A difluoro-terminated alkenyl liquid crystal compound, its preparation method and application

Abstract

This invention provides a difluoroterminated alkenyl liquid crystal compound, its preparation method, and its application. The difluoroterminated alkenyl liquid crystal compound has the structure shown in the general formula P. The alkenyl-terminated liquid crystal compound of this invention has a large response speed, a large refractive index, a clearing point, and a wide phase transition temperature. Its synthesis method has a high yield, simple post-processing, and is suitable for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of compound synthesis technology, and relates to a difluoroterminated alkenyl liquid crystal compound, its preparation method and application. Background Technology

[0002] Liquid crystal display (LCD) elements can be used in various household appliances such as clocks and calculators, measuring machines, automotive panels, word processors, computers, printers, and televisions. Based on display mode, they are classified into PC (phase change), TN (twist nematic), STN (super-twist nematic), ECB (electrically controlled birefringence), OCB (optically compensated bend), IPS (in-plane switching), and VA (vertical alignment). Based on the driving method, they are classified into PM (passive matrix) and AM (active matrix). PM is further divided into static and multiplex types. AM is divided into TFT (thin film transistor) and MIM (metal-insulator-metal). TFT types include amorphous silicon and polycrystalline silicon. The latter is divided into high-temperature type and low-temperature type according to the manufacturing process. Liquid crystal display elements are divided into reflective type using natural light, transmissive type using backlight, and transmissive type using both natural light and backlight according to the type of light source.

[0003] A liquid crystal composition with low viscosity can improve the response speed of a liquid crystal display (LCD) element. A fast response speed makes the LCD element suitable for animation display. Furthermore, injecting the liquid crystal composition into the LCD cell can shorten the injection time, improving workability.

[0004] Existing technologies disclose liquid crystal compositions with low power consumption and fast response, such as patent document CN102858918A. However, existing liquid crystal compositions have environmental problems (such as the use of chlorine-containing compounds), short lifespan (such as poor stability against UV or heat), low contrast (such as screen whitening under sunlight), and cannot simultaneously meet the performance balance requirements of appropriate optical anisotropy, appropriate dielectric anisotropy, high voltage retention rate, good UV resistance and high temperature stability in LCD TVs, tablet computers, etc.

[0005] From the perspective of liquid crystal material preparation, the various properties of liquid crystal materials are interdependent and mutually influential; improving one performance indicator may alter other properties. Therefore, preparing liquid crystal materials with suitable properties in all aspects often requires creative effort.

[0006] Liquid crystal materials are a crucial component of liquid crystal displays (LCDs), which currently enjoy significant global market demand and are widely used in electronic products. However, their lifespan is relatively short. This short lifespan naturally leads to problems such as waste pollution. Given the increasing emphasis on environmental protection, controlling the issue at its source—selecting environmentally friendly materials during the liquid crystal material manufacturing process—can significantly reduce the environmental costs of disposing of waste LCDs. Therefore, developing liquid crystal materials that are suitable in all aspects, economical, and environmentally friendly often requires creative effort. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a difluoroterminated alkenyl liquid crystal compound, its preparation method, and its applications.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] On one hand, the present invention provides a difluoro-terminated alkenyl liquid crystal compound having the structure shown in general formula P:

[0010]

[0011]

[0012] Where R represents hydrogen, an alkyl group with 1 to 12 carbon atoms (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12), an alkoxy group with 1 to 12 carbon atoms (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12), an alkenyl group with 2 to 12 carbon atoms (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12), or a group with 2 to 12 carbon atoms (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12). The alkyl group of 1 to 12 carbon atoms, the alkoxy group of 2 to 12 carbon atoms (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12) carbon atoms, wherein one or more of the alkyl group of 1 to 12 carbon atoms, the alkoxy group of 1 to 12 carbon atoms, the alkenyl group of 2 to 12 carbon atoms, the alkenoxy group of 2 to 12 carbon atoms, and the alkynyl group of 2 to 12 carbon atoms may be replaced by -CH=CH-, -C≡C-, -O-, -S-, -CO-, -CO-O- or -O-CO-;

[0013] ring and ring The same or different, each independently representing cyclohexene, cyclohexenyl, cyclopentyl, cyclopentenyl, cyclobutyl, propylene oxide, or substituted or unsubstituted benzene ring groups, wherein one or more of the -CH2- groups in cyclohexene, cyclohexenyl, cyclopentenyl, cyclobutyl, and propylene oxide can be replaced by -O-, and the substituted benzene ring group refers to one or more hydrogens on the benzene ring that can be replaced by a halogen, a fluorinated or unfluorinated alkyl or alkoxy group of 1-3 carbon atoms, or one or more -CH= groups on the benzene ring that can be replaced by -N= groups;

[0014] m represents an integer from 0 to 2 (e.g., 0, 1, or 2); m B Represents an integer from 0 to 2 (e.g., 0, 1, or 2);

[0015] n represents an integer from 1 to 6 (e.g., 1, 2, 3, 4, 5 or 6), and n1 represents an integer from 1 to 4 (e.g., 1, 2, 3 or 4).

[0016] X, X1, X2, or X3 may be the same or different, each representing independently H, halogen, 1-3 (e.g., 1, 2, or 3) fluorinated or unfluorinated alkyl or alkoxy groups, and X may be the same or different when n1 is not 1.

[0017] In this invention, "one or more" refers to one or at least two.

[0018] Preferably, X is selected from H, F, Cl, methyl, methoxy, trifluoromethyl, or trifluoromethoxy.

[0019] Preferably, X1, X2, and X3 represent hydrogen, fluorine, chlorine, methyl, or methoxy.

[0020] Preferably, ring and ring Whether they are the same or different, they are expressed independently of each other.

[0021] Preferably, The group can be selected from

[0022] Preferably, The group can be selected from

[0023] Preferably, Y represents methylene.

[0024] Preferably, the difluoro-terminated alkenyl liquid crystal compound is a compound having any of the following structures:

[0025]

[0026]

[0027] Preferably, R is selected from hydrogen, alkyl with 1 to 6 carbon atoms, alkoxy with 1 to 6 carbon atoms, alkenyl with 2 to 6 carbon atoms, alkenyloxy with 2 to 16 carbon atoms, and alkynyl with 2 to 6 carbon atoms, wherein one or more of the alkyl with 1 to 6 carbon atoms, alkoxy with 1 to 6 carbon atoms, alkenyl with 2 to 6 carbon atoms, alkenyloxy with 2 to 16 carbon atoms, and alkynyl with 2 to 6 carbon atoms can be replaced by -CH=CH-, -C≡C-, -O-, -S-, -CO-, -CO-O-, or -O-CO-;

[0028] More preferably, R is selected from hydrogen, alkyl groups of 1 to 6 carbon atoms, alkoxy groups of 1 to 6 carbon atoms, alkenyl groups of 2 to 6 carbon atoms, and alkenoxy groups of 2 to 16 carbon atoms, wherein one or more of the alkyl groups of 1 to 6 carbon atoms, alkoxy groups of 1 to 6 carbon atoms, alkenyl groups of 2 to 6 carbon atoms, and alkenoxy groups of 2 to 16 carbon atoms can be replaced by -CH=CH-, -C≡C-, -O-, -S-, -CO-, -CO-O-, or -O-CO-.

