Preparation method of organic fluorescent compound with piezo-chromic property
By preparing compounds such as (E)-2-(4-chloro-1H-pyrazol-1-yl)-3-(4-(diphenylamino)phenyl)acrylonitrile, the problem of low color contrast in pressure-sensitive chromatic molecules was solved, and significant changes and reversible properties of fluorescence emission were achieved, providing a new approach for the development of pressure-sensitive chromatic materials.
Patent Information
- Application Number
- CN202511607089.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-05
- Publication Date
- 2026-02-06
AI Technical Summary
Existing pressure-sensitive color-changing molecules have low color contrast and the color change is closely related to the magnitude and area of the applied force, making it difficult to achieve a noticeable color change phenomenon.
The starting compound was dissolved in acetonitrile solution by a preparation method, an alkaline substance was added and bromoacetonitrile was added dropwise for reaction, followed by column chromatography purification and reaction with 4-diphenylaminobenzaldehyde to synthesize compounds such as (E)-2-(4-chloro-1H-pyrazol-1-yl)-3-(4-(diphenylamino)phenyl)acrylonitrile, and donor and acceptor groups were introduced to improve the color-changing effect.
The prepared compound exhibits a fluorescence emission that changes from green to yellow-green under mechanical grinding. Its original properties can be restored by solvent evaporation and heating. It has obvious pressure-induced color change properties, and the raw materials are inexpensive. The synthesis method is simple and easy to operate.
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Figure CN121471143A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of fluorescent material preparation technology, specifically relating to a method for preparing an organic fluorescent compound with pressure-sensitive color-changing properties. Background Technology
[0002] Pyrochromic luminescent materials are intelligent luminescent materials that can switch their emission color in response to external stimuli (such as mechanical force, heat, and solvent evaporation) in the solid state. Pyrochromic materials can be used in pressure sensing, temperature sensing, and information encryption, thus the development of new pyrochromic materials holds great research potential. The color-changing function of pyrochromic materials is achieved through intermolecular and intramolecular effects, specifically manifested in the formation of different aggregation morphologies (multiple crystal forms), disruption of the quasi-molecular structure, chemical reactions of molecules, and changes in electron transfer states due to conformational flattening.
[0003] Currently, the development of novel pressure-sensitive color-changing materials still faces many challenges. On the one hand, while pressure-sensitive molecules exhibit noticeable color changes when the molecular packing pattern and intermolecular forces change, the color contrast of most pressure-sensitive molecules is relatively small, resulting in an insufficiently pronounced color change. On the other hand, the color change of pressure-sensitive luminescence is closely related to the magnitude and area of the applied force. Summary of the Invention
[0004] In view of this, the purpose of the present invention is to provide a method for preparing an organic fluorescent compound with pressure-sensitive color-changing properties, so as to solve the above problems.
[0005] To achieve the above objectives, the present invention provides the following technical solution:
[0006] This invention provides a method for preparing an organic fluorescent compound with piezochromic properties, comprising the following steps:
[0007] S1. Dissolve the starting compound in acetonitrile solution, add the first base and stir, then add bromoacetonitrile dropwise and stir overnight at room temperature.
[0008] S2. After filtration, retain the filtrate and rotary evaporate to obtain a solid crude product, which is then purified by column chromatography to obtain an intermediate compound.
[0009] S3. Dissolve the intermediate compound in anhydrous ethanol, add the second substance and stir until stable, then add 4-diphenylaminobenzaldehyde and stir at room temperature to react;
[0010] S4. After the reaction was completed, the mixture was filtered and the filter cake was washed with n-hexane. After drying, the target compounds (E)-2-(4-chloro-1H-pyrazol-1-yl)-3-(4-(diphenylamino)phenyl)acrylonitrile, (E)-2-(4-bromo-1H-pyrazol-1-yl)-3-(4-(diphenylamino)phenyl)acrylonitrile and (E)-2-(4-iodo-1H-pyrazol-1-yl)-3-(4-(diphenylamino)phenyl)acrylonitrile were obtained.
[0011] The starting compound is any one of 4-chloropyrazole, 4-bromopyrazole, or 4-iodopyrazole.
