Chiral luminescent molecule, preparation method thereof and chiral luminescent liquid crystal

Abstract

This application relates to the technical field of organic light-emitting materials, and particularly to a chiral light-emitting molecule and its preparation method, as well as a chiral light-emitting liquid crystal. The preparation method of the chiral light-emitting molecule includes the following steps: S1: Menthyl chloroformate, 4-phenol-2,1,3-benzothiadiazole, palladium catalyst, and acid-binding agent are sequentially added to a flask, followed by the addition of an organic solvent for dissolution and thorough stirring to obtain a mixture; S2: The mixture is injected into a nitrogen-filled reaction vessel, heated to 70–95°C, reacted for 5–10 hours, and then separated and purified to obtain the chiral light-emitting molecule. Compared with traditional preparation methods such as alkylation, acylation, dehydration, and ring-opening methods, the preparation method of this application significantly shortens the reaction time while increasing the yield; furthermore, this method is simple to operate, the reaction is mild, and it can be carried out under conventional laboratory conditions, reducing the cost of chiral light-emitting molecules.

Description

Technical Field

[0001] This application relates to the technical field of organic light-emitting materials, and in particular to a chiral light-emitting molecule and its preparation method, and a chiral light-emitting liquid crystal. Background Technology

[0002] Chirality is a fundamental property of nature, characterizing the asymmetry of matter. A molecule that does not overlap with its mirror image is called a chiral molecule. Fundamental questions in natural science are closely related to chirality. A special characteristic of chiral molecules or materials is their optical activity based on chirality, enabling them to recognize different polarized light sources. Chiral optical characteristics have shown great potential in optoelectronics, sensing, information storage, and displays. Various chiral spectra, such as circular dichroism (CD), optical rotational dispersion (ORD), electronic circular dichroism (ECD), and circularly polarized luminescence (CPL), have been used to identify and characterize chiral information in various chiral spectra. CPL materials are receiving increasing attention due to their wide applications in 3D displays, optical sensors, and optoelectronic devices.

[0003] Liquid crystals, after melting or dissolving in a solvent, lose the rigidity of solid matter but acquire the fluidity of liquids, while retaining some of the anisotropic ordered arrangement of molecules from crystalline materials. This forms an intermediate state that combines properties of both crystals and liquids. This oriented, ordered fluid existing during the solid-to-liquid transition is called a liquid crystal. Due to its unique physical and chemical properties, liquid crystals are widely used in important fields such as display devices and integrated circuits.

[0004] Due to the highly ordered nature of liquid crystals, and the fact that their molecular structures often consist of conjugated structures and flexible side chains, strong non-covalent interactions (such as hydrogen bonds, π-conjugation effects, and π-π stacking effects) can occur between luminescent molecules with similar conjugated structures, leading to co-assembly at the molecular level. Through the chiral induction of self-assembly by chiral luminescent molecules, previously non-luminescent but orderly stacked liquid crystal molecules can be transformed into chiral and luminescent supramolecular liquid crystals, greatly expanding the application scenarios and fields of liquid crystals. However, current methods for synthesizing chiral luminescent molecules are still insufficient. Domestic and international reports often rely on traditional methods such as alkylation, acylation, dehydration, and ring-opening, which either have low yields or long reaction times, hindering the widespread adoption and application of chiral luminescent molecules. Summary of the Invention

[0005] The purpose of this application is to improve the existing methods for preparing chiral luminescent molecules, which suffer from low yields or long reaction times. This application provides a method for preparing chiral luminescent molecules with high yields and short reaction times.

[0006] In the first aspect, this application provides a chiral luminescent molecule and its preparation method, and a chiral luminescent liquid crystal adopts the following technical solution:

[0007] A method for preparing a chiral luminescent molecule includes the following steps:

[0008] S1: Menthyl chloroformate, 4-phenol-2,1,3-benzothiadiazole, palladium catalyst and acid-binding agent are added sequentially to a flask, wherein the molar ratio of menthyl chloroformate, 4-phenol-2,1,3-benzothiadiazole, palladium catalyst and acid-binding agent is 1:1:(0.03~0.08):(0.10~0.20). Then an organic solvent is added to dissolve the mixture, and the mixture is stirred thoroughly to obtain a mixture.

