A liquid crystal compound, composition and its application

Abstract

This invention provides a liquid crystal compound, a composition, and their applications. The liquid crystal compound has the structure shown in Formula I. The liquid crystal compound and composition of this invention have advantages such as low rotational viscosity, high dielectric anisotropy, good miscibility, and stable performance, and also have the effect of reducing device driving voltage.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of liquid crystal display materials, and particularly relates to a liquid crystal compound, a composition and application thereof. BACKGROUND

[0002] In recent years, the application field of liquid crystal compounds has been significantly widened to various display devices, electro-optical devices, electronic elements, sensors, etc. For this reason, a number of different structures have been proposed, in particular in the field of nematic liquid crystals, which have hitherto found the most widespread application in flat panel displays. In particular in systems with TFT active matrix.

[0003] Color display mostly adopts active matrix display mode. TFT-LCD has been widely used in direct view type television, large screen projection television, computer terminal display and some military instrument display, and it is believed that TFT-LCD technology has a more broad application prospect.

[0004] Among them, "active matrix" includes two types: 1, OMS (metal oxide semiconductor) or other diode on the silicon wafer as a substrate. 2, thin film transistor (TFT) on the glass plate as a substrate.

[0005] Single crystal silicon as a substrate material limits the display size, because each part of the display device even the module assembly at its junction there are many problems. Therefore, the second thin film transistor is a promising active matrix type, and the photoelectric effect used is usually TN effect. TFT includes compound semiconductors such as Cdse, or TFT based on polycrystalline or amorphous silicon.

[0006] At present, TFT-LCD product technology has matured, successfully solving the technical problems of viewing angle, resolution, color saturation and brightness, and its display performance has approached or exceeded that of CRT display. Large size and small size TFT-LCD displays have gradually occupied the mainstream position of flat panel displays in their respective fields. However, due to the limitation of the liquid crystal material itself, TFT-LCD still has many defects such as insufficiently fast response, insufficiently low voltage, insufficiently high charge retention rate, etc. Therefore, it is particularly important to find a single crystal compound with low viscosity and high dielectric anisotropy.

[0007] As early as 1989, Merck Company of Germany described in patent US5045229 a liquid crystal compound monomer containing difluoromethoxy bridge bond, but no ideal corresponding compound was obtained. SUMMARY

[0008] In view of the above problems, the present application provides a liquid crystal compound with a difluoromethoxy bridge unit structure, a composition and application thereof.

[0009] In a first aspect, the present application provides a liquid crystal compound having the structure of Formula I:

[0010]

[0011] wherein: R is selected from H, unsubstituted or substituted alkyl or alkoxy groups having from 1 to 12 carbon atoms; the substitution means that one or more CH2groups of the alkyl or alkoxy groups having from 1 to 12 carbon atoms are each, independently of one another, replaced by -C≡C-, -CF2O-, -CH=CH-, -O-, -CO-O- or -O-CO- in such a way that the O atoms are not directly bonded to one another, and in which one or more H is replaced by halogen;

[0012] Ring A is selected from 1,4-cyclohexyl or 1,4-phenyl, wherein the C of the 1,4-cyclohexyl are each independently replaced by one or more O; the H of the 1,4-phenyl are each independently replaced by one or more halogen;

[0013] n is 0, 1 or 2;

[0014] L1, L2and L3are each independently selected from H or halogen;

[0015] Z is selected from a single bond, -(CH2)2-, -C≡C-, -CF2O-, -CH=CH-, -O-, -CO-O- or -C-O-.

[0016] According to some embodiments of the compounds according to the present application, the compounds are such that: R is selected from H, unsubstituted or substituted alkyl or alkoxy groups having from 1 to 5 carbon atoms, the substitution means that one or more CH2groups of the alkyl or alkoxy groups having from 1 to 5 carbon atoms are each, independently of one another, replaced by -CH=CH- or -O-, and in which one or more H is replaced by F;

[0017] Ring A is selected from 1,4-cyclohexyl or 1,4-phenyl, wherein the C of the 1,4-cyclohexyl are each independently replaced by one or two O; the H of the 1,4-phenyl are each independently replaced by one or more F;

[0018] n is 0, 1 or 2;

[0019] L1, L2and L3are each independently selected from H or F;

[0020] Z is a single bond.