[0012] When the starting compound is 4-chloropyrazole, the intermediate compound is 2-(4-chloro-1H-pyrazole-1-yl)acetonitrile;
[0013] When the starting compound is 4-bromopyrazole, the intermediate compound is 2-(4-bromo-1H-pyrazole-1-yl)acetonitrile;
[0014] When the starting compound is 4-iodopyrazole, the intermediate compound is 2-(4-iodo-1H-pyrazole-1-yl)acetonitrile;
[0015] When the intermediate compound is 2-(4-chloro-1H-pyrazol-1-yl)acetonitrile, the finished compound is (E)-2-(4-chloro-1H-pyrazol-1-yl)-3-(4-(diphenylamino)phenyl)acrylonitrile;
[0016] When the intermediate compound is 2-(4-bromo-1H-pyrazol-1-yl)acetonitrile, the finished compound is (E)-2-(4-bromo-1H-pyrazol-1-yl)-3-(4-(diphenylamino)phenyl)acrylonitrile;
[0017] When the intermediate compound is 2-(4-iodo-1H-pyrazol-1-yl)acetonitrile, the finished compound is (E)-2-(4-iodo-1H-pyrazol-1-yl)-3-(4-(diphenylamino)phenyl)acrylonitrile.
[0018] Further, in step S1, the reaction temperature is 10-30℃, the stirring reaction time at room temperature is 10-12h, the molar ratio of the starting compound to bromoacetonitrile is 1:1.5-2, and the volume ratio of acetonitrile to the mass ratio of the starting compound is 15ml / g to 50ml / g.
[0019] Further, in step S2, the first base substance used is any one of sodium ethoxide, sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate, sodium bicarbonate, potassium bicarbonate, tetraethylamine hydroxide, and triethylamine; the molar ratio of 4-chloropyrazole, 4-bromopyrazole, or 4-iodopyrazole to the base is 1:2-3.
[0020] Further, in step S3, the reaction temperature is 10-30℃, the reaction time is 10-15h; the molar ratio of the intermediate compound to 4-diphenylaminobenzaldehyde is 1:1-2; and the volume ratio of anhydrous ethanol to the mass ratio of the intermediate compound is 30ml / g to 100ml / g.
[0021] Further, in step S3, the second base substance used is any one of sodium ethoxide, sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate, sodium bicarbonate, potassium bicarbonate, tetraethylamine hydroxide, and triethylamine; the molar ratio of the intermediate compound to the base is 1:2-5.
[0022] Further, the (E)-2-(4-chloro-1H-pyrazol-1-yl)-3-(4-(diphenylamino)phenyl)acrylonitrile is named Cl-PANP;
[0023] (E)-2-(4-bromo-1H-pyrazol-1-yl)-3-(4-(diphenylamino)phenyl)acrylonitrile, also known as Br-PANP;
[0024] (E)-2-(4-iodo-1H-pyrazol-1-yl)-3-(4-(diphenylamino)phenyl)acrylonitrile, also known as I-PANP;
[0025] The structural formulas of the above compounds are shown below:
[0026]
[0027] Furthermore, the organic fluorescent compound with pressure-sensitive color-changing properties is used to prepare detection or chemical sensing materials.
[0028] Furthermore, under external pressure, the fluorescence changes by more than 10 nm; it can be restored to its initial state under heating or organic solvent conditions.
[0029] Furthermore, the organic solvent is any one of dichloromethane, ethyl acetate, and tetrahydrofuran.
[0030] Furthermore, the application is subject to external environmental pressures including grinding, or at least 0.1 MPa static pressure.
[0031] The beneficial effects of this invention are as follows:
[0032] 1. The compounds prepared by this invention exhibit significant piezochromic luminescence properties, and the raw materials are inexpensive and the synthesis method is simple and easy to operate. This method of introducing acceptors into the pyrazole ring skeleton to impart piezochromic luminescence properties provides a new approach for the development of piezochromic luminescent materials.
[0033] 2. The organic fluorescent compound prepared in this invention has a donor group that is a strong electron-donating diphenylamine group and an acceptor group that is an electron-withdrawing cyano group and a halopyrazole group. After mechanical grinding, the fluorescence emission of the compound changes from green light to yellow-green light emission, and can be restored to its original properties by solvent fumigation and heating.
