TWI792117B - A kind of negative dielectric liquid crystal compound and its preparation and application - Google Patents

Abstract

The invention belongs to the technical field of liquid crystal materials, and in particular relates to a negative dielectric liquid crystal compound and its preparation method and application. The compound of the invention has a structure as shown in general formula (I):

The liquid crystal compound provided by the present invention has a main chemical structure of dibenzothiophene or dibenzofuran, and the dielectric anisotropy of this type of structure itself is large. The liquid crystal compound provided by the present invention introduces a benzene ring into the molecular structure, and at the same time Fluorine atoms are introduced into the 4-position and 6-position to form a strong synergistic effect, so that the negative dielectric anisotropy of the liquid crystal compound is high, and at the same time, the clearing point is significantly improved, and it has relatively high optical anisotropy, moderate rotational viscosity and liquid crystal. Miscibility, excellent low temperature working effect, good thermal stability, chemical stability, optical stability and mechanical properties.

Description

A kind of negative dielectric liquid crystal compound and its preparation and application

The invention belongs to the technical field of liquid crystal materials, and in particular relates to a liquid crystal compound and its preparation method and application.

The application of liquid crystal materials as environmental materials in information display materials, organic optoelectronic materials and other fields has great research value and bright application prospects. 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, and no electromagnetic radiation. It can almost meet the requirements of various information displays, 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 and successfully solved technical problems such as viewing angle, resolution, color saturation and brightness. Large-size and small- and medium-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 smearing, liquid crystal materials are required to have a fast response speed, so liquid crystal materials are required to have as low a rotational viscosity as possible γ 1. In addition, in order to reduce the energy 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 process requirements of liquid crystal display devices, liquid crystal materials are required to have a wide variety of performance parameters, especially to reduce the rotational viscosity of liquid crystal materials γ 1 And improve the dielectric anisotropy △ε of the liquid crystal material. In order to improve the properties of materials to meet new requirements, the synthesis of new structural liquid crystal compounds and the study of structure-property relationship have become an important work in the field of liquid crystals.

The first object of the present invention is to provide a kind of liquid crystal compound, have the structure shown in general formula (I):

In the general formula (I), R1 and R2 are groups shown in a or b or c:

The a is selected from -H, -Cl, -F, -CN, -OCN, -OCF3, -CF3, -CHF2, -CH2F, -OCHF2, -SCN, -NCS, -SF5, C1-C15 alkyl , at least one of C1-C15 alkoxy, C2-C15 alkenyl or C2-C15 alkenyloxy;

The b is a group obtained by substituting one or at least two non-adjacent -CH2- in any group containing -CH2- in the above a by at least one of the following groups and is a group in which the oxygen atom is not directly connected : -CH=CH-, -C≡C-, -COO-, -OOC-, cyclobutyl, cyclopropyl, -O- or S-;

The c is a group obtained by replacing at least one hydrogen in any group of a or b with fluorine or chlorine;

A is selected from one or more of a single bond and the following groups:

Z is selected from single bond, -CH2-, -CH2-CH2-, -(CH2)3-, -(CH2)4-, -CH=CH-, -C≡C-, -COO-, -OOC-, At least one of -CF2O-, -OCH2-, -CH2O-, -OCF2-, -CF2CH2-, -CH2CF2-, -C2F4- or -CF=CF-;

X is selected from O or S; L is selected from H or F.

Preferably, the compound represented by the general formula (I) is selected from one of the following structures:

The R1 and R2 are groups shown in a or b or c as follows:

The a is selected from -H, -Cl, -F, -CN, -OCN, -OCF3, -CF3, -CHF2, -CH2F, -OCHF2, -SCN, -NCS, -SF5, C1-C7 alkyl , at least one of C1-C7 alkoxy, C2-C7 alkenyl and C2-C7 alkenyloxy;

The b is a group obtained by substituting one or at least two non-adjacent -CH2- in any group containing -CH2- in the above a by at least one of the following groups and is a group in which the oxygen atom is not directly connected : -CH=CH-, -C≡C-, -COO-, -OOC-, cyclobutyl, cyclopropyl, -O- and -S-;

Said c is a group obtained by replacing at least one hydrogen in any group of said a or b with fluorine or chlorine.

