A chiral fluorescence sensor, its preparation method and application

Abstract

The present invention discloses a chiral fluorescence sensor, its preparation method, and application. The chiral fluorescence sensor of the present invention uses 1,1'-binaphthol as a chiral raw material and is obtained through a substitution reaction, Bouveault aldehyde synthesis reaction, and hydrolysis reaction. The chiral fluorescence sensor of the present invention has good recognition effect for chiral amino acids and has good applicability, selectivity, and repeatability. The chiral fluorescence sensor can be used in 1×10 ‑5 mol / L low concentration, in Zn 2+ The presence of chiral valine was used for qualitative and quantitative analysis.

Description

Technical Field

[0001] The present invention belongs to the field of fluorescent compounds, and in particular relates to a chiral fluorescent sensor, a preparation method thereof, and an application thereof in identifying chiral amino acids. Background Art

[0002] In recent years, the study of chiral recognition of amino acids has become a hot topic among researchers. The D- and L-forms of amino acids play crucial roles in life. L-amino acids are the building blocks of proteins, and most of the amino acids involved in life activities such as metabolism, immune response, and endocrine regulation are L-amino acids. However, D-amino acids have specific functions in different organs and stages of life. Currently, the main techniques for distinguishing between chiral enantiomers include high-performance liquid chromatography, circular dichroism, electrophoresis, and fluorescence spectroscopy (DUAN C, WON M, VERWILST P, et al. In vivo maging of endogenously produced HClO in zebrafish and mice using a bright, photostable ratiometric fluorescence probe [J]. Anal Chem 2019, 91:4172–4178). Among these, the use of fluorescence for chiral recognition has attracted considerable attention due to its high efficiency, accuracy, and sensitivity.

[0003] Fluorophores commonly used in fluorescent probe design include coumarin, rhodamine, fluorescein, tetraphenylethylene, and their analogs. The advantages of coumarin and rhodamine as fluorescent groups are their high fluorescence quantum yields, resulting in large differences in fluorescence intensity when recognizing different substrates, and good recognition efficiency. However, their disadvantage is that they cannot recognize enantiomers of the same compound, which limits their application in chiral recognition of chiral compounds such as amino acids. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the first object of the present invention is to provide a chiral fluorescent sensor based on binaphthol. Under the action of zinc ions, the chiral fluorescent sensor can perform qualitative and quantitative detection of chiral amino acids with good selectivity and repeatability.

[0005] The second object of the present invention is to provide a method for preparing the aforementioned chiral fluorescence sensor;

[0006] The third object of the present invention is to provide the application of the aforementioned chiral fluorescence sensor in the recognition of chiral amino acids.

[0007] To achieve the purpose of the invention, the present invention provides the following technical solutions:

[0008] In a first aspect, the present invention provides a binaphthol derivative or a stereoisomer thereof, wherein the binaphthol derivative is shown in Formula I:

[0009]

[0010] In a second aspect, the present invention provides a method for preparing the aforementioned binaphthol derivative or its stereoisomers, and the synthetic route is as follows:

[0011]

[0012] Furthermore, the method specifically comprises the following steps:

[0013] Step (1): 2,6-pyridine dimethanol is subjected to a substitution reaction in hydrobromic acid to obtain compound 1;

[0014] Step (2): R / S-1,1-binaphthol is reacted with bromomethyl methyl ether and N,N-diisopropylethylamine to obtain compound R / S-2;

[0015] Step (3): Compound R / S-2 is reacted with anhydrous N,N-dimethylformamide and n-butyl lithium via Bouveault aldehyde synthesis to obtain compound R / S-3;

[0016] Step (4): Compound R / S-3 is reacted with compound 1 and anhydrous potassium carbonate in acetonitrile by substitution reaction to obtain compound R / S-4;

[0017] Step (5): Compound R / S-4 is hydrolyzed in concentrated hydrochloric acid to obtain compound R / S-5 (i.e., the compound represented by formula I).

[0018] Furthermore, in step (1), the reaction temperature is 100±5° C., and the reaction time is 12 to 24 hours, preferably 15 hours.