[0034] 3. Other advantages, objectives, and features of the present invention will be set forth in the following description and will be apparent to those skilled in the art to some extent, or may be learned by practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description
[0035] To make the purpose, technical solution, and beneficial effects of the invention clearer, the following figures are provided for illustration:
[0036] Figure 1 The synthetic routes for the target compounds Cl-PANP, Br-PAN, and PI-PANP of this invention are as follows;
[0037] Figure 2 The PL spectra of the original powder and the ground powder of the target compound Cl-PANP of this invention are shown.
[0038] Figure 3 This is a PL chromaticity coordinate distribution diagram of the original powder and the ground powder of the compound Cl-PANP of this invention.
[0039] Figure 4 The PXRD patterns of the original powder and the ground powder of Cl-PANP, the target compound of this invention;
[0040] Figure 5 The target compound of this invention, Cl-PANP 1 HNMR spectrum;
[0041] Figure 7 This is the time-of-flight mass spectrum of the target compound Cl-PANP in this invention;
[0042] Figure 6 The crystal structure diagram of the target compound Cl-PANP of this invention is shown.
[0043] Figure 8 The PL spectra of the original powder and the ground powder of Br-PANP, the target compound of this invention;
[0044] Figure 9 This is a PL chromaticity coordinate distribution diagram of the original powder and the ground powder of the compound Br-PANP of this invention.
[0045] Figure 10The PXRD patterns of the original powder and the ground powder of Br-PANP, the target compound of this invention;
[0046] Figure 11 The target compound of this invention, Br-PANP 1 HNMR spectrum;
[0047] Figure 12 This is the time-of-flight mass spectrum of the target compound Br-PANP in this invention;
[0048] Figure 13 This is a crystal structure diagram of the target compound Br-PANP of this invention.
[0049] Figure 14 The PL spectra of the original powder and the ground powder of the target compound I-PANP of this invention are shown.
[0050] Figure 15 This is a PL chromaticity coordinate distribution diagram of the original powder and the ground powder of the compound I-PANP of this invention.
[0051] Figure 16 The PXRD patterns of the original powder and the ground powder of the target compound I-PANP of this invention are shown.
[0052] Figure 17 The target compound of this invention, I-PANP 1 HNMR spectrum;
[0053] Figure 18 This is the time-of-flight mass spectrum of the target compound I-PANP in this invention;
[0054] Figure 19 This is a crystal structure diagram of I-PANP, the target compound of this invention. Detailed Implementation
[0055] like Figures 1-19 As shown, this invention provides a method for preparing an organic fluorescent compound with piezochromic properties, the synthetic route of which is as follows: Figure 1 As shown.
[0056] Example 1
[0057] S1. Add 1.02 g 4-chloropyrazole (10 mmol) and 3.45 g potassium carbonate (25 mmol) to a 250 ml round-bottom flask, add 50 ml acetonitrile, stir for 5 min until 4-chloropyrazole dissolves, add 1.35 ml bromoacetonitrile (20 mmol), add potassium carbonate, stir until stable, then add bromoacetonitrile dropwise, and stir the reaction at room temperature for 10 h.
[0058] S2. After the reaction is complete, filter the solution and retain the filtrate. Rotary evaporate the solution to obtain a solid crude product. Then, perform column chromatography to separate the product and purify it with ethyl acetate-petroleum ether (1:2, v / v) to obtain 2-(4-chloro-1H-pyrazol-1-yl)acetonitrile.
[0059] S3. Add 0.14 g of 2-(4-chloro-1H-pyrazol-1-yl)acetonitrile (1 mmol) and 0.34 g of sodium ethoxide (5 mmol) to a 100 ml round-bottom flask, add 10 ml of anhydrous ethanol, stir to dissolve, then add 0.34 g of 4-diphenylaminobenzaldehyde (1.25 mmol), and react at room temperature for 12 h.
[0060] S4. After the reaction is complete, filter the mixture and wash the filter cake with n-hexane. After drying the filter cake, the target compound (E)-2-(4-chloro-1H-pyrazol-1-yl)-3-(4-(diphenylamino)phenyl)acrylonitrile is obtained and named Cl-PANP.
