TW201414811A - Novel saturated dioxanaphthalene-based liquid crystal compound, composition and use thereof - Google Patents

Abstract

A novel saturated dioxanaphthalene-containing first liquid crystal compound is represented by formula (I). A method of making, composition thereof and liquid crystal display using the composition are also disclosed. The liquid crystal composition can be used for liquid crystal element of various display modes, such as TN, STN, TFT, VA, ECB, OCB, LCP, PDLC, BiNem, LC LENS, FFS and IPS.

Description

Novel dioxa-saturated naphthalene ring-type liquid crystal compounds and compositions thereof and application

The present invention relates to a novel liquid crystal compound containing a dioxa saturated naphthalene ring, and a liquid crystal composition comprising the liquid crystal compound and use thereof.

Physically, the matter is divided into three states, namely solid, liquid and gaseous. In nature, most materials exhibit only three states of solid state, liquid state and gas state with temperature. Liquid crystal (LC) is a new material state different from the usual solid, liquid and gaseous states. It can be in a certain state. The state of matter in which both the liquid and the crystal are characteristic in a temperature range, also referred to as a liquid crystal phase or an intermediate phase, is also referred to as the fourth state of the substance.

There are many types of liquid crystals, and there are thousands of naturally occurring and synthetic liquid crystals, but they are basically organic compounds. According to the conditions formed by the liquid crystal phase, the liquid crystal can be classified into a thermotropic liquid crystal, a lyotropic liquid crystal, an inductive liquid crystal, and a flow-through liquid crystal.

Currently, liquid crystal materials for display are basically thermotropic liquid crystals. Thermotropic liquid crystals can be classified into smectic crystals due to different molecular arrangement states. Liquid crystal (Smectic LC, also known as smectic liquid crystal), nematic liquid crystal (Nematic LC, also known as filamentous liquid crystal), cholesterol liquid crystal (Cholesteric LC, also known as spiral liquid crystal). The physical properties of these phases are known. Molecular structural features of compounds used in the field of optoelectronics, usually having a rigid backbone comprising, for example, linked 1,4-phenylene or 1,4-cyclohexylene or heterocyclic systems, as far as possible from each other The position is substituted by a terminal group such as an alkyl group, an alkoxy group or a cyano group.

A liquid crystal medium used in the field of optoelectronics is composed of a mixture of these compounds, and a compound which does not have a mutual transformation from a crystal phase to a liquid crystal is also used therein. Classified by liquid crystal display, liquid crystal compositions can be classified into dynamic scattering type (DS type), guest main type (GH type), twisted nematic type (TN type), super twisted nematic type (STN type), thin film transistor type. (TFT type) and ferroelectric type (FLC type). Liquid crystal materials have been widely used in the production of liquid crystal display elements such as tablet computers, various measuring instruments, automotive instrument panels, notebook computers, mobile phones, computers, and televisions.

Heretofore, various liquid crystal materials have been synthesized into a plurality of compounds, which can be used depending on the manner of display or the manner of driving and the use thereof. On the other hand, the demand for improving the performance of liquid crystal display elements has been increasing year by year. To meet this demand, it is necessary to continue to develop new liquid crystal compounds.

Accordingly, it is an object of the present invention to provide a novel liquid crystal compound containing a dioxa saturated naphthalene ring.

Thus, the first liquid crystal compound of the present invention has a structure represented by the following formula (I):

