Dibenzothiophene liquid crystal compound, preparation method therefor, and use thereof

Abstract

The present disclosure relates to a dibenzothiophene liquid crystal compound, a preparation method therefor, and use thereof. The liquid crystal compound provided by the present disclosure exhibits relatively large dielectric anisotropy, and also features a high clearing point, relatively high optical anisotropy, moderate rotational viscosity, and liquid crystal miscibility. Moreover, the liquid crystal compound exhibits excellent low-temperature operational performance, and has favorable properties such as good thermal stability, chemical stability, optical stability, and mechanical properties. Thus, the liquid crystal compound can effectively reduce the driving voltage of liquid crystal display devices to which it is applied, improve the response speed of the liquid crystal display devices, and also impart the liquid crystal display devices with a moderate optical anisotropy value, a high charge retention rate, and other characteristics.

Description

A diphenylthiophene liquid crystal compound, its preparation method and application

[0001] Cross-referencing

[0002] This application claims priority to Chinese Patent Application No. 202411820399.8, filed on December 11, 2024, entitled “A diphenylthiophene liquid crystal compound and its preparation method and application”, the entire disclosure of which is incorporated herein by reference. Technical Field

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

[0004] In recent years, LCD display devices have developed rapidly, resulting in various types such as small automotive LCD displays, portable LCD displays, and ultra-thin LCD displays. Taking televisions as an example, LCD display devices are characterized by their light weight, small footprint, and portability, as seen in laptops and mobile phones.

[0005] 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. Currently, TFT-LCD (Thin Film Transistor Liquid Crystal Display) 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 demands on display technology continue to increase, such as requiring liquid crystal displays to achieve faster response times, lower power consumption, wider temperature ranges, and better low-temperature stability.

[0006] Liquid crystal materials themselves play an important role in improving the performance of liquid crystal displays. Therefore, in order to improve the performance of liquid crystal displays, 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

[0007] To address the aforementioned technical problems, this disclosure provides a diphenylthiophene-based liquid crystal compound, its preparation method, and its applications.

[0008] In a first aspect, this disclosure provides a diphenylthiophene-based liquid crystal compound having a structure as shown in general formula I:

[0009] in:

[0010] R is H, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkyl group having 1 to 10 carbon atoms substituted with F, an alkoxy group having 1 to 10 carbon atoms substituted with F, an alkenyl group having 2 to 10 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms.

[0011] Z can be a single bond, -CH2-, -OCH2-CH2-, -O(CH2)3-, -O(CH2)4-, -COO-, -OOC-, -OCH2-, -CH2O-, -CF2O-, -OCF2-, -CF2CH2-, or -CH2CF2-. In this disclosure, a single bond can also be understood as Z not existing.

[0012] A is one of the following groups:

[0013] As a preferred embodiment of this disclosure, R is an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkyl group having 1 to 6 carbon atoms substituted with F, an alkoxy group having 1 to 6 carbon atoms substituted with F, an alkenyl group having 2 to 6 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms.

[0014] As a preferred embodiment of this disclosure, the alkyl group having 1 to 6 carbon atoms is methyl, ethyl, propyl, butyl, pentyl, or hexyl.

[0015] As a preferred embodiment of this disclosure, the propyl, butyl, pentyl, or hexyl groups are all straight-chain alkyl groups.

[0016] As a preferred embodiment of this disclosure, the alkoxy group having 1 to 6 carbon atoms is -OCH3, -OC2H5, -OC3H7, -OC4H9, or -OC5H. 11 -OC6H 13 .

[0017] As a preferred technical solution of this disclosure, -OC3H7, -OC4H9, and -OC5H 11 -OC6H 13 All are straight-chain alkoxy groups.

[0018] As a preferred embodiment of this disclosure, the alkenyl group having 2 to 6 carbon atoms is -CH=CH2, -CH2-CH=CH2, -C2H5-CH=CH2, -C3H6-CH=CH2, or -C4H8-CH=CH2.

[0019] As a preferred embodiment of this disclosure, -C2H5-CH=CH2, -C3H6-CH=CH2, and -C4H8-CH=CH2 are alkenyl groups with straight-chain terminal alkenyl groups.

[0020] As a preferred embodiment of this disclosure, the alkenyl group having 2 to 6 carbon atoms is -O-CH=CH2, -O-CH2-CH=CH2, -O-C2H5-CH=CH2, -O-C3H6-CH=CH2, or -O-C4H8-CH=CH2.

[0021] As a preferred embodiment of this disclosure, -O-C2H5-CH=CH2, -O-C3H6-CH=CH2, and -O-C4H8-CH=CH2 are straight-chain alkenyl groups.

[0022] As a preferred technical solution of this disclosure, the substitution site of F is not limited in this disclosure.