[0029] Preferably, R is selected from hydrogen, methyl, ethyl, n-propyl, methoxy, ethoxy, and vinyl.

[0030] More preferably, R is selected from ethyl or n-propyl.

[0031] Preferably, the liquid crystal compound containing terminal alkenyl groups is any one of the following compounds:

[0032]

[0033] On the other hand, the present invention provides a method for preparing the difluoro-terminated alkenyl liquid crystal compound as described above, the method comprising the following steps:

[0034] (1) Compound A reacts with a borate ester to give compound B, as shown in the following reaction formula:

[0035]

[0036] (2) The compound shown in formula B reacts with the compound of formula C to obtain the difluoro-terminated alkenyl liquid crystal compound shown in formula P. The reaction formula is as follows:

[0037]

[0038] Hal is selected from Cl, Br, or I.

[0039] Preferably, the borate ester in step (1) is selected from one or a combination of at least two of trimethyl borate, triisopropyl borate or tributyl borate.

[0040] Preferably, the molar ratio of compound A to borate ester in step (1) is 1:0.9 to 1:3, for example, 1:0.9, 1:1.0, 1:1.5, 1:2.0, 1:2.5, 1:3.0, etc., preferably 1:1 to 1:1.3.

[0041] Preferably, the reaction in step (1) is carried out in the presence of an alkaline substance.

[0042] Preferably, the alkaline substance is selected from any one of n-butyllithium, diisopropylaminolithium, sec-butyllithium, or tert-butyllithium, with n-butyllithium, diisopropylaminolithium, or sec-butyllithium being more preferred.

[0043] Preferably, the reaction in step (1) is carried out in an organic solvent selected from one or a combination of at least two of tetrahydrofuran, 2-methyltetrahydrofuran, diethyl ether or methyl tert-butyl ether, preferably tetrahydrofuran and / or 2-methyltetrahydrofuran.

[0044] Preferably, the reaction temperature in step (1) is -100 to 30°C (e.g., -100°C, -80°C, -60°C, -40°C, -20°C, -10°C, 0°C, 5°C, 10°C, 20°C or 30°C), and the reaction time is 0.5 to 24 hours (e.g., 0.5 hours, 1 hour, 3 hours, 5 hours, 8 hours, 10 hours, 12 hours, 15 hours, 18 hours, 20 hours, 22 hours or 24 hours).

[0045] Preferably, the reaction in step (1) is carried out under nitrogen protection.

[0046] Preferably, after the reaction in step (1) is completed, the mixture is separated, washed with water, concentrated, and crystallized to obtain the compound of formula C.

[0047] Preferably, the molar ratio of the compound of formula B to the compound of formula C in step (2) is 1.5:1 to 0.9:1, for example, 1.5:1, 1.4:1, 1.3:1, 1.2:1, 1.1:1, 1:1 or 0.9:1, etc., preferably 1.2:1 to 1:1.

[0048] Preferably, the reaction in step (2) is carried out in the presence of a catalyst.

[0049] Preferably, the catalyst is a palladium catalyst.

[0050] Preferably, the palladium catalyst is selected from any one of bis(dibenzylacetone)palladium, tetra(triphenylphosphine)palladium dichloride, bis(triphenylphosphine)palladium dichloride, dichloroditert-butyl-(4-dimethylaminophenyl)phosphine palladium, or 1,1'-bis(diphenylphosphine)ferrocene palladium dichloride, and is more preferably tetra(triphenylphosphine)palladium dichloride, bis(triphenylphosphine)palladium dichloride, or dichloroditert-butyl-(4-dimethylaminophenyl)phosphine palladium.

[0051] Preferably, the reaction in step (2) is carried out in the presence of an alkaline substance.

[0052] Preferably, the alkaline substance is selected from any one or a combination of at least two of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium phosphate, potassium hydroxide, or sodium hydroxide.

[0053] Preferably, the reaction in step (2) is carried out in an organic solvent selected from one or a combination of at least two of toluene, tetrahydrofuran, acetonitrile, dioxane, ethanol or dimethylformamide; preferably, one or a combination of at least two of benzene, tetrahydrofuran, acetonitrile or dioxane.

[0054] Preferably, the temperature of the reaction in step (2) is 40 to 130°C (e.g., 40°C, 50°C, 60°C, 80°C, 100°C, 110°C, 120°C or 130°C), and the reaction time is 0.5 to 24 h (e.g., 0.5 h, 1 h, 3 h, 5 h, 8 h, 10 h, 12 h, 15 h, 18 h, 20 h, 22 h or 24 h).

[0055] More preferably, the temperature of the reaction in step (2) is 40°C or 80-110°C, and the reaction time is 0.5-6h.

[0056] Preferably, the reaction in step (2) is carried out under nitrogen protection.

[0057] Preferably, after the reaction in step (2) is completed, the product is separated, washed with water, concentrated, and crystallized to obtain compound P.

[0058] On the other hand, the present invention provides a liquid crystal composition comprising at least one difluoro-terminated alkenyl liquid crystal compound as described above.

[0059] In some embodiments of the present invention, the difluoro-terminated alkenyl liquid crystal compound accounts for 1-20% by weight of the liquid crystal composition, for example, 0.1%, 0.5%, 1%, 3%, 5%, 7%, 9%, 10%, 11%, 13%, 15%, 17%, 19% or 20%.

[0060] The liquid crystal composition of the present invention further comprises: one or more compounds of general formula M:

[0061]

[0062] One or more compounds of general formula A-1

[0063] as well as

[0064] One or more compounds of general formula A-2

[0065]

[0066] R M1 and R M2 Each can independently represent -H, a straight-chain or branched alkyl group containing 1-12 carbon atoms, One or more non-adjacent -CH2- atoms in the straight-chain or branched alkyl group containing 1-12 carbon atoms can be independently replaced by -CH=CH-, -C≡C-, -O-, -CO-, -CO-O-, or -O-CO-.

[0067] R A1 and R A2 Each independently represents a straight-chain or branched alkyl group containing 1-12 carbon atoms. One or more non-adjacent -CH2- atoms in the straight-chain or branched alkyl group containing 1-12 carbon atoms can be independently replaced by -CH=CH-, -C≡C-, -O-, -CO-, -CO-O-, or -O-CO-, and the straight-chain or branched alkyl group containing 1-12 carbon atoms... One or more -H can be independently replaced by -F or -Cl;

[0068] Z M1 and Z M2Each can independently represent a single bond, -CO-O-, -O-CO-, -CH2O-, -OCH2-, -CH=CH-, -C≡C-, -CH2CH2-, or -(CH2)4-;

[0069] Z A11 Z A21 and Z A22 Each can independently represent a single bond, -CH2CH2-, -CF2CF2-, -CO-O-, -O-CO-, -O-CO-O-, -CH=CH-, -CF=CF-, -CH2O-, or -OCH2-;

[0070] L A11 L A12 L A13 L A21 and L A22 Each can independently represent -H, an alkyl group containing 1-3 carbon atoms, or a halogen;

[0071] X A1 and X A2 Each can independently represent a halogen, a haloalkyl or haloalkoxy group containing 1-5 carbon atoms, or a haloalkenyl or haloalkenoxy group containing 2-5 carbon atoms.