[0061] The qualitative test data for 2-(4-chloro-1H-pyrazole-1-yl)acetonitrile are as follows:
[0062] 1 H NMR (400MHz, CD3CN) δ7.52(s,1H),7.44(s,1H),5.02(s,2H);
[0063] The qualitative test data for (E)-2-(4-chloro-1H-pyrazole-1-yl)-3-(4-(diphenylamino)phenyl)acrylonitrile are as follows:
[0064] 1 H NMR (400MHz, DMSO-d6) δ8.64(s,1H),7.90(d,J=16.1Hz,2H),7.72(s,2H),7.43-7.37(m,4H),7.18(dd,J=18.0,7.4Hz,6H),6.96(d,J=8.8Hz,2H);
[0065] MS (ESI): Measured m / z is 397.1220 (Calculated value of C24 H18 N4 Cl: 397.1215).
[0066] Single crystal structure parameters: monoclinic crystal system, space group P21 / n, cell parameters are as follows: The unit cell volume is The number of molecules in the crystal lattice is Z=8, and the density is 1.333 g / cm³. 3 .
[0067] Example 2
[0068] S1. Add 1.46 g of 4-bromopyrazole (10 mmol) and 3.45 g of potassium carbonate (25 mmol) to a 250 ml round-bottom flask, add 50 ml of acetonitrile, stir for 5 min until 4-bromopyrazole dissolves, add 1.35 ml of bromoacetonitrile (20 mmol), add potassium carbonate, stir until stable, then add bromoacetonitrile dropwise, and stir the reaction at room temperature for 10 h.
[0069] S2. After the reaction is complete, filter the solution and retain the filtrate. Rotary evaporate the solution to obtain a solid crude product. Then, perform column chromatography to separate the product and purify it with ethyl acetate-petroleum ether (1:2, v / v) to obtain 2-(4-bromo-1H-pyrazol-1-yl)acetonitrile.
[0070] S3. Add 0.37 g of 2-(4-bromo-1H-pyrazol-1-yl)acetonitrile (2 mmol) and 0.68 g of sodium ethoxide (10 mmol) to a 100 ml round-bottom flask, add 10 ml of anhydrous ethanol, stir to dissolve, then add 0.68 g of 4-diphenylaminobenzaldehyde (2.5 mmol), and react at room temperature for 12 h.
[0071] S4. After the reaction is complete, filter the mixture and wash the filter cake with n-hexane. After drying the filter cake, the target compound (E)-2-(4-bromo-1H-pyrazol-1-yl)-3-(4-(diphenylamino)phenyl)acrylonitrile is obtained and named Br-PANP.
[0072] The qualitative test data for 2-(4-bromo-1H-pyrazole-1-yl)acetonitrile are as follows:
[0073] 1 H NMR (400MHz, CD3CN) δ7.48(s,1H),7.30(s,1H),4.87(s,2H);
[0074] The qualitative test data for (E)-2-(4-bromo-1H-pyrazol-1-yl)-3-(4-(diphenylamino)phenyl)acrylonitrile are as follows:
[0075] 1 H NMR (400MHz, DMSO-d6) δ8.62 (s, 1H), 7.90 (d, J = 11.5Hz, 2H), 7.77-7.69 (m, 2H), 7.42-7.37 (m, 4H), 7.21-7.13 (m, 6H), 6.98-6.93 (m, 2H).
[0076] MS (ESI): Measured m / z is 441.0709 (calculated value of C24 H18 N4 Br: 441.0710).
[0077] Single crystal structure parameters: triclinic crystal system, space group P-1, unit cell parameters: The unit cell volume is The number of molecules in the crystal lattice is Z=2, and the density is 1.474 g / cm³. 3 .
[0078] Example 3
[0079] S1. Add 1.93g of 4-iodopyrazole (10mmol) and 3.45g of potassium carbonate (25mmol) to a 250ml round-bottom flask, add 50ml of acetonitrile, stir for 5min until the 4-iodopyrazole dissolves, add 1.35ml of bromoacetonitrile (20mmol), add potassium carbonate, stir until stable, then add bromoacetonitrile dropwise, and stir the reaction at room temperature for 10h.