Further preferably, the R1 is ethoxy, the R2 is propyl, the A is a single bond, the Z is a single bond, the X is O or S, and the L is H or F.

As a preferred embodiment, the compound represented by the general formula (I) is selected from one of the following structures:

Another object of the present invention is to provide the preparation method of the liquid crystal compound of the present invention, comprising the following steps:

與

為原料，通過Suzuki反應，得到 1) to

and

As raw materials, through the Suzuki reaction, get

與有機鋰試劑反應，再與溴化試劑反應，得到 2)

Reaction with organolithium reagents, followed by bromination reagents, gives

與巰基丙酸乙酯或者甲醇鈉反應，得到

4)

在鹼催化下進行關環，即得

或

，在鹼催化下進行關環，得到

上述A、Z、R1、R2和L的指代與說明書前述部分的指代相同。 3)

React with ethyl mercaptopropionate or sodium methoxide to give

4)

Under base catalysis, the ring closure is carried out to obtain

or

, and undergoes ring closure under base catalysis to give

The designations of the above-mentioned A, Z, R1, R2 and L are the same as those in the preceding part of the description.

Another object of the present invention is to provide a composition comprising the liquid crystal compound described in the present invention.

Preferably, the mass percentage of the liquid crystal compound in the liquid crystal composition is 1-60%, preferably 3-50%, more preferably 5-25%.

The last object of the present invention is to protect the application of the liquid crystal compound or the liquid crystal composition described in the present invention in the field of liquid crystal display.

Preferably, the liquid crystal display field is a liquid crystal display device.

Further preferably, the liquid crystal display device is a TN, ADS, VA, PSVA, FFS or IPS liquid crystal display.

The liquid crystal compound of the present invention has the following beneficial effects:

The liquid crystal compound provided by the present invention has a main chemical structure of dibenzothiophene or dibenzofuran, and the dielectric anisotropy of this type of structure itself is large. The liquid crystal compound provided by the present invention introduces a benzene ring into the molecular structure, and at the same time Fluorine atoms are introduced into the 4-position and 6-position to form a strong synergistic effect, so that the negative dielectric anisotropy of the liquid crystal compound is high, and at the same time, the clearing point is significantly improved, and it has relatively high optical anisotropy, moderate rotational viscosity and liquid crystal. Miscibility, excellent low temperature working effect, good thermal stability, chemical stability, optical stability and mechanical performance; thus can effectively reduce the driving voltage, improve the response speed of the liquid crystal display device, and have better Charge retention and other characteristics.

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

Example 1

This embodiment relates to a kind of liquid crystal compound, and its structural formula is:

The synthetic route for preparing compound BYLC-01 is as follows:

Specific steps are as follows:

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

Under nitrogen protection, add 35g BYLC-01-1, 23.3g BYLC-01-2, 80ml toluene, 40ml deionized water, 20ml ethanol, 23.8g anhydrous sodium carbonate, 0.7g tetrakistriphenylphosphine palladium to the reaction flask , heated to reflux for 3 hours. After conventional post-treatment, chromatographic purification, eluting with n-hexane, and recrystallization from ethanol gave 33.0 g of white solid (compound BYLC-01-3), GC: 99.7%, yield: 87.3%.

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

Under the protection of nitrogen, add 30.4g BYLC-01-3 and 200ml tetrahydrofuran to the reaction bottle, add 0.12mol n-hexane solution of tert-butyllithium dropwise at -70~-80°C under temperature control, keep the reaction for 1 hour after dropping, and then control the temperature- Add 30.0g of bromine dropwise at 70~-80°C, then return to -30°C naturally. Add 400ml of saturated sodium sulfite aqueous solution for hydrolysis and destruction, carry out conventional post-treatment, ethanol recrystallization to obtain 31.0g of light yellow solid (compound BYLC-01-4), GC: 99.3%, yield 84.7%;

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

Under nitrogen protection, 25.0g of compound BYLC-01-4, 10.0g of ethyl mercaptopropionate, 12.9g of N,N-diisopropylethylamine, 0.31g of 2-dicyclohexylphosphine-2, 4,6-triisopropylbiphenyl, 0.25g tris(dibenzylideneacetone)dipalladium, 100ml dioxane, and react at a temperature of 90°C~100°C for 6 hours. carry out regular After regular post-treatment, chromatographic purification and elution with n-hexane gave 21.0 g of light yellow liquid (compound BYLC-01-5), GC: 95.8%, yield: 75%.