[0072] ring ring and ring Each represents independently

[0073] in, One or more of the -CH2- can be replaced by -O-. At most one -H in the halogen can be replaced by a halogen;

[0074] ring ring ring and ring Each represents independently in, One or more -CH2- bonds can be replaced by -O- bonds, and one or more single bonds in a ring can be replaced by double bonds. One or more -H can be replaced by -CN, -F or -Cl, and -CH= in one or more rings can be replaced by -N=;

[0075] n M1 n A11 and n A2 Each can independently represent 0, 1, 2, or 3, and when n M1 When = 2 or 3, the ring They can be the same or different, Z M2 They can be the same or different; when n A11 When = 2 or 3, the ring They can be the same or different, Z A11 They can be the same or different; when n A2 When = 2 or 3, the ring They can be the same or different, Z A21 They can be the same or different;

[0076] n A12 Represents 1 or 2, and when n A12 When = 2, ring They can be the same or different.

[0077] In some embodiments of the present invention, the compound of general formula M is selected from the group consisting of the following compounds:

[0078]

[0079]

[0080]

[0081] as well as

[0082]

[0083] In some embodiments of the present invention, the compound of general formula M accounts for 0.1%-90% of the weight percentage of the liquid crystal composition, for example 0.1%, 0.5%, 1%, 5%, 10%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 90%.

[0084] In some embodiments of the present invention, the content of the compound of general formula M must be appropriately adjusted according to the required properties such as solubility at low temperature, transition temperature, electrical reliability, birefringence, process adaptability, drip marks, burn-in, and dielectric anisotropy.

[0085] Regarding the weight percentage of the compound of general formula M in the liquid crystal composition of the present invention, the preferred lower limit is 0.1%, 1%, 10%, 20%, 30%, 40%, or 50% relative to the total weight of the liquid crystal composition of the present invention; the preferred upper limit is 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 35%, or 25% relative to the total weight of the liquid crystal composition of the present invention.

[0086] Regarding the content of compounds of general formula M, when it is necessary to maintain a low viscosity and a short response time in the liquid crystal composition of the present invention, it is preferable to have a higher lower limit and a higher upper limit; further, when it is necessary to maintain a high clearing point and good temperature stability in the liquid crystal composition of the present invention, it is preferable to have a higher lower limit and a higher upper limit; in order to keep the driving voltage low and increase the absolute value of dielectric anisotropy, it is preferable to have a lower lower limit and a lower upper limit.

[0087] In some embodiments of the present invention, where reliability is a priority, R is preferred. M1 and R M2 All are alkyl groups; when reducing the volatility of the compound is of priority, R is preferred. M1 and R M2 All are alkoxy groups; when viscosity reduction is a priority, R is preferred. M1 and R M2 At least one of them is an alkenyl group.

[0088] In some embodiments of the invention, the compound of general formula M is preferably free from the group consisting of compounds of general formulas M1, M2, M3, M4, M5, M7, M8, M9, M10, M11, M13, M15, M16, M17, M18, M19, M20, M21, M22, M23 and M24.

[0089] In some embodiments of the invention, compounds of general formula M are further preferably the group consisting of compounds of general formulas M1, M2, M4, M5, M9, M11, M13, M20 and M22.

[0090] In some embodiments of the present invention, in compounds of general formula M1, R M1 It refers to a straight-chain or branched alkyl or alkoxy group containing 1 to 7 carbon atoms; more preferably, it refers to a straight-chain or branched alkyl or alkoxy group containing 1 to 5 carbon atoms.

[0091] Preferred weight percentages of the compound of general formula M1 in the liquid crystal composition of the present invention: the preferred lower limit of the weight percentage of the compound of general formula M1 in the liquid crystal composition of the present invention relative to the total weight of the liquid crystal composition of the present invention is 1%, 3%, 5%, 7%, 10%, 13%, 15%, 17%, 20%, 23%, 25%, or 30%; the preferred upper limit of the weight percentage of the compound of general formula M1 in the liquid crystal composition of the present invention relative to the total weight of the liquid crystal composition of the present invention is 60%, 55%, 50%, 45%, 40%, 37%, 35%, 33%, 30%, 27%, 25%, 23%, 20%, 17%, 15%, 13%, or 10%.

[0092] To particularly improve the response time of the liquid crystal composition of the present invention, it is preferable that R in the compound of general formula M1 is... M1 It is ethyl, n-propyl, butyl, or pentyl, and R M2 Compounds that are methyl or methoxy, in which R is a methyl or methoxy compound, are compounds of general formula M1. M1 It is ethyl, n-propyl, butyl, or pentyl, and R M2 Compounds that are ethyl or ethoxylated, or compounds of general formula M1 in which R M1 It is n-propyl, butyl, or pentyl, and R M2 Compounds that are n-propyl or propoxy.

[0093] Relative to the total weight of the liquid crystal composition of the present invention, R in the compound of general formula M1 M1 It is n-propyl and R M2 The preferred lower limit for the weight percentage of the ethyl compound in the liquid crystal composition of the present invention is 1%, 2%, 3%, 5%, 7%, 10%, 13%, 15%, 18%, or 20%; relative to the total weight of the liquid crystal composition of the present invention, R in general formula M1 M1 It is n-propyl and R M2 The preferred upper limit for the weight percentage of the ethyl compound in the liquid crystal composition of the present invention is 20%, 17%, 15%, 13%, 10%, 8%, 7%, or 6%.

[0094] The preferred weight percentage of the compound of general formula M2 in the liquid crystal composition of the present invention is as follows: the lower limit of the weight percentage of the compound of general formula M2 in the liquid crystal composition of the present invention is 1%, 2%, 3%, 5%, 7% or 10% relative to the total weight of the liquid crystal composition of the present invention; the upper limit of the weight percentage of the compound of general formula M2 in the liquid crystal composition of the present invention is 20%, 15%, 13%, 10%, 8%, 7%, 6%, 5% or 3% relative to the total weight of the liquid crystal composition of the present invention.

[0095] The preferred weight percentage of the compound of general formula M4 in the liquid crystal composition of the present invention is as follows: the lower limit of the weight percentage of the compound of general formula M4 in the liquid crystal composition of the present invention is 1%, 2%, 3%, 5%, 7% or 10% relative to the total weight of the liquid crystal composition of the present invention; the upper limit of the weight percentage of the compound of general formula M4 in the liquid crystal composition of the present invention is 20%, 15%, 13%, 10%, 8%, 7%, 6%, 5% or 3% relative to the total weight of the liquid crystal composition of the present invention.