Wherein R ₁ represents -H, -F or a straight or branched alkyl or alkoxy group substituted with 1 to 5 carbon atoms via at least one halogen, and R ₂ represents -H, -F, - Cl, -CN, -NCS, -SCN, -OCN, -NCO, Or a linear or branched alkyl or alkoxy group having 1-10 carbon atoms substituted or unsubstituted with at least one halogen, wherein at least one of _-1 -CH ₂ - in R ₁ and R ₂ may be -O- , -S-, -SiH ₂ -, -CH=CH-, -C≡C-, -CF=CF-, -CH=CF-, , -COO- or -OCO-substituted, and any two heteroatoms are not directly bonded to each other; A ₁ , A ₂ , A ₃ and A ₄ may be the same or different and each independently represents the following cyclic structure: with Wherein the cyclic structure may also conform to at least one of the following a), b), c) and d): a) one or more hydrogen atoms in the cyclic structure may be -D, -F , -Cl, -CN, -CF ₃ , -OCF ₃ , -CH ₂ F, -OCH ₂ F, -CF ₂ H, -OCF ₂ H, -OCH ₃ or -CH ₃ substitution; b) the ring One or more -CH ₂ - in the structure is substituted by -O-, -SiH ₂ -, -S- or -CO-, and any two heteroatoms are not directly connected to each other; c) the aromatic structure of the cyclic structure One or more -CH= in the ring structure may be substituted by -N=; d) one or more of the ring structures Can be Substituting; Z ₁ , Z ₂ , Z ₃ and Z ₄ may be the same or different and each independently represented as a single bond, -COO-, -CF ₂ O-, -CH ₂ O-, -CH ₂ CH ₂ -, -CF ₂ CH ₂ -, -CF=CF-, -CH=CH-, -CH=CF-, -C ₂ F ₄ -, -(CH ₂ ) ₄ -, -(CF ₂ ) ₄ -, -OCF ₂ CF ₂ O-, -CF ₂ CF ₂ CF ₂ O-, -CH ₂ CH ₂ CF ₂ O-, -OCH ₂ CF ₂ O-, -CH ₂ CF ₂ OCH ₂ -, -CH=CHCF ₂ O- _{, -CF 2 OCH = CH -,} - CF 2 OCF = CH -, - CF 2 OCH = CF -, - CF = CFCF 2 O -, - CH = CHCH 2 CH 2 -, - CF 2 OCF = CF-, -CH ₂ CH=CHCH ₂ -, -C ₂ H ₄ OCH ₂ -, -OCH ₂ CH ₂ CH ₂ -, -CF=CF-CF=CF-, -C≡C-CF=CF-, -C≡ C-CF=CF-C≡C-, -C≡C-, -CF=CF-C≡C-CF=CF- or -C≡C-CF ₂ O-; and m, n and p can be the same Or different, each independently represents 0, 1 or 2, and m+n+p≧1; when m is 2, two Z ₂ -A ₂ may be the same or different; when n is 2, two Z ₃ -A ₃ may be the same or different; when p is 2, the two Z ₄ -A ₄ may be the same or different.

A second object of the present invention is to provide a method of preparing the first liquid crystal compound comprising the steps of:

(1) Dissolving dimethyl carbonate and sodium hydride in tetrahydrofuran, dropwise adding the compound of the formula (IV) under reflux, and then refluxing for 4 hours to obtain a compound of the formula (V);

(2) a compound of the formula (V) is slowly added dropwise to a solution of lithium tetrahydride in anhydrous tetrahydrofuran under a freezing point to obtain a compound of the formula (VI);

(3) adding a compound of the formula (VI), a compound of the formula (III) and p-toluenesulfonic acid monohydrate to a dichloromethane solution, and dehydrating under reflux for 6 hours to obtain a first liquid crystal compound of the formula (I);

The compound of the formula (III) and the compound of the formula (IV) are mainly synthesized by a commercially available intermediate or a conventional synthesis method, wherein the conventional synthesis method includes a reduction reaction, an oxidation reaction, an esterification reaction, a Wittig reaction, and carbon- Carbon cross-coupling reaction (Suzuki coupling, Negishi coupling, Heck coupling, Sonogashira coupling and transition metal catalyzed cross-coupling of Grignard reagents) The reaction, etc.), the Grignard reaction, the low temperature reaction, and the like are obtained.