[0009] S2: Inject the mixture from step S1 into a nitrogen-filled reactor, heat it to 70-95°C, react for 5-10 hours, separate and purify it to obtain chiral luminescent molecules;

[0010] The menthyl chloroformate is an R / S isomer of menthyl chloroformate, and the structural formula of the chiral luminescent molecule is as follows:

[0011]

[0012] By employing the above-mentioned technical solution, menthol chloroformate and 4-phenol-2,1,3-benzothiadiazole undergo a coupling reaction in the presence of a palladium catalyst and an acid-binding agent to obtain a chiral luminescent molecule. The synthetic route is as follows:

[0013]

[0014] Compared with traditional preparation methods such as alkylation, acylation, dehydration, and ring-opening, the preparation method of this application significantly shortens the reaction time while improving the yield; moreover, the method is simple to operate, the reaction is mild, and it can be carried out under conventional laboratory conditions, thus reducing the cost of chiral luminescent molecules.

[0015] Furthermore, the chiral luminescent molecule is composed of benzothiadiazole, a benzene ring, and R / S isomers of menthyl ester. Due to the electron-withdrawing ability of the nitrogen atom in benzothiadiazole, the benzothiadiazole molecule exhibits an electron-withdrawing effect, readily accepting external electrons. The conjugated structure of benzothiadiazole enhances the molecule's rigidity and stability. Therefore, the electron-withdrawing effect and conjugated structure of benzothiadiazole endow the chiral luminescent molecule with rich optical properties. The inclusion of the benzene ring further enhances the conjugation effect of the benzothiadiazole molecule, further improving its optical performance. Meanwhile, the different cis-trans isomers of menthyl chloroformate introduce chirality in different directions into the chiral luminescent molecule, enabling it to recognize polarized light sources.

[0016] Optionally, the palladium catalyst is selected from one of tetra(triphenylphosphine)palladium, palladium acetate, palladium chloride, bis(dibenzylacetone)palladium, and bis(tritert-butyl)palladium.

[0017] By adopting the above technical solution, the palladium catalyst can interact with the reactants, reduce the activation energy and activate the reactants, thereby lowering the reaction temperature and making the reaction easier to carry out.

[0018] Optionally, the acid-binding agent is selected from one of pyridine, triethylamine, sodium acetate, diisopropylethylamine, and sodium hydroxide.

[0019] By adopting the above technical solution, the addition of an acid-binding agent is intended to neutralize protons in the reaction system, adjust the pH of the reaction system, reduce the influence of acid on the reaction, and improve the reaction yield.

[0020] Optionally, the organic solvent is tetrahydrofuran.

[0021] By adopting the above technical solution, tetrahydrofuran is a polar solvent with good dissolving ability. It can dissolve reactants such as menthyl chloroformate and 4-phenol-2,1,3-benzothiadiazole, so that they can be fully mixed with palladium catalyst and acid-binding agent to form a homogeneous reaction system.

[0022] Optionally, in step S2, column chromatography is used for separation and purification.

[0023] By adopting the above technical solution, column chromatography is suitable for the separation and purification of components in complex mixtures. By adjusting the composition and conditions of the mobile phase, the target product can be separated and high-purity chiral luminescent molecules can be obtained.

[0024] Secondly, the chiral luminescent molecule provided in this application adopts the following technical solution:

[0025] A chiral luminescent molecule was prepared using the method described in this application.

[0026] By employing the above-mentioned technical solutions, chiral luminescent molecules with excellent optical properties and different chiral characteristics can be obtained, exhibiting stable aggregation-induced emission properties. Furthermore, the preparation method described in this application is simple, efficient, and yields high products, providing a solid foundation for the application and research of chiral luminescent molecules, and giving them enormous application potential in optics, electronics, and biology.

