Liquid crystal compound, preparation method therefor, and use thereof

Abstract

The present invention relates to the technical field of liquid crystal display materials, and in particular to a liquid crystal compound, a preparation method therefor, and a use thereof. The liquid crystal compound has a structure represented by the following general formula I: Formula (I). The liquid crystal compound having a specific structure of the present invention has advantages such as high dielectric anisotropy and good liquid crystal intersolubility. When the liquid crystal compound of the present invention is specifically applied to a liquid crystal composition, the dielectric anisotropy Δε of the liquid crystal composition can be significantly improved, and at the same time, appropriate refractive index anisotropy Δn is maintained. The obtained liquid crystal composition has significant fast response and low-voltage driving characteristics.

Description

A liquid crystal compound, its preparation method and application

[0001] Cross-referencing

[0002] This application claims priority to Chinese Patent Application No. 202411172611.4, filed on August 26, 2024, entitled “A liquid crystal compound and its preparation method and application,” the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] This invention relates to the field of liquid crystal display materials technology, and in particular to a liquid crystal compound, its preparation method, and its application. Background Technology

[0004] Liquid crystal materials, as environmentally friendly materials, have significant research value and promising application prospects in fields such as information display materials and organic optoelectronic materials. As a novel display material, liquid crystal materials offer numerous advantages, such as extremely low power consumption and low driving voltage. Compared to other materials, they also possess advantages such as small size, light weight, long lifespan, large display information capacity, and no electromagnetic radiation, making them suitable for almost all information display requirements, especially in TFT-LCD (Thin Film Transistor) products.

[0005] Liquid crystal materials require good chemical and thermal stability, good stability to electric fields and electromagnetic radiation, a wide nematic phase temperature range, appropriate refractive index and dielectric anisotropy, fast response speed and high voltage retention rate.

[0006] Currently, TFT-LCD technology is mature, successfully solving technical challenges such as viewing angle, resolution, color saturation, and brightness. Large-size and small-to-medium-size TFT-LCD displays have gradually become the mainstream flat panel displays in their respective fields. However, the requirements for display technology are constantly increasing, demanding faster response times and lower driving voltages to reduce power consumption. With the development of display technology, higher requirements are also being placed on liquid crystal materials, especially in terms of fast response times, reduced driving voltage, and lower power consumption.

[0007] To improve the properties of materials and adapt them to new requirements, the synthesis of novel liquid crystal compounds and the study of structure-property relationships have become an important task in the field of liquid crystals. Summary of the Invention

[0008] This invention provides a liquid crystal compound, its preparation method, and its application. The liquid crystal compound has advantages such as high dielectric anisotropy and good liquid crystal miscibility, and has important application value.

[0009] According to a first aspect of the present invention, a liquid crystal compound is provided having the structure shown in general formula I:

[0010] Wherein, R1 represents H, an alkyl group of 1-12 carbon atoms, or an alkoxy group of 1-12 carbon atoms, wherein one or more hydrogen atoms in the alkyl group of 1-12 carbon atoms or the alkoxy group of 1-12 carbon atoms may optionally be substituted with a halogen, and one or more -CH2- may be independently replaced by -C≡C-, -CH=CH-, -CF=CF-, -CF=CH-, -COO-, -OCO-, or -O- in such a way that the O atoms are not directly connected to each other;

[0011] Ring A and ring B each independently represent 1,4-phenylene, 1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene with 1-4 hydrogen atoms substituted by fluorine atoms, cycloalkyl with 3-6 carbon atoms, or cycloalkenyl with 3-6 carbon atoms; wherein one or more hydrogen atoms in the cycloalkyl or cycloalkenyl with 3-6 carbon atoms may optionally be substituted by fluorine atoms;

[0012] m is 0, 1, or 2, n is 0 or 1, and m and n are not both 0.

[0013] The liquid crystal compounds of this invention have advantages such as high dielectric anisotropy and good liquid crystal miscibility. When the liquid crystal compounds of this invention are specifically applied to conventional liquid crystal compositions, the dielectric anisotropy Δε of the liquid crystal composition can be significantly improved while maintaining an appropriate refractive index anisotropy Δn. The resulting liquid crystal composition has significant fast response characteristics and low voltage driving characteristics.

[0014] To further improve the performance of the liquid crystal compound, R1 further represents H or an alkyl group having 1-5 carbon atoms or an alkoxy group having 1-5 carbon atoms; ring A and ring B each independently represent 1,4-phenylene, 1,4-cyclohexylene or 1,4-phenylene with 1-4 hydrogen atoms substituted by fluorine atoms.