[0096] Regarding the preferred weight percentage of the compound of general formula M9 in the liquid crystal composition of the present invention: the preferred lower limit of the weight percentage of the compound of general formula M9 in the liquid crystal composition of the present invention relative to the total weight of the liquid crystal composition of the present invention is 1%, 2%, 3%, 5%, 7%, 10%, 14%, 16%, 20%, 23%, 26%, 30%, 35%, or 40%; the preferred upper limit of the weight percentage of the compound of general formula M9 in the liquid crystal composition of the present invention relative to the total weight of the liquid crystal composition of the present invention is 50%, 40%, 35%, 30%, 20%, 15%, 10%, or 5%.

[0097] In some embodiments of the present invention, depending on the required properties such as solubility at low temperatures, transition temperature, electrical reliability, and birefringence, R in a compound containing the general formula M9 is preferred. M1 It is a straight-chain or branched alkenyl group containing 2-4 carbon atoms, and R M2 The compound is CH3-, and the alkenyl group containing 2-4 carbon atoms, either straight-chain or branched, is further preferred.

[0098] Relative to the total weight of the liquid crystal composition of the present invention, the compound of general formula M9 contains R M1 for And R M2 The preferred lower limit for the weight percentage of the CH3- compound in the liquid crystal composition of the present invention is 1%, 3%, 5%, 7%, 9%, 11%, 12%, 13%, 18%, or 21%, and the preferred upper limit is 45%, 40%, 35%, 30%, 25%, 23%, 20%, 18%, 15%, 13%, 10%, or 8%. When both compounds are present, the preferred lower limit for the weight percentage of the two compounds in the liquid crystal composition of the present invention relative to the total weight of the liquid crystal composition of the present invention is 3%, 5%, 7%, 9%, 11%, 13%, 15%, 19%, 24%, or 30%, and the preferred upper limit is 45%, 40%, 35%, 30%, 25%, 23%, 20%, 18%, 15%, 13%, 11%, or 9%.

[0099] The preferred weight percentage of the compound of general formula M10 in the liquid crystal composition of the present invention is as follows: the lower limit of the weight percentage of the compound of general formula M10 in the liquid crystal composition of the present invention is 1%, 2%, 3%, 4%, 5%, 7%, 10%, 14%, 16% or 20% relative to the total weight of the liquid crystal composition of the present invention; the upper limit of the weight percentage of the compound of general formula M10 in the liquid crystal composition of the present invention is 45%, 40%, 35%, 30%, 20%, 15%, 10% or 5% relative to the total weight of the liquid crystal composition of the present invention.

[0100] In some embodiments of the present invention, depending on the required properties such as solubility at low temperatures, transition temperature, electrical reliability, and birefringence, R in a compound containing the general formula M10 is preferred. M1 It is a straight-chain or branched alkenyl group containing 2-4 carbon atoms, and R M2 The compound is CH3-, and the alkenyl group containing 2-4 carbon atoms, either straight-chain or branched, is further preferred.

[0101] Relative to the total weight of the liquid crystal composition of the present invention, the compound of general formula M10 contains R M1 for And R M2 The preferred lower limit for the weight percentage of the CH3- compound in the liquid crystal composition of the present invention is 1%, 3%, 4%, 5%, 7%, 9%, 11%, 12%, 13%, 18%, or 20%, and the preferred upper limit is 40%, 35%, 30%, 25%, 23%, 20%, 18%, 15%, 13%, 10%, or 8%. When both compounds are present, the preferred lower limit for the weight percentage of the two compounds in the liquid crystal composition of the present invention relative to the total weight of the liquid crystal composition of the present invention is 3%, 5%, 7%, 9%, 11%, 13%, 15%, 19%, 24%, or 30%, and the preferred upper limit is 45%, 40%, 35%, 30%, 25%, 23%, 20%, 18%, 15%, or 13%.

[0102] Regarding the preferred weight percentage of the compound of general formula M11 in the liquid crystal composition of the present invention: the preferred lower limit of the weight percentage of the compound of general formula M11 in the liquid crystal composition of the present invention relative to the total weight of the liquid crystal composition of the present invention is 1%, 2%, 3%, 5%, 7%, 10%, 14%, 16%, 20%, 23%, 26%, 30%, 35%, or 40%; the preferred upper limit of the weight percentage of the compound of general formula M11 in the liquid crystal composition of the present invention relative to the total weight of the liquid crystal composition of the present invention is 50%, 40%, 35%, 30%, 20%, 15%, 10%, or 5%.

[0103] In some embodiments of the invention, the compound of general formula M11 is preferably R. M1 It is n-propyl or n-pentyl, and R M2 Compounds that are C2H5-, or preferably R M1 for And R M2 Compounds that are n-propyl, or preferably R M1 It is n-propyl, n-butyl, or n-pentyl, and R M2 Compounds that are CH3O-; R is particularly preferred. M1 It is n-propyl, and R M2 It is a compound with C2H5-.

[0104] Regarding the preferred weight percentage of the compound of general formula M13 in the liquid crystal composition of the present invention: the preferred lower limit of the weight percentage of the compound of general formula M13 in the liquid crystal composition of the present invention relative to the total weight of the liquid crystal composition of the present invention is 1%, 2%, 3%, 5%, 7%, 10%, 14%, 16%, 20%, 23%, 26%, 30%, 35%, or 40%; the preferred upper limit of the weight percentage of the compound of general formula M13 in the liquid crystal composition of the present invention relative to the total weight of the liquid crystal composition of the present invention is 50%, 40%, 35%, 30%, 20%, 15%, 10%, or 5%.

[0105] In some embodiments of the invention, the compound of general formula M13 is preferably R. M1 and R M2 Each independently represents a straight-chain or branched alkyl compound containing 2-5 carbon atoms, or preferably R M1 and R M2 One of them is The other is a compound of CH3- or C2H5-.

[0106] Regarding the preferred weight percentage of the compound of general formula M15 in the liquid crystal composition of the present invention: the preferred lower limit value of the weight percentage of the compound of general formula M15 in the liquid crystal composition of the present invention relative to the total weight of the liquid crystal composition of the present invention is 1%, 2%, 3%, 5%, 7%, 10%, 12%, 14%, 16%, 18%, 20%, 23%, 26%, 30%, 35%, or 40%; the preferred upper limit value of the weight percentage of the compound of general formula M15 in the liquid crystal composition of the present invention relative to the total weight of the liquid crystal composition of the present invention is 50%, 40%, 35%, 30%, 25%, 22%, 20%, 18%, 15%, 12%, 10%, 8%, or 5%.

