CN113717735B - Positive dielectric anisotropic liquid crystal compound, liquid crystal composition and liquid crystal display device - Google Patents

Abstract

The invention relates to a positive dielectric anisotropy liquid crystal compound, a liquid crystal composition and a liquid crystal display device. The liquid crystal compound of the present invention _is a liquid crystal compound represented by the following formula I, which can obtain a reduced G _{1 /} The value of K ₁₁ can thus reduce the response time, which is beneficial to realize a fast response.

Description

Positive dielectric anisotropy liquid crystal compound, liquid crystal composition and liquid crystal display device

Technical Field

The present invention relates to the technical field of liquid crystal display materials, and more specifically to a positive dielectric anisotropy liquid crystal composition and a liquid crystal display device.

Background Art

At present, the application scope of liquid crystal compounds is expanding more and more widely. They can be used in various types of displays, electro-optical devices, sensors, etc., such as televisions, mobile phones, industrial control displays, and car displays. There are many types of liquid crystal compounds used in the above display fields, among which nematic liquid crystals are the most widely used. Nematic liquid crystals have been used in passive TN and STN matrix displays and systems with TFT active matrices.

For the application field of thin film transistor technology (TFT-LCD), although the market has been very huge in recent years and the technology has gradually matured, people's requirements for display technology are also constantly increasing, especially in terms of achieving fast response, reducing driving voltage to reduce power consumption, etc. Liquid crystal materials, as one of the important optoelectronic materials for liquid crystal displays, play an important role in improving the performance of liquid crystal displays.

For liquid crystal compositions, how to obtain a reduced response time while maintaining appropriate optical anisotropy values, dielectric anisotropy, and K ₃₃ /K ₁₁ values is an urgent problem to be solved in the art.

Summary of the invention

On one hand, the present invention provides a novel positive dielectric anisotropy liquid crystal compound. By using the liquid crystal compound of the present invention in a liquid crystal composition, a reduced G ₁ /K ₁₁ value can be obtained on the basis of maintaining appropriate optical anisotropy values, dielectric anisotropy, and K ₃₃ /K ₁₁ values, thereby achieving a rapid response on the basis of maintaining appropriate optical anisotropy values, dielectric anisotropy, and K ₃₃ /K ₁₁ values.

On the other hand, the present invention provides a liquid crystal composition, which contains the aforementioned liquid crystal compound of the present invention, thereby being able to obtain a fast response while maintaining appropriate optical anisotropy values, dielectric anisotropy, and K ₃₃ /K ₁₁ values. Furthermore, the liquid crystal composition also has an improved VHR value, thereby being able to overcome or reduce defects such as afterimages in the final display.

Another aspect of the present invention provides a liquid crystal display device, which has a fast response time due to the liquid crystal compound of the present invention. Furthermore, the liquid crystal display device of the present invention has reduced defects such as afterimages due to the use of a liquid crystal composition with a high VHR value, thereby achieving display advantages of reduced power consumption and improved stability.

The present invention includes the following technical solutions.

In one aspect, the present invention provides a novel positive dielectric anisotropic liquid crystal compound, which is a liquid crystal compound represented by the following formula I:

wherein _R1 represents H, an alkyl group having 1 to 8 carbon atoms, or an alkenyl group having 2 to 8 carbon atoms, wherein up to 4 H groups are optionally substituted by F;

R ₂ represents H, F, an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, one or two non-adjacent -CH ₂ - groups are optionally substituted by -O-, and up to 4 H groups are optionally substituted by F;

m is 1 or 2;

n is selected from 1, 2, 3 or 4;

o is 1 or 2;

Z ₁ represents -C ₂ H ₄ -, -CH ₂ O-, -S-, -CF ₂ O- or -COO-, wherein 0 to 4 H in -C ₂ H ₄ - are optionally replaced by F;

Z ₂ represents a single bond, -CF ₂ O- or -COO-;

Ring A, Ring B, and Ring C each independently represent a group consisting of 1,4-cyclohexylene, 1-methyl-1,4-cyclohexylene, 2-methyl-1,4-cyclohexylene, 2-oxacyclohexane-1,4-diyl, 2,6-dioxacyclohexane-1,4-diyl, cyclohexene-1,4-diyl, 1,4-phenylene, 2-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene, 2-fluoro-3-trifluoromethyl-1,4-phenylene, 2,3-bis(trifluoromethyl)-1,4-phenylene, 2-fluoro-3-trifluoromethoxy-1,4-phenylene, 2,3-bis(trifluoromethoxy)-1,4-phenylene, 2,6-difluoro-substituted -1,4-phenylene, 2,5-difluoro-substituted-1,4-phenylene, 2-fluoro-6-trifluoromethyl-1,4-phenylene, 2-fluoro-5-trifluoromethyl-1,4-phenylene, 2-fluoro-6-trifluoromethoxy-1,4-phenylene, 2-fluoro-5-trifluoromethoxy-1,4-phenylene, 2,6-bis(trifluoromethyl)-1,4-phenylene, 2,5-bis(trifluoromethyl)-1,4-phenylene, 2,6-bis(trifluoromethoxy)-1,4-phenylene, 2,5-bis(trifluoromethoxy)-1,4-phenylene, 2-trifluoromethyl-6-trifluoromethoxy-1,4-phenylene, 2-trifluoromethyl-5-trifluoromethoxy-1,4-phenylene.

In another aspect, the present invention provides a liquid crystal composition comprising the liquid crystal compound of the present invention.

On the other hand, the present invention provides a liquid crystal display device, which contains the aforementioned liquid crystal compound of the present invention, or the aforementioned liquid crystal composition of the present invention; the liquid crystal display device is an active matrix display device, or a passive matrix display device.

Effects of the Invention

The beneficial effect of the present invention is that, compared with the prior art, by using the positive dielectric anisotropic liquid crystal compound of the present invention in the liquid crystal composition, a reduced G ₁ /K ₁₁ value can be obtained on the basis of maintaining appropriate optical anisotropy values, dielectric anisotropy, and K ₃₃ /K ₁₁ values, thereby obtaining a fast response. In addition, by containing the aforementioned liquid crystal compound of the present invention in the liquid crystal composition of the present invention, a high VHR is obtained after UV light irradiation, thereby overcoming/reducing defects such as afterimages in the final display device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a mass spectrum of the compound CVEPGU-V-F prepared in Example 1 of the present invention.

FIG2 is a mass spectrum of the compound CVEPUQU-V-F prepared in Example 2 of the present invention.

DETAILED DESCRIPTION

[Liquid Crystalline Compounds]

The novel positive dielectric anisotropic liquid crystal compound of the present invention is a liquid crystal compound represented by the following formula I:

wherein _R1 represents H, an alkyl group having 1 to 8 carbon atoms, or an alkenyl group having 2 to 8 carbon atoms, wherein up to 4 H groups are optionally substituted by F;

R ₂ represents H, F, an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, one or two non-adjacent -CH ₂ - groups are optionally substituted by -O-, and up to 4 H groups are optionally substituted by F;

m is 1 or 2;

n is selected from 1, 2, 3 or 4;

o is 1 or 2;

Z ₁ represents -C ₂ H ₄ -, -CH ₂ O-, -S-, -CF ₂ O- or -COO-, wherein 0 to 4 H in -C ₂ H ₄ - are optionally replaced by F;

Z ₂ represents a single bond, -CF ₂ O- or -COO-;

Ring A, Ring B, and Ring C each independently represent a group consisting of 1,4-cyclohexylene, 1-methyl-1,4-cyclohexylene, 2-methyl-1,4-cyclohexylene, 2-oxacyclohexane-1,4-diyl, 2,6-dioxacyclohexane-1,4-diyl, cyclohexene-1,4-diyl, 1,4-phenylene, 2-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene, 2-fluoro-3-trifluoromethyl-1,4-phenylene, 2,3-bis(trifluoromethyl)-1,4-phenylene, 2-fluoro-3-trifluoromethoxy-1,4-phenylene, 2,3-bis(trifluoromethoxy)-1,4-phenylene, 2,6-difluoro-substituted -1,4-phenylene, 2,5-difluoro-substituted-1,4-phenylene, 2-fluoro-6-trifluoromethyl-1,4-phenylene, 2-fluoro-5-trifluoromethyl-1,4-phenylene, 2-fluoro-6-trifluoromethoxy-1,4-phenylene, 2-fluoro-5-trifluoromethoxy-1,4-phenylene, 2,6-bis(trifluoromethyl)-1,4-phenylene, 2,5-bis(trifluoromethyl)-1,4-phenylene, 2,6-bis(trifluoromethoxy)-1,4-phenylene, 2,5-bis(trifluoromethoxy)-1,4-phenylene, 2-trifluoromethyl-6-trifluoromethoxy-1,4-phenylene, 2-trifluoromethyl-5-trifluoromethoxy-1,4-phenylene.