[0019] Furthermore, in step (2), the molar ratio of R / S-1,1-binaphthol to bromomethyl methyl ether is 1:1 to 1:1.2, preferably 1:1.1.

[0020] Furthermore, in step (2) and step (3), the solvent is anhydrous tetrahydrofuran.

[0021] Furthermore, in step (3), the molar ratio of the compound R / S-2 to anhydrous N,N-dimethylformamide is 1:1 to 1:2, preferably 1:1.5.

[0022] Furthermore, in step (4), the molar ratio of the compound R / S-3 to the compound 1 is 1:0.8 to 1:1.2, preferably 1:1; the solvent can be acetonitrile, acetone, N,N-dimethylformamide, tetrahydrofuran, etc., preferably acetonitrile.

[0023] In a third aspect, the present invention provides the use of the aforementioned binaphthol derivative or its stereoisomer as a chiral fluorescence sensor in identifying chiral amino acids.

[0024] Furthermore, the chiral amino acid is alanine, serine, phenylalanine, valine, leucine and arginine.

[0025] Furthermore, the fluorescence detection conditions are as follows: a 1% water / tetrahydrofuran solution mixed solution is used as the system; the concentration of the binaphthol derivative or its stereoisomer in the system is 1×10 -5 mol / L, zinc ion concentration is 1×10 -5 Chiral amino acids were identified by fluorescence spectroscopy at 100 mol / L; excitation wavelength λexc = 310 nm, slit: 5 / 5 nm.

[0026] Beneficial effects

[0027] The inventors have shown through experiments that at 1×10 -5 At a low concentration of 1 mol / L, the binaphthol derivative represented by Formula I or its stereoisomers can be used as a chiral recognition fluorescence sensor for valine to perform qualitative and quantitative analysis of the enantiomeric composition.

[0028] The present invention has a good recognition effect on the two enantiomers of valine and can be used to determine the enantiomeric composition of valine. Specifically, the fluorescence intensity of compound R-5 for D-valine is 5.1 times that of L-valine. In addition, compound R-5 can also perform chiral recognition of serine enantiomers (D / L-serine), alanine enantiomers (D / L-alanine), and phenylalanine enantiomers (D / L-phenylalanine), with the advantages of high sensitivity and a wide recognition range. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 In the presence of Zn 2+ Fluorescence change curve of chiral fluorescence sensor (fluorescent probe) R-5 recognizing valine enantiomers in a solution.

[0030] Figure 2 In the presence of Zn 2+ Fluorescence change curve of chiral fluorescence sensor (fluorescent probe) R-5 recognizing alanine enantiomer in solution

[0031] Figure 3 In the presence of Zn 2+Fluorescence change curve of chiral fluorescence sensor (fluorescent probe) R-5 recognizing serine enantiomers in a solution.

[0032] Figure 4 In the presence of Zn 2+ Fluorescence change curve of chiral fluorescence sensor (fluorescent probe) R-5 recognizing arginine enantiomers in a solution.

[0033] Figure 5 In the presence of Zn 2+ Fluorescence change curve of chiral fluorescence sensor (fluorescent probe) R-5 recognizing phenylalanine enantiomers in a solution.

[0034] Figure 6 In the presence of Zn 2+ Fluorescence change curve of chiral fluorescence sensor (fluorescent probe) R-5 recognizing leucine enantiomer in solution.

[0035] Figure 7 .EE value curve of chiral fluorescence sensor R / S-5 for D / L-valine recognition. DETAILED DESCRIPTION

[0036] The present invention is further described in detail below with reference to the examples. Reagents or instruments used without manufacturer's indication are considered to be conventional products that can be purchased on the market.