[0021] According to some embodiments of the compounds according to the present application, the compounds are such that: R is selected from H, unsubstituted alkyl groups having from 1 to 5 carbon atoms;

[0022] Ring A is selected from 1,4-cyclohexyl or 1,4-phenyl, wherein each C of the 1,4-cyclohexyl group is independently optionally substituted with one or two O; each H of the 1,4-phenyl group is independently optionally substituted with one or two F;

[0023] n is 0, 1 or 2;

[0024] L2and L3are both H, and L1is F;

[0025] Z is a single bond.

[0026] According to some embodiments of the compounds of the present application, the compounds have a structure according to any one or several of the general formulae I-1 to I-15:

[0027]

[0028]

[0029] wherein R is selected from alkyl or alkoxy groups containing 1 to 7 carbon atoms, preferably each R independently represents an alkyl group having 2 to 5 carbon atoms.

[0030] According to some embodiments of the compounds of the present application, the compounds are selected from one or several of the following structures:

[0031]

[0032]

[0033]

[0034]

[0035]

[0036] In a second aspect of the present application, a liquid crystal composition is provided, comprising the liquid crystal compound according to the first aspect of the present application.

[0037] According to some embodiments of the liquid crystal composition of the present application, the liquid crystal compound is present in the liquid crystal composition in a weight percentage of 1% to 80% (such as 1%, 5%, 10%, 12%, 15%, 23%, 28%, 35%, 43%, 48%, 57%, 68%, 72%, 75%, 78%, 80%).

[0038] According to some embodiments of the liquid crystal composition of the present application, the liquid crystal compound is present in the liquid crystal composition in a weight percentage of 3% to 50%.

[0039] In a third aspect, the present application provides a use of the liquid crystal compound according to the first aspect of the present application or the liquid crystal composition according to the second aspect of the present application in a liquid crystal display device.

[0040] According to some embodiments of the use of the present application, the liquid crystal display device is a TN, ADS, FFS or IPS liquid crystal display.

[0041] The liquid crystal compound and the liquid crystal composition according to the present application have the advantages of low rotational viscosity, high dielectric anisotropy, good miscibility, stable performance, and the effect of reducing the driving voltage of the device. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with examples. The specific examples described herein are only used to explain the present application and do not constitute any limitation on the present application. In addition, in the following description, the description of the known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present disclosure. Such structures and technologies are also described in many publications.

[0043] The abbreviations of the performance test parameters in the embodiments of the present application are as follows:

[0044] Δε represents the dielectric anisotropy at 25℃ and 1kHz;

[0045] γ1 represents the rotational viscosity at 25℃ (mPa·s);

[0046] △n is the optical anisotropy, no is the refractive index (589nm, 25℃);

[0047] C.p is the clearing point of the liquid crystal composition (℃);

[0048] VHR charge retention rate (%): the mixed liquid crystal is injected into the liquid crystal cell, placed in a thermostat, after the temperature is stable, the test procedure is entered, and the charge retention rate value is obtained by manual sampling. The measurement voltage is 5V, the power-on time is 5ms, and the holding time is 500ms.

[0049] The synthesis route of the intermediate compound IM is as follows:

[0050]

[0051] (1) Synthesis of compound IM-1

[0052] Into a 500ml dry and clean three-necked flask, 17.6g of 3,4,5-trifluorobenzoic acid, 0.45g of palladium acetate, 0.72g of 2-methyl-2-(6-oxo-l,6-dihydropyridin-2-yl)propanoic acid, 28.8g of cesium acetate, 300ml of N,N-dimethylacetamide were added, stirred, 34ml of hydrogen peroxide (35% aqueous solution) was added, and the temperature was raised to 60°C for 24 hours. The reaction solution was acidified with hydrochloric acid, desolved, and recrystallized to obtain 13.5g of compound IM-1 at a yield of 70%, HPLC: 98%.

[0053] (2) Synthesis of compound IM-2

[0054] Into a 500ml dry and clean three-necked flask, 60g of ethanol, 19.2g of compound IM-1 were added, stirred and dissolved, 19.2g of concentrated sulfuric acid was slowly added, and the temperature was raised to 85°C for 4 hours. The reaction solution was extracted with ethyl acetate and water, washed until neutral, desolved, and recrystallized to obtain 20.2g of compound IM-2 at a yield of 92%, GC: 99%.