[0015] To further improve the performance of the liquid crystal compound, the liquid crystal compound is further selected from one of the following compounds:

[0016] According to a second aspect of the present invention, the present invention also provides a method for preparing the above-mentioned liquid crystal compound, the synthetic route of which is as follows:

[0017] Specifically, the steps include the following:

[0018] Step (1): By reacting the first organolithium reagent with the methyl reagent, we obtain Step (2): The reaction with a second organolithium reagent, followed by a reaction with a borate ester, yields...

[0019] Step (3): Through an oxidation reaction with an oxidizing agent, we obtain

[0020] Step (4): with The result obtained in step (3) The reactants react to obtain

[0021] In this context, the R1, m, n, ring A, and ring B in the compounds involved in each step correspond to the groups represented by R1, m, n, ring A, and ring B in the liquid crystal compound.

[0022] In the above scheme, the preparation method of the liquid crystal compound of the present invention uses readily available raw materials, includes four synthetic reaction steps, each synthetic reaction is easy to control, the whole preparation method is simple and widely applicable.

[0023] Furthermore, in step (1), The molar ratio of the first organolithium reagent to the methyl reagent is 1:(1.0~1.8):(1.0~2.0), and the reaction temperature is -50~-100℃;

[0024] Wherein, the first organolithium reagent is selected from one or more of n-butyllithium, sec-butyllithium, tert-butyllithium, or n-butyllithium and potassium tert-butoxide; the methyl reagent is selected from one or more of iodomethane, bromomethane, dimethyl carbonate, or dimethyl sulfate.

[0025] In the above scheme, by reasonably controlling the types and amounts of each raw material in step (1) and the reaction, it is beneficial to improve the reaction efficiency.

[0026] Furthermore, in step (2), The molar ratio of the second organolithium reagent to the borate ester is 1:(1.0~1.8):(1.0~2.0), and the reaction temperature is -50~-100℃;

[0027] The second organolithium reagent is selected from one or more of n-butyllithium, sec-butyllithium, tert-butyllithium, or n-butyllithium and potassium tert-butoxide; the borate ester is selected from one or more of trimethyl borate, triisopropyl borate, tributyl borate, or triisobutyl borate.

[0028] In the above scheme, by reasonably controlling the types and amounts of each raw material in step (2) and the reaction, it is beneficial to improve the reaction efficiency.

[0029] Furthermore, in step (3), The molar ratio of the oxidant to the oxidant is 1:(1.0~4.0), and the reaction temperature is 40~80℃; the oxidant is selected from hydrogen peroxide or m-chloroperoxybenzoic acid, preferably hydrogen peroxide.

[0030] In the above scheme, by reasonably controlling the types and amounts of each raw material in step (3) and the reaction, it is beneficial to improve the reaction efficiency.

[0031] Furthermore, in step (4), and The reaction occurs under the action of a dehydrating agent, yielding...

[0032] in, The molar ratio of the dehydrating agent to the dehydrating agent is 1:(1.0~2.0):(1.0~3.0), and the reaction temperature is -10~50℃; preferably, the dehydrating agent is N,N'-diisopropylcarbodiimide.

[0033] In the above scheme, by reasonably controlling the types and amounts of each raw material in step (4) and the reaction, it is beneficial to improve the reaction efficiency.

[0034] The preparation method described in this invention may involve conventional post-processing when necessary. Specific conventional post-processing includes: extraction with dichloromethane, ethyl acetate, or toluene; separation; washing with water; drying; evaporation using a vacuum rotary evaporator; and purification of the obtained product by vacuum distillation, recrystallization, and / or chromatographic separation.

[0035] The liquid crystal compound described in this invention can be obtained stably and efficiently using the above preparation method.

[0036] According to a third aspect of the present invention, the present invention also provides a liquid crystal composition comprising the above-described liquid crystal compound; wherein the liquid crystal compound accounts for 1 to 60% by mass of the liquid crystal composition, preferably 3 to 50%, more preferably 5 to 25%.

[0037] According to a fourth aspect of the invention, the invention also provides the use of the above-described liquid crystal compound in a liquid crystal display device. Optionally, the liquid crystal display device includes, but is not limited to, TN, ADS, VA, PSVA, FFS, or IPS liquid crystal displays.

[0038] The present invention provides a liquid crystal compound that, by using the liquid crystal compound or a composition containing the liquid crystal compound, exhibits extremely high negative dielectric anisotropy and low rotational viscosity, thereby effectively reducing the driving voltage and improving the response speed of the liquid crystal display device. It also has the characteristics of moderate optical anisotropy and high charge retention rate. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0040] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the invention.