[0037] The chiral fluorescent sensor synthesis route of the present invention is as follows:

[0038]

[0039] Example 1 Synthesis of Compound 1

[0040] 2,6-Pyridine dimethanol (100 mg, 108 mmol) and hydrobromic acid (48%, 1 ml) were refluxed at 100°C for 15 h. After completion of the reaction, saturated sodium hydroxide solution was added dropwise at 0°C until the pH reached 14. The mixture was extracted with dichloromethane and dried over anhydrous Na2SO4. The solvent was removed under reduced pressure and separated by column chromatography (petroleum ether:ethyl acetate = 10:1) to give a white solid in a yield of 77.15%. 1H NMR (300 MHz, Chloroform-d) δ 7.75 (t, J = 7.7 Hz, 1H), 7.41 (d, J = 7.6 Hz, 1H), 7.23 (d, J = 7.7 Hz, 1H), 4.82 (s, 2H), 4.61 (s, 2H).

[0041] Example 2 Synthesis of Compound R / S-2

[0042] Under nitrogen protection, R / S-naphthol (4.29 g, 1 mmol) and DIPEA (5.45 ml, 2.1 mmol) were dissolved in anhydrous tetrahydrofuran at 0°C and stirred for 1 hour. MOMBr (1.35 ml, 1.1 mmol) was then slowly added dropwise, stirred at 0°C for 10 minutes, and then stirred at room temperature overnight. After the reaction, acetic acid (0.90 g, 1 mmol) was added dropwise to neutralize the DIPEA. The mixture was extracted with water and ethyl acetate, dried over anhydrous NaSO, and the solvent removed under reduced pressure. The mixture was separated by column chromatography (petroleum ether:ethyl acetate = 25:1) to afford a white solid in a 71.3% yield. 1HNMR(500MHz,Chloroform-d)δ9.73(s,1H),8.02–7.97(m,2H),7.93(d,J=8.3Hz,1H),7.87(d,J =8.6Hz,1H),7.51–7.41(m,4H),7.38–7.34(m,1H),7.34–7.28(m,2H),4.93(s,2H),3.46(s,3H).

[0043] Example 3 Synthesis of Compound R / S-3

[0044] Under N₂ protection, R / S-2 (3.07 g, 3 mmol) was dissolved in 20 ml of anhydrous THF at 0°C. n-Butyl lithium (13.02 ml, 10.5 mmol) was slowly added dropwise. The mixture was stirred for 0.5 h and then at room temperature for 1.5 h. DMF (1.12 ml, 4.5 mmol) was slowly added dropwise and stirred at room temperature overnight. The reaction was quenched with saturated NH₄Cl, extracted with ethyl acetate, dried over anhydrous Na₂SO₄, and concentrated under reduced pressure. Column chromatography (petroleum ether:ethyl acetate = 15:1) afforded a yellow solid in a 43% yield. 1H NMR (300MHz, DMSO-d6) δ10.48(s,1H),9.77(s,1H),8.61(s,1H),8.25(d,J=8.1Hz,1H),8.03–7.86(m,2H),7.61– 7.19(m,6H),7.15(d,J=8.4Hz,1H),6.98–6.89(m,1H),4.85(d,J=5.8Hz,1H),4.67(d,J=5.8Hz,1H),2.99(s,3H).

[0045] Example 4 Synthesis of Compound R / S-4

[0046] Under nitrogen protection, compound R / S-3 (53.8 mg, 1 mmol) and anhydrous KCO (103.65 mg, 5 mmol) were dissolved in 20 ml of acetonitrile and stirred at room temperature for 30 min. Compound 1.1 (30.3 mg, 1 mmol) was then added dropwise, and the mixture was refluxed at 85°C overnight. After completion of the reaction, the mixture was extracted with water and ethyl acetate, dried over anhydrous NaSO, and concentrated under reduced pressure. TLC separation (dichloromethane:methanol = 120:1) gave a pale yellow solid in a 72% yield. 1H NMR(500MHz,Chloroform-d)δ8.41(d,J=2.2Hz,1H),8.13–8.07(m,1H),8.01–7.90(m,3H),7.55–7.46(m,2H),7.46– 7.41(m,2H),7.38–7.26(m,4H),5.22(s,2H),4.99(s,2H),4.74(d,J=5.5Hz,2H),3.57(t,J=5.7Hz,1H),3.47(s,3H).

