Force-induced chiral liquid crystal compounds, and methods of making and using the same

Abstract

This invention relates to the field of functional materials technology, specifically to a force-induced chiral liquid crystal compound, its preparation method, and its applications. The invention involves esterification, reduction, bromination, cyano substitution, and Knaufenberg-Gale condensation reactions to link a chiral alkyl chain-modified cyanostylene atom to trimesoaldehyde, yielding a liquid crystal molecule with a disk-like structure. This liquid crystal compound forms a non-helical columnar liquid crystal structure when unstressed, but can transform into a thermodynamically more stable monochiral helical columnar liquid crystal structure upon application of mechanical force, exhibiting significant circular dichroism and circularly polarized emission characteristics, with an emission asymmetry factor as high as 0.3. The force-induced chiral liquid crystal compound provided by this invention allows for dynamic modulation of chiral optical signals through simple mechanical stimulation, offering simple operation, direct response, and good reversibility.

Description

Technical Field

[0001] This invention relates to the field of functional materials technology, specifically to a force-induced chiral liquid crystal compound, its preparation method, and its applications. Background Technology

[0002] Chiral liquid crystal materials, due to the presence of chiral centers, can form a monochiral helical structure, thus endowing them with photoelectric properties not found in ordinary liquid crystal compounds, such as selective reflection, circular dichroism, and circularly polarized luminescence. This gives them broad application prospects in displays, sensing, and information anti-counterfeiting. Traditionally, the dynamic modulation of circularly polarized luminescence in liquid crystals mainly relies on external stimuli such as light, electricity, and heat. Photoresponsive liquid crystal materials often incorporate photosensitive units such as azobenzene, utilizing their photoisomerization to change molecular configuration or chirality, thereby adjusting the helical pitch or phase state to achieve modulation of the circularly polarized luminescence signal. Electroresponsive liquid crystal materials utilize dielectric anisotropy, driving molecular rearrangement through an electric field to achieve rapid switching or photon bandgap shifting.

[0003] In their 2024 paper "Light-DrivenSign Inversion of Circularly Polarized Luminescence Enabled by Dichroism Modulation in Cholesteric Liquid Crystals" published in Volume 36 of *Advanced Materials*, Yang Li et al. disclosed a method for achieving circularly polarized luminescence signal modulation under photoinduced conditions by doping a photoresponsive dichroic dye into a cholesteric liquid crystal compound modified with a chiral tail chain. However, this compound exhibits low isomerization efficiency and poor reversibility of its photoresponsive units, and high-precision control, such as sign reversal of chiral optical signals, still requires complex multi-component system design, thus limiting the practical application of chiral liquid crystal materials in dynamic optoelectronic devices and information encryption.

[0004] Alberto Concellón et al., in their 2021 paper "Electric-Field-Induced Chirality in Columnar Liquid Crystals" published in Volume 143 of the *Journal of the American Chemical Society*, disclosed a chiral tail-chain modified disk-shaped liquid crystal that can form a monochiral helical columnar liquid crystal structure under electric field induction. However, this chiral liquid crystal requires external electric field stimulation to form a monochiral helical structure, and electro-control requires complex electrode structures, encapsulation, and a continuous power supply. Furthermore, high electric fields may induce electrochemical side reactions or dielectric breakdown.

[0005] Therefore, existing chiral liquid crystal compounds suffer from complex modulation methods, low efficiency, poor reversibility, or high dependence on equipment when achieving dynamic and reversible chiral optical signal modulation, thus limiting their application in emerging scenarios such as flexible, wearable, and bio-integrated applications. Summary of the Invention

[0006] To overcome the shortcomings of existing chiral liquid crystal compounds in achieving dynamic chiral optical signal modulation, such as complex modulation methods, low efficiency, poor reversibility, or high equipment dependence, this invention provides a force-induced chiral liquid crystal compound, its preparation method, and its applications. This liquid crystal compound can directly, efficiently, and reversibly form a thermodynamically more stable monochiral helical columnar liquid crystal structure under force stimulation.