The aforementioned 2-fluoro-1,4-phenylene group represents two divalent groups as described below, wherein the fluorine substituent may be located on the left side or on the right side.

2-Methyl-1,4-cyclohexylene represents the following two divalent groups:

The same rules apply to other similar groups.

The "alkyl group having 1 to 8 carbon atoms" represented by the aforementioned _R1 may be a linear alkyl group, a branched alkyl group or a cyclic alkyl group, and examples thereof include methyl, ethyl, n-propyl, isopropyl, cyclopropyl, cyclopentyl, n-butyl, isobutyl, tert-butyl, cyclobutyl, n-pentyl, isopentyl, cyclopentyl, hexyl, heptyl, octyl and the like.

The "alkenyl group having 2 to 8 carbon atoms" represented by _R1 above may be a straight-chain alkenyl group, a branched alkenyl group or an alkenyl group having a cyclic alkyl chain, and is not particularly limited. Examples thereof include ethenyl, propenyl, butenyl, 2-methylpropenyl, 1-pentenyl, 2-pentenyl, 2-methyl-1-butenyl, 3-methyl-1-butenyl, 2-methyl-2-butenyl, pentenyl, hexenyl, and heptenyl.

In the aforementioned "alkyl having 1 to 8 carbon atoms" and "alkenyl having 2 to 8 carbon atoms", 4 or less H groups may be substituted with F, for example, 0, 1, 2, 3 or 4 H groups may be substituted with F. For example, when the methyl group represented by _R1 is substituted with F, it may be _-CH2F , _-CHF2 or _-CF3 . Groups obtained by replacing other groups with F are similar to the aforementioned groups, and detailed description is omitted here.

The "alkyl group having 1 to 8 carbon atoms" represented by the aforementioned _R2 may be a linear alkyl group, a branched alkyl group or a cyclic alkyl group, and examples thereof include methyl, ethyl, n-propyl, isopropyl, cyclopropyl, cyclopentyl, n-butyl, isobutyl, tert-butyl, cyclobutyl, n-pentyl, isopentyl, cyclopentyl, hexyl, heptyl, octyl and the like.

The "alkenyl group having 2 to 8 carbon atoms" represented by _R2 described above may be a straight-chain alkenyl group, a branched alkenyl group or an alkenyl group having a cyclic alkyl chain, and is not particularly limited. Examples thereof include ethenyl, propenyl, butenyl, 2-methylpropenyl, 1-pentenyl, 2-pentenyl, 2-methyl-1-butenyl, 3-methyl-1-butenyl, 2-methyl-2-butenyl, pentenyl, hexenyl, and heptenyl.

In the aforementioned "alkyl having 1 to 8 carbon atoms" or "alkenyl having 2 to 8 carbon atoms" represented by R ₂ , one or two non-adjacent -CH ₂ - groups may be substituted by -O-. For example, when R ₂ represents -CH ₂ CH ₃ , the group obtained by replacing -CH ₂ - therein with O is -OCH ₃ ; when R ₂ represents -CH ₂ CH ₂ CH ₃ , the group obtained by replacing one -CH ₂ - therein with O is -OCH ₂ CH ₃ , and so on. They are not listed here one by one.

The aforementioned "alkyl group having 1 to 8 carbon atoms", "alkenyl group having 2 to 8 carbon atoms" represented by R ₂ , and a group in which one or two non-adjacent -CH ₂ - groups are optionally substituted by -O-, and further, 4 or less H groups are optionally substituted by F. For example, when R ₂ represents -CH ₃ , the groups in which 1 to 3 H groups are substituted by F are -CH ₂ F, -CHF ₂ , and -CF ₃ , respectively; when R ₂ represents -OCH ₃ , the groups in which 1 to 3 H groups are substituted by F are -OCH ₂ F, -OCHF ₂ , and -OCF ₃ , respectively.

Preferably, R ₂ represents H, F, -CH ₂ F, -CHF ₂ , -CF ₃ , -OCH ₂ F, -OCHF ₂ , or -OCF ₃ . More preferably, it represents F, -OCH ₂ F, or -OCF ₃ .

The positive dielectric anisotropic liquid crystal compound of the present invention has the structure shown in the aforementioned formula I, and thus can obtain a reduced G ₁ /K ₁₁ value while maintaining appropriate optical anisotropy values, dielectric anisotropy, and K ₃₃ /K ₁₁ values, thereby obtaining a rapid response. Therefore, when used in a liquid crystal composition, the response time can be reduced, which is conducive to achieving a rapid response.

Preferably, the liquid crystal compound represented by the aforementioned formula I is selected from the group consisting of compounds represented by the following formulas I-1 to I-36:

Wherein, R ₁ and R ₂ have the same definitions as above.

[Synthesis of positive dielectric anisotropy liquid crystal compounds]

The synthesis method of the positive dielectric anisotropic liquid crystal compound of the present invention is described below.

The compound represented by Formula I can be synthesized by combining methods of organic synthetic chemistry. For example, in the case of a compound having a -CH=CH-CH ₂ -CH ₂ - structure, the -CH=CH-CH ₂ -CH ₂ - structure can be synthesized as follows:

An organic bromide (a1) having at least one ring structure reacts with p-bromophenyl propionaldehyde ethylene acetal to obtain a compound (a2) in which the aforementioned ring structure is connected to propionaldehyde ethylene acetal. The compound (a2) is hydrolyzed with formic acid, and the propionaldehyde ethylene acetal of the compound (a2) is hydrolyzed to generate a compound (a3) in which propionaldehyde is connected to the ring structure. The aforementioned compound (a3) is further reacted with iodomethane phosphonium salt (such as 4-vinylcyclohexyl iodomethane phosphonium salt) in a system containing potassium tert-butoxide and THF to obtain a compound (a4) having a -CH=CH-CH ₂ -CH ₂ - structure. The aforementioned reaction process is shown in the following reaction process diagram 1.

If necessary, the 4-vinylcyclohexyl iodomethane phosphonium salt can be replaced by other iodomethane phosphonium salts to obtain compounds in which -CH=CH-CH ₂ -CH ₂ - is connected to different structures.

Reaction scheme 1

(2) Synthesis Example 1

The synthetic route of the compound shown in the aforementioned formula A-6 is as shown in the above-mentioned synthetic route diagram. Specifically, trifluorophenylboric acid and 2-fluoro-4-bromoiodobenzene react under stirring, heating and reflux in a reaction system containing tetrahydrofuran, sodium carbonate and tetrakis (triphenylphosphine) palladium to generate the compound shown in formula A-1. Then, the compound shown in formula A-1 reacts with triisopropyl borate in anhydrous tetrahydrofuran in the presence of butyl lithium n-hexane and THF to generate the compound shown in formula A-2. Then, the compound shown in formula A-2 reacts with p-bromophenyl propionaldehyde acetal under the action of catalyst bis (di-tert-butyl-4-dimethylaminophosphine) palladium chloride to generate the compound shown in formula A-3. The compound shown in formula A-3 is hydrolyzed in a system containing formic acid to obtain the compound shown in formula A-4. The compound shown in formula A-4 is further reacted with 4-vinylcyclohexyl iodomethane phosphonium salt in a system containing potassium tert-butoxide and THF to obtain the compound shown in A-5. Then, the compound represented by the above formula A-5 is heated in a system containing toluene, sodium benzenesulfinate and concentrated hydrochloric acid to cause configuration inversion, thereby obtaining the compound represented by A-6.