[0023] As a preferred technical solution of this disclosure, Z is -CH2-, -OCH2-CH2-, -O(CH2)3-, -O(CH2)4-, -COO-, -OOC-, -OCH2-, -CH2O-, -CF2O-, -OCF2-, -CF2CH2- or -CH2CF2-.

[0024] As a preferred embodiment of this disclosure, A is one of the following groups:

[0025] As a preferred embodiment of this disclosure, the diphenylthiophene liquid crystal compound is selected from any one of the following compounds:

[0026] Secondly, this disclosure provides a method for preparing the diphenylthiophene-based liquid crystal compound described in the first aspect, the method comprising the following steps:

[0027] (1) Compound A is metallized with lithium reagent and then reacted with borate ester to obtain compound B;

[0028] (2) Compound B and compound C were reacted via a suzuki reaction to obtain compound D;

[0029] (3) Compound D undergoes a substitution reaction with (CF3SO2)2O to obtain compound E;

[0030] (4) Compound E was reacted with ethyl mercaptopropionate to obtain compound F;

[0031] (5) Compound F undergoes cyclization under alkaline catalysis to obtain the diphenylthiophene liquid crystal compound.

[0032] The preparation method provided in this disclosure can obtain the liquid crystal compound described in this disclosure more stably and efficiently.

[0033] In this disclosure, those skilled in the art can use conventional post-processing methods as needed when using the above preparation method.

[0034] As a preferred technical solution of this disclosure, the conventional post-processing includes: extraction with dichloromethane, ethyl acetate or toluene, separation, washing with water, drying, evaporation in a vacuum rotary evaporator, and purification of the obtained product by vacuum distillation or recrystallization and / or chromatographic separation.

[0035] The preparation method provided in this disclosure includes the following examples of preparation routes:

[0036] Thirdly, this disclosure provides a liquid crystal composition comprising the diphenylthiophene liquid crystal compound described in the first aspect.

[0037] As a preferred embodiment of this disclosure, the diphenylthiophene liquid crystal compound has a mass percentage content of 0.1-60% in the liquid crystal composition, preferably 0.1-50%, more preferably 0.1-40%, for example 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, etc.

[0038] Fourthly, this disclosure provides an application of the diphenylthiophene liquid crystal compound described in the first aspect or the liquid crystal composition described in the third aspect in the field of liquid crystal displays.

[0039] As a preferred technical solution of this disclosure, the application is in a liquid crystal display device.

[0040] As a preferred technical solution of this disclosure, the liquid crystal display device includes, but is not limited to, VA (Vertical Alignment), TN (Twisted Nematic), STN (Super-twisted Nematic), FFS (Fringing Field Switching), or IPS (In Plane Switching) liquid crystal displays.

[0041] The technical solution provided in this disclosure has the following advantages compared with the prior art:

[0042] (1) The diphenylthiophene liquid crystal compound provided in this disclosure has large dielectric anisotropy, high brightness, relatively high optical anisotropy, moderate rotational viscosity and liquid crystal miscibility, excellent low-temperature performance, and good thermal stability, chemical stability, optical stability and mechanical properties.

[0043] (2) The application of the diphenylthiophene liquid crystal compound provided in this disclosure can effectively reduce the driving voltage and improve the response speed of the liquid crystal display device. At the same time, it has the characteristics of moderate optical anisotropy and high charge retention rate. Detailed Implementation

[0044] To better understand the above-mentioned objectives, features, and advantages of this disclosure, the solutions disclosed herein will be further described below. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0045] Numerous specific details are set forth in the following description in order to provide a full understanding of this disclosure, but this disclosure may also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only some, and not all, of the embodiments of this disclosure.

[0046] In the following embodiments, unless otherwise specified, all raw materials used are available from publicly available commercial sources.

[0047] For the performance testing of the following liquid crystal materials, the various performance parameters of the liquid crystal compounds were obtained by linear fitting according to conventional testing methods in this field. The specific meanings of each performance parameter are as follows:

[0048] Δn represents optical anisotropy (25℃); Δε represents dielectric anisotropy (25℃, 1000Hz); γ1 represents rotational viscosity (mPa·s, 25℃).

[0049] Example 1

[0050] This embodiment provides a diphenylthiophene-based liquid crystal compound with the following structural formula:

[0051] The synthesis route is as follows:

[0052] (1) Synthesis of compound BYLC-01-1:

[0053] Under nitrogen protection, 62 g (0.261 mol) was added to the reaction flask. 150 mL of tetrahydrofuran was added dropwise to a 0.45 mol n-butyllithium solution in hexane at a controlled temperature of -70 to -80 °C. After the addition was complete, the reaction was carried out at a controlled temperature for 1 hour. Then, 48.0 g of trimethyl borate (0.45 mol) was added dropwise at a controlled temperature of -60 to -70 °C, and the mixture was allowed to cool naturally to -30 °C. The mixture was then acidified with 400 mL of 2M hydrochloric acid aqueous solution. After routine post-treatment, recrystallization from petroleum ether yielded 66.2 g of a pale yellow solid (compound BYLC-01-1, 0.235 mol), HPLC: 99.5%, yield: 90%.

