WO2022000982A1 - Liquid crystal compound containing dibenzothiophene structure and use thereof - Google Patents

Abstract

The invention relates to a liquid crystal compound and the application field thereof, and particularly relates to a liquid crystal compound containing a dibenzothiophene structure and the use thereof. The liquid crystal compound has a structure as shown by general formula I or general formula II; and the compound has an extremely high negative dielectric anisotropy and also significantly improves the clearing point, has a relatively high optical anisotropy, a moderate rotational viscosity and liquid crystal intersolubility, has excellent low-temperature work effects, has good thermal stability, chemical stability, optical stability and mechanical properties, etc., thereby effectively reducing a driving voltage, improving the response speed of a liquid crystal display device, and also having characteristics such as a high charge retention rate.

Description

A liquid crystal compound containing dibenzothiophene structure and its application

cross reference

This application claims the priority of Chinese Patent Application No. 202010626287.4 filed on July 1, 2020, entitled "A Liquid Crystal Compound Containing a Dibenzothiophene Structure and Its Application", the entire disclosure of which is incorporated by reference in its entirety This article.

technical field

The invention relates to a liquid crystal compound and its application field, in particular to a liquid crystal compound containing a dibenzothiophene structure and its application.

Background technique

As environmental materials, liquid crystal materials have great research value and bright application prospects in the fields of information display materials and organic optoelectronic materials. Liquid crystal materials have many advantages as new display materials, such as extremely low power consumption and low driving voltage. At the same time, compared with other materials, it also has the advantages of small size, light weight, long life, large amount of displayed information, no electromagnetic radiation, etc. It can almost meet the requirements of various information display, especially in TFT-LCD (Thin Film Transistor Technology) products aspect.

In the TFT active matrix system, there are mainly TN (Twisted Nematic, twisted nematic structure) mode, IPS (In-Plane Switching, plane switching) mode, FFS (Fringe Field Switching, fringe field switching technology) mode and VA ( Vertical Alignment, vertical orientation) mode and other main display modes.

At present, TFT-LCD product technology has matured, successfully solving technical problems such as viewing angle, resolution, color saturation and brightness. Large- and small-sized TFT-LCD displays have gradually occupied the mainstream position of flat-panel displays in their respective fields. For dynamic image display applications, in order to achieve high-quality display and eliminate image afterimage and trailing, the liquid crystal material is required to have a fast response speed, so the liquid crystal material is required to have as low a rotational viscosity γ1 as possible. In addition, in order to reduce the power consumption of the liquid crystal display device, the driving voltage of the liquid crystal needs to be as low as possible, so it is required to increase the dielectric anisotropy Δε of the liquid crystal.

Liquid crystal materials are the core functional materials of liquid crystal display devices. In order to meet the requirements of various performance parameters of liquid crystal display devices and adapt to the technological requirements of liquid crystal display devices, liquid crystal materials are required to have a wide range of performance parameters, especially to reduce the rotational viscosity of liquid crystal materials. γ1 and increase the dielectric anisotropy Δε of the liquid crystal material. In order to improve the properties of materials and adapt them to new requirements, the synthesis of new liquid crystal compounds and the study of structure-property relationship have become an important work in the field of liquid crystals.

SUMMARY OF THE INVENTION

The first objective of the present invention is to provide a liquid crystal compound containing a dibenzothiophene structure, so as to improve the deficiencies of existing liquid crystal materials and enhance the application value of such liquid crystal compounds.

The liquid crystal compound of the present invention has the structure represented by the general formula I or the general formula II:

Wherein, R ₁ and R ₂ independently represent -H, -Cl, -F, -CN, -OCN, -OCF ₃ , -CF ₃ , -CHF ₂ , -CH ₂ F, -OCHF ₂ , -SCN, -NCS, -SF ₅ , C ₁ -C ₁₅ alkyl group, C ₁ -C ₁₅ alkoxy group, C ₂ -C ₁₅ alkenyl group or C ₂ -C ₁₅ alkenyloxy group; or, any of the above containing -CH ₂ - group in a -CH ₂ - or at least two non-adjacent -CH ₂ - is -CH = CH -, - C≡C - , - COO -, - OOC-, cyclobutyl, Cyclopropyl, -O- or -S-substituted; or, at least one hydrogen in any of the above hydrogen-containing groups is replaced by fluorine or chlorine;