[0055] (3) Synthesis of compound IM-3

[0056] Into a 500ml dry and clean three-necked flask, 100ml of N,N-dimethylformamide, 22g of compound IM-2, 16.2g of potassium carbonate were added, and the temperature was raised to 65°C for 10 hours. The reaction solution was extracted with ethyl acetate and water, washed until neutral, desolved, and recrystallized to obtain 26g of compound IM-3 at a yield of 85%, GC: 99%.

[0057] (4) Synthesis of compound IM-4

[0058] Into a 500ml dry and clean three-necked flask, 100ml of deionized water, 100ml of ethanol, 12g of sodium hydroxide were added, stirred and dissolved, 30.6g of compound IM-3 was added, and the temperature was raised to 50°C for 4 hours. The reaction solution was filtered and recrystallized to obtain 20.5g of compound IM-4 at a yield of 85%, HPLC: 99%.

[0059] (5) Synthesis of compound IM-5

[0060] Into a 500ml dry and clean three-necked flask, 66g of acetic anhydride, 25g of compound IM-4 were added, and 0.8g of pyridine was added dropwise, and the temperature was raised to 135°C for 20 hours. The reaction solution was concentrated and desolved, and distilled under reduced pressure to obtain 20.9g of compound IM-5 at a yield of 91%, GC: 98%.

[0061] (6) Synthesis of compound IM

[0062] Into a 500ml dry and clean three-necked flask, 60ml deionized water, 60ml ethanol, 6g sodium hydroxide were added, stirred until dissolved, then 23g compound IM-5 was added, heated to 60°C for 4 hours. After the reaction solution was acidified, cooled, filtered, recrystallized, 15.2g of compound IM was obtained, yield 84%, GC: 99%. The obtained IM was analyzed by GC-MS, and the m / z of the product was 188.

[0063] Example 1: The structure of liquid crystal compound LC-01 is as follows:

[0064]

[0065] The synthesis route of compound LC-01 is as follows:

[0066]

[0067] (1) Synthesis of compound LC-01-1

[0068] Under nitrogen protection, 96.5g 3,5-difluorobromobenzene (0.5mol), 91g 2-fluoro-4-propylphenylboronic acid (0.5mol), 500ml toluene, 200ml ethanol, 200ml deionized water, 138g anhydrous potassium carbonate (1mol), 0.3g bis [di-tert-butyl-(4-dimethylaminophenyl) phosphine] palladium (II) dichloride were added into the reaction flask, heated to 70°C for 8 hours. Washed with water until neutral, column chromatography, ethanol recrystallization to obtain white solid compound LC-01-1 114g, GC: 99.9%, yield: 91%;

[0069] (2) Synthesis of compound LC-01-2:

[0070] Into a 2L three-necked flask, 120.8g LC-01-1, 1L tetrahydrofuran were added, stirring until the solid was completely dissolved, nitrogen was removed three times, the temperature was lowered to-70°C, the temperature was controlled at-65 to-75°C, 232ml 2.5M butyllithium was added dropwise, after the dropwise addition was completed, 100ml tetrahydrofuran was used to rinse the dropping funnel, the temperature was controlled at-65 to-75°C for 1 hour, a solution of 141g difluorodibromomethane in 0.5L tetrahydrofuran was added dropwise, and the temperature was naturally raised to-20°C.

[0071] Into the reaction solution, 40ml concentrated hydrochloric acid and 200ml water were added dropwise, stirred for 30 minutes, then the water phase was separated, 0.5L petroleum ether was added, washed with 1L water three times, the solvent was rotary evaporated, and the product was recrystallized with ethanol to obtain white solid compound LC-01-2, 127g, yield 70%.

[0072] (3) Synthesis of compound LC-01

[0073] Into a 2L three-necked flask was placed 113.4 g of compound LC-01-1, 700 ml of DMF, and stirring was started. Then, 51.6 g of compound IM, 62.1 g of potassium carbonate were added, and nitrogen was introduced three times. The reaction was heated to 90-95°C, and stirring was continued for 5 hours.

[0074] The reaction solution was extracted with 400 ml of toluene, and washed with water until neutral. The solvent was removed by distillation, and the product was recrystallized from petroleum ether and ethanol to obtain white solid LC-01, 119.8 g, in a yield of 85.0%, and with a GC purity of 99.9%.

[0075] 1 H-NMR (CDC13, 400 MHz): δ: 0.90-2.60 (m, 7H), 3.50-4.60 (m, IH), 6.50-7.60 (m, 6H).