[0041] Unless otherwise specified, all raw materials are available from publicly available commercial sources.

[0042] Following conventional testing methods in this field, various performance parameters of the liquid crystal compound were obtained through linear fitting. The specific meanings of each performance parameter are as follows:

[0043] △n represents optical anisotropy (25℃); △ε represents dielectric anisotropy (25℃, 1000Hz); γ1 represents rotational viscosity (mPa.s, 25℃); CP represents clearing point (℃).

[0044] Example 1

[0045] This embodiment provides a liquid crystal composition with the following structural formula:

[0046] The synthetic route for preparing compound BYLC-01 is shown below:

[0047] The specific steps are as follows:

[0048] (1) Synthesis of compound BYLC-01-1:

[0049] Under nitrogen protection, 40.0 g of 2-fluoro-4-bromobenzonitrile and 280 ml of tetrahydrofuran were added to the reaction flask. A 0.24 mol n-butyllithium solution in n-hexane was added dropwise at -70 to -80 °C. After the addition was complete, the reaction was maintained at this temperature for 1 hour. Then, 38.3 g of iodomethane was added dropwise at -70 to -80 °C, and the mixture was allowed to cool naturally to -30 °C. 300 ml of saturated sodium bisulfite aqueous solution was added for hydrolysis. After routine post-treatment, column chromatography purification yielded 38.5 g of a pale yellow liquid (compound BYLC-01-1), GC: 98.5%, yield 90%.

[0050] (2) Synthesis of compound BYLC-01-2:

[0051] Under nitrogen protection, 32.0 g of BYLC-01-1 and 150 ml of tetrahydrofuran were added to the reaction flask. A 0.18 mol n-butyllithium solution in n-hexane was added dropwise at -70 to -80 °C. After the addition was complete, the reaction was maintained at this temperature for 1 hour. Then, 23.4 g of trimethyl borate was added dropwise at -70 to -80 °C, and the mixture was allowed to cool naturally to -30 °C. The mixture was acidified with 300 ml of 2M hydrochloric acid aqueous solution, and after routine post-treatment, recrystallized from petroleum ether to obtain 23.6 g of a pale yellow solid (compound BYLC-01-2). HPLC: 98.5%, yield 88%.

[0052] (3) Synthesis of compound BYLC-01-3:

[0053] 23.2 g of compound BYLC-01-2 and 100 mL of tetrahydrofuran were added to a reaction flask, and 0.26 mol of hydrogen peroxide was added dropwise under reflux. After the addition was complete, the mixture was refluxed for 1 hour. After routine post-processing, 18.6 g of a pale pink solid (compound BYLC-01-3) was obtained, with a GC content of 99.2% and a yield of 95%.

[0054] (4) Synthesis of compound BYLC-01:

[0055] Under nitrogen protection, 18.1 g of compound BYLC-01-3, 18.7 g of ethylcyclohexylcarboxylic acid, 3 g of 4-dimethylaminopyridine, and 100 ml of dichloromethane were added to a reaction flask. 17.7 g of DIC was added dropwise at a controlled temperature of -5 to 5 °C. After the addition was complete, the reaction was maintained at this temperature for 0.5 hours, then allowed to rise naturally to room temperature for 3 hours. The reaction was quenched with 100 ml of water, and the reaction was followed by routine post-treatment to obtain 29.6 g of a white solid (compound BYLC-01), GC: 99.6%, yield 85.4%.

[0056] The obtained white solid BYLC-01 was analyzed by GC-MS, and the m / z of the product was 289.1 (M+).

[0057] 1H-NMR (300MHz, CDCl3): 0.85-1.90 (m, 14H), 2.15-2.94 (m, 4H), 7.10-7.85 (m, 2H).

[0058] Example 2

[0059] This embodiment provides a liquid crystal composition with the following structural formula:

[0060] The synthetic route for preparing compound BYLC-02 is shown below:

[0061] The specific steps are as follows:

[0062] Synthesis of compound BYLC-02:

[0063] Under nitrogen protection, 30.2 g of compound BYLC-01-3, 47.6 g of ethyl dicyclohexylcarboxylic acid, 3.6 g of 4-dimethylaminopyridine, and 150 ml of dichloromethane were added to a reaction flask. 28.5 g of DIC was added dropwise at a controlled temperature of -5 to 5 °C. After the addition was complete, the reaction was maintained at this temperature for 0.5 hours, then allowed to rise naturally to room temperature for 3 hours. The reaction was quenched with 200 ml of water, and after routine post-treatment, 63.9 g of a white solid (compound BYLC-02) was obtained, with a GC content of 99.7% and a yield of 86.2%.