A ₁ represents a single bond or one of the following groups:

A ₂ represents a single bond or one of the following groups:

Z ₁ and Z ₂ each independently represent a single bond, -O-, -CH ₂ -, -CH ₂ -CH ₂ -, -(CH ₂ ) ₃ -, -(CH ₂ ) ₄ -, -CH=CH- , -C≡C-, -COO-, -OOC-, -CF ₂ O-, -OCH ₂ -, -CH ₂ O-, -OCF ₂ -, -CF ₂ CH ₂ -, -CH ₂ CF ₂ - , -C ₂ F ₄ - or -CF=CF-;

a and b each independently represent 0, 1 or 2.

As a further preferred technical solution, the liquid crystal compound is selected from one of the following compounds:

As a preferred technical solution, the liquid crystal compound is selected from one of the following compounds:

The second object of the present invention is to provide a method for preparing the liquid crystal compound.

Specifically, when the liquid crystal compound is the compound of general formula I, the preparation method includes the following steps:

1) with

and

As raw material, through Suzuki reaction, obtain

2)

Reaction with trifluoromethanesulfonic anhydride to give

3)

Reaction with ethyl mercaptopropionate to obtain

4)

Obtained by base-catalyzed ring closure

As the optimization of the above technical solution, in the step 1),

and

The feeding molar ratio is 0.9～1.5:1.0;

As the optimization of the above-mentioned technical solution, in the step 2),

The molar ratio of the feed to trifluoromethanesulfonic anhydride is 0.1-0.3:0.1-0.5;

As the optimization of the above-mentioned technical scheme, in the step 3),

The molar ratio of mercaptopropionate to ethyl mercaptopropionate is 0.1-0.3:0.1-0.3;

As the optimization of the above technical scheme, in the step 4),

The feeding molar ratio with alkali is 0.1～1.0:1.0.

When the liquid crystal compound is the compound of general formula II, the preparation method includes the following steps:

1) with

and

As raw material, through Suzuki reaction, obtain

2)

Reaction with trifluoromethanesulfonic anhydride to give

3)

Reaction with ethyl mercaptopropionate to obtain

4)

Obtained by base-catalyzed ring closure

As the optimization of the above technical solution, in the step 1),

and

The feeding molar ratio is 0.9～1.5:1.0;

As the optimization of the above-mentioned technical scheme, in the described step 2),

The molar ratio of the feed to trifluoromethanesulfonic anhydride is 0.1-0.3:0.1-0.5;

As the optimization of the above-mentioned technical scheme, in the step 3),

The molar ratio of mercaptopropionate to ethyl mercaptopropionate is 0.1-0.3:0.1-0.3;

As the optimization of the above technical scheme, in the step 4),

The feeding molar ratio with alkali is 0.1～1.0:1.0.

The above-mentioned reaction raw materials can be synthesized through public commercial routes or methods known in the literature.

The method of the present invention may involve conventional post-treatment when necessary, and the conventional post-treatment is specifically as follows: extraction with dichloromethane, ethyl acetate or toluene, liquid separation, washing with water, drying, and evaporation on a vacuum rotary evaporator, the obtained The product can be purified by vacuum distillation or recrystallization and/or chromatographic separation.

By adopting the above preparation method, the liquid crystal compound of the present invention can be obtained stably and efficiently.

The third object of the present invention is to provide a liquid crystal composition containing the above-mentioned liquid crystal compound.

As a preference of the above technical solution, the mass percentage of the liquid crystal compound in the liquid crystal composition is 1-60%; preferably 3-50%; more preferably 5-25%.

The fourth object of the present invention is to provide the application of the above-mentioned liquid crystal compound and/or the above-mentioned liquid crystal composition in the field of liquid crystal display; preferably in the application of liquid crystal display device, the liquid crystal display device includes but is not limited to TN, ADS, VA , PSVA, FFS or IPS LCD monitor.