(2) Synthesis Example 2

Preparation of CVEPUQU-V-F

The synthesis route of the compound represented by the aforementioned formula B-6 is shown in the above-mentioned synthesis route diagram.

Specifically, the compound shown in formula B-1 reacts with triisopropyl borate in the presence of anhydrous tetrahydrofuran and butyl lithium n-hexane to obtain the compound shown in formula B-2, and then the compound shown in formula B-2 reacts with p-bromophenyl propionaldehyde ethylene glycol in the presence of a catalyst bis(di-tert-butyl-4-dimethylaminophosphine) palladium chloride to generate the compound shown in formula B-3. The compound shown in formula B-3 is hydrolyzed in the presence of formic acid to obtain the compound shown in formula B-4. The compound shown in formula B-4 reacts with 4-vinyl cyclohexyl iodomethane phosphonium salt in the presence of potassium tert-butoxide and THF to obtain the compound shown in formula B-5 containing E and Z configurations. Then, the compound shown in the aforementioned formula B-5 is heated in a system containing toluene, sodium benzenesulfinate, and concentrated hydrochloric acid to reverse its configuration to obtain the compound shown in B-6.

For the synthesis of other structures of the liquid crystal compound of the present invention, those skilled in the art can select appropriate synthesis routes and conditions for preparation as required.

[Liquid crystal composition]

The liquid crystal composition of the present invention contains the liquid crystal compound represented by the above-mentioned formula I.

The liquid crystal composition of the present invention may contain one or more liquid crystal compounds represented by formula I. The liquid crystal composition of the present invention may contain only the liquid crystal compound represented by formula I as a liquid crystal compound component. The composition of the present invention may contain the compound represented by formula I in a range of, for example, 1 to 99% by mass.

The liquid crystal composition of the present invention is a liquid crystal composition having positive dielectric anisotropy.

By using the liquid crystal compound represented by formula I of the present invention in the liquid crystal composition of the present invention, a reduced G ₁ /K ₁₁ value can be obtained while maintaining appropriate optical anisotropy values, dielectric anisotropy, and K ₃₃ /K ₁₁ values, thereby obtaining a fast response. Furthermore, the liquid crystal composition of the present invention also has an improved VHR value, thereby reducing/eliminating defects such as afterimages of liquid crystal display devices.

In addition to the liquid crystal compound represented by the aforementioned formula I, the liquid crystal composition of the present invention may contain other liquid crystal compounds. The other liquid crystal compounds that may be contained may have positive dielectric anisotropy or negative dielectric anisotropy.

In some embodiments of the liquid crystal composition of the present invention, preferably, it further comprises:

At least one compound of formula II;

At least one compound of formula III: and

At least one compound of formula IV:

in,

R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and R ₈ each independently represent an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an alkenyloxy group having 3 to 5 carbon atoms;

H on any carbon atom in R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and R ₈ is independently optionally substituted by F, and one or two non-adjacent -CH ₂ - are optionally substituted by -O-;

Z ₃ represents a single bond or -CH ₂ O-;

Z ₄ represents -C ₂ H ₄ -, -CH ₂ O-, -S-, -CF ₂ O- or -COO-, wherein 0 to 4 H in -C ₂ H ₄ - are optionally replaced by F;

s is selected from 1, 2, 3 or 4;

p represents 0, 1, 2 or 3;

q, r, and v each independently represent 0, 1, or 2;

Ring A1, Ring A2, Ring A3, Ring A4, Ring A5, and Ring A6 each independently represent a group selected from the group consisting of 1,4-cyclohexylene, 1-methyl-1,4-cyclohexylene, 2-methyl-1,4-cyclohexylene, 2-oxacyclohexane-1,4-diyl, 2,6-dioxacyclohexane-1,4-diyl, cyclohexene-1,4-diyl, 1,4-phenylene, 2-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene, 2-fluoro-3-trifluoromethyl-1,4-phenylene, 2,3-bis(trifluoromethyl)-1,4-phenylene, 2-fluoro-3-trifluoromethoxy-1,4-phenylene, 2,3-bis(trifluoromethoxy)-1,4-phenylene, ,6-difluoro-substituted-1,4-phenylene, 2,5-difluoro-substituted-1,4-phenylene, 2-fluoro-6-trifluoromethyl-1,4-phenylene, 2-fluoro-5-trifluoromethyl-1,4-phenylene, 2-fluoro-6-trifluoromethoxy-1,4-phenylene, 2-fluoro-5-trifluoromethoxy-1,4-phenylene, 2,6-bis(trifluoromethyl)-1,4-phenylene, 2,5-bis(trifluoromethyl)-1,4-phenylene, 2,6-bis(trifluoromethoxy)-1,4-phenylene, 2,5-bis(trifluoromethoxy)-1,4-phenylene, 2-trifluoromethyl-6-trifluoromethoxy-1,4-phenylene, 2-trifluoromethyl-5-trifluoromethoxy-1,4-phenylene.

R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and R ₈ each independently represent an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms or an alkenyloxy group having 3 to 5 carbon atoms; H on any carbon atom in R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and R ₈ each independently may be optionally substituted by F, and one or two non-adjacent -CH ₂ - groups may be optionally substituted by -O-.

Examples of the alkyl group having 1 to 5 carbon atoms represented by R ₃ , R ₄ , R ₅ , R ₆ , R ₇ or R ₈ include linear or branched alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl and isopentyl, and cycloalkyl groups such as cyclopropyl, cyclobutyl and cyclopentyl.

Examples of the "alkoxy group having 1 to 5 carbon atoms" represented by R ₃ , R ₄ , R ₅ , R ₆ , R ₇ or R ₈ include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, n-pentyloxy, isopentyloxy, and cycloalkyloxy groups such as cyclopropyloxy, cyclopentyloxy and cyclobutyloxy.

Examples of the "alkenyl group having 2 to 5 carbon atoms" represented by R ₃ , R ₄ , R ₅ , R ₆ , R ₇ or R ₈ include ethenyl, propenyl, butenyl, 2-methylpropenyl, 1-pentenyl, 2-pentenyl, 2-methyl-1-butenyl, 3-methyl-1-butenyl and 2-methyl-2-butenyl.

Examples of the "alkenyloxy group having 3 to 5 carbon atoms" represented by R ₃ , R ₄ , R ₅ , R ₆ , R ₇ or R ₈ include vinyloxy, propenyloxy, butenyloxy, 2-methylpropenyloxy, 1-pentenyloxy, 2-pentenyloxy, 2-methyl-1-butenyloxy, 3-methyl-1-butenyloxy and 2-methyl-2-butenyloxy.

In the case where R ₃ , R ₄ , R ₅ , R ₆ , R ₇ or R ₈ each independently represents an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms or an alkenyloxy group having 3 to 5 carbon atoms, H on any carbon atom in these groups is each independently optionally substituted with F, and one or two non-adjacent -CH ₂ - groups in these groups are optionally substituted with -O-.

Z ₃ represents a single bond or -CH ₂ O-.

Z ₄ represents -C ₂ H ₄ -, -CH ₂ O-, -S-, -CF ₂ O- or -COO-, wherein 0 to 4 H in -C ₂ H ₄ - are optionally substituted with F. Examples of the group in which -C ₂ H ₄ - is substituted with F include -CH ₂ CHF-, -CH ₂ CF ₂ -, -CHFCF ₂ - or -CF ₂ CF ₂ -.

In the aforementioned positive dielectric anisotropic liquid crystal composition, preferably, the compound represented by the aforementioned formula II is selected from the group consisting of compounds represented by the following formulas II-1 to II-10.

R ₃ and R ₄ are as defined above; (F) represents F or H.