(4) Synthesis of compound BYLC-01:

Under nitrogen protection, 20.0 g of compound BYLC-01-5, 9.0 g of potassium tert-butoxide, and 200 ml of tetrahydrofuran were added to the reaction flask, and reacted at 65° C. to 70° C. for 6 hours. After conventional post-processing, chromatographic purification, eluting with n-hexane, and ethanol crystallization gave 11.6 g of a white solid (compound BYLC-01), GC: 99.7%, yield: 75.8%.

The obtained white solid BYLC-01 was analyzed by GC-MS, and the m/z of the product was 356.1 (M+).

Example 2

This embodiment relates to a kind of liquid crystal compound, and its structural formula is:

Prepared by the following method:

Referring to Example 1, BYLC-02-1 replaces BYLC-01-1.

The obtained white solid BYLC-02 was analyzed by GC-MS, and the m/z of the product was 374.1 (M+).

Example 3

This embodiment relates to a kind of liquid crystal compound, and its structural formula is:

The route for preparing compound BYLC-03 is as follows:

(1) Synthesis of compound BYLC-03-2:

Under nitrogen protection, add 50g (0.2mol) compound BYLC-01-1, 49.3g (0.21mol) compound BYLC-03-1, 400ml toluene, 200ml deionized water, 200ml ethanol, 55.2g anhydrous potassium carbonate to the reaction flask , 0.6g tetrakistriphenylphosphine palladium, heated to reflux for 12 hours. After conventional post-processing, chromatographic purification, ethanol recrystallization to obtain 62.6 g of white solid (compound BYLC-01-3), GC: 99.4%, yield: 87%;

(2) Synthesis of compound BYLC-03:

Under nitrogen protection, 18g (0.05mol) of compound BYLC-03-2, 100ml of N,N-dimethylformamide, and 13.8g of sodium hydride were added to the reaction flask, and the reaction was carried out at a temperature of 130-140°C for 6 hours. After conventional post-treatment, chromatographic purification, eluting with n-hexane, and recrystallization from ethanol gave 12.7 g of a white solid (compound BYLC-01), GC: 99.9%, yield: 75%.

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

The obtained white solid BYLC-01 was analyzed by GC-MS, and the m/z of the product was 340.1 (M+).

Example 4

This embodiment relates to a kind of liquid crystal compound, and its structural formula is:

With reference to Example 3, it is prepared by the following method:

BYLC-02-1 replaces BYLC-01-1.

The obtained white solid BYLC-04 was analyzed by GC-MS, and the m/z of the product was 358.1 (M+).

Comparative example 1

This embodiment relates to a kind of liquid crystal compound, and its structural formula is:

Experimental example

This experimental example relates to the determination of related properties of the compounds described in Examples 1 and 2 and Comparative Example.

According to the conventional detection methods in this field, for example, the detection of △ε is tested by INSTEC liquid crystal detection instrument, the detection of γ1 is tested by viscometer, the detection of △n is tested by Abbe refractometer, and the detection of Cp is tested by differential calorimeter scanner .

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.

The performance parameters of the compounds BYLC-01, BYLC-02, BYLC-03, BYLC-04 prepared in Examples 1-4 were compared with those of the liquid crystal compounds in Comparative Example 1. The test results are shown in Table 1:

As can be clearly seen from the test results in Table 1, the liquid crystal compound provided by the present invention is compared with the traditional similar chemical structure compound, and the liquid crystal compound provided by the present invention has larger optical anisotropy Δn, good rotational viscosity γ 1 , while having proper negative dielectric anisotropy Δε, it has a higher clearing point Cp, which can effectively increase the clearing point of the liquid crystal composition, shorten the response time of the liquid crystal display device, and increase the working temperature of the liquid crystal composition.