[0054] (2) Synthesis of compound BYLC-01-2

[0055] Under nitrogen protection, 66.2 g (0.235 mol) of compound BYLC-01-1 and 81.1 g (0.235 mol) of compound were added to the reaction flask. 200 ml N,N-dimethylformamide, 100 ml deionized water, 72.8 g anhydrous potassium carbonate (0.53 mol), and 0.5 g tetrakis(triphenylphosphine) palladium were added and heated to 70 °C for 3 hours. Post-treatment: chromatographic purification was performed, followed by elution with n-hexane and recrystallization from ethanol to give 100.5 g of a white solid (compound BYLC-01-2, 0.2 mol), GC: 99.8%, yield: 85%.

[0056] (3) Synthesis of compound BYLC-01-3

[0057] 100.5 g of compound BYLC-01-2 (0.2 mol), 0.3 g of succinic acid, 13.4 g of Et3N, and 180 ml of dichloromethane were added to a 500 ml three-necked flask. The mixture was stirred, protected with N2, and the temperature was controlled at 5–10 °C. 85 g of (CF3SO2)2O (0.300 mol) was added dropwise. After the addition was complete, the mixture was stirred naturally overnight. The reaction solution was washed twice with water (200 ml × 2), dried over anhydrous sodium sulfate, passed through a 40 g silica gel column, and evaporated to dryness to obtain 114.2 g of a white solid (compound BYLC-01-3, 0.18 mol), GC: 99.8%, yield: 90%.

[0058] (4) Synthesis of compound BYLC-01-4

[0059] Under nitrogen protection, 114.2 g of compound BYLC-01-3 (0.18 mol), 28 g of ethyl mercaptopropionate, 26 g of N,N-diisopropylethylamine, 0.7 g of 2-dicyclohexylphosphine-2,4,6-triisopropylbiphenyl, 0.7 g of tris(dibenzylacetone)dipalladium, and 280 mL of dioxane were added to a reaction flask. The reaction was carried out at 100℃~105℃ for 6 hours. After routine post-treatment, the mixture was purified by chromatography and eluted with n-hexane to give 89.1 g of a pale yellow liquid (compound BYLC-01-4), GC: 95.8%, yield: 80%.

[0060] (5) Synthesis of compound BYLC-01

[0061] Under nitrogen protection, 89.1 g of compound BYLC-01-4 (0.144 mol), 200 ml of N,N-dimethylformamide, and 32 g of potassium tert-butoxide were added to a reaction flask. The reaction was carried out at 130–140 °C for 4 hours. The reaction was monitored by TLC until it was complete. After routine post-treatment, the product was purified by chromatography, eluted with n-hexane, and recrystallized from ethanol to give 49.8 g of white solid (compound BYLC-01, 0.1 mol), GC: 99.9%, yield 70%.

[0062] The obtained white solid BYLC-01 was analyzed by GC-MS, and the m / z of the product was 498 (M+).

[0063] Example 2

[0064] This embodiment provides a diphenylthiophene-based liquid crystal compound with the following structural formula:

[0065] The preparation method was the same as in Example 1. The obtained white solid BYLC-02 was analyzed by GC-MS, and the m / z of the product was 484 (M+).

[0066] Example 3

[0067] This embodiment provides a diphenylthiophene-based liquid crystal compound with the following structural formula:

[0068] The preparation method was the same as in Example 1. The obtained white solid BYLC-03 was analyzed by GC-MS, and the m / z of the product was 482 (M+).

[0069] Example 4

[0070] This embodiment provides a diphenylthiophene-based liquid crystal compound with the following structural formula:

[0071] The preparation method was the same as in Example 1. The obtained white solid BYLC-04 was analyzed by GC-MS, and the m / z of the product was 496 (M+).

[0072] Example 5

[0073] This embodiment provides a diphenylthiophene-based liquid crystal compound with the following structural formula:

[0074] The preparation method was the same as in Example 1. The obtained white solid BYLC-05 was analyzed by GC-MS, and the m / z of the product was 442 (M+).

[0075] Example 6

[0076] This embodiment provides a diphenylthiophene-based liquid crystal compound with the following structural formula:

[0077] The preparation method was the same as in Example 1. The obtained white solid BYLC-06 was analyzed by GC-MS, and the m / z of the product was 428 (M+).

[0078] Example 7

[0079] This embodiment provides a diphenylthiophene-based liquid crystal compound with the following structural formula:

[0080] The preparation method was the same as in Example 1. The obtained white solid BYLC-07 was analyzed by GC-MS, and the m / z of the product was 500 (M+).