Preferably, _R3 is a linear alkyl group having 1 to 5 carbon atoms or an alkenyl group having 2 to 5 carbon atoms. Examples of the linear alkyl group having 1 to 5 carbon atoms include methyl, ethyl, n-propyl, n-butyl, and n-pentyl. Examples of the alkenyl group having 2 to 5 carbon atoms include vinyl, propenyl, butenyl, and pentenyl.

_R4 is preferably a linear alkyl group having 1 to 5 carbon atoms or an alkenyl group having 2 to 5 carbon atoms. Examples of the linear alkyl group having 1 to 5 carbon atoms include methyl, ethyl, n-propyl, n-butyl, and n-pentyl. Examples of the alkenyl group having 2 to 5 carbon atoms include vinyl, propenyl, butenyl, and pentenyl.

In the aforementioned positive dielectric anisotropic liquid crystal composition, preferably, the compound represented by the aforementioned formula III is selected from the group consisting of compounds represented by the following formulas III-1 to III-21.

R ₅ and R ₆ are the same as defined above.

In the aforementioned positive dielectric anisotropic liquid crystal composition, preferably, the compound represented by the aforementioned formula IV is selected from the group consisting of compounds represented by the following formulae IV-1 to IV-44.

R ₇ and R ₈ are the same as defined above.

Preferably, _R7 represents an alkyl group having 1 to 5 carbon atoms or an alkoxy group having 1 to 5 carbon atoms.

Preferably, R ₈ represents an alkyl group having 1 to 5 carbon atoms or an alkoxy group having 1 to 5 carbon atoms.

In the aforementioned liquid crystal composition, the weight percentage of the liquid crystal compound represented by the aforementioned formula I relative to the total amount of the liquid crystal composition is preferably, for example, 1 to 40%.

In the aforementioned liquid crystal composition, the weight percentage of the liquid crystal compound represented by the aforementioned formula II relative to the total amount of the liquid crystal composition is, for example, 1 to 90%.

In the aforementioned liquid crystal composition, the weight percentage of the liquid crystal compound represented by the aforementioned formula III is 1 to 30% relative to the total amount of the liquid crystal composition. Considering the acquisition of suitable Δn, Δε, viscosity, VHR, rotational viscosity/elastic constant, etc., it is preferably 1 to 25%, and more preferably 1 to 20%.

In the aforementioned positive dielectric anisotropic liquid crystal composition, the weight percentage of the liquid crystal compound represented by the aforementioned formula IV is 1 to 30% relative to the total amount of the liquid crystal composition. Considering the acquisition of suitable Δn, Δε, viscosity, VHR, rotational viscosity/elastic constant, etc., it is preferably 1 to 25%, and more preferably 1 to 20%.

In some embodiments of the aforementioned positive dielectric anisotropic liquid crystal composition, the components may be contained in the following ratios. For example, the weight percentage of the compound represented by the aforementioned formula I is 1 to 40%, the weight percentage of the compound represented by the aforementioned formula II is 1 to 70%, the weight percentage of the compound represented by the aforementioned formula III is 1 to 30%, and the weight percentage of the compound represented by the aforementioned formula IV is 1 to 30%.

In some embodiments of the aforementioned positive dielectric anisotropic liquid crystal composition, a compound represented by the following formula V may also be contained.

Wherein, R ₉ represents an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an alkenyloxy group having 3 to 5 carbon atoms; H on any carbon atom in R ₉ is independently optionally substituted by F, and one or two non-adjacent -CH ₂ - groups are optionally substituted by -O-.

R ₁₀ represents H, F, an alkyl group having 1 to 8 carbon atoms, or an alkenyl group having 2 to 8 carbon atoms, wherein one or two non-adjacent -CH ₂ - groups are optionally substituted by -O-, and four or less H groups are optionally substituted by F.

Ring A7 and Ring A8 each independently represent a group selected from the group consisting of 1,4-cyclohexylene, 1-methyl-1,4-cyclohexylene, 2-methyl-1,4-cyclohexylene, 2-oxacyclohexane-1,4-diyl, 2,6-dioxacyclohexane-1,4-diyl, cyclohexene-1,4-diyl, 1,4-phenylene, 2-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene, 2-fluoro-3-trifluoromethyl-1,4-phenylene, 2,3-bis(trifluoromethyl)-1,4-phenylene, 2-fluoro-3-trifluoromethoxy-1,4-phenylene, 2,3-bis(trifluoromethoxy)-1,4-phenylene, 2,6-difluoro-substituted- 1,4-phenylene, 2,5-difluoro-substituted-1,4-phenylene, 2-fluoro-6-trifluoromethyl-1,4-phenylene, 2-fluoro-5-trifluoromethyl-1,4-phenylene, 2-fluoro-6-trifluoromethoxy-1,4-phenylene, 2-fluoro-5-trifluoromethoxy-1,4-phenylene, 2,6-bis(trifluoromethyl)-1,4-phenylene, 2,5-bis(trifluoromethyl)-1,4-phenylene, 2,6-bis(trifluoromethoxy)-1,4-phenylene, 2,5-bis(trifluoromethoxy)-1,4-phenylene, 2-trifluoromethyl-6-trifluoromethoxy-1,4-phenylene, 2-trifluoromethyl-5-trifluoromethoxy-1,4-phenylene;

Z ₅ represents a single bond, -CF ₂ O- or -COO-;

t means 1, 2, 3 or 4;

u represents 1 or 2.

Preferably, the compound represented by the aforementioned formula V is selected from the group consisting of compounds represented by the following formulae V-1 to IV-37.

Here, R ₉ and R ₁₀ have the same meanings as above.

Preferably, R ₉ represents H, an alkyl group having 1 to 5 carbon atoms, or an alkenyl group having 2 to 8 carbon atoms, and more preferably represents H, an alkyl group having 1 to 3 carbon atoms, or an alkenyl group having 2 to 4 carbon atoms.

Preferably, R ₁₀ is F, -CF ₃ , -CHF ₂ , -CH ₂ F, -OCF ₃ , -OCHF ₂ , or -OCH ₂ F. More preferably, it is F, -CF ₃ , -OCF ₃ , or -OCF ₃ .

In the aforementioned positive dielectric anisotropic liquid crystal composition, when containing the compound represented by the aforementioned formula V, the weight percentage of the liquid crystal compound represented by the aforementioned formula V relative to the total amount of the liquid crystal composition can be, for example, 1 to 30%. Considering the acquisition of suitable Δn, Δε, viscosity, VHR, rotational viscosity/elastic constant, etc., it is preferably 1 to 25%, and more preferably 1 to 20%.

In some embodiments of the aforementioned liquid crystal composition, for example, the components may be contained in the following ratios: the weight percentage of the compound represented by the aforementioned formula I is 1 to 40%, the weight percentage of the compound represented by the aforementioned formula II is 1 to 70%, the weight percentage of the compound represented by the aforementioned formula III is 1 to 30%, the weight percentage of the compound represented by the aforementioned formula IV is 1 to 30%, and the weight percentage of the compound represented by the aforementioned formula V is 1 to 30%.

In some embodiments of the aforementioned positive dielectric anisotropic liquid crystal composition, in view of obtaining a lower viscosity to improve the response speed, reduce defects such as afterimages, etc., preferably, it further comprises one or more compounds represented by the following formula VI:

In Formula VI, R ₁₁ and R ₁₂ each independently represent an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, an alkenyl group having 2 to 7 carbon atoms, or an alkenyloxy group having 2 to 7 carbon atoms; and, H on any carbon atom in R ₁₁ and R ₁₂ each independently may be optionally substituted by F, and one or two non-adjacent -CH ₂ - may be optionally substituted by -O-;

Ring D represents 1,4-cyclohexylene, cyclohexene-1,4-diyl, 2-oxacyclohexane-1,4-diyl, 2,6-dioxacyclohexane-1,4-diyl, 1,4-phenylene, 2-fluoro-1,4-diphenylene, 2-methyl-1,4-diphenylene, or 2,3-difluoro-1,4-phenylene, wherein any H atom is optionally substituted by -F or -CH ₃ ;

Ring E represents a group consisting of groups selected from the following:

Z ₆ represents a single bond, -CH ₂ O-, -CF ₂ O-, -COO-, or -CH ₂ CH ₂ -;

w, x, y, and z each independently represent 0, 1, 2, or 3.