[0080] S2. After the reaction is complete, filter the solution and retain the filtrate. Rotary evaporate the solution to obtain a solid crude product. Then, perform column chromatography to separate the product and purify it with ethyl acetate-petroleum ether (1:3, v / v) to obtain 2-(4-iodo-1H-pyrazol-1-yl)acetonitrile.
[0081] S3. Add 0.46 g of 2-(4-bromo-1H-pyrazol-1-yl)acetonitrile (2 mmol) and 0.68 g of sodium ethoxide (10 mmol) to a 100 ml round-bottom flask, add 10 ml of anhydrous ethanol, stir to dissolve, then add 0.68 g of 4-diphenylaminobenzaldehyde (2.5 mmol), and react at room temperature for 12 h.
[0082] S4. After the reaction is complete, filter the mixture and wash the filter cake with n-hexane. After drying the filter cake, the target compound (E)-2-(4-iodo-1H-pyrazol-1-yl)-3-(4-(diphenylamino)phenyl)acrylonitrile is obtained and named I-PANP.
[0083] The qualitative test data for 2-(4-iodo-1H-pyrazole-1-yl)acetonitrile are as follows:
[0084] 1 H NMR (400MHz, CD3CN) δ7.75(s,1H),7.61(s,1H),5.16(s,2H);
[0085] The qualitative test data for (E)-2-(4-iodo-1H-pyrazole-1-yl)-3-(4-(diphenylamino)phenyl)acrylonitrile are as follows:
[0086] 1H NMR (400MHz, DMSO-d6) δ8.54(s,1H),7.87(d,J=3.8Hz,2H),7.72(d,J=8.9Hz,2H),7.42-7.36(m,4H),7.16(dd,J=18.3,7.3Hz,6H),6.96(s,2H).
[0087] MS(ESI): The measured m / z is 489.0576 (calculated value of C24 H18 N4 I: 489.0571).
[0088] Single crystal structure parameters: monoclinic system, space group P21 / c, cell parameters are as follows: The unit cell volume is The number of molecules in the crystal lattice is Z=8, and the density is 1.562 g / cm³. 3 .
[0089] in conclusion:
[0090] The fluorescence spectrum of Cl-PANP prepared in Example 1 is as follows: Figure 2 As shown in the figure, the fluorescence emission peak of the compound shifts from 510 nm to 520 nm after grinding, indicating that the compound has pressure-induced color change properties.
[0091] Example 2
[0092] The fluorescence spectrum of Br-PANP prepared in Example 2 is as follows. Figure 8 As shown in the figure, the fluorescence emission peak of the compound shifts from 505 nm to 520 nm after grinding, indicating that the compound has pressure-induced color change properties.
[0093] Example 3
[0094] The fluorescence spectrum of the I-PANP prepared in Example 3 is as follows: Figure 14 As shown in the figure, after grinding, the fluorescence emission peak of the compound shifts from 507 nm to 524 nm, indicating that the compound has good pressure-induced color change properties.
[0095] The PL chromaticity coordinate distribution diagrams of raw and ground powders of Cl-PANP, Br-PANP, and I-PANP are shown below. Figure 3 , Figure 9 and Figure 15 As shown, this is the CIE 1931 chromaticity diagram of the photoluminescence (PL) of the pressure-sensitive color-changing material, generated using Origin-PL2CIE. This diagram is mainly used to visually present the difference in the color of the emitted light before and after pressing, providing a visual basis for the pressure-sensitive color-changing effect.
[0096] PXRD patterns of raw and ground powders of Cl-PANP, Br-PANP, and I-PANP are as follows: Figure 4 , Figure 10 , Figure 16 As shown in the figure, it can be seen that after grinding, the intensity of the diffraction peaks in the diffraction angle range of 5° to 30° is significantly reduced, broadened, or even disappears. This indicates that the destruction of the crystal structure after grinding, which leads to the change in the molecular packing mode, is the fundamental reason for the pressure-induced discoloration.