[0007] To achieve the aforementioned technical objectives, the technical solution adopted by this invention is as follows: This invention provides a force-induced chiral liquid crystal compound, the structural formula of which is shown below: ; In the formula, R is (S)-3,7-dimethyloctyl or (R)-3,7-dimethyloctyl.

[0008] This invention provides a method for preparing a force-induced chiral liquid crystal compound, comprising the following steps: In the presence of a base and a catalyst, methyl 3,4-dihydroxybenzoate and a chiral alkyl bromide undergo an esterification reaction to yield methyl 3,4-di(decoxy)benzoate; the chiral alkyl bromide is (S)-1-bromo-3,7-dimethyloctane or (R)-1-bromo-3,7-dimethyloctane. In the presence of a reducing agent, methyl 3,4-di(decoxy)benzoate undergoes a reduction reaction to yield 3,4-di(decoxy)benzyl alcohol. The 3,4-di(decoxy) Benzyl alcohol and phosphorus tribromide undergo a bromination reaction to give 4-(bromomethyl)-1,2-di(decoxy)benzene; 4-(bromomethyl)-1,2-di(decoxy)benzene, trimethylnitrile silane, and tetrabutylammonium fluoride undergo a substitution reaction to replace bromine with cyano group to give 3,4-di(decoxy)phenylacetonitrile; 3,4-di(decoxy)phenylacetonitrile undergoes a Knevengel condensation reaction with trimesoaldehyde under alkaline conditions to give a mechanoinduced chiral liquid crystal compound.

[0009] Preferably, the method for synthesizing methyl 3,4-di(decoxy)benzoate is as follows: under a protective atmosphere, methyl 3,4-dihydroxybenzoate, a chiral alkyl bromide, a base, and a catalyst are subjected to an esterification reaction in a first solvent to obtain methyl 3,4-di(decoxy)benzoate.

[0010] Preferably, the molar ratio of methyl 3,4-dihydroxybenzoate to chiral alkyl bromide is 1:2 to 3.

[0011] Preferably, the molar ratio of methyl 3,4-dihydroxybenzoate, catalyst, and base is 1:0.1-0.2:5-6.

[0012] Preferably, the base used in the synthesis of methyl 3,4-di(decoxy)benzoate is potassium carbonate, and the catalyst is tetrabutylammonium iodide. Tetrabutylammonium iodide has both lipophilic long-chain alkyl groups and hydrophilic ammonium ions in its structure; it extracts phenoxy anions from the aqueous or solid phase into the organic phase, allowing them to fully contact the reactants, thus greatly improving the reaction efficiency.

[0013] Preferably, the first solvent is an amide solvent.

[0014] Preferably, the first solvent is N,N-dimethylformamide.

[0015] Preferably, the method for synthesizing 3,4-di(decoxy)benzyl alcohol is as follows: after dissolving methyl 3,4-di(decoxy)benzoate in a second solvent, a reducing agent is added to undergo a reduction reaction to obtain 3,4-di(decoxy)benzyl alcohol.

[0016] Preferably, the molar ratio of methyl 3,4-di(decoxy)benzoate to reducing agent is 1:1 to 2.

[0017] Preferably, the reducing agent is lithium aluminum hydride; the second solvent is a furan-based solvent.

[0018] Preferably, the second solvent is tetrahydrofuran.

[0019] Preferably, the method for synthesizing 4-(bromomethyl)-1,2-di(decoxy)benzene is as follows: after dissolving 3,4-di(decoxy)benzyl alcohol in a third solvent, phosphorus tribromide is added to undergo a bromination reaction to obtain 4-(bromomethyl)-1,2-di(decoxy)benzene.

[0020] Preferably, the molar ratio of 3,4-bis(decyloxy)benzyl alcohol to phosphorus tribromide is 1:1 to 2.

[0021] Preferably, the third solvent is a halogenated hydrocarbon solvent.

[0022] Preferably, the third solvent is dichloromethane.

[0023] Preferably, the method for synthesizing 3,4-di(decoxy)phenylacetonitrile is as follows: after dissolving 4-(bromomethyl)-1,2-di(decoxy)benzene in a fourth solvent, trimethylnitrile silane and tetrabutylammonium fluoride are added to undergo a substitution reaction to replace bromine with cyano group, thereby obtaining 3,4-di(decoxy)phenylacetonitrile.