[0107] Regarding the preferred weight percentage of the compound of general formula M16 in the liquid crystal composition of the present invention: the preferred lower limit of the weight percentage of the compound of general formula M16 in the liquid crystal composition of the present invention relative to the total weight of the liquid crystal composition of the present invention is 1%, 2%, 3%, 5%, 7%, 10%, 12%, 14%, 16%, 18%, 20%, 23%, 26%, 30%, 35%, or 40%; the preferred upper limit of the weight percentage of the compound of general formula M16 in the liquid crystal composition of the present invention relative to the total weight of the liquid crystal composition of the present invention is 50%, 40%, 35%, 30%, 25%, 22%, 20%, 18%, 15%, 12%, 10%, 8%, or 5%.

[0108] Regarding the weight percentage of compounds of general formulas M20 to M24 in the liquid crystal composition of the present invention, the preferred lower limit values ​​are 1%, 2%, 3%, 5%, 7%, 10%, 14%, 16%, or 20% relative to the total weight of the liquid crystal composition of the present invention; and the preferred upper limit values ​​are 30%, 25%, 23%, 20%, 18%, 15%, 12%, 10%, or 5% relative to the total weight of the liquid crystal composition of the present invention.

[0109] In some embodiments of the present invention, the compound of general formula A-1 is selected from the group consisting of the following compounds:

[0110]

[0111]

[0112]

[0113] as well as

[0114]

[0115] in,

[0116] R A1 Indicates a straight-chain or branched alkyl group containing 1-8 carbon atoms. One or more non-adjacent -CH2- groups in the straight-chain or branched alkyl groups containing 1-8 carbon atoms may be independently replaced by -CH=CH-, -C≡C-, -O-, -CO-, -CO-O- or -O-CO-, and one or more -H groups present in these groups may be independently replaced by -F or -Cl.

[0117] R vand R w Each can be represented independently as -CH2- or -O-;

[0118] L A11 L A12 L A11 ’ L A12 ’ L A14 L A15 and L A16 Each can be represented independently as -H or -F;

[0119] L A13 and L A13 ’ Each can be independently represented as -H or -CH3;

[0120] X A1 It indicates -F, -CF3, or -OCF3; and

[0121] v and w each independently represent 0 or 1.

[0122] In some embodiments of the present invention, the compound of general formula A-1 accounts for 0.1%-80% by weight of the liquid crystal composition, for example 0.1%, 0.5%, 1%, 5%, 10%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75% or 80%.

[0123] Regarding the preferred weight percentage of the compound of general formula A-1 in the liquid crystal composition of the present invention: the preferred lower limit value of the weight percentage of the compound of general formula A-1 in the liquid crystal composition of the present invention relative to the total weight of the liquid crystal composition of the present invention is 0.1%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 12%, 14%, 15%, 17%, 18% or 20%; the preferred upper limit value of the weight percentage of the compound of general formula A-1 in the liquid crystal composition of the present invention relative to the total weight of the liquid crystal composition of the present invention is 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30% or 25%.

[0124] Regarding the preferred content of the compound of general formula A-1, in order to keep the viscosity of the liquid crystal composition of the present invention low and the response speed fast, it is preferable to keep the lower limit value slightly low and the upper limit value slightly low; furthermore, in order to keep the clearing point of the liquid crystal composition of the present invention high and the temperature stability good, it is preferable to keep the lower limit value slightly low and the upper limit value slightly low; in addition, in order to keep the driving voltage low and to increase the absolute value of dielectric anisotropy, it is preferable to keep the lower limit value slightly high and the upper limit value slightly high.

[0125] In some embodiments of the present invention, the compound of general formula A-1 is preferably selected from the group consisting of compounds of general formula A-1-1, general formula A-1-4, general formula A-1-7, general formula A-1-13, general formula A-1-14, general formula A-1-15, general formula A-1-16 and general formula A-1-17.

[0126] In some embodiments of the invention, the compound of general formula A-1 is further preferably the group consisting of compounds of general formulas A-1-4, A-1-7, A-1-13, A-1-14 and A-1-15.

[0127] In some embodiments of the present invention, the compound of general formula A-2 is selected from the group consisting of the following compounds:

[0128]

[0129]

[0130]

[0131] as well as

[0132]

[0133] in,

[0134] R A2 This refers to a straight-chain or branched alkyl group containing 1-8 carbon atoms, wherein one or more non-adjacent -CH2- groups in the straight-chain or branched alkyl group containing 1-8 carbon atoms can be independently replaced by -CH=CH-, -C≡C-, -O-, -CO-, -CO-O- or -O-CO-, and one or more -H groups present in these groups can be independently replaced by -F or -Cl;

[0135] L A21 L A22 L A23 L A24 and L A25 Each can be represented independently as -H or -F; and

[0136] X A2 It represents -F, -CF3, -OCF3, or -CH2CH2CH=CF2.

[0137] In some embodiments of the present invention, the compound of general formula A-2 accounts for 0.1%-80% by weight of the liquid crystal composition, for example 0.1%, 0.5%, 1%, 5%, 10%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75% or 80%.

[0138] Regarding the preferred weight percentage of the compound of general formula A-2 in the liquid crystal composition of the present invention: the preferred lower limit value of the weight percentage of the compound of general formula A-2 in the liquid crystal composition of the present invention relative to the total weight of the liquid crystal composition of the present invention is 0.1%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 12%, 14%, 15%, 17%, 18% or 20%; the preferred upper limit value of the weight percentage of the compound of general formula A-2 in the liquid crystal composition of the present invention relative to the total weight of the liquid crystal composition of the present invention is 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30% or 25%.

[0139] Regarding the preferred content of the compound of general formula A-2, in order to keep the viscosity of the liquid crystal composition of the present invention low and the response speed fast, it is preferable to keep the lower limit value slightly low and the upper limit value slightly low; furthermore, in order to keep the clearing point of the liquid crystal composition of the present invention high and the temperature stability good, it is preferable to keep the lower limit value slightly low and the upper limit value slightly low; in addition, in order to keep the driving voltage low and to increase the absolute value of dielectric anisotropy, it is preferable to keep the lower limit value slightly high and the upper limit value slightly high.

[0140] In some embodiments of the present invention, the compound of general formula A-2 is preferably selected from the group consisting of compounds of general formula A-2-4, general formula A-2-8, general formula A-2-11 and general formula A-2-12.

[0141] In addition to the compounds mentioned above, the liquid crystal compositions of the present invention may also contain conventional nematic liquid crystals, smectic liquid crystals, cholesteric liquid crystals, antioxidants, ultraviolet absorbers, infrared absorbers, polymerizable monomers, or light stabilizers.

[0142] The following shows possible dopants that are preferably added to the liquid crystal composition according to the invention.

[0143]

[0144]

[0145] as well as

[0146]

[0147] In some embodiments of the present invention, preferably, the dopant accounts for 0-5% of the weight percentage of the liquid crystal composition; more preferably, the dopant accounts for 0-1% of the weight percentage of the liquid crystal composition.