Experimental example 4

Light stability, thermal stability

Photostability Test Method

The liquid crystal mixture is selected, and the liquid crystal model BYLC-HJ-1000 (manufactured by Bayi Space-Time Liquid Crystal Technology Co., Ltd.) is used as the liquid crystal mixture. First, the stability of the voltage retention rate of the liquid crystal mixture (BYLC-HJ-1000) itself was determined. The liquid crystal mixture (BYLC-HJ-1000) itself was tested in a test box with materials for homeotropic alignment and planar ITO electrodes by means of cold Cathode ((CCFL)-LCD backlight) illumination to study their stability against light.

The corresponding test box was exposed to light for 1000 hours, and then the voltage retention rate was determined after 5 minutes at a temperature of 100°C under different conditions. In addition, for each individual mixture, six For each test box, the values shown are the mean of six individual values and their standard deviations, including cases where the standard deviation is less than the precision of the above measurements.

Thermal Stability Test Method

The test box obtained above was sealed and stored in a conventional laboratory heating box at 100°C for 120 hours, and its voltage retention rate was measured after 5 minutes at 100°C, 1V and 60Hz (VHR, heating, 120 hours).

The measurement results

The compound of Example 1 (i.e. BYLC-01) was added to the liquid crystal mixture BYLC-HJ-1000 (manufactured by Bayi Space-Time Liquid Crystal Technology Co., Ltd.) at a ratio of 5% to obtain the mixture M-1. Example 2 (i.e. BYLC-02), embodiment 3 (i.e. BYLC-03), embodiment 4 (i.e. BYLC-04), and comparative example 1 were added to the liquid crystal mixture BYLC-HJ-1000 (Bayilion Time and Space Liquid Crystal Technology Co., Ltd. Manufacturing), obtain respectively mixture M-2, M-3, M-4, M-5 and study its stability according to the method described above, the results are shown in the table below:

It can be seen from the above mixture experiment examples that the VHR of the mixture using the compound provided by the present invention is better than that of the starting mixture and the mixture of the comparative example before exposure, and the VHR changes little after exposure, showing excellent thermal stability It has good stability for thermal and UV exposure degradation and stable high VHR, which effectively reduces the probability of image delay, maintains a low threshold voltage, improves response time, and extends service life.

Although, the present invention has been described in detail with general description, specific implementation and test above, but on the basis of the present invention, some modifications or improvements can be made to it, which will be obvious to those skilled in the art . Therefore, the modifications or improvements made on the basis of not departing from the spirit of the present invention all belong to the protection scope of the present invention.

Claims (7)

A negative dielectric liquid crystal compound is characterized in that the compound is selected from one of the following structures:

A method for preparing a liquid crystal compound as claimed in claim 1, comprising the following steps: 1) with

and

As raw materials, through the Suzuki reaction, get

2)

Reaction with organolithium reagents, followed by bromination reagents, gives

3)

React with ethyl mercaptopropionate or sodium methoxide to give

4)

Under base catalysis, the ring closure is carried out to obtain

Above-mentioned A is a single bond, Z is a single bond, R ₁ is ethoxyl group, R ₂ is propane group and L is selected from H or F. A liquid crystal composition, which includes the liquid crystal compound described in Claim 1. The liquid crystal composition according to claim 3, wherein the mass percentage of the liquid crystal compound in the liquid crystal composition is 1-60%. A liquid crystal compound as an application in the field of liquid crystal display, which contains the liquid crystal compound described in Claim 1. A liquid crystal composition as an application in the field of liquid crystal display, which contains the liquid crystal composition described in Claim 3 or 4. A liquid crystal display device, comprising the liquid crystal compound of claim 1 or the liquid crystal composition of claim 3, 4, the liquid crystal display device can be a TN, ADS, VA, PSVA, FFS or IPS liquid crystal display device.