[0027] Thirdly, the chiral luminescent liquid crystal provided in this application adopts the following technical solution:

[0028] A chiral luminescent liquid crystal comprises: a nematic liquid crystal and chiral luminescent molecules;

[0029] The method for preparing the chiral luminescent liquid crystal includes the following steps:

[0030] The nematic liquid crystal is dissolved in dichloromethane, then chiral luminescent molecules are incorporated, and the mixture is homogenized by ultrasonication for 5–40 min to ensure uniform dispersion of the chiral agent molecules in the nematic liquid crystal, thus obtaining a chiral luminescent liquid crystal.

[0031] By employing the above technical solution, after the nematic liquid crystal is dissolved in dichloromethane, it forms an intermediate state that combines some properties of both crystals and liquids. Then, with the assistance of ultrasound, chiral agent molecules are uniformly dispersed within the nematic liquid crystal, causing the nematic liquid crystal and chiral luminescent molecules to co-assemble at the molecular level, resulting in a chiral luminescent liquid crystal with chiral characteristics. Through the chiral induction effect of the self-assembly of chiral luminescent molecules, the rotation and vibration within the chiral luminescent liquid crystal molecules are restricted during aggregation, reducing energy consumption pathways and allowing energy to be released more efficiently in the form of light. This transforms the originally non-luminescent but orderly stacked liquid crystal molecules into chiral and luminescent supramolecular liquid crystals, giving the chiral luminescent liquid crystal aggregation-induced emission properties.

[0032] Optionally, the nematic liquid crystal is 4'-n-pentyl-4-cyanobiphenyl.

[0033] By adopting the above technical solution, the structural formula of 4'-n-pentyl-4-cyanobiphenyl is:

[0034]

[0035] It consists of a conjugated structure and flexible side chains; 4'-n-pentyl-4-cyanobiphenyl can generate strong non-covalent interactions with chiral luminescent molecules that have a conjugated structure, such as hydrogen bonds, π-conjugation effect, and π-π stacking effect, thereby producing co-assembly behavior at the molecular level and constructing a chiral luminescent liquid crystal with aggregation-induced emission properties; while the flexible side chains provide fluidity, enabling the chiral luminescent molecules to be uniformly dispersed in the liquid crystal and improving optical performance.

[0036] Optionally, the mass ratio of the nematic liquid crystal to the chiral luminescent molecule is 100:(1-5).

[0037] By adopting the above technical solution and adjusting the mass ratio of nematic liquid crystal and chiral light-emitting molecules, chiral light-emitting liquid crystals with different optical properties can be obtained to meet different application requirements.

[0038] In summary, this application includes at least one of the following beneficial technical effects:

[0039] 1. Compared with traditional preparation methods such as alkylation, acylation, dehydration, and ring-opening, the preparation method of this application significantly shortens the reaction time while improving the yield; moreover, the method is simple to operate, the reaction is mild, and it can be carried out under conventional laboratory conditions, thus reducing the cost of chiral luminescent molecules;

[0040] 2. The chiral luminescent molecule is composed of benzothiadiazole, a benzene ring, and R / S isomers of menthyl ester. Due to the electron-withdrawing ability of the nitrogen atom in benzothiadiazole, the benzothiadiazole molecule exhibits an electron-withdrawing effect, readily accepting external electrons. Furthermore, the conjugated structure of benzothiadiazole enhances the molecule's rigidity and stability. Therefore, the electron-withdrawing effect and conjugated structure of benzothiadiazole endow the chiral luminescent molecule with rich optical properties. The inclusion of the benzene ring further enhances the conjugation effect of the benzothiadiazole molecule, further improving its optical performance. Meanwhile, the different cis-trans isomers of menthyl chloroformate introduce chirality in different directions into the chiral luminescent molecule, enabling it to recognize polarized light sources.