[0148] Furthermore, the antioxidants, light stabilizers, and other additives used in the liquid crystal composition of the present invention are preferably the following substances:

[0149]

[0150]

[0151]

[0152]

[0153] Where n represents a positive integer from 1 to 12.

[0154] Preferably, the light stabilizer is selected from the light stabilizers shown below:

[0155]

[0156] In some embodiments of the present invention, preferably, the light stabilizer accounts for 0-5% of the total weight percentage of the liquid crystal composition; for example, 0%, 0.1%, 0.5%, 1%, 2%, 3%, 4% or 5%; more preferably, the light stabilizer accounts for 0-1% of the total weight percentage of the liquid crystal composition; particularly preferably, the light stabilizer accounts for 0.01-0.1% of the total weight percentage of the liquid crystal composition.

[0157] On the other hand, the present invention provides a liquid crystal display element comprising the liquid crystal composition described above.

[0158] Compared with the prior art, the present invention has the following beneficial effects:

[0159] The difluoroterminated alkenyl liquid crystal compound of the present invention has a large response speed, a large refractive index and a clearing point, and a wide phase transition temperature; its synthesis method has a high yield and simple post-processing, making it suitable for industrial production. Detailed Implementation

[0160] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0161] Example 1:

[0162] Preparation of compound P-1

[0163]

[0164] In a 500 ml three-necked flask, add 200 ml of tetrahydrofuran and 20.4 g (100 mmol) of compound A-1, purge with nitrogen more than 3 times, cool to -70 °C, add 42 ml (105 mmol, 2.5 M) of n-butyllithium dropwise while maintaining the temperature at -70 °C, keep warm for 1 h, add 20.68 g (110 mmol) of triisopropyl borate dropwise, and keep warm at -70 °C for 2 h.

[0165] The mixture was naturally heated to -35°C, and 10% dilute hydrochloric acid was added to adjust the pH to 3. It was then naturally heated to room temperature, and concentrated under a negative pressure of 60°C (-0.095 MPa) until no tetrahydrofuran was detected. The precipitated solid was slurried with water to obtain a white solid, which was then dried to obtain 23.5 g of white solid B-1. The yield was 94.8%.

[0166] In a 500ml three-necked flask, add 150ml toluene, 30ml ethanol, 100ml water, and 13.8g potassium carbonate (100mmol). Then add 23.5g (94.8mmol) B-1 and 23.5g (95mmol) C-1. Under nitrogen protection, add 0.07g (0.1mmol) dichlorodi-tert-butyl-(4-dimethylaminophenyl)phosphine palladium. After nitrogen purging, slowly raise the temperature to 70℃ and react at 70-75℃ for 3 hours.

[0167] Post-processing: Cool to room temperature, transfer to a separatory funnel, separate the phases, extract the aqueous phase with 2 x 100 ml toluene, combine the oil phases, wash with 3 x 100 ml water until neutral, and concentrate toluene at 70°C under negative pressure (-0.095 MPa). Dissolve the concentrated product in petroleum ether and pass through a silica gel column, evaporate the solvent at 50°C to obtain 35 g of white solid. Recrystallize twice with toluene / ethanol (freezing at -30°C for 3 h), filter through a Buchner funnel, and dry to obtain 30.5 g of white solid.

[0168] Gas chromatograph purity of compound P-1 (Agilent 7820 gas chromatograph): 99.92%; yield: 87%.

[0169] Mass spectrometry data M+ (370): 41 (13%), 55 (16%), 77 (23%), 237 (15%), 250 (42%), 264 (20%), 293 (100%), 294 (48%), 370 (56%).

[0170] Example 2:

[0171] Preparation of compound P-1

[0172]

[0173] In a 500 ml three-necked flask, add 200 ml tetrahydrofuran and 20.4 g (100 mmol) of compound A-1, purge with nitrogen more than 3 times, cool to -60 °C, and add 102 ml (102 mmol, 1.0 M) of lithium diisopropylaminotrimethylammonium dropwise while maintaining the temperature at -60 °C. Keep warm for 2 h, then add 11.4 g (110 mmol) of trimethyl borate dropwise and keep the reaction at -60 °C for 2 h.

[0174] The mixture was naturally heated to -40℃, and 10% dilute hydrochloric acid was added to adjust the pH to 4. It was then naturally heated to room temperature, and concentrated under a negative pressure of 60℃ (-0.095 MPa) until no tetrahydrofuran was detected. The precipitated solid was slurried with water to obtain a white solid, which was then dried to obtain 23.5 g of white solid B-1. The yield was 94.8%.

[0175] In a 500ml three-necked flask, add 150ml toluene, 30ml ethanol, 100ml water, and 13.8g potassium carbonate (100mmol). Then add 23.5g (94.8mmol) B-1 and 23g (93mmol) C-1. Under nitrogen protection, add 0.14g (0.2mmol) bis(triphenylphosphine)palladium dichloride. After nitrogen purging, slowly raise the temperature to 70℃ and react at 70-75℃ for 5 hours.

[0176] Post-processing: Cool to room temperature, transfer to a separatory funnel, separate the phases, extract the aqueous phase with 2 x 100 ml toluene, combine the oil phases, wash with 3 x 100 ml water until neutral, and concentrate toluene at 70°C under negative pressure (-0.095 MPa). Dissolve the concentrated product in petroleum ether and pass through a silica gel column, evaporate the solvent at 50°C to obtain 34.5 g of white solid. Recrystallize twice with toluene / ethanol (freezing at -30°C for 3 h), filter through a Buchner funnel, and dry to obtain 30 g of white solid.

[0177] Compound P-1 purity: 99.93%; yield: 87.2%.

[0178] Mass spectrometry data M+ (370): 41 (13%), 55 (16%), 77 (23%), 237 (15%), 250 (42%), 264 (20%), 293 (100%), 294 (48%), 370 (56%).

[0179] Example 3:

[0180] Preparation of compound P-2

[0181]

[0182] In a 500 ml three-necked flask, add 200 ml tetrahydrofuran and 21.8 g (100 mmol) of compound A-2, purge with nitrogen more than 3 times, cool to -80 °C, add 100 ml (100 mmol, 1.0 M) sec-butyllithium dropwise while maintaining the temperature at -80 °C, keep warm for 30 min, add 10.9 g (105 mmol) trimethyl borate dropwise, and keep warm at -80 °C for 3 h.

[0183] The mixture was naturally heated to -30°C, and 10% dilute hydrochloric acid was added to adjust the pH to 3. It was then naturally heated to room temperature, and concentrated under a negative pressure of 60°C (-0.095 MPa) until no tetrahydrofuran was detected. The precipitated solid was slurried with water to obtain a white solid, which was then dried to obtain 24.5 g of white solid B-2. The yield was 93.5%.

[0184] In a 500ml three-necked flask, add 150ml toluene, 30ml ethanol, 100ml water, and 13.8g potassium carbonate (100mmol). Then add 24.5g (93.5mmol) B-2 and 25.6g (92mmol) C-2. Under nitrogen protection, add 0.07g (0.1mmol) dichlorodi-tert-butyl-(4-dimethylaminophenyl)phosphine palladium. After nitrogen purging, slowly raise the temperature to 70℃ and react at 70-75℃ for 3 hours.