In the liquid crystal compound provided by the present invention, the main chemical structure is dibenzothiophene, and the dielectric anisotropy of such a structure itself is relatively large. The introduction of fluorine atoms into the 4th and 6th positions of thiophene forms a strong synergistic effect, which makes the liquid crystal compound have extremely high negative dielectric anisotropy, and at the same time significantly improves the clearing point, relatively high optical anisotropy, moderate rotational viscosity and Liquid crystal mutual solubility, excellent performance at low temperature, good thermal stability, chemical stability, optical stability and mechanical properties; thus effectively reducing the driving voltage, improving the response speed of the liquid crystal display device, and having a charge retention rate Advanced features.

detailed description

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

The raw materials can be obtained from open commercial sources unless otherwise specified.

According to conventional detection methods in the art, various performance parameters of the liquid crystal compound are obtained by linear fitting, wherein the specific meanings of each performance parameter are as follows:

Δn represents optical anisotropy (25°C); Δε represents dielectric anisotropy (25°C, 1000Hz); γ1 represents rotational viscosity (mPa·s, 25°C); Cp represents clearing point.

Example 1

A liquid crystal compound containing a dibenzothiophene structure, its structural formula is:

The synthetic route for the preparation of compound BYLC-01 is shown below:

Specific steps are as follows:

(1) Synthesis of compound BYLC-01-3:

Under nitrogen protection, add 46.8g (0.2mol) compound BYLC-01-1, 47.6g (0.2mol) compound BYLC-01-2, 400ml toluene, 200ml deionized water, 200ml ethanol, 55.2g anhydrous to the reaction flask Potassium carbonate, 0.6 g of tetrakistriphenylphosphine palladium, heated and refluxed for 12 hours. Carry out routine post-treatment, chromatographic purification, and ethanol recrystallization to obtain 62 g of white solid (compound BYLC-01-3), GC: 99.4%, yield: 89%;

(2) Synthesis of compound BYLC-01-4:

Under nitrogen flow protection, add 300 mL of dichloromethane to the glass reaction flask, start stirring, and add 62 g of BYLC-01-3. Cool to 0°C, add 35.67g pyridine, 2.75g DMAP, control the temperature to -15～-10°C, and add 86.5g trifluoromethanesulfonic anhydride dropwise. After completion, the temperature was controlled to -10 °C, and the mixture was stirred at -10 to -5 °C for 3 h. Cool to -10°C, add 100ml of water, control the temperature to 0-5°C, stir for 10min after completion, let stand for liquid separation for 10min, separate the layers, wash the organic layer with water 100ml*3 times, combine the organic layers, add 50g of anhydrous sodium sulfate to dry, Spin dry solvent;

200ml of ethanol was heated to 80°C to dissolve, and it was naturally lowered to room temperature of 17°C under stirring, and stirred at this temperature for 0.5h, and then filtered to obtain 68.4g of compound BYLC-01-4, yield 80%, HPLC 98.5%;

(3) Synthesis of compound BYLC-01-5:

Under nitrogen protection, add 57.64g (0.12mol) compound BYLC-01-4, 19.3g ethyl mercaptopropionate, 300ml toluene, 33.1g anhydrous potassium carbonate, 1.1g tris(dibenzylideneacetone) to the reaction flask Dipalladium, 1.0 g of 2-dicyclohexylphosphine-2',6'-dimethoxybiphenyl, heated and refluxed for 16 hours. Routine post-treatment was performed, and chromatographic purification was performed to obtain (compound BYLC-01-5) 34.4 g, GC: 93.1%, yield: 60%;

(4) Synthesis of compound BYLC-01:

Under nitrogen protection, 23.9g (0.05mol) of compound BYLC-01-5, 100ml of N,N-dimethylformamide, 13.8g of anhydrous potassium carbonate were added to the reaction flask, and the temperature was controlled at 130-140°C for 6 hours. Carry out routine post-treatment, chromatographic purification, n-hexane elution, and ethanol recrystallization to obtain 13.2 g of white solid (compound BYLC-01), GC: 99.8%, yield: 77%.