Examples of the alkyl group having 1 to 8 carbon atoms represented by R ₁₁ and R ₁₂ include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl and n-octyl.

Examples of the "alkoxy group having 1 to 8 carbon atoms" represented by R ₁₁ and R ₁₂ include methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, heptyloxy and octyloxy.

Examples of the “alkenyl group having 2 to 7 carbon atoms” represented by the aforementioned R ₁₁ and R ₁₂ include vinyl, 1-propenyl, 2-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl, 5-hexenyl, 1-heptenyl, 2-heptenyl, 3-heptenyl, 4-heptenyl, 5-hexenyl, 1-heptenyl, 2-heptenyl, 3-heptenyl, 4-heptenyl, 5-heptenyl, 6-heptenyl and the like.

Examples of the "alkenyloxy group having 2 to 7 carbon atoms" represented by R ₁₁ and R ₁₂ include vinyloxy, allyloxy, 3-butenyloxy, 3-pentenyloxy, 4-pentenyloxy, 3-hexenyloxy, 4-hexenyloxy, 5-hexenyloxy, 3-heptenyloxy, 4-heptenyloxy, 5-hexenyloxy, 6-heptenyloxy and the like.

In the aforementioned alkyl having 1 to 8 carbon atoms, alkoxy having 1 to 8 carbon atoms, alkenyl having 2 to 7 carbon atoms, or alkenyloxy having 2 to 7 carbon atoms represented by R ₁₁ and R ₁₂ , H in these groups may be independently substituted by F, and one or two non-adjacent -CH ₂ - may be substituted by -O-.

The compound represented by the aforementioned formula VI is preferably selected from the group consisting of compounds represented by the following formula VI-1 to formula VI-78.

When the liquid crystal composition of the present invention contains the compound represented by the aforementioned formula VI, the weight percentage of the compound represented by the aforementioned formula VI in the liquid crystal composition may be, for example, 1 to 20%, preferably 1 to 10%.

In the liquid crystal composition of the present invention, in addition to the liquid crystal compounds listed above, those skilled in the art may also add other liquid crystal compounds and non-liquid crystal compounds without destroying the desired properties of the liquid crystal composition.

The positive dielectric anisotropic liquid crystal composition of the present invention may optionally further include various functional additives, such as UV stabilizers, antioxidants, chiral dopants, polymerization initiators, and may contain one or more of them.

The aforementioned antioxidants can be listed, for example:

m represents an integer from 1 to 10;

As the chiral dopant, for example,

Wherein, R ₀ represents an alkyl group having 1 to 10 carbon atoms;

As the light stabilizer, for example,

Wherein, Z ₀ represents an alkylene group having 1 to 20 carbon atoms, in which any one or more hydrogen atoms may be substituted by halogen atoms, and any one or more -CH ₂ - atoms may be substituted by -O- atoms.

As the ultraviolet absorber, for example,

or Here, R ₀₁ represents an alkyl group having 1 to 10 carbon atoms.

The amount of the additives added may be, for example, 0.01% to 1.5% of the total mass of the liquid crystal composition.

[Liquid crystal display device]

A second aspect of the present invention provides a liquid crystal display device, which uses the aforementioned liquid crystal composition of the present invention. In the liquid crystal display device of the present invention, there is no particular limitation as long as it contains the aforementioned liquid crystal composition. Those skilled in the art can select other components and structures of a suitable liquid crystal display device according to the required performance.

The driving mode of the liquid crystal display device of the present invention is preferably, for example, an IPS mode or an FFS mode.

Example

In order to explain the present invention more clearly, the present invention is further described below in conjunction with preferred embodiments. It should be understood by those skilled in the art that the following specific description is illustrative rather than restrictive, and should not be used to limit the scope of protection of the present invention.

In the present invention, the preparation methods are conventional methods unless otherwise specified, the raw materials used are available from public commercial channels unless otherwise specified, the percentages are by mass, the temperatures are in degrees Celsius (°C), and the liquid crystal compounds are also liquid crystal monomers.

The structure of the liquid crystal monomer used in the examples of the present application is represented by the following codes, and the code representation method of the liquid crystal ring structure, end group, and connecting group is shown in the following Table (I) and Table (II).

Table (I): Corresponding codes of ring structures

Table (II): Corresponding codes of terminal groups and linking groups

Example:

[Liquid Crystalline Compounds]

Example 1: Preparation of CVEPGU-V-F

Reaction Scheme 2: Preparation of CVEPGU-V-F

CVEPGU-V-F was prepared according to the preparation route shown in the above reaction scheme 2.

The specific instructions are as follows:

A-1 Structure: Preparation of the indicated compounds

Under nitrogen protection, add 387g 3,4,5-trifluorophenylboric acid, 2500ml tetrahydrofuran, 450g sodium carbonate, 950ml deionized water and 12g tetrakis(triphenylphosphine)palladium into a three-necked flask. Heat to weak reflux under stirring, and dropwise add a solution prepared by 600g 2-fluoro-4-bromoiodobenzene and 1100ml tetrahydrofuran for about 3 hours. After the dropwise addition is completed, continue the reflux reaction for 16 hours.

The temperature was lowered to 40°C, toluene and water were added to the reaction solution, and the aqueous layer was separated after stirring. After toluene extraction, the mixed solution of toluene and ethanol was crystallized to obtain 366 g of the compound represented by formula A-1 in the form of white powder.

A-2 Structure: Preparation of the indicated compounds

First, replace the air in a clean three-necked flask with nitrogen for 10 minutes. Then, add 306g of the compound shown in formula A-1 and 1200ml of anhydrous tetrahydrofuran in sequence. Turn on the stirring and cool it with liquid nitrogen. When the temperature drops to -78°C, start to drop 430ml of 2.5M butyl lithium n-hexane solution. The temperature is controlled at -70 to -80°C during the whole process. After the drop is completed, keep warm for 1 hour. After the insulation is completed, drop the pre-prepared THF solution of triisopropyl borate (prepared by dissolving 280g of triisopropyl borate in 300ml of tetrahydrofuran). When dropping, the internal temperature is controlled at -70 to -80°C. The drop is completed in about 1 hour. After the insulation is completed for 30 minutes, the temperature is naturally raised for about 2 to 3 hours.

When the temperature rises to about -20°C, the reaction solution is added to dilute hydrochloric acid for hydrolysis. After the hydrolyzate is stirred for 0.5 hours, the layers are separated, the lower aqueous phase is extracted twice with ethyl acetate, the organic phases are combined, and the pH value is neutralized with sodium bicarbonate to 6-7. The solvent is removed by rotary evaporation to obtain 256 g of white powder, i.e., the compound represented by formula A-2, which is used directly in the next step without purification.

Formula A-3 structure: Preparation of the indicated compounds

Under nitrogen protection, add 700g of deionized water to the reaction bottle, start stirring, add 190g of anhydrous sodium carbonate to the three-necked flask, and stir for about 10 minutes to dissolve. Then add 1000ml of toluene, 450ml of ethanol, 232g of p-bromophenylpropionaldehyde ethylene acetal, and 243g of the intermediate I-2 prepared in the previous step. After the addition, replace the air in the kettle with nitrogen for 1 hour, and add 0.5g of catalyst bis(di-tert-butyl-4-dimethylaminophosphine)palladium chloride. After adding the catalyst, stir and heat to 75℃～80℃, and keep warm for 2.5 hours until the reaction is completed.

After the reaction solution was cooled to 20-30°C, stirring was stopped, and the organic layer was set aside. The aqueous phase was extracted twice with toluene, and the organic phases were combined, washed with water until neutral, vacuum evaporated to dryness, and recrystallized from ethanol to obtain 325 g of intermediate A-3.

A-4 Structure: Preparation of the indicated compounds

Under nitrogen protection, add 440 ml of toluene, 320 g of the intermediate A-3 prepared in the previous step, and 1200 ml of formic acid into a three-necked flask, stir at room temperature until completely dissolved, then heat to 60-65°C, and stir for 5 hours until the residual amount of intermediate A-3 is ≤0.02%.