[0185] Post-processing: After cooling to room temperature, transfer to a separatory funnel, separate the phases, extract the aqueous phase with 2 x 100 ml of toluene, combine the oil phases, wash with 3 x 100 ml of water until neutral, and concentrate toluene at 70°C under negative pressure (-0.095 MPa). Dissolve the concentrated product in petroleum ether and pass it through a silica gel column, evaporate the solvent at 50°C to obtain 39.3 g of white solid. Recrystallize twice with toluene / ethanol (freezing at -30°C for 3 h), filter through a Buchner funnel, and dry to obtain 36 g of white solid.

[0186] Compound P-1 purity: 99.92%; yield: 85.1%.

[0187] Mass spectrometry data M+ (460): 55 (11%), 69 (13%), 77 (23%), 313 (17%), 326 (41%), 340 (23%), 383 (100%), 384 (55%), 460 (58%).

[0188] Example 4:

[0189] Preparation of compound P-3

[0190]

[0191] P-3 was obtained by referring to the method in Example 1.

[0192] Compound P-3 purity: 99.9%; yield: 86.3%.

[0193] Mass spectrometry data M+(402): 55 (12%), 69 (15%), 77 (22%), 255 (18%), 268 (46%), 282 (26%), 325 (100%), 326 (48%), 402 (47%).

[0194] Example 5:

[0195] Preparation of compound P-4

[0196]

[0197] P-3 was obtained by referring to the method in Example 2.

[0198] Compound P-2 purity: 99.92%; yield: 86%.

[0199] Mass spectrometry data M+ (426): 55 (10%), 69 (11%), 294 (18%), 307 (34%), 321 (22%), 364 (100%), 365 (34%), 402 (48%).

[0200] Application examples of liquid crystal compositions:

[0201] The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope.

[0202] Unless otherwise specified, all proportions in this invention are weight ratios, and all temperatures are in degrees Celsius.

[0203] For ease of explanation, in the following embodiments, the group structures of the liquid crystal compositions are represented by the codes listed in Table 2:

[0204] Table 2 Group structure codes of liquid crystal compounds

[0205]

[0206]

[0207] Take the following compound with the following structural formula as an example:

[0208]

[0209] If the structural formula is represented by the codes listed in Table 1, it can be expressed as: nCCGF, where n in the code represents the number of C atoms in the alkyl group at the left end. For example, if n is "3", it means that the alkyl group is -C3H7. In the code, C represents cyclohexyl, G represents 2-fluoro-1,4-phenylene, and F represents fluorine.

[0210] In the following embodiments, the abbreviated codes for performance test items are shown in Table 3.

[0211] Table 3 Abbreviated Codes for Performance Test Items

[0212] Test Project Code meaning Δn Optical anisotropy (589nm, 25℃) Cp Clearing point (nematic-isotropic phase transition temperature, °C) Δε Dielectric anisotropy (1kHz, 25℃) γ1 Rotational viscosity (25℃, mPa·s) t(-30℃) Low-temperature storage stability (stored at -30℃ and observed for 240 h, h)

[0213] Wherein, Δn: was obtained by measuring using an Abbe refractometer under a sodium lamp (589nm) light source at 25℃.

[0214] Cp: ​​Measured using an MP70 melting point apparatus.

[0215] Δε: Δε = ε ∥ -ε ⊥ , where ε ∥ ε is the dielectric constant parallel to the molecular axis. ⊥ The dielectric constant is perpendicular to the molecular axis. Test conditions: 25℃, 1KHz, VA type test box, box thickness 5.8μm.

[0216] γ1: Measured using the LCM-2 type liquid crystal property evaluation system; test conditions: 25℃, 160-240V, test cell thickness 20μm.

[0217] t(-30℃): The time recorded when crystal precipitation is observed after the nematic liquid crystal medium is placed in a 7µm antiparallel cell and stored at a constant temperature of -30℃.

[0218] All other components used in the liquid crystal compositions of the following application examples can be synthesized by known methods or are commercially available.

[0219] The liquid crystal compositions in the following examples are prepared by mixing according to the proportions of each component (the parentheses at the end of each component in each example are the general formulas for the components) and by conventional preparation methods such as heating, ultrasonication, suspension, etc.

[0220] Application Example 1

[0221] In this application example, the liquid crystal composition comprises the components in the following table by mass percentage, and its performance test results are listed in the table below:

[0222]

[0223] Application Example 2

[0224] In this application example, the liquid crystal composition comprises the components in the following table by mass percentage, and its performance test results are listed in the table below:

[0225]

[0226]

[0227] Application Example 3

[0228] In this application example, the liquid crystal composition comprises the components in the following table by mass percentage, and its performance test results are listed in the table below:

[0229]

[0230] Application Example 4

[0231] In this application example, the liquid crystal composition comprises the components in the following table by mass percentage, and its performance test results are listed in the table below:

[0232]

[0233] Comparative Example 1

[0234] In this comparative example, the liquid crystal composition comprises the components in the following table by mass percentage, and its performance test results are listed in the table below:

[0235]

[0236] Comparative Example 2

[0237] In this comparative example, the liquid crystal composition comprises the components in the following table by mass percentage, and its performance test results are listed in the table below:

[0238]

[0239] It can be seen that the liquid crystal monomer of the present invention has a high clearing point Cp, a low viscosity γ1, and a fast response speed.

[0240] The applicant declares that this invention illustrates the difluoroterminated alkenyl liquid crystal compound, its preparation method, and its application through the above embodiments. However, this invention is not limited to the above embodiments, meaning that this invention does not necessarily rely on the above embodiments for implementation. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection and disclosure scope of this invention.

Claims

1. A difluoroterminated alkenyl liquid crystal compound, characterized in that, The difluoro-terminated alkenyl liquid crystal compound has the structure shown in general formula P: in, R represents hydrogen, an alkyl group with 1 to 12 carbon atoms, an alkoxy group with 1 to 12 carbon atoms, an alkenyl group with 2 to 12 carbon atoms, an alkenyloxy group with 2 to 12 carbon atoms, or an alkynyl group with 2 to 12 carbon atoms, wherein one or more of the alkyl group with 1 to 12 carbon atoms, the alkoxy group with 1 to 12 carbon atoms, the alkenyl group with 2 to 12 carbon atoms, the alkenyloxy group with 2 to 12 carbon atoms, or the alkynyl group with 2 to 12 carbon atoms may be replaced by -CH=CH-, -C≡C-, -O-, -S-, -CO-, -CO-O-, or -O-CO-; ring and ring The same or different, each independently representing cyclohexene, cyclohexenyl, cyclopentyl, cyclopentenyl, cyclobutyl, propylene oxide, or substituted or unsubstituted benzene ring groups, wherein one or more of the -CH2- groups in cyclohexene, cyclohexenyl, cyclopentenyl, cyclobutyl, and propylene oxide can be replaced by -O-, and the substituted benzene ring group refers to one or more hydrogens on the benzene ring that can be replaced by a halogen, a fluorinated or unfluorinated alkyl or alkoxy group of 1-3 carbon atoms, or one or more -CH= groups on the benzene ring that can be replaced by -N= groups; m represents an integer from 0 to 2; B Represents integers from 0 to 2; n represents integers from 1 to 6, and n1 represents integers from 1 to 4; Y represents -O- or alkylene groups with 1-6 carbon atoms, or alkene groups with 1-6 carbon atoms; X, X1, X2, or X3 may be the same or different, and each independently represents H, halogen, 1-3 carbon atoms of fluorinated or unfluorinated alkyl or alkoxy groups. When n1 is not 1, X may be the same or different.