[0024] Preferably, the molar ratio of 4-(bromomethyl)-1,2-bis(decoxy)benzene, trimethylnitrile silane and tetrabutylammonium fluoride is 1:1 to 2:1 to 2.

[0025] Preferably, the fourth solvent is a nitrile solvent.

[0026] Preferably, the fourth solvent is acetonitrile.

[0027] Preferably, 3,4-bis(decoxy)phenylacetonitrile, trimesonaldehyde and a base undergo a Knauvengel condensation reaction in a fifth solvent to obtain a force-induced chiral liquid crystal compound.

[0028] Preferably, the molar ratio of 3,4-bis(decoxy)phenylacetonitrile, trimesin, and base is 3-4:1:3.

[0029] Preferably, in the Knauvengel condensation reaction, the base used under alkaline conditions is tetrabutylammonium hydroxide; the fifth solvent is an alcohol solvent.

[0030] Preferably, the alcohol solvent is ethanol.

[0031] This invention provides an application of a force-induced chiral liquid crystal compound as a stimulus-responsive circularly polarized luminescent material.

[0032] Preferably, the application method is as follows: dissolve the force-induced chiral liquid crystal compound in a solvent, coat it on a substrate, and prepare a thin film; after applying a shear force of 10MPa to 20MPa to the thin film, the thin film changes from the initial non-spiral columnar liquid crystal structure to a monochiral spiral columnar liquid crystal structure; at the same time, under ultraviolet light excitation of 365nm to 400nm, the force-induced thin film generates a circularly polarized light emission signal.

[0033] Preferably, the concentration of the force-induced chiral liquid crystal compound is 3 mg / mL.

[0034] Preferably, the solvent is dichloromethane.

[0035] Compared with the prior art, the present invention has the following beneficial effects: The force-induced chiral liquid crystal compound of this invention can generate a monochiral helical columnar structure under force stimulation, thereby exhibiting significant chiral optical characteristics. This invention constructs a liquid crystal molecule with a disk-like structure by linking a chiral alkyl chain-modified cyanostylene moiety to pyromellitic trimethylaldehyde. In the initial state, due to the steric hindrance of the chiral tail chain, the molecule tends to form a non-helical columnar liquid crystal structure. When mechanical force is applied, the molecule rearranges under force stimulation, overcoming the steric hindrance and transforming into a thermodynamically more stable monochiral helical columnar liquid crystal structure. This force-induced helical structure formation endows the material with significant circular dichroism and circularly polarized luminescence characteristics, with a luminescence asymmetry factor as high as 0.3. This avoids the problems of low photosensitive unit isomerization efficiency and poor reversibility in optical modulation, and also eliminates the need for complex electrode structures and continuous power supply required in electrical modulation.

[0036] The force-induced chiral liquid crystal provided by this invention can generate and dynamically control chiral optical signals through simple mechanical force stimulation. It has the advantages of simple operation, direct response, good reversibility and no need for additional equipment, providing a new way for the development of novel flexible, wearable, bio-integrated dynamic optoelectronic devices and information encryption materials. Attached Figure Description

[0037] Figure 1 The hydrogen NMR spectrum of the chiral liquid crystal compound prepared in Example 1.

[0038] Figure 2 The hydrogen NMR spectrum of the chiral liquid crystal compound prepared in Example 2.

[0039] Figure 3 Two-dimensional small-angle X-ray scattering pattern of the chiral liquid crystal compound prepared in Example 1.

[0040] Figure 4 The circular dichroism absorption spectra of the chiral liquid crystal compounds prepared in Examples 1 and 2 are shown.