[0097] The proton NMR spectra of Cl-PANP, Br-PANP, and I-PANP are as follows: Figure 5 , Figure 11 , Figure 17 As shown, the data is as follows:
[0098] Cl-PANP: 1 H NMR (400MHz, DMSO-d6) δ8.64 (s, 1H), 7.90 (d, J = 16.1Hz, 2H), 7.72
[0099] (s,2H),7.43-7.37(m,4H),7.18(dd,J=18.0,7.4Hz,6H),6.96(d,J=8.8Hz,2H);
[0100] Br-PANP: 1 H NMR (400MHz, DMSO-d6) δ8.62 (s, 1H), 7.90 (d, J = 11.5Hz, 2H), 7.77-7.69
[0101] (m,2H),7.42-7.37(m,4H),7.21-7.13(m,6H),6.98-6.93(m,2H).
[0102] I-PANP: 1 H NMR (400MHz, DMSO-d6) δ8.54(s,1H),7.87(d,J=3.8Hz,2H),7.72(d,J=8.9Hz,2H),7.42-7.36(m,4H),7.16(dd,J=18.3,7.3Hz,6H),6.96(s,2H).
[0103] Time-of-flight mass spectra of Cl-PANP, Br-PANP, and I-PANP are shown below. Figure 6 , Figure 12 , Figure 18 As shown, the data is as follows:
[0104] Cl-PANP: MS (ESI): Measured m / z is 397.1220 (Calculated value of C24 H18 N4 Cl: 397.1215);
[0105] Br-PANP: MS (ESI): Measured m / z is 441.0709 (calculated value of C24 H18 N4 Br: 441.0710);
[0106] I-PANP: MS (ESI): The measured m / z is 489.0576 (calculated value of C24 H18 N4 I: 489.0571).
[0107] Crystal structure diagrams of Cl-PANP, Br-PANP, and I-PANP are shown below. Figure 7 , Figure 13 , Figure 19 As shown, the data is as follows:
[0108] Cl-PANP single crystal structure parameters: monoclinic crystal system, space group P21 / n, unit cell parameters are as follows: The unit cell volume is The number of molecules in the crystal lattice is Z=8, and the density is 1.333 g / cm³. 3 ;
[0109] Br-PANP single crystal structure parameters: triclinic crystal system, space group P-1, unit cell parameters: The unit cell volume is The number of molecules in the crystal lattice is Z=2, and the density is 1.474 g / cm³. 3 ;
[0110] I-PANP single crystal structure parameters: monoclinic crystal system, space group P21 / c, unit cell parameters are as follows: The unit cell volume is The number of molecules in the crystal lattice is Z=8, and the density is 1.562 g / cm³. 3 .
[0111] When compounds Cl-PANP, Br-PANP, and I-PANP are placed in a mortar and ground, a change in fluorescence color can be observed. The fluorescence changes by more than 10 nm. The compounds can be restored to their state before grinding by dissolving them in dichloromethane and then recrystallizing them. Under external pressure, they can be restored to their initial state under heating or organic solvent conditions. It is a reversible pressure-sensitive color-changing material.
[0112] Finally, it should be noted that the above preferred 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 through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.