A third object of the present invention is to provide a liquid crystal composition comprising at least one first liquid crystal compound as described above.

A fourth object of the present invention is to provide a liquid crystal display element comprising the liquid crystal composition as described above.

The first liquid crystal compound of the formula (I) has a relatively high dielectric anisotropy and a relatively low viscosity, and is suitably used for forming a liquid crystal composition and a liquid crystal display element.

The present invention will be described in detail below. Preferably, A ₁ , A ₂ , A ₃ and A ₄ may be the same or different, each independently represented as or . More preferably, A ₁ , A ₂ , A ₃ and A ₄ may be the same or different, each independently represented as or

Preferably, Z ₁ , Z ₂ , Z ₃ and Z ₄ may be the same or different and are each independently represented by -COO-, -CF ₂ O-, -CH ₂ O-, -CH ₂ CH ₂ -, - CF=CF-, -CH=CH-, -C ₂ F ₄ -, -(CH ₂ ) ₄ -, -C ₄ F ₈ -, -OCF ₂ CF ₂ O-, -CH ₂ CH ₂ CF ₂ O- , -CF=CFCF ₂ O-, -C ₂ H ₄ OCH ₂ -, -OCH ₂ CH ₂ CH ₂ -, -C≡C- or a single bond. More preferably, Z ₁ , Z ₂ , Z ₃ and Z ₄ may be the same or different and are each independently represented by -COO-, -CF ₂ O-, -CH ₂ O-, -CH ₂ CH ₂ -, - CF=CF-, -CH=CH-, -C ₂ F ₄ -, -C ₄ F ₈ -, -OCF ₂ CF ₂ O-, -CF=CFCF ₂ O-, -C≡C- or a single bond.

Preferably, m, n and p may be the same or different, each independently representing 0, 1 or 2, and 1 ≦ m + n + p ≦ 4; when m is 2, two Z _{2 -} A ₂ may The same or different; when n is 2, two Z ₃ -A ₃ may be the same or different; when p is 2, two Z ₄ -A ₄ may be the same or different.

Preferably, the first liquid crystal compound is selected from the group consisting of: ;as well as Wherein, L ₁ to L ₈ may be the same or different and are each independently represented as -H, -D, -F, -Cl, -CN, -CF ₃ , -OCF ₃ , -CH ₂ F, -OCH ₂ F , -CF ₂ H, -OCF ₂ H, -OCH ₃ or -CH ₃ .

Preferably, the liquid crystal composition comprises one to five first liquid crystal compounds as described above. More preferably, the liquid crystal composition comprises two to four first liquid crystal compounds as described above.

Preferably, the liquid crystal composition further comprises a conventional liquid crystal compound which can be mixed in a pure state or with other components to form a liquid crystal composition.

Some such compounds are mentioned, for example, in DE 1804894 and CN 1158602 A.

Preferably, the liquid crystal composition further comprises at least one second liquid crystal compound represented by the following formula (II):