[0041] Figure 5 The circularly polarized emission spectra of the chiral liquid crystal compounds prepared in Examples 1 and 2 are shown. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] This invention uses methyl 3,4-dihydroxybenzoate as the starting material, introduces a chiral tail chain through esterification, followed by reduction, bromination, and cyano substitution, and finally connects the three side chain molecules to the central pyromellitic trimethylaldehyde core via a Knauvengel condensation reaction, forming a product with... C 3 The target molecule is a symmetrical, disk-shaped compound. The specific reaction mechanism is as follows: using methyl 3,4-dihydroxybenzoate as the starting material and potassium carbonate as a weak base, a proton is abstracted from the phenolic hydroxyl group of methyl 3,4-dihydroxybenzoate in the reaction system, generating a highly reactive phenoxy anion. This phenoxy anion acts as a nucleophile, undergoing a nucleophilic substitution reaction on the carbon atom attached to the bromine atom in a chiral alkyl bromide to yield methyl 3,4-di(decoxy)benzoate. Subsequently, under the action of a reducing agent, the ester group of methyl 3,4-di(decoxy)benzoate is reduced in one step to an alcohol, yielding 3,4-di(decoxy)benzyl alcohol. The 3,4-di(decoxy)benzyl alcohol undergoes a bromination reaction with phosphorus tribromide to give 4-(bromomethyl)-1,2-di(decoxy)benzene. Then, in a trimethylnitrile silane / tetrabutylammonium fluoride system, it undergoes a substitution reaction with 4-(bromomethyl)-1,2-di(decoxy)benzene, replacing the bromine with a cyano group to generate 3,4-di(decoxy)phenylacetonitrile. Finally, it undergoes a Knauvengel condensation reaction with trimesin under alkaline conditions to obtain a mechanoinduced chiral liquid crystal compound.

[0044] Example 1 The preparation method of chiral liquid crystal compounds based on S-tail chains includes the following steps: Step 1: 2.0 g of methyl 3,4-dihydroxybenzoate, 6.6 g of (S)-1-bromo-3,7-dimethyloctane, 0.7 g of tetrabutylammonium iodide, and 10.0 g of potassium carbonate were sequentially added to a reaction flask. Under a nitrogen atmosphere, 150 mL of N,N-dimethylformamide was added, and the mixture was dissolved by sonication and reacted at 80 °C for 12 hours. After the reaction, N,N-dimethylformamide was removed using a rotary evaporator; the product was then dissolved in dichloromethane, washed with saturated NaCl solution, concentrated, and purified by column chromatography using petroleum ether and dichloromethane (volume ratio of petroleum ether to dichloromethane 20:1) as eluent to obtain 4.8 g of the product, namely methyl 3,4-di(((S)-3,7-dimethyloctyl)oxy)benzoate.

[0045] Step 2: Add 4.8 g of methyl 3,4-bis(((S)-3,7-dimethyloctyl)oxy)benzoate to a round-bottom flask and dissolve it in 50 mL of tetrahydrofuran. Place the flask in a low-temperature stirrer and stir at 0°C for 15 minutes until fully dissolved. Then slowly add 0.6 g of lithium aluminum hydride and continue the reaction for 12 hours. After the reaction is complete, slowly add water at 0°C until no more bubbles are produced. Then add dichloromethane and wash with saturated NaCl. After concentration and drying, 4.1 g of the product, namely 3,4-bis(((S)-3,7-dimethyloctyl)oxy)benzyl alcohol, is obtained.

[0046] Step 3: Add 4.1 g of 3,4-bis(((S)-3,7-dimethyloctyl)oxy)benzyl alcohol to a round-bottom flask and dissolve it in 100 mL of dichloromethane. Place the flask in a low-temperature stirrer and stir at 0°C for 15 minutes until fully dissolved. Then slowly add 1.4 mL of phosphorus tribromide and continue the reaction for 12 hours. After the reaction is complete, slowly add water until no more bubbles are produced. Add dichloromethane, then wash with saturated NaCl solution, concentrate and dry to obtain 4.5 g of the product 3,4-bis(((S)-3,7-dimethyloctyl)oxy)phenylbenzyl bromide.

[0047] Step 4: 4.5 g of 3,4-bis(((S)-3,7-dimethyloctyl)oxy)phenylbenzyl bromide was dissolved in acetonitrile in a round-bottom flask, followed by the addition of 1.8 mL of trimethylnitrile silane and 4.4 g of tetrabutylammonium fluoride. The mixture was stirred at room temperature. The reaction was monitored in real time using thin-layer chromatography. After the reaction was complete, the acetonitrile was removed by rotary evaporation, and then dissolved in dichloromethane. The solution was then washed with saturated NaCl solution, concentrated, and purified by column chromatography using petroleum ether and dichloromethane (volume ratio of petroleum ether to dichloromethane 20:1) as eluent to obtain 0.9 g of the product, namely 3,4-bis(((S)-3,7-dimethyloctyl)oxy)phenylacetonitrile.