[0081] Example 8

[0082] This embodiment provides a diphenylthiophene-based liquid crystal compound with the following structural formula:

[0083] The preparation method was the same as in Example 1. The obtained white solid BYLC-08 was analyzed by GC-MS, and the m / z of the product was 486 (M+).

[0084] Example 9

[0085] This embodiment provides a diphenylthiophene-based liquid crystal compound with the following structural formula:

[0086] The preparation method was the same as in Example 1. The obtained white solid BYLC-09 was analyzed by GC-MS, and the m / z of the product was 482 (M+).

[0087] Example 10

[0088] This embodiment provides a diphenylthiophene-based liquid crystal compound with the following structural formula:

[0089] The preparation method was the same as in Example 1. The obtained white solid BYLC-10 was analyzed by GC-MS, and the m / z of the product was 396 (M+).

[0090] Comparative Example

[0091] This comparative example provides a diphenylthiophene-based liquid crystal compound with the following structural formula:

[0092] Performance testing:

[0093] The performance of the liquid crystal compounds provided in the examples and comparative examples was tested according to conventional testing methods in the art, as follows:

[0094] (1) γ1: Measured using a viscometer;

[0095] (2) Δn: Measured using an Abbe refractometer;

[0096] (3) Δε: Tested using an INSTEC liquid crystal testing instrument;

[0097] The performance parameters of the liquid crystal compound were obtained by linear fitting. The specific meanings of each performance parameter are as follows, and the results are shown in Table 1:

[0098] Δn represents optical anisotropy (25℃); Δε represents dielectric anisotropy (25℃, 1000Hz); γ1 represents rotational viscosity (mPa·s, 25℃).

[0099] Table 1

[0100] Performance tests show that the liquid crystal compound provided in this disclosure has greater negative dielectric anisotropy and lower rotational viscosity.

[0101] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0102] The above description is merely a specific embodiment of this disclosure, enabling those skilled in the art to understand or implement it. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not to be limited to the embodiments described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A diphenylthiophene-based liquid crystal compound, characterized in that, It has a structure as shown in general formula I: in: R is H, alkyl with 1 to 10 carbon atoms, alkoxy with 1 to 10 carbon atoms, alkyl with 1 to 10 carbon atoms substituted by F, alkoxy with 1 to 10 carbon atoms substituted by F, alkenyl or alkenyloxy with 2 to 10 carbon atoms. Z is a single bond, -CH2-, -OCH2-CH2-, -O(CH2)3-, -O(CH2)4-, -COO-, -OOC-, -OCH2-, -CH2O-, -CF2O-, -OCF2-, -CF2CH2- or -CH2CF2-; A is one of the following groups:

2. The diphenylthiophene liquid crystal compound according to claim 1, characterized in that, R is an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkyl group having 1 to 6 carbon atoms substituted with F, an alkoxy group having 1 to 6 carbon atoms substituted with F, an alkenyl group having 2 to 6 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms.

3. The diphenylthiophene liquid crystal compound according to claim 1, characterized in that, Z can be -CH2-, -OCH2-CH2-, -O(CH2)3-, -O(CH2)4-, -COO-, -OOC-, -OCH2-, -CH2O-, -CF2O-, -OCF2-, -CF2CH2-, or -CH2CF2-.

4. The diphenylthiophene liquid crystal compound according to claim 1, characterized in that, A is one of the following groups:

5. The diphenylthiophene liquid crystal compound according to any one of claims 1-4, characterized in that, The diphenylthiophene-based liquid crystal compound is selected from any one of the following compounds:

6. The method for preparing the diphenylthiophene liquid crystal compound according to any one of claims 1-5, characterized in that, The preparation method includes the following steps: (1) Compound A is metallized with lithium reagent and then reacted with borate ester to obtain compound B; (2) Compound B and compound C were reacted via a suzuki reaction to obtain compound D; (3) Compound D undergoes a substitution reaction with (CF3SO2)2O to obtain compound E; (4) Compound E was reacted with ethyl mercaptopropionate to obtain compound F; (5) Compound F undergoes cyclization under alkaline catalysis to obtain the diphenylthiophene liquid crystal compound.

7. A liquid crystal composition, characterized in that, The liquid crystal composition contains a diphenylthiophene liquid crystal compound as described in any one of claims 1-5.

8. The liquid crystal composition according to claim 7, characterized in that, The diphenylthiophene-based liquid crystal compound has a mass percentage content of 0.1-40% in the liquid crystal composition.

9. The application of the diphenylthiophene liquid crystal compound of any one of claims 1-5 or the liquid crystal composition of claim 7 or 8 in the field of liquid crystal displays.

10. The application according to claim 9, characterized in that, The application is in a liquid crystal display device.

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