Wherein R ₃ and R ₄ may be the same or different and each independently represents -H, -F, -Cl, -CN, -NCS, -SCN, -OCN, -NCO, -OCH=CF ₂ or 1-20 carbon atoms with at least one halogen substituted or unsubstituted straight or branched chain alkyl, alkenyl or alkoxy, wherein, in at least one -CH ₂ R ₃ and R ₄ - may be -O-, -S-, -SiH ₂ -, -CH=CH-, -C≡C-, -CF=CF-, -CH=CF-, , -COO- or -OCO-substituted, and any two heteroatoms are not directly connected to each other; B ₁ , B ₂ , B ₃ and B ₄ may be the same or different, each independently represented , 2-chloro-3-fluoro-1,4-phenylene, indane-2,5-diyl, piperidinyl-1,4-diyl, naphthalene-2,6-diyl, decahydronaphthalene- a group of 2,6-diyl and 1,2,3,4-tetrahydronaphthalene-2,6-diyl, wherein One or two non-adjacent -CH ₂ - may be replaced by -O- or -S- Any of the above H may be independently replaced by F, One or two non-adjacent -CH= may be replaced by -N= Any of the Hs may be independently replaced by F, One or two non-adjacent -CH ₂ - may be replaced by -O- Arbitrary independently H may be substituted by F; Y _1, Y ₂ and Y ₃ may be the same or different, each independently represent _{-OCO-, -COO -, - CF 2} O -, - CH 2 O-, -OCH ₂ -, -CH ₂ CH ₂ -, -CF ₂ CH ₂ -, -CF=CF-, -CH=CH-, -CH(CH ₃ )CH ₂ -, -CH ₂ CH(CH ₃ )- , -(CH ₂ ) ₃ O-, -COS-, -SCO-, -CH=CF-, -C ₂ F ₄ -, -(CH ₂ ) ₄ -, -C ₄ F ₈ -, -OCF ₂ CF ₂ O-, -CF ₂ CF ₂ CF ₂ O-, -CH ₂ CH ₂ CF ₂ O-, -CH ₂ CF ₂ OCH ₂ -, -CH=CHCF ₂ O-, -CF ₂ OCH=CH-, - CF ₂ OCF=CH-, -CF ₂ OCH=CF-, -CF=CFCF ₂ O-, -CF ₂ OCF=CF-, -CH=CHCH ₂ CH ₂ -, -C ₂ H ₄ OCH ₂ -, - CH ₂ CH=CHCH ₂ -, -OCH ₂ CH ₂ CH ₂ -, -CF=CF-CF=CF-, -C≡C-CF=CF-, -C≡C-CF=CF-C≡C- , -CF=CF-C≡C-CF=CF-, -C≡C-CF ₂ O-, -C≡C- or a single bond, wherein any one of Y ₁ and Y ₂ -CH ₂ - It may be substituted by -SiH ₂ -; a, b and c may be the same or different, each independently representing 0, 1 or 2; when a is 2, two B ₁ -Y ₁ may be the same or different; when b is At 2 o'clock, the two B ₂ -Y ₂ may be the same or different; when c is 2, the two B ₃ -Y ₃ may be the same or different.

More preferably, the second liquid crystal compound is selected from the group consisting of: as well as

Preferably, the liquid crystal composition comprises from 5 to 20% by weight of the total liquid crystal composition of the first liquid crystal compound and from 80 to 95% by weight based on the total weight of the liquid crystal composition. More preferably, the liquid crystal composition comprises 8-15% by weight of the total liquid crystal composition of the first liquid crystal compound and 85 to 92% of the second liquid crystal compound based on the total weight of the liquid crystal composition.

The present invention will be further illustrated by the following examples, but it should be understood that this embodiment is intended to be illustrative only and not to be construed as limiting.

Take a compound of the following structural formula as an example:

The structural formula is represented by the code listed in Table 1, which can be expressed as: 3PUQUF, Q in the code represents difluoromethyloxy; C in the code represents 1,4-cyclohexylene; U in the code represents 2,5-Difluoro-1,4-phenylene.

<Example 1>

The synthesis of the compound HCLC- 08 is as follows:

Among them, 4-[difluoro-(3,4,5-trifluorophenoxy)methyl]-3,5-difluorobenzaldehyde can be synthesized by a conventional method (for the synthesis method, reference can be made to the patent DE 102011011268) .

(1) Synthesis of HCLC -08-2

In a 1 L three-necked flask, 70.5 g of dimethyl carbonate, 300 mL of tetrahydrofuran (THF) and 18.86 g of sodium hydride were added, the temperature was raised to reflux, and 55 g of 4-n-propylcyclohexanone in 100 mL of THF was added dropwise, and the addition was completed in 30 minutes. The reaction was stopped after 4 hours of reflux reaction. After that, first add 100 mL of water, then add 2M (2mol/L) hydrochloric acid solution to adjust to pH<2, extract with 200mL of ethyl acetate, wash with sodium bicarbonate solution until neutral, and then remove water with anhydrous sodium sulfate, then Column chromatography was carried out using petroleum ether: ethyl acetate = 10:1 as a solvent, and the collected chromatography was concentrated to give 62 g of HCLC -08-2, HPLC purity: 97.8%, yield 79.8%.