Stop stirring, let stand to separate the layers, take the lower formic acid phase, extract once with 100 ml of toluene, combine the toluene phases, wash once with water, wash once with saturated sodium bicarbonate, and finally wash with saturated brine until neutral, add anhydrous sodium sulfate to the organic phase, stir and dry, filter, and vacuum evaporate the filtrate to obtain 250 g of intermediate A-4, which can be directly used for the next step without purification.

A-5 Structure: Preparation of the indicated compounds

Under nitrogen protection, add 700 ml of toluene and 96 g of 4-vinylcyclohexyl iodomethane phosphonium salt to the reaction bottle, stir at 20-30°C for about 30 minutes, and cool to -5-0°C. Add a solution prepared by 25 g of potassium tert-butoxide and 150 ml of THF to the reaction bottle, and control the temperature at -5-0°C during the addition. After the addition is completed, continue to keep warm for 2 hours. Prepare a solution of 150 ml of toluene and 55 g of intermediate I-4, control the temperature at -5-0°C, and add it dropwise to the reaction bottle. After the addition is completed, keep warm for 3 hours.

The mixture was quenched with tap water, and the mixture was allowed to stand for stratification. The organic phases were combined and washed with water until neutral. The mixture was dried with anhydrous sodium sulfate by stirring for 0.5 to 1 hour. The anhydrous sodium sulfate was filtered and the filtrate was decompressed and desolventized. The solid after desolventization was added with petroleum ether and boiled, and the filtrate was retained for later use. The solid obtained by decompression was repeated twice with petroleum ether. The filtrates were combined and passed through a silica gel column. The column liquid was decompressed and desolventized to obtain 68 g of crude product A-5 containing cis and trans forms, which was directly used for the next configuration transformation.

Single crystal A-6 (CVEPGU-VF) structure: Preparation of the indicated compounds

Under nitrogen protection, add 150 ml of toluene, 50 g of the intermediate I-5 obtained in the previous step, 12 g of sodium benzenesulfinate, and 7 ml of 36% concentrated hydrochloric acid (wt%) into the reaction flask, stir at room temperature until completely dissolved, then raise the temperature to 60°C, and stir at 60-65°C for 8 hours.

After the reaction is completed, 20 ml of deionized water is added to the reaction bottle. After stirring for 30 minutes, the stirring is stopped, the mixture is allowed to stand for stratification, and the lower aqueous phase is separated and extracted twice with toluene. The combined organic phases are washed with water three times until neutral. The organic phase is desolvated under reduced pressure to obtain 48 g of crude product. The crude product is crystallized three times with ethanol and n-hexane to obtain a white solid. The material after drying and recrystallization is passed through a silica gel (70-200 mesh) chromatography column and eluted with n-heptane to obtain 30 g of trans-CVEPGU-V-F, the mass spectrum of which is shown in Figure 1.

MS (EI, m/z): 149,315,464

Example 2: Preparation of CVEPUQU-V-F

Reaction Scheme 3: Preparation Scheme of CVEPUQU-V-F

CVEPUQU-V-F was prepared according to reaction scheme 3 as shown above.

B-2 Structure: Preparation of the indicated compounds

Pass nitrogen into the three-necked flask to replace the air inside for 10 minutes. Then add 195g of raw material B-1, 1000ml of anhydrous tetrahydrofuran and 140g of triisopropyl borate in sequence. Turn on the stirring, pass liquid nitrogen to cool down, and when the temperature drops to -100℃, start to drop 210ml of 2.5M butyl lithium n-hexane solution, and control the temperature at -90～-100℃ throughout the process. After the drop is completed, keep warm for 1 hour. After keeping warm for 30 minutes, naturally heat up for about 2～3 hours.

When the temperature rises to about -30°C, the reaction solution is added to dilute hydrochloric acid for hydrolysis. The hydrolyzate is stirred for 1 hour and then allowed to stand for stratification. The lower aqueous phase is extracted twice with ethyl acetate, the organic phases are combined, and the pH value is neutralized with sodium bicarbonate to 6-7. The solvent is removed by rotary evaporation to obtain 159 g of white powder, namely intermediate B-2, which is used directly in the next step without purification.

B-3 Structure: Preparation of the indicated compounds

Under nitrogen protection, add 300g of deionized water to the reaction bottle, start stirring, add 76g of anhydrous sodium carbonate to the three-necked flask, and stir for about 10 minutes to dissolve the sodium carbonate. Then add 460ml of toluene, 150ml of ethanol, 93g of p-bromophenylpropionaldehyde ethylene acetal, and 135g of the intermediate B-2 prepared in the previous step. After the addition, replace the air in the bottle with nitrogen for 30 minutes, and add 0.15g of the catalyst bis(di-tert-butyl-4-dimethylaminophosphine)palladium chloride. After adding the catalyst, stir and heat to 75℃～80℃, and keep warm for 3 hours until the reaction is completed.

After the reaction solution was cooled to 20-30°C, 300 ml of water was added, stirred for 15 minutes, and the organic layer was set aside. The aqueous phase was extracted twice with toluene, and the organic phases were combined, washed with water until neutral, vacuum evaporated to dryness, and recrystallized from ethanol to obtain 140 g of intermediate B-3, which was used directly in the next step.

B-4 Structure: Preparation of the indicated compounds

Under nitrogen protection, add 150 ml of toluene, 120 g of the intermediate B-3 prepared in the previous step, and 360 ml of formic acid into a three-necked flask. After stirring at room temperature until completely dissolved, raise the temperature to 60-65°C and stir for 3 hours until the remaining amount of raw material B-3 is ≤0.02%.

Stop stirring, let stand and separate, use the organic layer, extract the lower formic acid phase once with 200 ml toluene, combine the toluene phases, wash once with water, once with saturated sodium bicarbonate, and finally with saturated brine until neutral, add anhydrous sodium sulfate to the organic phase, stir and dry, filter, and transfer the filtrate to desolventize to obtain 105 g of intermediate B-4, which is directly used for the next step without purification.

B-5 Structure: Preparation of the indicated compounds

Under nitrogen protection, add 400ml tetrahydrofuran and 73g 4-vinylcyclohexyl iodomethane phosphonium salt to the reaction bottle, stir at 20-30℃ for about 30 minutes, and cool to -15--10℃. Add a solution prepared by 20g potassium tert-butoxide and 125ml THF to the reaction bottle, and control the temperature at -15--10℃ during the addition. After the addition is completed, heat to -5-0℃ and keep warm for 2 hours. Prepare a solution of 150ml toluene and 55g intermediate B-4, control the temperature at -15--10℃ and add it to the reaction bottle, and keep warm for 3 hours after the addition is completed.

The mixture was quenched with deionized water, and the organic layer was set aside. After the aqueous layer was extracted with toluene, the organic phases were combined and washed with water until neutral. The mixture was stirred and dried with anhydrous sodium sulfate for 0.5 to 1 hour. The anhydrous sodium sulfate was filtered and the filtrate was decompressed and desolventized. After desolventization, petroleum ether was added to the solid and boiled, and the filtrate was retained for use. The solid obtained by suction filtration was repeated twice with petroleum ether. The filtrates from the three hot filtrations were combined and passed through a silica gel column. The column liquid was decompressed and desolventized to obtain 62 g of a crude product of the compound shown in B-5 containing cis and trans forms, which was directly used for the next configuration conversion.

Single crystal B-6 (CVEPUQU-VF) structure: Preparation

Under nitrogen protection, add toluene (120 ml), 52.5 g of intermediate B-5 obtained in the previous step, 12.5 g of sodium benzenesulfinate, and 7.5 ml of 36% concentrated hydrochloric acid (wt%) into the reaction bottle. After stirring at room temperature until completely dissolved, raise the temperature to 60°C and stir at 60-65°C for 12 hours.