[0041] 3. Through the chiral induction effect of self-assembly of chiral luminescent molecules, the movement within the molecules is restricted during the aggregation process, and the energy consumption pathways are reduced, so that energy is released more effectively in the form of light. This transforms the originally non-luminescent but ordered stacked liquid crystal molecules into chiral and luminescent supramolecular liquid crystals, giving the chiral luminescent liquid crystals aggregation-induced luminescence properties. Attached Figure Description

[0042] Figure 1 This is the fluorescence emission spectrum of the R-isomer chiral luminescent molecule prepared in Example 1 of this application;

[0043] Figure 2 This is the fluorescence emission spectrum of the S-isomer chiral luminescent molecule prepared in Example 1 of this application;

[0044] Figure 3 This is the CD spectrum of the R-isomer chiral luminescent molecule prepared in Example 1 of this application after being doped with a poor solvent;

[0045] Figure 4 This is the CD spectrum of the S-isomer chiral luminescent molecule prepared in Example 1 of this application after being doped with a poor solvent;

[0046] Figure 5 It is the R-isomer of the chiral luminescent molecule prepared in Example 1 of this application. 1 H-NMR spectrum;

[0047] Figure 6 It is the S-isomer chiral luminescent molecule prepared in Example 1 of this application. 1 H-NMR spectrum;

[0048] Figure 7 These are the CD spectra of chiral luminescent liquid crystals with different doping ratios of the R isomers in this application;

[0049] Figure 8 These are CD spectra of chiral luminescent liquid crystals of different doping ratios of the S-isomer type in this application;

[0050] Figure 9 This is a polarized light microscope image of the R-isomer chiral luminescent liquid crystal prepared in Example 3 of this application. Detailed Implementation

[0051] The present application will be further described in detail below with reference to embodiments and comparative examples.

[0052] To avoid unnecessary details, unless otherwise specified, all items used in the following examples are commercially available products, and all methods used are conventional methods unless otherwise specified.

[0053] Menthyl chloroformate is an R / S isomer of menthyl chloroformate; the nematic liquid crystal is a commercial liquid crystal 4'-n-pentyl-4-cyanobiphenyl (5CB).

[0054] Example

[0055] Example 1

[0056] The method for preparing chiral luminescent molecules provided in this embodiment includes the following steps:

[0057] S1. Add a spindle-shaped magnetic stir bar to a double-necked round-bottom flask, weigh out 2.18 g of menthol chloroformate, 2.36 g of 4-phenol-2,1,3-benzothiadiazole, 0.11 g of palladium acetate and 0.12 g of pyridine, and add them to the flask in sequence. Then add an appropriate amount of tetrahydrofuran as a solvent, and stir magnetically to fully dissolve and mix the reactants to obtain a mixture.

[0058] S2: Inject the mixture from step S1 into a nitrogen-filled reactor, heat it to 85°C, reflux it for 8 hours, and after the reaction is complete, use column chromatography to separate and purify it to obtain chiral luminescent molecules with a purity greater than 99%.

[0059] Example 2

[0060] The difference between this embodiment and Embodiment 1 is that the 0.11g palladium acetate in step S1 is replaced with 0.9g palladium chloride.

[0061] Example 3

[0062] The difference between this embodiment and Embodiment 1 is that the 1.1g palladium acetate in step S1 is replaced with 2.9g bis(dibenzylacetone)palladium.

[0063] Example 4

[0064] The difference between this embodiment and Embodiment 1 is that the 1.1g palladium acetate in step S1 is replaced with 2.6g di(tri-tert-butyl)palladium.

[0065] Example 5

[0066] The difference between this embodiment and Embodiment 1 is that the 1.1g palladium acetate in step S1 is replaced with 6.0g tetra(triphenylphosphine)palladium.

[0067] Example 6

[0068] The difference between this embodiment and embodiment 5 is that the 1.2g pyridine in step S1 is replaced with 1.5g triethylamine.

[0069] Example 7

[0070] The difference between this embodiment and embodiment 5 is that the 1.2g pyridine in step S1 is replaced with 1.2g sodium acetate.

[0071] Example 8

[0072] The difference between this embodiment and embodiment 5 is that the 1.2g pyridine in step S1 is replaced with 1.9g diisopropylethylamine.

[0073] Example 9

[0074] The difference between this embodiment and embodiment 5 is that the 1.2g pyridine in step S1 is replaced with 0.6g sodium hydroxide.

[0075] Example 10

[0076] The difference between this embodiment and embodiment 5 is that the reaction temperature in step S2 is 70°C.