[0048] Step 5: Dissolve 0.9 g of 3,4-bis(((S)-3,7-dimethyloctyl)oxy)phenylacetonitrile and 0.1 g of trimesin in ethanol, then add tetrabutylammonium hydroxide and react at room temperature. During the reaction, a bright yellow flocculent precipitate gradually forms, and the reaction is monitored in real time using thin-layer chromatography. After the reaction is complete, the flocculent precipitate is collected by filtration and repeatedly washed with ethanol to obtain 0.7 g of a pale yellow solid product, namely (2Z,2'Z,2''Z)-3,3',3''-(phenyl-1,3,5-triyl)tris[2-(3,4-bis(((S)-3,7-dimethyloctyl)oxy)phenyl)acrylonitrile], as a force-induced chiral S-type liquid crystal material; its structural formula is shown below:

[0049] .

[0050] Example 2 The preparation method of chiral liquid crystal compounds based on R-type tail chains includes the following steps: Step 1: 0.7 g of methyl 3,4-dihydroxybenzoate, 2.2 g of (R)-1-bromo-3,7-dimethyloctane, 0.8 g of tetrabutylammonium iodide, and 11.0 g of potassium carbonate were added sequentially to a reaction flask. Under a nitrogen atmosphere, 150 mL of N,N-dimethylformamide was added, and the mixture was dissolved by sonication. The reaction was then carried out at 80 °C for 12 hours. After the reaction, N,N-dimethylformamide was removed using a rotary evaporator. The product was then dissolved in dichloromethane, washed with saturated NaCl solution, concentrated, and purified by column chromatography using petroleum ether and dichloromethane (volume ratio of petroleum ether to dichloromethane 20:1) as eluent to obtain 1.8 g of the product, namely methyl 3,4-di(((R)-3,7-dimethyloctyl)oxy)benzoate.

[0051] Step 2: Add 1.8 g of methyl 3,4-bis(((R)-3,7-dimethyloctyl)oxy)benzoate to a round-bottom flask and dissolve it in 50 mL of tetrahydrofuran. Place the flask in a low-temperature stirrer and stir at 0°C for 15 minutes until fully dissolved. Then slowly add 0.2 g of lithium aluminum hydride and continue the reaction for 12 hours. After the reaction is complete, slowly add water at 0°C until no more bubbles are produced; then add dichloromethane and wash with saturated NaCl. After concentration and drying, 1.5 g of the product, namely 3,4-bis(((R)-3,7-dimethyloctyl)oxy)benzyl alcohol, is obtained.

[0052] Step 3: Add 1.5 g of 3,4-bis(((R)-3,7-dimethyloctyl)oxy)benzyl alcohol to a round-bottom flask and dissolve it in 100 mL of dichloromethane. Place the flask in a low-temperature stirrer and stir at 0°C for 15 minutes until fully dissolved. Then slowly add 0.5 mL of phosphorus tribromide and continue the reaction for 12 hours. After the reaction is complete, slowly add water until no more bubbles are produced. Add dichloromethane, then wash with saturated NaCl solution, concentrate and dry to obtain 1.7 g of product, namely 3,4-bis(((R)-3,7-dimethyloctyl)oxy)phenylbenzyl bromide.

[0053] Step 4: 1.7 g of 3,4-bis(((R)-3,7-dimethyloctyl)oxy)phenylbenzyl bromide was dissolved in acetonitrile in a round-bottom flask, followed by the addition of 0.6 ml of trimethylnitrile silane and 1.7 g of tetrabutylammonium fluoride. The mixture was stirred at room temperature. After the reaction was complete, the acetonitrile was removed by rotary evaporation, and then dissolved in dichloromethane. The solution was then washed with saturated NaCl solution, concentrated, and purified by column chromatography using petroleum ether and dichloromethane (volume ratio of petroleum ether to dichloromethane 20:1) as eluent to obtain 0.5 g of the product, namely 3,4-bis(((R)-3,7-dimethyloctyl)oxy)phenylacetonitrile.