After the reaction is completed, 40 ml of deionized water is added to the reaction bottle, and after stirring for 30 minutes, the stirring is stopped, and the mixture is allowed to stand for stratification. The lower aqueous phase is separated and extracted twice with toluene. The organic phases are combined and washed three times with water until neutral. The organic phase is desolvated under reduced pressure to obtain 47.5 g of crude product. The crude product is crystallized four times with a mixed solvent of ethanol and toluene to obtain a white solid. The material after drying and recrystallization is passed through a silica gel (70-200 mesh) chromatography column and eluted with n-heptane to obtain 26.5 g of trans-CVEPUQU-V-F, the mass spectrum of which is shown in Figure 2.

MS (EI, m/z): 149, 252, 401, 548.

The liquid crystal compounds listed in the following table were prepared by a method similar to the synthesis of CVEPGU-VF and CVEPUQU-VF described above, and T _ni , Δn, and Δε were measured after 10% of each compound monomer was compatible with 90% of the mother liquid crystal. The T _ni , Δn, and Δε of the monomer were then calculated using the extrapolation method.

The components and their mass percentages in the parent liquid crystal are as follows:

CCG-2-F 10% CCP-V-1 20% CCP-V2-1 20% CPU-3-F 20% CP-3-O2 15% CP-3-O1 15%

_Tni represents the temperature at which the liquid crystal monomer changes from the nematic phase to the clear phase, and its temperature is measured by MP-90 equipment.

Δε represents dielectric anisotropy, Δε＝ε _∥ -ε _⊥ , where ε _∥ is the dielectric constant parallel to the molecular axis, and ε _⊥ is the dielectric constant perpendicular to the molecular axis. Test conditions: 25°C, INSTEC: ALCT-IR1, 18 μm vertical box.

Δn represents optical anisotropy, Δn= _ne - _no , wherein _no is the refractive index of ordinary light, _ne is the refractive index of extraordinary light, and the test conditions are: 589nm, 25±0.2℃.

Serial number Liquid crystal compound structure T _ni (℃) Δn Δε 1 CVEDGUQU-V-F 205.9 0.1760 33.8 2 CVEPGU-V-T 158.5 0.2250 20.6 3 CVEPGU-3-F 173.5 0.2300 13.3 4 CVEPGU-3-OT 180.5 0.2215 17.5 5 CVEPGU-V-F 168.0 0.2285 12.9 6 CVEPGU-V-OT 174.5 0.2190 17.0 7 CVEPGUQU-3-F 232.5 0.2585 24.5 8 CVEPUQU-V-OT 110.5 0.1590 22.5 9 CVEPUQU-V-F 102.3 0.1678 18.2 10 CVEPPGU-3-F 335.2 0.3470 14.0 11 CVEPPGU-V-F 330.5 0.3450 13.5

[Preparation of Liquid Crystal Composition]

Liquid crystal compositions of different compositions were prepared in the following examples and comparative examples, wherein the monomer structure, dosage (weight percentage) of the specific compounds used in each example, and the test results of the performance parameters of the obtained liquid crystal medium are shown in the following table.

The temperature unit involved in each embodiment is ° C, and the specific meanings of other symbols and test conditions are as follows:

Gamma1 (mPa.s) represents the rotational viscosity coefficient of the liquid crystal compound, and the determination method is as follows: instrument INSTEC: ALCT-IR1, test box thickness 18 micron vertical box, temperature 25°C, abbreviated as "G1";

K ₁₁ is the torsion elastic constant, K ₃₃ is the splay elastic constant, and the test conditions are: 25 °C, INSTEC: ALCT-IR1, 18 μm vertical box;

Δε represents dielectric anisotropy, Δε＝ε _∥ -ε _⊥ , where ε _∥ is the dielectric constant parallel to the molecular axis, and ε _⊥ is the dielectric constant perpendicular to the molecular axis. Test conditions: 25°C, INSTEC:ALCT-IR1, 18 μm vertical box;

Δn represents optical anisotropy, Δn= _ne - _no , wherein _no is the refractive index of ordinary light, _ne is the refractive index of extraordinary light, and the test conditions are: 589nm, 25±0.2℃.

VHR represents the voltage holding ratio (%) after ultraviolet light irradiation. The test conditions are 20±2°C, voltage ±5V, pulse width 1ms, and voltage holding time 16.7ms. The test equipment is ALCT-IV1 liquid crystal performance comprehensive tester. In the ultraviolet light polymerization of the polymerizable compound used in the VHR test, ultraviolet light with a wavelength of 365nm and an irradiation intensity of 2.5Mw/ ^cm2 is used for light irradiation, and the irradiation time is 34 minutes.

In the present invention, the preparation method of the liquid crystal composition is as follows: each liquid crystal monomer is weighed according to a certain ratio and put into a stainless steel beaker, the stainless steel beaker containing each liquid crystal monomer is placed on a magnetic stirring device to heat and melt, after most of the liquid crystal monomers in the stainless steel beaker are melted, a magnetic rotor is added to the stainless steel beaker, the mixture is stirred evenly, and the liquid crystal composition is obtained after cooling to room temperature.

The obtained liquid crystal composition is filled between two substrates of a liquid crystal display for performance testing.

The liquid crystal compounds represented by the above formulas I to VI are combined with other ingredients to obtain the liquid crystal compositions of the embodiments showing positive dielectric anisotropy. The compositions and contents of the components in the liquid crystal compositions of the embodiments are shown in the following table. In addition, the compounds represented by the general formula I in Embodiment 1 and Embodiment 5 are replaced by universal positive liquid crystal compounds to obtain Comparative Examples 1 and 2.

Table 1 Component ratio and performance parameters of the liquid crystal composition of Example 1

Table 2 Component ratio and performance parameters of the liquid crystal composition of Example 2

Table 3 Component ratio and performance parameters of the liquid crystal composition of Example 3

Table 4 Component ratio and performance parameters of the liquid crystal composition of Example 4

Table 5 Component ratio and performance parameters of the liquid crystal composition of Example 5

Table 6 Component ratio and performance parameters of the liquid crystal composition of Example 6

Table 7 Component ratio and performance parameters of the liquid crystal composition of Example 7

Table 8 Component ratios and performance parameters of the liquid crystal composition of Example 8

The formulation of Comparative Example 1 is shown in Table 9 below, and its components do not contain the compound represented by Formula I of the present invention.

Table 9 Component ratio and performance parameters of the liquid crystal medium of comparative example 1

The formulation of Comparative Example 2 is shown in Table 10 below, and its components do not contain the compound represented by Formula I of the present invention.

Table 10 Component ratio and performance parameters of the liquid crystal medium of comparative example 2

Although the present invention does not exhaust all liquid crystal mixtures claimed for protection, it is foreseeable that, based on the above disclosed embodiments, those skilled in the art can obtain other similar liquid crystal materials in a similar manner by combining their own professional attempts without creative work. Due to limited space, only representative implementations are listed here.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims (14)