2. The difluoro-terminated alkenyl liquid crystal compound according to claim 1, characterized in that, ring and ring Whether they are the same or different, they are expressed independently of each other. Preferably, X is selected from H, F, Cl, methyl, methoxy, trifluoromethyl, or trifluoromethoxy; Preferably, X1, X2, and X3 represent hydrogen, fluorine, chlorine, methyl, or methoxy.

3. The difluoroterminated alkenyl liquid crystal compound according to claim 1, characterized in that, Groups are selected from Preferably, Groups are selected from Preferably, Y represents methylene.

4. The difluoro-terminated alkenyl liquid crystal compound according to any one of claims 1-3, characterized in that, The difluoro-terminated alkenyl liquid crystal compound is a compound having any of the following structures:

5. The difluoro-terminated alkenyl liquid crystal compound according to any one of claims 1-4, characterized in that, R is selected from hydrogen, alkyl with 1 to 6 carbon atoms, alkoxy with 1 to 6 carbon atoms, alkenyl with 2 to 6 carbon atoms, alkenyloxy with 2 to 16 carbon atoms, and alkynyl with 2 to 6 carbon atoms, wherein one or more of the alkyl with 1 to 6 carbon atoms, alkoxy with 1 to 6 carbon atoms, alkenyl with 2 to 6 carbon atoms, alkenyloxy with 2 to 16 carbon atoms, and alkynyl with 2 to 6 carbon atoms may be replaced by -CH=CH-, -C≡C-, -O-, -S-, -CO-, -CO-O-, or -O-CO-; More preferably, R is selected from hydrogen, alkyl groups of 1 to 6 carbon atoms, alkoxy groups of 1 to 6 carbon atoms, alkenyl groups of 2 to 6 carbon atoms, and alkenoxy groups of 2 to 16 carbon atoms, wherein one or more of the alkyl groups of 1 to 6 carbon atoms, alkoxy groups of 1 to 6 carbon atoms, alkenyl groups of 2 to 6 carbon atoms, and alkenoxy groups of 2 to 16 carbon atoms can be replaced by -CH=CH-, -C≡C-, -O-, -S-, -CO-, -CO-O-, or -O-CO-.

6. The difluoro-terminated alkenyl liquid crystal compound according to any one of claims 1-5, characterized in that, The liquid crystal compound containing terminal alkenyl groups is any one of the following compounds:

7. The method for preparing the difluoro-terminated alkenyl liquid crystal compound according to any one of claims 1-6, characterized in that, The preparation method includes the following steps: (1) Compound A reacts with a borate ester to give compound B, as shown in the following reaction formula: (2) The compound shown in formula B reacts with the compound of formula C to obtain the difluoro-terminated alkenyl liquid crystal compound shown in formula P. The reaction formula is as follows: Hal is selected from Cl, Br, or I.

8. The preparation method according to claim 7, characterized in that, The borate ester in step (1) is selected from one or a combination of at least two of trimethyl borate, triisopropyl borate or tributyl borate; Preferably, the molar ratio of compound A to borate ester in step (1) is 1:0.9 to 1:3, more preferably 1:1 to 1:1.3; Preferably, the reaction in step (1) is carried out in the presence of an alkaline substance; Preferably, the alkaline substance is selected from any one of n-butyllithium, diisopropylaminolithium, sec-butyllithium or tert-butyllithium, with n-butyllithium, diisopropylaminolithium or sec-butyllithium being more preferred. Preferably, the reaction in step (1) is carried out in an organic solvent selected from one or a combination of at least two of tetrahydrofuran, 2-methyltetrahydrofuran, diethyl ether or methyl tert-butyl ether, preferably tetrahydrofuran and / or 2-methyltetrahydrofuran; Preferably, the reaction temperature in step (1) is -100 to 30°C, and the reaction time is 0.5 to 24 hours; Preferably, the reaction in step (1) is carried out under nitrogen protection; Preferably, after the reaction in step (1) is completed, the mixture is separated, washed with water, concentrated, and crystallized to obtain the compound of formula C; Preferably, the molar ratio of the compound of formula B to the compound of formula C in step (2) is 1.5:1 to 0.9:1, more preferably 1.2:1 to 1:1; Preferably, the reaction in step (2) is carried out in the presence of a catalyst; Preferably, the catalyst is a palladium catalyst; Preferably, the palladium catalyst is selected from any one of bis(dibenzylacetone)palladium, tetra(triphenylphosphine)palladium dichloride, bis(triphenylphosphine)palladium dichloride, dichloroditert-butyl-(4-dimethylaminophenyl)phosphine palladium or 1,1'-bis(diphenylphosphine)ferrocene palladium dichloride, and is more preferably tetra(triphenylphosphine)palladium dichloride, bis(triphenylphosphine)palladium dichloride or dichloroditert-butyl-(4-dimethylaminophenyl)phosphine palladium; Preferably, the reaction in step (2) is carried out in the presence of an alkaline substance; Preferably, the alkaline substance is selected from any one or a combination of at least two of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium phosphate, potassium hydroxide, or sodium hydroxide; Preferably, the reaction in step (2) is carried out in an organic solvent selected from one or a combination of at least two of toluene, tetrahydrofuran, acetonitrile, dioxane, ethanol, or dimethylformamide; preferably, one or a combination of at least two of benzene, tetrahydrofuran, acetonitrile, or dioxane. Preferably, the reaction temperature in step (2) is 40–130°C, and the reaction time is 0.5–24 h; More preferably, the temperature of the reaction in step (2) is 40°C or 80-110°C, and the reaction time is 0.5-6 hours; Preferably, the reaction in step (2) is carried out under nitrogen protection; Preferably, after the reaction in step (2) is completed, the product is separated, washed with water, concentrated, and crystallized to obtain compound P.

9. A liquid crystal composition, characterized in that, The liquid crystal composition includes a liquid crystal compound containing a terminal alkenyl group as described in any one of claims 1-6.

10. A liquid crystal display element, characterized in that, The liquid crystal display element comprises a liquid crystal composition as described in any one of claims 1-6.

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