[0054] Step 5: Dissolve 0.5 g of 3,4-bis(((R)-3,7-dimethyloctyl)oxy)phenylacetonitrile and 0.06 g of trimesin in ethanol, then add tetrabutylammonium hydroxide and react at room temperature; during the process, a bright yellow flocculent precipitate gradually forms. After the reaction is complete, filter and collect the flocculent precipitate, and wash repeatedly with ethanol to obtain 0.4 g of a pale yellow solid product, namely (2Z,2'Z,2''Z)-3,3',3''-(phenyl-1,3,5-triyl)tris[2-(3,4-bis(((R)-3,7-dimethyloctyl)oxy)phenyl)acrylonitrile], as a force-induced chiral R-type liquid crystal material; its structural formula is shown below:

[0055] .

[0056] Test 1: The liquid crystal compounds prepared in Examples 1 and 2 were subjected to NMR analysis, and their proton NMR spectra are shown below. Figure 1 and Figure 2 ,from Figure 1 and Figure 2 The results show that the corresponding peak positions and hydrogen ratios are consistent with the theory, indicating that the target compound was successfully synthesized in Examples 1 and 2.

[0057] Test 2: Two-dimensional small-angle X-ray scattering tests were performed on the liquid crystal compound prepared in Example 1. The results are shown in [Figure Number]. Figure 3 ,from Figure 3 As can be seen, chiral liquid crystal compounds self-assemble to form hexagonal columnar liquid crystal structures.

[0058] Test 3: Taking Example 1 as an example, the chiral liquid crystal compound (3 mg) prepared in Example 1 was dissolved in dichloromethane (1 mL), and a uniform thin film was prepared by spin coating to obtain S-type liquid crystal film and R-type liquid crystal film. A shear force of approximately 10 MPa was applied to the film, and then circular dichroism absorption spectroscopy and circularly polarized emission spectroscopy were performed. The excitation wavelength for the circularly polarized emission spectroscopy was 365 nm, and the results are shown in […]. Figure 4 and Figure 5 .

[0059] from Figure 4The results show that, in their initial state, the CCD signals of S-type and R-type liquid crystal films are weak or lack obvious characteristic signals, indicating that the molecules form a non-helical columnar liquid crystal structure with low chiral optical activity. After applying a certain shear force to the initial film, the film exhibits a significant enhancement of the CCD signal, with obvious positive and negative Cotton effects appearing at the characteristic absorption peak positions, and the CCD signals of the S-type and R-type compounds showing opposite signs. This indicates that the helical columnar liquid crystal structure formed after force induction possesses strong chiral optical properties. This result confirms that mechanical stimulation can effectively induce the liquid crystal compound to transform from a non-helical structure into a thermodynamically more stable monochiral helical columnar liquid crystal structure, thereby achieving the generation and dynamic control of chiral optical signals.

[0060] from Figure 5 It can be seen that both chiral liquid crystal compounds exhibit significant force-induced circularly polarized luminescence properties. Before force induction, the S-type and R-type liquid crystal films showed virtually no circularly polarized luminescence signals, indicating that the initial non-spiral columnar liquid crystal structure did not possess circularly polarized luminescence activity. After shear force induction, both the S-type and R-type liquid crystal films exhibited strong circularly polarized luminescence signals, and the signs of their luminescence signals were opposite, which is consistent with... Figure 3 The Cotton effect signs in the mid-circular dichroism absorption spectra are completely consistent, further confirming that force induces the formation of a monochiral helical columnar liquid crystal structure with opposite chirality. Furthermore, the luminescence asymmetry factor (glum) of both films reaches 0.3, indicating that the force-induced helical structure possesses excellent chiral optical purity.

[0061] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the invention.

[0062] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A force-induced chiral liquid crystal compound, characterized in that, The structural formula of the force-induced chiral liquid crystal compound is shown below: ； In the formula, R is (S)-3,7-dimethyloctyl or (R)-3,7-dimethyloctyl.