1. A positive dielectric anisotropic liquid crystal compound selected from the group consisting of compounds represented by the following formulas I-1 to I-36: wherein _R1 represents H, an alkyl group having 1 to 8 carbon atoms, or an alkenyl group having 2 to 8 carbon atoms, wherein up to 4 H groups are optionally substituted by F; R ₂ represents H, F, an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, one or two non-adjacent -CH ₂ - groups are optionally substituted by -O-, and four or less H groups are optionally substituted by F. 2 . A liquid crystal composition comprising the liquid crystal compound according to claim 1 . 3. The liquid crystal composition according to claim 2, which is a positive dielectric anisotropic liquid crystal composition, further comprising: at least one compound represented by formula II; At least one compound of formula III: and At least one compound of formula IV: wherein R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and R ₈ each independently represent an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an alkenyloxy group having 3 to 5 carbon atoms; H on any carbon atom in R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and R ₈ each independently may be optionally substituted by F, and one or two non-adjacent -CH ₂ - groups may be optionally substituted by -O-; Z ₄ represents -C ₂ H ₄ -, -CH ₂ O-, -S-, -CF ₂ O- or -COO-, wherein 0 to 4 H in -C ₂ H ₄ - are optionally replaced by F; Z ₃ represents a single bond or -CH ₂ O-; p represents 0, 1, 2 or 3; q, r, and v each independently represent 0, 1, or 2; s is selected from 1, 2, 3 or 4; Ring A1, Ring A2, Ring A3, Ring A4, Ring A5, and Ring A6 each independently represent a group selected from the group consisting of 1,4-cyclohexylene, 1-methyl-1,4-cyclohexylene, 2-methyl-1,4-cyclohexylene, 2-oxacyclohexane-1,4-diyl, 2,6-dioxacyclohexane-1,4-diyl, cyclohexene-1,4-diyl, 1,4-phenylene, 2-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene, 2-fluoro-3-trifluoromethyl-1,4-phenylene, 2,3-bis(trifluoromethyl)-1,4-phenylene, 2-fluoro-3-trifluoromethoxy-1,4-phenylene, 2,3-bis(trifluoromethoxy)-1,4-phenylene, ,6-difluoro-substituted-1,4-phenylene, 2,5-difluoro-substituted-1,4-phenylene, 2-fluoro-6-trifluoromethyl-1,4-phenylene, 2-fluoro-5-trifluoromethyl-1,4-phenylene, 2-fluoro-6-trifluoromethoxy-1,4-phenylene, 2-fluoro-5-trifluoromethoxy-1,4-phenylene, 2,6-bis(trifluoromethyl)-1,4-phenylene, 2,5-bis(trifluoromethyl)-1,4-phenylene, 2,6-bis(trifluoromethoxy)-1,4-phenylene, 2,5-bis(trifluoromethoxy)-1,4-phenylene, 2-trifluoromethyl-6-trifluoromethoxy-1,4-phenylene, 2-trifluoromethyl-5-trifluoromethoxy-1,4-phenylene. 4. The liquid crystal composition according to claim 3, wherein the compound represented by formula II is selected from the series consisting of compounds represented by formula II-1 to II-10 below: R ₃ and R ₄ have the same definitions as in claim 3; (F) represents F or H. 5. The liquid crystal composition according to claim 3, wherein the compound represented by formula III is selected from the series consisting of compounds represented by formula III-1 to III-21 below: R ₅ and R ₆ have the same definitions as in claim 3. 6. The liquid crystal composition according to claim 3, characterized in that the compound represented by formula IV is selected from the series consisting of compounds represented by formulas IV-1 to IV-44 below: R ₇ represents an alkenyl group having 2 to 5 carbon atoms, and H on any carbon atom in R ₇ is independently optionally substituted by F, and one or two non-adjacent -CH ₂ - are optionally substituted by -O-; R ₈ represents an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an alkenyloxy group having 3 to 5 carbon atoms; H on any carbon atom in R ₈ is independently optionally substituted by F, and one or two non-adjacent -CH ₂ - groups are optionally substituted by -O-. 7. The positive dielectric anisotropic liquid crystal composition according to claim 3, further comprising a compound represented by the following formula V: Wherein, R ₉ represents an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an alkenyloxy group having 3 to 5 carbon atoms; H on any carbon atom in R ₉ is independently optionally substituted by F, and one or two non-adjacent -CH ₂ - groups are optionally substituted by -O-; R ₁₀ represents H, F, an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, wherein one or two non-adjacent -CH ₂ - groups are optionally substituted by -O-, and no more than 4 H groups are optionally substituted by F; Ring A7 and Ring A8 each independently represent a group consisting of groups selected from the following: 1,4-cyclohexylene, 1-methyl-1,4-cyclohexylene, 2-methyl-1,4-cyclohexylene, 2-oxacyclohexane-1,4-diyl, 2,6-dioxacyclohexane-1,4-diyl, cyclohexene-1,4-diyl, 1,4-phenylene, 2-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene, 2-fluoro-3-trifluoromethyl-1,4-phenylene, 2,3-bis(trifluoromethyl)-1,4-phenylene, 2-fluoro-3-trifluoromethoxy-1,4-phenylene, 2,3-bis(trifluoromethoxy)-1,4-phenylene, 2,6-difluoro-substituted-1,4-phenylene, 2,5-difluoro-1,4-phenylene Fluorine-substituted-1,4-phenylene, 2-fluoro-6-trifluoromethyl-1,4-phenylene, 2-fluoro-5-trifluoromethyl-1,4-phenylene, 2-fluoro-6-trifluoromethoxy-1,4-phenylene, 2-fluoro-5-trifluoromethoxy-1,4-phenylene, 2,6-bis(trifluoromethyl)-1,4-phenylene, 2,5-bis(trifluoromethyl)-1,4-phenylene, 2,6-bis(trifluoromethoxy)-1,4-phenylene, 2,5-bis(trifluoromethoxy)-1,4-phenylene, 2-trifluoromethyl-6-trifluoromethoxy-1,4-phenylene, 2-trifluoromethyl-5-trifluoromethoxy-1,4-phenylene; Z ₅ represents a single bond, -CF ₂ O- or -COO-; t means 1, 2, 3 or 4; u represents 1 or 2. 8. The liquid crystal composition according to claim 7, characterized in that the compound represented by formula V is selected from the series consisting of compounds represented by formulas V-1 to V-37 below: Here, R ₉ and R ₁₀ have the same definitions as in claim 7. 9. The liquid crystal composition according to claim 3, further comprising one or more compounds represented by the following formula VI: In the formula VI, R ₁₁ and R ₁₂ each independently represent an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, an alkenyl group having 2 to 7 carbon atoms, or an alkenyloxy group having 2 to 7 carbon atoms; and, H on any carbon atom in R ₁₁ and R ₁₂ each independently may be optionally substituted by F, and one or two non-adjacent -CH ₂ - may be optionally substituted by -O-; Ring D represents 1,4-cyclohexylene, cyclohexene-1,4-diyl, 2-oxacyclohexane-1,4-diyl, 2,6-dioxacyclohexane-1,4-diyl, 1,4-phenylene, 2-fluoro-1,4-diphenylene, 2-methyl-1,4-diphenylene, or 2,3-difluoro-1,4-phenylene, wherein any H atom is optionally substituted by -F or -CH ₃ ; Ring E represents a group consisting of groups selected from the following: or Z ₆ represents a single bond, -CH ₂ O-, -CF ₂ O-, -COO-, or -CH ₂ CH ₂ -; w, x, y, and z each independently represent 0, 1, 2, or 3. 10. The liquid crystal composition according to claim 9, characterized in that the compound represented by formula VI is selected from the group consisting of compounds represented by formula VI-1 to formula VI-78: 11. The liquid crystal composition according to claim 3 is characterized in that, in the liquid crystal composition, the weight percentage of the compound represented by formula I is 1 to 40%, the weight percentage of the compound represented by formula II is 1 to 70%, the weight percentage of the compound represented by formula III is 1 to 30%, and the weight percentage of the compound represented by formula IV is 1 to 30%. 12. The liquid crystal composition according to claim 7 is characterized in that, in the liquid crystal composition, the weight percentage of the compound represented by formula I is 1 to 40%, the weight percentage of the compound represented by formula II is 1 to 70%, the weight percentage of the compound represented by formula III is 1 to 30%, the weight percentage of the compound represented by formula IV is 1 to 30%, and the weight percentage of the compound represented by formula V is 1 to 30%. 13. The liquid crystal composition according to claim 9 is characterized in that, in the liquid crystal composition, the weight percentage of the compound represented by formula I is 1 to 40%, the weight percentage of the compound represented by formula II is 1 to 70%, the weight percentage of the compound represented by formula III is 1 to 30%, the weight percentage of the compound represented by formula IV is 1 to 30%, the weight percentage of the compound represented by formula V is 1 to 30%, and the weight percentage of the compound represented by formula VI is 1 to 20%. 14. A liquid crystal display device, characterized in that the liquid crystal composition comprises the liquid crystal compound according to claim 1, or the liquid crystal composition according to any one of claims 2 to 13; and the liquid crystal display device is an active matrix display device or a passive matrix display device.