The structural characterization information of compound BYLC-01 is as follows:

The resulting white solid BYLC-01 was analyzed by GC-MS and the product had m/z of 344.0 (M+).

Example 2

According to the technical solution of Example 1, the following liquid crystal compounds can be synthesized by simply replacing the corresponding raw materials without changing any substantive operations:

The structural characterization information of compound BYLC-02 is as follows:

The resulting white solid, BYLC-02, was analyzed by GC-MS, and the m/z of the product was 330.1 (M+).

Example 3

According to the technical solution of Example 1, the following liquid crystal compounds can be synthesized by simply replacing the corresponding raw materials without changing any substantive operations:

The structural characterization information of compound BYLC-03 is as follows:

The resulting white solid, BYLC-03, was analyzed by GC-MS, and the m/z of the product was 316.0 (M+).

Example 4

According to the technical solution of Example 1, the following liquid crystal compounds can be synthesized by simply replacing the corresponding raw materials without changing any substantive operations:

The structural characterization information of compound BYLC-04 is as follows:

The obtained white solid BYLC-04 was analyzed by GC-MS, and the m/z of the product was 362.1 (M+);

Example 5

According to the technical solution of Example 1, the following liquid crystal compounds can be synthesized by simply replacing the corresponding raw materials without changing any substantive operations:

The structural characterization information of compound BYLC-05 is as follows:

The resulting white solid, BYLC-05, was analyzed by GC-MS, and the m/z of the product was 330.1 (M+).

Example 6

According to the technical solution of Example 1, the following liquid crystal compounds can be synthesized by simply replacing the corresponding raw materials without changing any substantive operations:

The structural characterization information of compound BYLC-06 is as follows:

The resulting white solid, BYLC-06, was analyzed by GC-MS, and the m/z of the product was 358.1 (M+).

Experimental example 1

Compounds BYLC-01, BYLC-02, BYLC-03, BYLC-04, BYLC-05, BYLC-06 prepared in Examples 1 to 6 were compared with Comparative Example 1 (another known common liquid crystal compound) Various performance parameters of the liquid crystal compound are obtained by linear fitting according to the conventional detection methods in the field, and the detection results are shown in Table 1:

Table 1: Performance test results of liquid crystal compounds

It can be clearly seen from the test results in Table 1 that, compared with traditional compounds with similar chemical structures, the liquid crystal compounds provided by the present invention maintain a large optical anisotropy Δn, good rotational viscosity γ1 and At the same time of mutual solubility of liquid crystal, it has higher negative dielectric anisotropy Δε and significantly higher clearing point Cp, thereby effectively improving the negative dielectric anisotropy of liquid crystal composition, improving the response time, and improving the liquid crystal composition. Operating temperature.

Although the present invention has been described in detail above with general description, specific embodiments and tests, some modifications or improvements can be made on the basis of the present invention, which is obvious to those skilled in the art . Therefore, these modifications or improvements made without departing from the spirit of the present invention fall within the scope of the claimed protection of the present invention.

Industrial Applicability

The present invention provides a liquid crystal compound, especially a liquid crystal compound containing a dibenzothiophene structure and an application thereof; the liquid crystal compound has a structure represented by general formula I or general formula II:

The compound has extremely high negative dielectric anisotropy, and at the same time significantly improves the clearing point, relatively high optical anisotropy, moderate rotational viscosity and liquid crystal mutual solubility, excellent performance at low temperature, good thermal stability, chemical stability Therefore, it 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 high charge retention rate, and has good economic value and application prospects.

