+ -2 for D / L-DOPA at different temperatures is greater than that of D-Cys·Oet·HCl-Cu 2+ -1, which is consistent with its catalytic difference effect. It shows that the helical morphology is beneficial to the improvement of the enantioselective catalytic performance of the catalyst.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing spherical and helical supramolecular chiral nanocatalysts, characterized in that: Here are the steps: Step 1, dissolving D / L-cysteine ​​ethyl ester hydrochloride in ultrapure water to obtain an aqueous solution of D / L-cysteine ​​ethyl ester hydrochloride, then adding sodium hydroxide to obtain a mixture, ultrasonicating the mixture until the solution is clarified to obtain a mixed solution A, dissolving cupric chloride dihydrate in ultrapure water to obtain a cupric chloride dihydrate aqueous solution, and setting aside; Step 2, adding the mixed solution A dropwise into the copper chloride dihydrate aqueous solution in a water bath to obtain a mixed solution B, and continuously stirring the reaction; Step 3: After the reaction is completed, the precipitate is collected by centrifugation, and washed with water and ethanol to obtain a high enantioselective supramolecular chiral nanocatalyst, wherein the high enantioselective supramolecular chiral nanocatalyst is a spherical supramolecular chiral nanocatalyst or a helical supramolecular chiral nanocatalyst.

2. The method for preparing a spherical and helical supramolecular chiral nanocatalyst according to claim 1, characterized in that: The molar ratio of D / L-cysteine ​​ethyl ester hydrochloride to cupric chloride dihydrate is 1.4-1.6:1, the concentration of D / L-cysteine ​​ethyl ester hydrochloride in mixed solution B is 70-80 mM, and the concentration of cupric chloride dihydrate in mixed solution B is 50 mM.

3. The method for preparing a spherical and helical supramolecular chiral nanocatalyst according to claim 2, characterized in that: When the highly enantioselective supramolecular chiral nanocatalyst is a spherical supramolecular chiral nanocatalyst, the ratio of the sodium hydroxide to the D / L-cysteine ​​ethyl ester hydrochloride aqueous solution is 70-85 mg:10 mL; When the highly enantioselective supramolecular chiral nanocatalyst is a helical supramolecular chiral nanocatalyst, the ratio of the sodium hydroxide to the D / L-cysteine ​​ethyl ester hydrochloride aqueous solution is 98 mg:10 mL.

4. The method for preparing a spherical and helical supramolecular chiral nanocatalyst according to claim 1, characterized in that: When the highly enantioselective supramolecular chiral nanocatalyst is a spherical supramolecular chiral nanocatalyst, the stirring reaction temperature in step 2 is 22-25°C, and the reaction time is 6-10 min; when the highly enantioselective supramolecular chiral nanocatalyst is a helical supramolecular chiral nanocatalyst, the stirring reaction temperature in step 2 is 7-10°C, and the reaction time is 3h-3.5h.

5. The method for preparing a spherical and helical supramolecular chiral nanocatalyst according to claim 1, characterized in that: In the step 3, the centrifugation condition is 6000-7000 rpm for 5 min.

6. The method for preparing a spherical and helical supramolecular chiral nanocatalyst according to claim 1, characterized in that: In the step 3, washing with water and ethanol is specifically as follows: washing with water for 1-3 times, and then washing with ethanol for 2-3 times, and the obtained high enantioselective supramolecular chiral nanocatalyst is dispersed in ethanol and stored for later use.

7. A spherical and helical supramolecular chiral nanocatalyst prepared by the method according to any one of claims 1 to 6.

8. Use of the spherical and helical supramolecular chiral nanocatalyst according to claim 7 in the enantioselective catalysis of D / L-DOPA.

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