2. A method for preparing the force-induced chiral liquid crystal compound according to claim 1, characterized in that, Includes the following steps: In the presence of a base and a catalyst, methyl 3,4-dihydroxybenzoate and a chiral alkyl bromide undergo an esterification reaction to yield methyl 3,4-di(decoxy)benzoate; the chiral alkyl bromide is (S)-1-bromo-3,7-dimethyloctane or (R)-1-bromo-3,7-dimethyloctane. In the presence of a reducing agent, methyl 3,4-di(decoxy)benzoate undergoes a reduction reaction to yield 3,4-di(decoxy)benzyl alcohol. The reaction of 3,4-bis(decyloxy)benzyl alcohol with phosphorus tribromide yields 4-(bromomethyl)-1,2-bis(decyloxy)benzene; A substitution reaction was carried out on 4-(bromomethyl)-1,2-bis(decoxy)benzene, trimethylnitrile silane and tetrabutylammonium fluoride to replace bromine with cyano group, yielding 3,4-bis(decoxy)phenylacetonitrile; 3,4-Di(decoxy)phenylacetonitrile and pyromellitic trimethylolpropionate undergo a Knauvengel condensation reaction under alkaline conditions to obtain a mechanoinduced chiral liquid crystal compound.

3. The method for preparing the force-induced liquid crystal compound according to claim 2, characterized in that, The method for synthesizing methyl 3,4-di(decoxy)benzoate is as follows: under a protective atmosphere, methyl 3,4-dihydroxybenzoate, chiral alkyl bromide, base and catalyst are subjected to an esterification reaction in a first solvent to obtain methyl 3,4-di(decoxy)benzoate.

4. The method for preparing the force-induced liquid crystal compound according to claim 3, characterized in that, The molar ratio of methyl 3,4-dihydroxybenzoate to chiral alkyl bromide is 1:2 to 3; The molar ratio of methyl 3,4-dihydroxybenzoate, catalyst, and base is 1:0.1-0.2:5-6; The base used in the synthesis of methyl 3,4-di(decoxy)benzoate is potassium carbonate, the catalyst is tetrabutylammonium iodide, and the first solvent is an amide solvent.

5. The method for preparing the force-induced chiral liquid crystal compound according to claim 2, characterized in that, The molar ratio of methyl 3,4-bis(decoxy)benzoate to reducing agent is 1:1 to 2; The reducing agent is lithium aluminum hydride.

6. The method for preparing the force-induced chiral liquid crystal compound according to claim 2, characterized in that, The molar ratio of 3,4-bis(decyloxy)benzyl alcohol to phosphorus tribromide is 1:1 to 2.

7. The method for preparing the force-induced chiral liquid crystal compound according to claim 2, characterized in that, The molar ratio of 4-(bromomethyl)-1,2-bis(decoxy)benzene, trimethylnitrile silane and tetrabutylammonium fluoride is 1:1 to 2:1 to 2.

8. The method for preparing the force-induced chiral liquid crystal compound according to claim 2, characterized in that, In the Knauvengel condensation reaction, the base used under alkaline conditions is tetrabutylammonium hydroxide; The molar ratio of 3,4-bis(decoxy)phenylacetonitrile, trimesin, and base is 3–4:1:

3.

9. The use of the force-induced chiral liquid crystal compound of claim 1 as a stimulus-responsive circularly polarized luminescent material.

10. The application of the force-induced chiral liquid crystal compound according to claim 9 as a stimulus-responsive circularly polarized luminescent material, characterized in that, The application method is as follows: a force-induced chiral liquid crystal compound is dissolved in a solvent and coated onto a substrate to prepare a thin film; after applying a shear force of 10MPa to 20MPa to the thin film, the film changes from an initial non-helical columnar liquid crystal structure to a monochiral helical columnar liquid crystal structure; at the same time, under ultraviolet light excitation of 365nm to 400nm, the force-induced thin film generates a circularly polarized light emission signal. The concentration of the force-induced chiral liquid crystal compound was 3 mg / mL; the solvent was dichloromethane.

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