(2) Synthesis of HCLC -08-1

Under a nitrogen atmosphere and 0 to -5 ° C, 55 g of HCLC -08-2 in 100 mL of anhydrous tetrahydrofuran was slowly added dropwise to 26.6 g of lithium tetrahydrogenate in 1.2 L of tetrahydrofuran. After the completion of the dropwise addition, the mixture was heated to room temperature. After reacting for 6 hours, 20 g of ethyl acetate was added dropwise, and 28 g of water was added dropwise. The metaaluminate was filtered off, and the filtrate was evaporated to dryness to give 43.5 g of pale yellow oil, using petroleum ether (PE): ethyl acetate. EA=1:1) was used as a column chromatography for column chromatography, and then washed with ethyl acetate. The chromatographic solutions were combined, and the solvent was evaporated under reduced pressure with a rotary concentrator to obtain 35.8 g of colorless transparent liquid ( HCLC -08-1) ), purity: 93.7% (cis-trans isomer), yield 74.8%.

(3) Synthesis of HCLC -08

Add 9.2 g of HCLC -08-1, 16.3 g of 4-[difluoro-(3,4,5-trifluorophenoxy)methyl]-3,5-difluorobenzaldehyde, 0.3 to a 500 mL three-necked flask. g p-toluenesulfonic acid monohydrate and 250 mL of dichloromethane, heated in water and refluxed to separate water, reacted for 6 hours, and monitored by GC until 4-[difluoro-(3,4,5-trifluorophenoxy)methyl] -3,5-difluorobenzaldehyde residue, naturally cooled to room temperature; the reaction solution was poured into 100 mL of saturated aqueous sodium hydrogencarbonate solution, transferred to a separating funnel, and the aqueous layer was extracted twice with 100 mL of dichloromethane. The organic layer was combined and washed twice with saturated aqueous sodium hydrogen sulfate, and then evaporated and evaporated. The crude product was subjected to column chromatography with petroleum ether and ethyl acetate (8:1), and the solvent was evaporated to dryness to give a pale yellow solid (19.8 g) and recrystallized three times with 50 mL of anhydrous ethanol to give a white solid 6.9. g HCLC -08, purity 99.6%.

_{^{1 H NMR (300MHz, CDCl 3}} ) δ 7.02 (dt, J = 2.7,1.6Hz, 2H), 6.93-6.83 (m, 2H), 5.79 (s, 1H), 3.74 (dd, J = 24.8,15.8Hz , 1H), 3.49 (dd, J = 24.9, 15.7 Hz, 1H), 3.26 (dt, J = 20.9, 15.2 Hz, 1H), 2.59-2.39 (m, 1H), 2.04-1.82 (m, 2H), 1.78-1.57 (m, 2H), 1.57-1.18 (m, 7H), 0.95-0.76 (m, 3H).

<Example 2>

The synthesis of the compound HCLC -08C is as follows:

Wherein, 4-[difluoro-(3,4,5-trifluorophenoxy)methyl]-3,5-difluorophenylboronic acid can be synthesized by a conventional method (for the synthesis method, reference may be made to the European Journal of Organic Chemistry, 2008, V20 p3479-3487).