[0047] Example 5 Synthesis of Compound R / S-5

[0048] Compound 1.4 (160 mg) was dissolved in 5 mL of THF at 0°C. 1 mL of concentrated hydrochloric acid was slowly added dropwise, and the mixture was stirred for 0.5 h, then for 5 h at room temperature. After the reaction, saturated sodium bicarbonate solution was added dropwise until the pH reached 7. The mixture was extracted with ethyl acetate, dried over anhydrous Na2SO4, and concentrated under reduced pressure. TLC separation (dichloromethane:methanol = 120:1) gave a yellow solid in a 68.8% yield. 1H NMR (300MHz, DMSO-d6) δ10.38(s,1H),10.26(s,1H),8.69(s,1H),8.23–8.14(m,1H),8.09(d,J=9.1Hz,1H),8.03–7.94(m,1H),7.64–7 .50(m,2H),7.50–7.25(m,5H),7.11–6.96(m,2H),6.75(d,J=7.7Hz,1H),5.41(t,J=5.8Hz,1H),5.23(d,J=2.4Hz,2H),4.52(d,J=A5.8 Hz,2H).

[0049] Example 6 Preparation of Chiral Recognition Solution

[0050] 1. Preparation of Chiral Recognition Solution

[0051] (1) Accurately weigh 4.01 mg of compound R-5 into a 5 ml centrifuge tube, add 3 ml of tetrahydrofuran solution to make 1x10 - 3 mol / L solution is recorded as solution A.

[0052] (2) Accurately weigh 2.43 mg of each valine enantiomer, place them in a 5 ml centrifuge tube, add 3 ml of water and prepare 1 x 10 - 3 mol / L solutions, denoted as solution B1 and solution B2.

[0053] (3) Accurately weigh 7.34 mg of anhydrous zinc acetate, place it in a 5 ml centrifuge tube, add 3 ml of water to make 1x10 - 3 mol / L solution is recorded as solution C.

[0054] (4) Add 30 μl of solution A and 60 μl of solution C to two 5 ml centrifuge tubes, respectively. Then, add 30 μl of solution B1 to one of the tubes and 30 μl of solution B2 to the other. Then, add tetrahydrofuran to both tubes to make the total liquid volume 3 ml. This is the chiral recognition solution. Oscillate the tubes to mix the solutions evenly. Let them stand for 3 hours and perform fluorescence spectroscopy at an excitation wavelength of λexc = 310 nm and a slit of 5 / 5 nm.

[0055] 2. Referring to the preparation of the mixed solution of compound R-5 and D / L-valine, chiral recognition mixed solutions of compound R-5 and serine enantiomer (D / L-serine), alanine enantiomer (D / L-alanine), arginine enantiomer (D / L-arginine), leucine enantiomer (D / L-leucine) and phenylalanine enantiomer (D / L-phenylalanine) were prepared respectively. Except for the different amino acid types, the rest remained unchanged.

[0056] Example 7 Chiral Recognition Results

[0057] The detailed information of chiral recognition results is shown in Table 1.

[0058] Table 1

[0059]

[0060]

[0061] As can be seen from Table 1, the chiral fluorescence sensor R-5 has a certain recognition effect on amino acids at low concentrations, and has the advantages of high sensitivity and wide recognition range.

[0062] Example 8 Quantitative Analysis of Enantiomeric Composition Using Chiral Fluorescence Sensor

[0063] Take the above solutions A, B1, B2 and C, add tetrahydrofuran and water to dilute, and prepare 3 mL of 1% water / tetrahydrofuran mixed solution, which contains compound S-5 or R-5 (0.01 mM, 1 equivalent), total L- / D-valine (0.02 mM, 3 equivalents), and zinc acetate (0.02 mM, 2 equivalents). Then, fluorescence spectroscopy test is performed to explore the quantitative analysis results of the composition of threonine enantiomers by probes S-5 and R-5.

[0064] Fluorescence test conditions: Fluoromax-4 fluorescence spectrophotometer, room temperature, λexc=43.5 nm, slit: 5 / 5 nm.