Claims (10)

1. A liquid crystal compound containing a dibenzothiophene structure, characterized in that it has the structure shown in general formula I or general formula II:

   

   Wherein, R ₁ and R ₂ independently represent -H, -Cl, -F, -CN, -OCN, -OCF ₃ , -CF ₃ , -CHF ₂ , -CH ₂ F, -OCHF ₂ , -SCN, -NCS, -SF ₅ , C ₁ -C ₁₅ alkyl group, C ₁ -C ₁₅ alkoxy group, C ₂ -C ₁₅ alkenyl group or C ₂ -C ₁₅ alkenyloxy group; or, any of the above containing -CH ₂ - group in a -CH ₂ - or at least two non-adjacent -CH ₂ - is -CH = CH -, - C≡C - , - COO -, - OOC-, cyclobutyl, Cyclopropyl, -O- or -S-substituted; or, at least one hydrogen in any of the above hydrogen-containing groups is replaced by fluorine or chlorine;

   A ₁ represents a single bond or one of the following groups:

   

   A ₂ represents a single bond or one of the following groups:

   

   

   Z ₁ and Z ₂ each independently represent a single bond, -O-, -CH ₂ -, -CH ₂ -CH ₂ -, -(CH ₂ ) ₃ -, -(CH ₂ ) ₄ -, -CH=CH- , -C≡C-, -COO-, -OOC-, -CF ₂ O-, -OCH ₂ -, -CH ₂ O-, -OCF ₂ -, -CF ₂ CH ₂ -, -CH ₂ CF ₂ - , -C ₂ F ₄ - or -CF=CF-;

   a and b each independently represent 0, 1 or 2.
2. The liquid crystal compound according to claim 1, wherein the liquid crystal compound is selected from one of the following compounds:

   

   

   

   
3. The liquid crystal compound according to claim 2, wherein the liquid crystal compound is selected from one of the following compounds:

   
4. A method for preparing the liquid crystal compound according to any one of claims 1 to 3, characterized in that it comprises the following steps:

   1) with

   

   and

   

   As raw material, through Suzuki reaction, obtain

   

   2)

   

   Reaction with trifluoromethanesulfonic anhydride to give

   

   3)

   

   Reaction with ethyl mercaptopropionate to obtain

   

   4)

   

   Obtained by base-catalyzed ring closure

   
5. preparation method according to claim 4, is characterized in that, in described step 1),

   

   and

   

   The feeding molar ratio is 0.9～1.5:1.0;

   And/or, in described step 2),

   

   The molar ratio of the feed to trifluoromethanesulfonic anhydride is 0.1-0.3:0.1-0.5;

   And/or, in described step 3),

   

   The molar ratio of mercaptopropionate to ethyl mercaptopropionate is 0.1-0.3:0.1-0.3;

   And/or, in described step 4),

   

   The feeding molar ratio with alkali is 0.1～1.0:1.0.
6. A method for preparing the liquid crystal compound according to any one of claims 1 to 3, characterized in that it comprises the following steps:

   1) with

   

   and

   

   As raw material, through Suzuki reaction, obtain

   

   2)

   

   Reaction with trifluoromethanesulfonic anhydride to give

   

   3)

   

   Reaction with ethyl mercaptopropionate to obtain

   

   4)

   

   Obtained by base-catalyzed ring closure

   
7. preparation method according to claim 6, is characterized in that, in described step 1),

   

   and

   

   The feeding molar ratio is 0.9～1.5:1.0;

   And/or, in the described step 2),

   

   The molar ratio of the feed to trifluoromethanesulfonic anhydride is 0.1-0.3:0.1-0.5;

   And/or, in described step 3),

   

   The molar ratio of mercaptopropionate to ethyl mercaptopropionate is 0.1-0.3:0.1-0.3;

   And/or, in described step 4),

   

   The feeding molar ratio with alkali is 0.1～1.0:1.0.
8. A liquid crystal composition comprising the liquid crystal compound according to any one of claims 1 to 3.
9. The liquid crystal composition according to claim 8, wherein the mass percentage of the liquid crystal compound in the liquid crystal composition is 1-60%; preferably 3-50%; more preferably 5-25%.
10. Application of the liquid crystal compound of any one of claims 1 to 3 and/or the liquid crystal composition of claim 8 or 9 in the field of liquid crystal display;

    Application in liquid crystal display devices including TN, ADS, VA, PSVA, FFS or IPS liquid crystal displays is preferred.