[0064] The obtained white solid BYLC-02 was analyzed by GC-MS, and the m / z of the product was 371.1 (M+).

[0065] 1H-NMR (300MHz, CDCl3): 0.85-1.90 (m, 24H), 2.15-2.94 (m, 4H), 7.10-7.85 (m, 2H).

[0066] Example 3

[0067] This embodiment provides a liquid crystal composition with the following structural formula:

[0068] The synthetic route for preparing compound BYLC-03 is shown below:

[0069] The specific steps are as follows:

[0070] Synthesis of compound BYLC-03:

[0071] Under nitrogen protection, 22.6 g of compound BYLC-01-3, 36.9 g of propylcyclohexylbenzoic acid, 2.7 g of 4-dimethylaminopyridine, and 150 ml of dichloromethane were added to a reaction flask. 26.0 g of DIC was added dropwise at a controlled temperature of -5 to 5 °C. After the addition was complete, the reaction was maintained at this temperature for 0.5 hours, then allowed to rise naturally to room temperature for 3 hours. The reaction was quenched with 200 ml of water, and the reaction was post-treated according to standard procedures to obtain 50.3 g of a white solid (compound BYLC-03), GC: 99.5%, yield 88.5%.

[0072] The obtained white solid BYLC-03 was analyzed by GC-MS, and the m / z of the product was 379.1 (M+).

[0073] 1 H-NMR (300MHz, CDCl3): 0.85-1.90(m,16H), 2.15-2.94(m,4H), 7.10-7.85(m,4H), 7.95-8.95(m,2H).

[0074] Based on the technical solutions of Examples 1 and 2, the following liquid crystal compounds can be synthesized simply by replacing the corresponding raw materials without changing any substantial operations.

[0075] Example 4

[0076] This embodiment provides a liquid crystal composition with the following structural formula:

[0077] The obtained white solid BYLC-04 was analyzed by GC-MS, and the m / z of the product was 293.1 (M+).

[0078] 1 H-NMR (300MHz, CDCl3): 0.85-1.90 (m, 12H), 2.15-2.94 (m, 4H), 7.10-7.85 (m, 1H).

[0079] Example 5

[0080] This embodiment provides a liquid crystal composition with the following structural formula:

[0081] The obtained white solid BYLC-05 was analyzed by GC-MS, and the m / z of the product was 297.1 (M+).

[0082] 1 H-NMR (300MHz, CDCl3): 0.85-1.90(m,5H), 2.15-2.94(m,5H), 6.75-7.75(m,4H), 7.95-8.75(m,2H).

[0083] Example 6

[0084] This embodiment provides a liquid crystal composition with the following structural formula:

[0085] The obtained white solid BYLC-06 was analyzed by GC-MS, and the m / z of the product was 385.1 (M+).

[0086] 1 H-NMR (300MHz, CDCl3): 0.85-1.90 (m, 26H), 2.15-2.94 (m, 4H), 7.10-7.85 (m, 2H).

[0087] Comparative Example 1

[0088] This comparative example provides a liquid crystal composition with the following structural formula:

[0089] Comparative Example 2

[0090] This comparative example provides a liquid crystal composition with the following structural formula:

[0091] Experimental Example 1

[0092] The performance parameter data of the liquid crystal compounds in Examples 1-6, Comparative Examples 1 and 2 were compared and compiled, and the test results are shown in Table 1:

[0093] Table 1: Performance test results of liquid crystal compounds

[0094] As can be clearly seen from the test results in Table 1, the liquid crystal compound provided by the present invention has the advantage of large dielectric anisotropy.

[0095] Experiment Example 2

[0096] The liquid crystal compounds of Example 2 and Comparative Example 2 were added to the liquid crystal composition BYHJ-1 at a weight ratio of 8%, respectively. The composition of the liquid crystal composition BYHJ-1 is shown in Table 2 below, resulting in liquid crystal compositions BYHJ-11 and BYHJ-22.

[0097] Table 2 Weight percentage of each component in the BYHJ-1 liquid crystal composition

[0098] The solubility of the above liquid crystal compositions BYHJ-11 and BYHJ-22 ​​was tested respectively, and the test results are shown in Table 3:

[0099] Table 3: Solubility test results of liquid crystal compositions

[0100] As can be clearly seen from the test results in Table 3, the liquid crystal compound provided by the present invention has better solubility in liquid crystal compositions compared with traditional compounds with similar chemical structures.

[0101] As can be clearly seen from the test results in Tables 1 and 3, the liquid crystal compound provided by the present invention has the characteristics of large dielectric anisotropy, good mutual solubility and stable performance compared with traditional compounds with similar chemical structures. When applied to liquid crystal compositions, it can reduce the driving voltage of devices and has broad application prospects.