(1) Synthesis of HCLC -08 C -1

In a 250 mL dry clean single-mouth bottle, 4.0 g of p-bromobenzaldehyde and 6.7 g of 4-[difluoro-(3,4,5-trifluorophenoxy)methyl]-3,5-difluorophenylboronic acid were added. After 4.0 g of anhydrous sodium carbonate, 20 mL of deionized water, 50 mL of toluene and 20 mL of absolute ethanol were replaced by argon gas, 0.3 g of Pd[P(Ph) ₃ ] _{4 was added} . The mixture was heated under reflux for 6 hours under an argon atmosphere, and the reaction liquid was cooled and separated, and the organic phase was subjected to column chromatography using 6:1 petroleum ether and ethyl acetate as a solvent, and the chromatography liquid was evaporated to dryness by a rotary concentrator. Solvent, 7.6 g of a pale yellow solid were obtained to give crude. The crude product was 15mL of petroleum ether and recrystallized twice 15mL of absolute ethanol, to give 6.5g white solid (HCLC -08 C -1), purity: 99.5%, yield 82%.

(2) Synthesis of HCLC -08 C

Add 2.9g of HCLC -08-1, 6.5g of HCLC -08 C -1, 0.3g of p-toluenesulfonic acid monohydrate and 70mL of dichloromethane to a 100mL three-necked flask, heat and reflux in water bath for 6 hours, GC monitored until no residual HCLC -08 C -1, cooled to room temperature; the reaction mixture was poured into 20mL saturated aqueous sodium bicarbonate, carved into the funnel, and the aqueous layer was separated and extracted twice with 50mL of methylene chloride, The organic layer was combined and washed twice with saturated aqueous sodium hydrogen sulfate. The crude product was subjected to column chromatography with petroleum ether and ethyl acetate (8:1), and the solvent was evaporated to dryness to yield 6.9 g of pale yellow solid, which was recrystallized three times with 30 mL of anhydrous ethanol and 20 mL of toluene. White solid 2.85 g HCLC -08 C , purity: 99.7%, yield 32%.

_{^{1 H NMR (300MHz, CDCl 3}} ) δ 7.74-7.61 (m, 2H), 7.61-7.48 (m, 2H), 7.30 (dt, J = 16.3,1.6Hz, 2H), 6.91-6.81 (m, 2H) , 5.66 (s, 1H), 3.73 (dd, J = 24.7, 15.8 Hz, 1H), 3.48 (dd, J = 24.7, 15.8 Hz, 1H), 3.25 (dt, J = 21.1, 15.2 Hz, 1H), 2.62-2.36 (m, 1H), 2.07-1.80 (m, 2H), 1.81-1.16 (m, 9H), 1.03-0.78 (m, 3H).

<Example 3>

Example 3 is a characteristic measurement result of the liquid crystal composition of the present invention: wherein Cp (° C.) represents a clearing point (nematic-isotropic phase transition temperature), and η represents a flow viscosity (mPa‧s, 20 ° C, unless otherwise In addition, Δn represents optical anisotropy (589 nm, 20 ° C), and Δ ε represents dielectric anisotropy (1 kHz, 25 ° C).

The liquid crystal compositions prepared according to the respective compounds and the weight percentages listed in Table 2 below were subjected to characteristic measurement, and the test data are shown in Table 2 below:

In summary, the present invention has remarkable performance in dielectric anisotropy and has a relatively low viscosity, and is suitable for use in a liquid crystal composition and a liquid crystal display element, so that the object of the present invention can be achieved.

However, the above is only the preferred embodiment of the present invention, and the scope of the present invention is not limited thereto, that is, the simple equivalent changes and modifications made by the content of the patent application and the contents of the patent specification of the present invention. All remain within the scope of the invention patent.