[0076] LC-01 has the following properties: melting point 46.2°C, Δn 0.181, Δε 28.3, γ1 89 mPa-s, m / z 486.

[0077] Example 2: The structure of liquid crystal compound LC-02 is shown below:

[0078]

[0079] The synthetic route for preparing compound LC-02 is shown below:

[0080]

[0081] (1) Synthesis of compound LC-02-1

[0082] Under nitrogen protection, 134.5 g of trans-2-(4-bromophenyl)-5-ethyltetrahydro-2H-pyran (0.5 mol), 79 g of 3,5-difluorophenylboronic acid (0.5 mol), 600 ml of toluene, 300 ml of ethanol, 300 ml of deionized water, 138 g of anhydrous potassium carbonate (1 mol), and 0.3 g of bis[ditert-butyl-(4-dimethylaminophenyl)phosphine]palladium(II) dichloride were added into a reaction flask, and the mixture was heated to 70°C for 8 hours. The reaction solution was washed with water until neutral, and column chromatography and recrystallization were performed to obtain white solid compound LC-02-1, 140.5 g, with a GC purity of 99.9% and a yield of 93%.

[0083] (2) Synthesis of compound LC-02-2

[0084] Into a 2L three-necked flask, 130g LC-02-1, 1L tetrahydrofuran, start stirring, until the solid is completely dissolved, pump out nitrogen three times, lower the temperature to -70°C, control the temperature at -65 to -75°C, drop 206ml 2.5M butyl lithium, after dropping, wash the dropping funnel with 100ml tetrahydrofuran, control the temperature at -65 to -75°C, react for 1 hour, control the temperature at -65 to -75°C, drop 0.5L tetrahydrofuran solution containing 126g difluorodibromomethane, after dropping, naturally raise the temperature to -20°C.

[0085] Into the reaction solution, drop a solution composed of 40ml concentrated hydrochloric acid and 200ml water, after stirring for 30 minutes, separate the water phase, add 0.5L petroleum ether, wash with 1L water three times, spin dry the solvent, recrystallize with methylbenzene and ethanol, obtain yellow solid LC-02-2 133g, yield 72%.

[0086] (3) Synthesis of compound LC-02

[0087] Into a 2L three-necked flask, 129g compound LC-02-2, 800ml DMF, start stirring, add 51.6g compound IM, 62.1g potassium carbonate, pump out nitrogen three times, start heating and raise the temperature, control the temperature at 90 to 95°C, react for 5 hours.

[0088] Into the reaction solution, add 500ml methylbenzene to extract, wash with water until neutral, spin dry the solvent, recrystallize with petroleum ether and ethanol, obtain white solid LC-01 136.2g, yield 87.0%, gas phase purity (GC) 99.9%.

[0089] 1 H-NMR (CDCI3, 400MHz): δ: 0.90-2.60 (m, 10H), 3.50-4.60 (m, 4H), 6.50-7.60 (m, 7H).

[0090] The performance of LC-02 is as follows: melting point: 72.3°C, Δn is 0.186, Δε is 30.4, γ1 is 185mPa-s, m / z is 538.

[0091] According to the technical solutions of examples 1 and 2, other liquid crystal compounds of the patent can be synthesized by simply replacing the raw materials containing corresponding groups.

[0092] Example 3: Liquid crystal composition

[0093] The following liquid crystal compounds were taken in weight parts and liquid crystal compositions were prepared. The specific proportions and the performance parameters of the obtained liquid crystal compositions are shown in Table 1, Table 2, and Table 3. The content of each component in the examples is expressed as a percentage by mass. The example liquid crystal compounds in Table 1, Table 2, and Table 3 were replaced by a conventional difluoromethoxy compound, i.e., a comparative compound, to obtain a comparative example. The proportions and performance parameters of the components of the comparative example are shown in Table 4, Table 5, and Table 6.