[0102] Furthermore, when the liquid crystal compound provided by this invention is specifically applied to liquid crystal compositions in conventional systems, it is found that it can significantly improve the dielectric anisotropy Δε of the liquid crystal composition while maintaining an appropriate refractive index anisotropy Δn. The resulting liquid crystal composition has significant fast response characteristics and low voltage driving characteristics.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A liquid crystal compound, characterized in that, It has the structure shown in general formula I: Wherein, R1 represents H, an alkyl group of 1-12 carbon atoms, or an alkoxy group of 1-12 carbon atoms, wherein one or more hydrogen atoms in the alkyl group of 1-12 carbon atoms or the alkoxy group of 1-12 carbon atoms may optionally be substituted with a halogen, and one or more -CH2- may be independently replaced by -C≡C-, -CH=CH-, -CF=CF-, -CF=CH-, -COO-, -OCO-, or -O- in such a way that the O atoms are not directly connected to each other; Ring A and ring B each independently represent 1,4-phenylene, 1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene with 1-4 hydrogen atoms substituted by fluorine atoms, cycloalkyl with 3-6 carbon atoms, or cycloalkenyl with 3-6 carbon atoms; wherein one or more hydrogen atoms in the cycloalkyl or cycloalkenyl with 3-6 carbon atoms may optionally be substituted by fluorine atoms; m is 0, 1, or 2, n is 0 or 1, and m and n are not both 0.

2. The liquid crystal compound according to claim 1, characterized in that, R1 represents H or an alkyl group having 1-5 carbon atoms or an alkoxy group having 1-5 carbon atoms; ring A and ring B each independently represent 1,4-phenylene, 1,4-cyclohexylene or 1,4-phenylene with 1-4 hydrogen atoms substituted by fluorine atoms.

3. The liquid crystal compound according to claim 1, characterized in that, The liquid crystal compound is selected from one of the following compounds:

4. The method for preparing the liquid crystal compound according to any one of claims 1-3, characterized in that, The synthesis route is as follows: Specifically, the steps include the following: Step (1): By reacting the first organolithium reagent with the methyl reagent, we obtain Step (2): The reaction with a second organolithium reagent, followed by a reaction with a borate ester, yields... Step (3): Through an oxidation reaction with an oxidizing agent, we obtain Step (4): with The result obtained in step (3) The reactants react to obtain In this context, the R1, m, n, ring A, and ring B in the compounds involved in each step correspond to the groups represented by R1, m, n, ring A, and ring B in the liquid crystal compound.

5. The preparation method according to claim 4, characterized in that, In step (1), The molar ratio of the first organolithium reagent to the methyl reagent is 1:(1.0~1.8):(1.0~2.0), and the reaction temperature is -50~-100℃; Wherein, the first organolithium reagent is selected from one or more of n-butyllithium, sec-butyllithium, tert-butyllithium, or n-butyllithium and potassium tert-butoxide; the methyl reagent is selected from one or more of iodomethane, bromomethane, dimethyl carbonate, or dimethyl sulfate.

6. The preparation method according to claim 4, characterized in that, In step (2), The molar ratio of the second organolithium reagent to the borate ester is 1:(1.0~1.8):(1.0~2.0), and the reaction temperature is -50~-100℃; The second organolithium reagent is selected from one or more of n-butyllithium, sec-butyllithium, tert-butyllithium, or n-butyllithium and potassium tert-butoxide; the borate ester is selected from one or more of trimethyl borate, triisopropyl borate, tributyl borate, or triisobutyl borate.

7. The preparation method according to claim 4, characterized in that, In step (3), The molar ratio of the oxidant to the oxidant is 1:(1.0~4.0), and the reaction temperature is 40~80℃; the oxidant is selected from hydrogen peroxide or m-chloroperoxybenzoic acid, preferably hydrogen peroxide.

8. The preparation method according to claim 4, characterized in that, In step (4), and The reaction occurs under the action of a dehydrating agent, yielding... in, The molar ratio of the dehydrating agent to the dehydrating agent is 1:(1.0~2.0):(1.0~3.0), and the reaction temperature is -10~50℃; preferably, the dehydrating agent is N,N'-diisopropylcarbodiimide.

9. A liquid crystal composition, characterized in that, The liquid crystal compound comprises any one of claims 1-3; the liquid crystal compound accounts for 1-60% of the mass percentage of the liquid crystal composition, preferably 3-50%, more preferably 5-25%.

10. The use of the liquid crystal compound according to any one of claims 1-3 in a liquid crystal display device.

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