Claims (10)

A first liquid crystal compound represented by the following formula (I): Wherein R ₁ represents -H, -F or a linear or branched alkyl or alkoxy group having 1 to 5 carbon atoms substituted or unsubstituted with at least one halogen, and R ₂ represents -H, -F, - Cl, -CN, -NCS, -SCN, -OCN, -NCO, Or a linear or branched alkyl or alkoxy group having 1-10 carbon atoms substituted or unsubstituted with at least one halogen, wherein at least one of _-1 -CH ₂ - in R ₁ and R ₂ may be -O- , -S-, -SiH ₂ -, -CH=CH-, -C≡C-, -CF=CF-, -CH=CF-, , -COO- or -OCO-substituted, and any two heteroatoms are not directly bonded to each other; A ₁ , A ₂ , A ₃ and A ₄ may be the same or different and each independently represents the following cyclic structure: or Wherein, the cyclic structure may also conform to at least one of the following a), b), c) and d): a) one or more hydrogen atoms in the cyclic structure may be -D, -F, -Cl, -CN, -CF ₃ , -OCF ₃ , -CH ₂ F, -OCH ₂ F, -CF ₂ H, -OCF ₂ H, -OCH ₃ or -CH ₃ substitution; b) the cyclic structure One or more -CH ₂ - is substituted by -O-, -SiH ₂ -, -S- or -CO-, and any two heteroatoms are not directly bonded to each other; c) the aromatic ring of the cyclic structure One or more -CH= in the structure may be substituted by -N=; d) one or more of the cyclic structures Can be Substituting; Z ₁ , Z ₂ , Z ₃ and Z ₄ may be the same or different and each independently represented as a single bond, -COO-, -CF ₂ O-, -CH ₂ O-, -CH ₂ CH ₂ -, -CF ₂ CH ₂ -, -CF=CF-, -CH=CH-, -CH=CF-, -C ₂ F ₄ -, -(CH ₂ ) ₄ -, -(CF ₂ ) ₄ -, -OCF ₂ CF ₂ O-, -CF ₂ CF ₂ CF ₂ O-, -CH ₂ CH ₂ CF ₂ O-, -OCH ₂ CF ₂ O-, -CH ₂ CF ₂ OCH ₂ -, -CH=CHCF ₂ O- _{, -CF 2 OCH = CH -,} - CF 2 OCF = CH -, - CF 2 OCH = CF -, - CF = CFCF 2 O -, - CH = CHCH 2 CH 2 -, - CF 2 OCF = CF-, -CH ₂ CH=CHCH ₂ -, -C ₂ H ₄ OCH ₂ -, -OCH ₂ CH ₂ CH ₂ -, -CF=CF-CF=CF-, -C≡C-CF=CF-, -C≡ C-CF=CF-C≡C-, -C≡C-, -CF=CF-C≡C-CF=CF- or -C≡C-CF ₂ O-; and m, n and p can be the same Or different, each independently represents 0, 1 or 2, and m+n+p≧1; when m is 2, two Z ₂ -A ₂ may be the same or different; when n is 2, two Z ₃ -A ₃ may be the same or different; when p is 2, the two Z ₄ -A ₄ may be the same or different. The first liquid crystal compound according to claim 1, wherein m, n and p may be the same or different, each independently representing 0, 1 or 2, and 1 ≦ m + n + p ≦ 4; when m is 2 The two Z ₂ -A ₂ may be the same or different; when n is 2, the two Z ₃ -A ₃ may be the same or different; when p is 2, the two Z ₄ -A ₄ may be the same or different. The first liquid crystal compound according to any one of claims 1 to 2, wherein the first liquid crystal compound is selected from the group consisting of: ;as well as Wherein, L ₁ to L ₈ may be the same or different and are each independently represented as -H, -D, -F, -Cl, -CN, -CF ₃ , -OCF ₃ , -CH ₂ F, -OCH ₂ F , -CF ₂ H, -OCF ₂ H, -OCH ₃ or -CH ₃ . A liquid crystal composition comprising at least one first liquid crystal compound according to any one of claims 1 to 3. The liquid crystal composition according to claim 4, wherein the liquid crystal composition comprises one to five first liquid crystal compounds