Claims
1. A method for preparing an organic fluorescent compound with piezochromic properties, characterized in that: Includes the following steps, S1. Dissolve the starting compound in acetonitrile solution, add the first base and stir, then add bromoacetonitrile dropwise and stir overnight at room temperature. S2. After filtration, retain the filtrate and rotary evaporate to obtain a solid crude product, which is then purified by column chromatography to obtain an intermediate compound. S3. Dissolve the intermediate compound in anhydrous ethanol, add the second substance and stir until stable, then add 4-diphenylaminobenzaldehyde and stir at room temperature to react; S4. After the reaction was completed, the mixture was filtered and the filter cake was washed with n-hexane. After drying, the target compounds (E)-2-(4-chloro-1H-pyrazol-1-yl)-3-(4-(diphenylamino)phenyl)acrylonitrile, (E)-2-(4-bromo-1H-pyrazol-1-yl)-3-(4-(diphenylamino)phenyl)acrylonitrile and (E)-2-(4-iodo-1H-pyrazol-1-yl)-3-(4-(diphenylamino)phenyl)acrylonitrile were obtained. The starting compound is any one of 4-chloropyrazole, 4-bromopyrazole, or 4-iodopyrazole. When the starting compound is 4-chloropyrazole, the intermediate compound is 2-(4-chloro-1H-pyrazole-1-yl)acetonitrile; When the starting compound is 4-bromopyrazole, the intermediate compound is 2-(4-bromo-1H-pyrazole-1-yl)acetonitrile; When the starting compound is 4-iodopyrazole, the intermediate compound is 2-(4-iodo-1H-pyrazole-1-yl)acetonitrile; When the intermediate compound is 2-(4-chloro-1H-pyrazol-1-yl)acetonitrile, the finished compound is (E)-2-(4-chloro-1H-pyrazol-1-yl)-3-(4-(diphenylamino)phenyl)acrylonitrile; When the intermediate compound is 2-(4-bromo-1H-pyrazol-1-yl)acetonitrile, the finished compound is (E)-2-(4-bromo-1H-pyrazol-1-yl)-3-(4-(diphenylamino)phenyl)acrylonitrile; When the intermediate compound is 2-(4-iodo-1H-pyrazol-1-yl)acetonitrile, the finished compound is (E)-2-(4-iodo-1H-pyrazol-1-yl)-3-(4-(diphenylamino)phenyl)acrylonitrile.
2. The method for preparing an organic fluorescent compound with piezochromic properties according to claim 1, characterized in that: In step S1, the reaction temperature is 10-30℃, the stirring reaction time at room temperature is 10-12 h, the molar ratio of the starting compound to bromoacetonitrile is 1:1.5-2, and the volume ratio of acetonitrile to the mass ratio of the starting compound is 15 ml / g to 50 ml / g.
3. The method for preparing an organic fluorescent compound with piezochromic properties according to claim 3, characterized in that: In step S2, the first base substance used is any one of sodium ethoxide, sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate, sodium bicarbonate, potassium bicarbonate, tetraethylamine hydroxide, and triethylamine; the molar ratio of 4-chloropyrazole, 4-bromopyrazole, or 4-iodopyrazole to the base is 1:2-3.
4. The method for preparing an organic fluorescent compound with pressure-sensitive color-changing properties according to claim 3, characterized in that: In step S3, the reaction temperature is 10-30℃ and the reaction time is 10-15h; the molar ratio of the intermediate compound to 4-diphenylaminobenzaldehyde is 1:1-2; and the volume ratio of anhydrous ethanol to the mass ratio of the intermediate compound is 30 ml / g to 100 ml / g.
5. The method for preparing an organic fluorescent compound with piezochromic properties according to claim 4, characterized in that: In step S3, the second base substance used is any one of sodium ethoxide, sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate, sodium bicarbonate, potassium bicarbonate, tetraethylamine hydroxide, and triethylamine; the molar ratio of the intermediate compound to the base is 1:2-5.
6. The method for preparing an organic fluorescent compound with piezochromic properties according to claim 5, characterized in that: The (E)-2-(4-chloro-1H-pyrazol-1-yl)-3-(4-(diphenylamino)phenyl)acrylonitrile is named Cl-PANP; (E)-2-(4-bromo-1H-pyrazol-1-yl)-3-(4-(diphenylamino)phenyl)acrylonitrile, also known as Br-PANP; (E)-2-(4-iodo-1H-pyrazol-1-yl)-3-(4-(diphenylamino)phenyl)acrylonitrile, also known as I-PANP; The structural formulas of the above compounds are shown below:
7. The organic fluorescent compound with pressure-sensitive color-changing properties according to any one of claims 1-6, used to prepare detection or chemical sensing materials.
8. The organic fluorescent compound with piezochromic properties according to claim 7, characterized in that: Under external pressure, the fluorescence changes by more than 10 nm; it can be restored to its initial state under heating or organic solvent conditions.
9. The organic fluorescent compound with piezochromic properties according to claim 8, characterized in that: The organic solvent is any one of dichloromethane, ethyl acetate, and tetrahydrofuran.
10. The organic fluorescent compound with pressure-sensitive color-changing properties according to claim 7, wherein the external environmental pressure during application includes grinding or at least 0.1 MPa static pressure.