[0065] like Figure 7 As shown, whether compound S-5 or compound R-5 is mixed with valine enantiomers, the solution fluorescence in the mixed system changes sharply with the change in enantiomeric composition, and the two curves are mirror images of each other. In addition, no matter which curve is used, the enantiomeric excess (ee. value) of D- / L-valine in the range of 0 to 100% can be measured. Based on these two standard curves, any content of the two enantiomeric components in the valine enantiomeric mixture can be measured. This further illustrates that compound S-5 and compound R-5 have high sensitivity and can be used for enantiomeric purity determination at very low concentrations, which has broad application prospects in real life.

[0066] The protection content of the present invention is not limited to the above embodiments. Without departing from the spirit and scope of the inventive concept, changes and advantages that can be thought of by those skilled in the art are included in the present invention and are protected by the appended claims.

Claims

1. A chiral binaphthol derivative, characterized in that: The structure of the chiral binaphthol derivative is shown in Formula I: 。 2. The method for preparing the chiral binaphthol derivative according to claim 1, characterized in that: The following steps are involved: Step (1): 2,6-pyridine dimethanol is subjected to a substitution reaction in hydrobromic acid to obtain compound 1; Step (2): R / S-1,1-binaphthol is reacted with bromomethyl methyl ether and N,N-diisopropylethylamine to obtain compound R / S-2; Step (3): Compound R / S-2 is reacted with anhydrous N,N-dimethylformamide and n-butyl lithium via Bouveault aldehyde synthesis to obtain compound R / S-3; Step (4): Compound R / S-3 is reacted with compound 1 and anhydrous potassium carbonate in acetonitrile by substitution reaction to obtain compound R / S-4; Step (5): Compound R / S-4 is hydrolyzed in concentrated hydrochloric acid to obtain the compound of formula I.

3. The method for preparing a chiral binaphthol derivative according to claim 2, wherein: In step (1), the reaction temperature is 100±5°C and the reaction time is 12 to 24 hours.

4. The method for preparing a chiral binaphthol derivative according to claim 3, wherein: In step (1), the reaction time is 15 hours.

5. The method for preparing a chiral binaphthol derivative according to claim 2, wherein: In step (2), the molar ratio of R / S-1,1-binaphthol to bromomethyl methyl ether is 1:1 to 1:1.

2.

6. The method for preparing a chiral binaphthol derivative according to claim 5, wherein: In step (2), the molar ratio of R / S-1,1-binaphthol to bromomethyl methyl ether is 1:1.

1.

7. The method for preparing a chiral binaphthol derivative according to claim 2, wherein: In step (3), the molar ratio of the compound R / S-2 to anhydrous N,N-dimethylformamide is 1:1 to 1:

2.

8. The method for preparing a chiral binaphthol derivative according to claim 7, wherein: In step (3), the molar ratio of the compound R / S-2 to anhydrous N,N-dimethylformamide is 1:1.

5.

9. The method for preparing a chiral binaphthol derivative according to claim 2, wherein: In step (4), the molar ratio of compound R / S-3 to compound 1 is 1:0.8 to 1:1.

2.

10. The method for preparing a chiral binaphthol derivative according to claim 9, wherein: In step (4), the molar ratio of compound R / S-3 to compound 1 is 1:

1.

11. The method for preparing a chiral binaphthol derivative according to claim 2, wherein: In step (4), the solvent is selected from any one of acetonitrile, acetone, N,N-dimethylformamide, and tetrahydrofuran.

12. The method for preparing a chiral binaphthol derivative according to claim 11, wherein: In step (4), the solvent is acetonitrile.

13. Use of the chiral binaphthol derivative according to claim 1 in recognition of chiral amino acids.

14. The use according to claim 13, characterized in that The chiral amino acid is alanine, serine, phenylalanine, valine, arginine or leucine.

15. The use according to claim 13 or 14, characterized in that The fluorescence detection conditions were as follows: a 1% water / tetrahydrofuran solution mixture was used as the system; the concentration of the chiral binaphthol derivative in the system was 1×10 -5 mol / L, zinc ion concentration is 1×10 -5 Chiral amino acids were identified by fluorescence spectroscopy at 100 mol / L; excitation wavelength λexc = 310 nm, slit: 5 / 5 nm.

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