[0077] Example 11

[0078] The difference between this embodiment and embodiment 5 is that the reaction temperature in step S2 is 75°C.

[0079] Example 12

[0080] The difference between this embodiment and embodiment 5 is that the reaction temperature in step S2 is 80°C.

[0081] Example 13

[0082] The difference between this embodiment and embodiment 5 is that the reaction temperature in step S2 is 90°C.

[0083] Example 14

[0084] The difference between this embodiment and embodiment 5 is that the reaction temperature in step S2 is 95°C.

[0085] Example 15

[0086] The difference between this embodiment and embodiment 5 is that the reaction time in step S2 is 5 hours.

[0087] Example 16

[0088] The difference between this embodiment and embodiment 5 is that the reaction time in step S2 is 6 hours.

[0089] Example 17

[0090] The difference between this embodiment and embodiment 5 is that the reaction time in step S2 is 7 hours.

[0091] Example 18

[0092] The difference between this embodiment and embodiment 5 is that the reaction time in step S2 is 9 hours.

[0093] Example 19

[0094] The difference between this embodiment and embodiment 5 is that the reaction time in step S2 is 10 hours.

[0095] Table 1 is specially prepared to present the experimental data of Examples 1 to 19 more intuitively.

[0096] Table 1: Experimental data from Examples 1-19

[0097]

[0098]

[0099] Performance testing

[0100] The following performance tests were performed on the chiral luminescent molecule provided in Example 1.

[0101] I. Emission Spectroscopy Test: A steady-state / transient fluorescence spectrometer (FLS980) was used with an excitation wavelength of 350 nm and a test temperature of room temperature to test chiral luminescent molecules with different volume fractions.

[0102] II. Circular Dichroism (CD) Spectroscopy: A Chirascan circular dichroism spectrometer was used, with a scanning range of 200-800 nm. Chiral luminescent molecules were doped with the poorly suited solvent dichloromethane, and the fluorescence spectra of chiral luminescent molecules with different doping ratios were measured to determine their fluorescence properties.

[0103] III. Compound structure testing: A Bruker 400MHz superconducting nuclear magnetic resonance spectrometer was used, with deuterated chloroform as the solvent.

[0104] See Figure 1 and Figure 2 The fluorescence emission spectra showed that the fluorescence intensity of the R / S isomeric chiral luminescent molecules did not decrease with increasing aggregation degree, but rather increased. This indicates that the R / S isomeric chiral luminescent molecules all possess stable aggregation-induced emission (AIE) properties. Essentially, they utilize chiral characteristics to restrict intramolecular rotation (RIR), molecular planarization, and twisted intramolecular charge transfer (TICT), thereby significantly reducing energy consumption in the aggregated state and enhancing the luminescence of the system. These chiral luminescent molecules have applications in many important fields such as organic light-emitting diodes, sensors, and bioimaging.

[0105] See Figure 3 and Figure 4 Circular dichroism (CD) chromatogram results showed that both R / S isomeric chiral luminescent molecules exhibited characteristic CD peaks, with the R-type chiral molecules showing a positive CD peak and the S-type chiral molecules showing a weaker signal and a slightly negative CD signal. This indicates that the chirality of the menthol group in the chiral luminescent molecules was successfully transferred to the molecular backbone, giving the chiral luminescent molecules chiral characteristics.

[0106] See Figure 5 and Figure 6 It can be seen that the molecular proton spectrum peak energies correspond one-to-one with the target product, and the number is reasonable, indicating that the obtained product is an R / S isomer chiral luminescent molecule.

[0107] IV. Reaction Yield

[0108] The reaction yield is calculated as follows:

[0109] The reaction yield is calculated as follows: (Actual product amount / Theoretical maximum product amount) × 100%.

[0110] The reaction yields of Examples 1-19 were tested, and the test results are shown in Table 2.