[0094] Table 1 Weight parts and performance parameters of each component in the example liquid crystal composition

[0095]

[0096] Table 2 Weight parts and performance parameters of each component in the example liquid crystal composition

[0097]

[0098]

[0099] Table 3 Weight parts and performance parameters of each component in the example liquid crystal composition

[0100]

[0101]

[0102] Table 4 Weight parts and performance parameters of each component in the comparative example liquid crystal composition

[0103]

[0104] Table 5 Weight parts and performance parameters of each component in the comparative example liquid crystal composition

[0105]

[0106]

[0107] Table 6 Weight parts and performance parameters of each component in the comparative example liquid crystal composition

[0108]

[0109]

[0110] As can be clearly seen from the test results of Tables 1-6, the compounds of the present application, when applied to the liquid crystal composition of the conventional system, can improve the dielectric anisotropy Δε of the liquid crystal composition, while maintaining a low rotational viscosity γ1 and a proper refractive index anisotropy Δn, and the obtained liquid crystal composition has a remarkable fast response feature and a low voltage driving feature. The addition amount of the compound is preferably 1-80%, and more preferably 3-50%.

[0111] In addition to the compositions exemplified in the test examples, other liquid crystal compositions to which other liquid crystal compounds having a difluoromethylether bridge structure provided by the present application are added can also obtain excellent optical and electrical properties.

[0112] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the present application and fall within the protection scope of the present application.

Claims

1. A liquid crystal compound having a structure represented by Formula I: ###0001### Formula I wherein: R is selected from the group consisting of unsubstituted alkyl groups having from 1 to 12 carbon atoms; ring A is selected from the group consisting of 1,4-cyclohexyl or 1,4-phenyl, wherein each of the C's of the 1,4-cyclohexyl group is independently substituted with one or more O's; and each of the H's of the 1,4-phenyl group is independently substituted with one or more F's; n is 0, 1, or 2; L1 is F; L2 and L3 are H; and Z is a single bond. wherein: R is selected from the group consisting of unsubstituted alkyl groups having from 1 to 5 carbon atoms; ring A is selected from the group consisting of 1,4-cyclohexyl or 1,4-phenyl, wherein each of the C's of the 1,4-cyclohexyl group is independently substituted with one or two O's; and each of the H's of the 1,4-phenyl group is independently substituted with one or two F's; n is 0, 1, or 2; L2 and L3 are H; and Z is a single bond. the compound has a structure represented by any one or more of Formulas I-1 to I-15: ###0002### I-1 I-2 I-3 I-4 I-5 I-6 I-7 I-8 I-9 I-10 I-11 I-12 I-13 I-14 I-15 wherein: R is selected from the group consisting of alkyl groups having from 1 to 7 carbon atoms.

2. The compound of claim 1, wherein each R is independently an alkyl group having from 2 to 5 carbon atoms. the compound is selected from one or more of the following structures: ###0003### ###0004### ###0005### ###0006### ###0007### ###0008### ###0009### ###0010### ###0011### ###0012### ###0013### ###0014### ###0015### ###0016### ###0017### ###0018### ###0019### ###0020### ###0021### ###0022### ###0023### ###0024### ###0025### ###0026### ###0027### ###0028### ###0029### ###0030### ###0031### ###0032### ###0033### ###0034### ###0035### ###0036### ###0037### ###0038### ###0039### ###0040### ###0041### ###0042### ###0043### ###0044### ###0045### ###0046### ###0047### ###0048### ###0049### ###0050### ###0051### ###0052### ###0053### ###0054### ###0055### ###0056### ###0057### ###0058### ###0059### ###0060### ###0061### ###0062### ###0063### ###0064### ###0065### ###0066### ###0067### ###0068### ###0069### ###0070### ###0071### ###0072### ###0073### ###0074### ###0075### ###0076### ###0077### ###0078### ###0079### ###0080### ###0081### ###0082### ###0083### ###0084### ###0085### ###0086### ###0087### ###0088### ###0089### ###0090### ###0091### ###0092### ###0093### ###0094### ###0095### ###0096### ###0097### ###0098### ###0099### ###0100### ###0101### ###0102### ###0103### ###0104### ###0105### ###0106### ###0107### ###0108### ###0109### ###0110### ###0111### ###0112### ###0113### ###0114### ###0115### ###0116### ###0117### ###0118### ###0119### ###0120### ###0121### ###0122### ###0123### ###0124### ###0125### ###0126### ###0127### ###0128### ###0129### ###0130### ###0131### ###0132### ###0133### ###0134### ###0135### ###0136### ###0137### ###0138### ​ ​ ​ 3. The compound of claim 1, wherein ​ ​ 4. The compound of claim 3, wherein ​ 5. The compound of claim 1, wherein ​ ​ 7. The composition of claim 6, wherein, ​ 8. The composition of claim 6, wherein, ​ ​ 10. Use according to claim 9, characterized in that, ​

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