according to any one of claims 1 to 3. The liquid crystal composition according to claim 5, wherein the liquid crystal composition further comprises at least one second liquid crystal compound represented by the following formula (II): Wherein R ₃ and R ₄ may be the same or different and each independently represents -H, -F, -Cl, -CN, -NCS, -SCN, -OCN, -NCO, -OCH=CF ₂ or 1-20 carbon atoms with at least one halogen substituted or non-substituted with halogen, straight-chain or branched alkyl, alkenyl or alkoxy, wherein, in R ₃ and R ₄ at least one -CH ₂ - may be replaced by -O- , -S-, -SiH ₂ -, - CH=CH-, -C≡C-, -CF=CF-, -CH=CF-, , -CO -O- or -OCO-substituted, and any two heteroatoms are not directly connected to each other; B ₁ , B ₂ , B ₃ and B ₄ may be the same or different, each independently represented , 2-chloro-3-fluoro-1,4-phenylene, indane-2,5-diyl, piperidinyl-1,4-diyl, naphthalene-2,6-diyl, decahydronaphthalene- 2,6-diyl or 1,2,3,4-tetrahydronaphthalene-2,6-diyl, wherein One or two non-adjacent -CH ₂ - may be replaced by -O- or -S- Any of the above H may be independently replaced by F, One or two non-adjacent -CH= may be replaced by -N= Any of the Hs may be independently replaced by F, One or two non-adjacent -CH ₂ - may be replaced by -O- Arbitrary independently H may be substituted by F; Y _1, Y ₂ and Y ₃ may be the same or different, each independently represents -OCO -, - COO -, - CF 2 O -, - CH 2 O-, -OCH ₂ -, -CH ₂ CH ₂ -, -CF ₂ CH ₂ -, -CF=CF-, -CH=CH-, -CH(CH ₃ )CH ₂ -, -CH ₂ CH(CH ₃ )- , -(CH ₂ ) ₃ O-, -COS-, -SCO-, -CH=CF-, -C ₂ F ₄ -, -(CH ₂ ) ₄ -, -C ₄ F ₈ -, -OCF ₂ CF ₂ O-, -CF ₂ CF ₂ CF ₂ O-, -CH ₂ CH ₂ CF ₂ O-, -CH ₂ CF ₂ OCH ₂ -, -CH=CHCF ₂ O-, -CF ₂ OCH=CH-, - CF ₂ OCF=CH-, -CF ₂ OCH=CF-, -CF=CFCF ₂ O-, -CF ₂ OCF=CF-, -CH=CHCH ₂ CH ₂ -, -C ₂ H ₄ OCH ₂ -, - CH ₂ CH=CHCH ₂ -, -OCH ₂ CH ₂ CH ₂ -, -CF=CF-CF=CF-, -C≡C-CF=CF-, -C≡C-CF=CF-C≡C- , -CF=CF-C≡C-CF=CF-, -C≡C-CF ₂ O-, -C≡C- or a single bond, wherein any one of Y ₁ and Y ₂ -CH ₂ - It may be substituted by -SiH ₂ -; a, b and c may be the same or different, each independently representing 0, 1 or 2; when a is 2, two B ₁ -Y ₁ may be the same or different; when b is At 2 o'clock, the two B ₂ -Y ₂ may be the same or different; when c is 2, the two B ₃ -Y ₃ may be the same or different. The liquid crystal composition according to claim 6, wherein the second liquid crystal compound is selected from the group consisting of: ;as well as The liquid crystal composition according to claim 7, wherein the liquid crystal composition comprises 5 to 20% by weight of the total liquid crystal composition of the first liquid crystal compound and 80 to 95% by weight based on the total weight of the liquid crystal composition. A second liquid crystal compound. The liquid crystal composition according to claim 8, wherein the liquid crystal composition comprises 8-15% by weight of the total liquid crystal composition of the first liquid crystal compound and 85 to 92% by weight based on the total weight of the liquid crystal composition. A second liquid crystal compound. A liquid crystal element comprising the liquid crystal composition according to any one of claims 4 to 9.