[0111] Table 2: Reaction Yields of Examples 1-19

[0112]

[0113]

[0114] Referring to Tables 1 and 2, in Examples 1-5, the amount of palladium catalyst added was 0.5 mmol, and the molar ratio of menthyl chloroformate, 4-phenol-2,1,3-benzothiadiazole, and palladium catalyst was 1:1:0.05. The difference between Examples 1-5 was the use of different palladium catalysts. The test results show that different palladium catalysts affect the reaction yield. In Example 5, tetrakis(triphenylphosphine)palladium was selected as the catalyst, resulting in the highest reaction yield of 92.8%.

[0115] In addition, in Examples 5-9, the amount of acid-binding agent added was 1.5 mmol, and the molar ratio of menthyl chloroformate, 4-phenol-2,1,3-benzothiadiazole to the acid-binding agent was 1:1:0.15; the difference was that different acid-binding agents were used. The test results showed that pyridine was the optimal acid-binding agent, which could effectively promote the coupling reaction and improve the reaction yield.

[0116] Based on the test results of Examples 5, 10-14, it can be seen that different reaction temperatures affect the product yield. Both excessively high and low reaction temperatures will lead to a decrease in reaction yield. The optimal reaction temperature is 85°C. At this temperature, the coupling reaction can be effectively promoted while avoiding side reactions, thus improving the reaction yield.

[0117] Based on the test results of Examples 5 and 15-19, it can be seen that if the reaction time is too short, some raw materials will not be converted into the desired chiral luminescent molecules, leading to a decrease in reaction yield; while if the reaction time is too long, unnecessary side reactions will occur, generating byproducts, thus affecting the yield of the target product. Therefore, the reaction time of 8 hours in Example 5 is the optimal reaction time, with the highest reaction yield.

[0118] Based on a reasonable reaction mechanism and research foundation, this application optimizes the selection of reaction conditions, catalysts, and acid-binding agents to improve the reaction yield. This preparation method allows for the selective and efficient synthesis of chiral luminescent molecules, making it a more commonly used and sustainable synthetic route. Among all the embodiments, Example 5 is the optimal embodiment, using tetrakis(triphenylphosphine)palladium as the palladium catalyst, pyridine as the acid-binding agent, a reaction temperature of 85°C, and a reaction time of 8 hours, achieving a final reaction yield of 92.8%.

[0119] Compared with traditional methods such as alkylation, acylation, dehydration, and ring-opening, the preparation method of this application has a shorter reaction time and a higher reaction yield. Furthermore, the preparation method is simple to operate, the reaction is mild, and it can be carried out in a conventional laboratory, which can effectively reduce the cost of chiral luminescent molecules.

[0120] Application examples

[0121] Application Example 1

[0122] The method for preparing chiral luminescent liquid crystal provided in Application Example 1 includes the following steps:

[0123] An appropriate amount of 4'-n-pentyl-4-cyanobiphenyl was added to a flask and dissolved in dichloromethane. Then, chiral luminescent molecules were incorporated, with a mass ratio of 4'-n-pentyl-4-cyanobiphenyl to chiral luminescent molecules of 100:5. The mixture was stirred with ultrasonic assistance for 5 minutes to ensure that the chiral agent molecules were uniformly dispersed in the 4'-n-pentyl-4-cyanobiphenyl, thus obtaining a chiral luminescent liquid crystal.

[0124] The chiral luminescent molecule used is the chiral luminescent molecule improved in Example 1.

[0125] Application Examples 2-5

[0126] The difference between Application Examples 2-5 and Application Example 1 is that the ultrasound time is different.

[0127] Performance testing

[0128] V. Circular Dichroism Spectroscopy Test

[0129] A Chirascan circular dichroism spectrometer was used, with a scanning range of 200–800 nm. The chiral luminescent liquid crystal provided in Example 1 was tested, and chiral luminescent liquid crystals with different doping ratios were also tested. Specifically, the mass ratio of 4'-n-pentyl-4-cyanobiphenyl to chiral luminescent molecules was 100:0 (i.e., no chiral luminescent molecules), 100:1, 100:2, and 100:5. The test structure is shown in [reference needed]. Figures 7-8 .

[0130] VI. Polarizing Microscope Test: Using an Olympus BX53M polarizing microscope, with a sample detail size of 20 micrometers, view the polarizing microscope images of Application Examples 1-5 and measure the pitch of the liquid crystal fingerprint structure. Figure 9 Table 3 shows the test results of the pitch, based on the polarizing microscope images from Application Example 3.

[0131] Table 3: Pitch of liquid crystal fingerprint structures at different ultrasonic times

[0132] Ultrasound time (min) 5 10 20 30 40 Pitch (μm) 5.63 4.07 3.27 2.94 3.42

[0133] See Figures 7-8 Figure 1-5 shows chiral luminescent liquid crystals with a doping ratio of 100:5. The CD test results show that when the doping mass ratio is 100:5, the CD signal increases significantly, indicating that the system has the potential for strong circularly polarized emission and that chiral luminescent liquid crystals have been successfully constructed.

[0134] See Figure 9The results of polarized light microscopy of the chiral luminescent liquid crystal showed that the chiral molecules successfully induced the formation of the fingerprint structure, namely the cholesteric phase liquid crystal, which indicates that the nematic liquid crystal 5CB was successfully transformed into the cholesteric chiral luminescent liquid crystal.

[0135] Referring to Table 3, it can be seen that different ultrasonic times affect the pitch of the liquid crystal fingerprint structure, and the pitch affects the optical properties of the liquid crystal, including refractive index and optical rotation. Therefore, by adjusting the ultrasonic time, chiral luminescent liquid crystals with different pitches can be obtained, resulting in chiral luminescent liquid crystals with different optical properties, which can be applied to various fields such as 3D displays, optical sensors, and optoelectronic devices.

[0136] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for preparing a chiral luminescent molecule, characterized in that, Includes the following steps: S1: Menthyl chloroformate, 4-phenol-2,1,3-benzothiadiazole, palladium catalyst and acid-binding agent are added sequentially to a flask, wherein the molar ratio of menthyl chloroformate, 4-phenol-2,1,3-benzothiadiazole, palladium catalyst and acid-binding agent is 1:1:(0.03~0.08):(0.10~0.20). Then an organic solvent is added to dissolve the mixture, and the mixture is stirred thoroughly to obtain a mixture. S2: Inject the mixture from step S1 into a nitrogen-filled reactor, heat it to 70-95°C, react for 5-10 hours, separate and purify it to obtain chiral luminescent molecules; The menthyl chloroformate is an R / S isomer of menthyl chloroformate, and the structural formula of the chiral luminescent molecule is as follows: 。 2. The method for preparing chiral luminescent molecules according to claim 1, characterized in that, The palladium catalyst is selected from one of tetra(triphenylphosphine)palladium, palladium acetate, palladium chloride, bis(dibenzylideneacetone)palladium, and bis(tritert-butyl)palladium.

3. The method for preparing chiral luminescent molecules according to claim 1, characterized in that, The acid-binding agent is selected from one of pyridine, triethylamine, sodium acetate, diisopropylethylamine, and sodium hydroxide.

4. The method for preparing chiral luminescent molecules according to claim 1, characterized in that, The organic solvent is tetrahydrofuran.

5. The method for preparing chiral luminescent molecules according to claim 1, characterized in that, In step S2, column chromatography is used for separation and purification.

6. A chiral luminescent molecule, characterized in that, It is prepared by the method for preparing chiral luminescent molecules as described in any one of claims 1 to 5.

7. A chiral light-emitting liquid crystal, characterized in that, include: Nematic liquid crystal, chiral light-emitting molecules as described in claim 6; The method for preparing the chiral luminescent liquid crystal includes the following steps: The nematic liquid crystal is dissolved in dichloromethane, then chiral luminescent molecules are incorporated, and the mixture is homogenized by ultrasonication for 5–40 minutes to ensure that the chiral luminescent molecules are uniformly dispersed in the nematic liquid crystal, thus obtaining a chiral luminescent liquid crystal.

8. The chiral light-emitting liquid crystal according to claim 7, characterized in that, The nematic liquid crystal is 4'-n-pentyl-4-cyanobiphenyl.

9. The chiral light-emitting liquid crystal according to claim 7, characterized in that, The mass ratio of the nematic liquid crystal to the chiral luminescent molecule is 100:(1-5).

Images