TWI869571B - Liquid crystal composition and liquid crystal display device - Google Patents

Abstract

A liquid crystal composition includes a liquid crystal component. The liquid crystal component includes a liquid crystal compound represented by formula I and a liquid crystal compound represented by one of formulas II and III. The definitions of ring A to ring E, Z ¹ , X ¹ , X ² , R ¹ to R ⁵ , m, n, o and q in formulas I to III are respectively as described in the specification and the scope of the patent application. The liquid crystal compound of formula I cooperates with the liquid crystal compound of formula II or formula III, so that the liquid crystal composition has high transmittance, thereby making the liquid crystal display device have better contrast.

Description

Liquid crystal composition and liquid crystal display device

The present invention relates to a liquid crystal composition and a liquid crystal display device, and in particular to a liquid crystal composition containing a liquid crystal compound having a terminal group containing fluorine, and a liquid crystal display device containing the liquid crystal composition.

With the widespread use of liquid crystal display devices, consumers have higher requirements for the specifications of the liquid crystal display devices, such as resolution, contrast, brightness, etc. When the liquid crystal composition used in the liquid crystal display device has a higher transmittance, the contrast of the liquid crystal display device can be effectively increased. And if the liquid crystal composition has a higher transmittance, the liquid crystal display device can also achieve a certain brightness at a lower voltage, thereby achieving the effect of power saving.

Therefore, in order to make the liquid crystal display device have a better contrast and save power, it is necessary to develop a liquid crystal composition with high transmittance.

Therefore, the first object of the present invention is to provide a liquid crystal composition with high transmittance.

Therefore, the liquid crystal composition of the present invention includes a liquid crystal component.

The liquid crystal component includes a liquid crystal compound represented by Formula I, and a liquid crystal compound represented by one of Formula II and Formula III: [Formula I] [Formula II] [Formula III] ; In the formula I to the formula III, Ring A and Ring B each independently represent 1,4-cyclohexylene or 1,4-phenylene, and the above groups are unsubstituted or hydrogen at any position on the ring is substituted by fluorine; Ring C, Ring D and Ring E each independently represent 1,4-cyclohexylene, 1,4-phenylene, naphthalene-2,6-diyl, indane-1,5-diyl or indane-2,5-diyl, and the above groups are unsubstituted or hydrogen at any position on the ring is substituted by fluorine, a linear alkyl group or a branched alkyl group, and the above alkyl group is unsubstituted or at least one _-CH2- is substituted by -O- or -C=C-; ^Z1 represents _-COO- , -OCO-, _-OCH2- , _-CH2O- , _-CH2CH2 - or a single bond; ^X1 and ^X2 each independently represent a _C1 - _C5 alkylene group, the alkylene group is unsubstituted or at least one _-CH2- is substituted by -O-; ^R1 represents hydrogen or fluorine; ^R2 and ^R3 each independently represent hydrogen, a _C1 - _C12 straight-chain alkyl group, a _C3 - _C12 branched-chain alkyl group, a _C1 - _C12 straight-chain alkoxy group, a _C3 - _C12 branched-chain alkoxy group, a _C2 - _C12 straight-chain alkenyl group, a _C3 -C12 branched-chain alkenyl group, a _C2 - _C12 straight-chain oxyalkylene group or a _C3 - _C12 branched-chain oxyalkylene group, the alkyl, alkoxy, alkenyl or oxyalkylene group being unsubstituted; ^R4 represents hydrogen, a _C1 - _C12 straight-chain alkyl group, a _C3 - _C12 branched-chain C 1 -C ₁₂ branched chain alkyl, C ₁ -C ₁₂ straight chain alkoxy, C ₃ -C ₁₂ branched chain alkoxy, C ₂ -C ₁₂ straight chain alkenyl, C ₃ -C ₁₂ branched chain alkenyl, C ₂ -C ₁₂ straight chain oxyalkenyl or C ₃ -C ₁₂ branched chain oxyalkenyl, the above alkyl, alkoxy, alkenyl or oxyalkenyl is unsubstituted or hydrogen on any carbon is substituted by fluorine; R ⁵ represents hydrogen, fluorine, chlorine, C ₁ -C ₁₂ straight chain alkyl, C ₃ -C ₁₂ branched chain alkyl, C ₁ -C ₁₂ straight chain alkoxy, C ₃ -C ₁₂ branched chain alkoxy, C ₂ -C ₁₂ straight chain alkenyl, C _{3 -C 12 branched chain alkenyl, C 2} -C ₁₂ straight chain oxyalkenyl, C ₂ -C _wherein the _alkyl , alkoxy, alkenyl or oxyalkenyl group is unsubstituted or any hydrogen on carbon is substituted by fluorine; _m and n represent 0, 1 or 2 respectively, and the sum of m and n is 1 or 2, when m is 2, each ring A is the same or different, when n is 2, each ring B is the same or different; o represents 1, 2 or 3, when o is 2 or 3, each ring C is the same or different, and each ^Z1 is the same or different; q represents 1, 2 or 3, when q is 2 or 3, each ring E is the same or different.

The second object of the present invention is to provide a liquid crystal display device with better contrast.

Therefore, the liquid crystal display device of the present invention includes the above-mentioned liquid crystal composition.

The effect of the present invention is that the liquid crystal composition of the present invention has high transmittance through the interaction between the liquid crystal compound of formula I and the liquid crystal compound of formula II or formula III, which is beneficial for the subsequent application of the liquid crystal composition to a liquid crystal display device, so that the liquid crystal display device has a better contrast, and the liquid crystal display device can achieve a certain brightness at a lower voltage and has the effect of saving power.

The liquid crystal composition of the present invention comprises a liquid crystal component, wherein the liquid crystal component comprises a liquid crystal compound represented by formula I and a liquid crystal compound represented by one of formulas II and III.

[Liquid crystal compound of formula I] [Formula I]

In the formula I, Ring A and Ring B each independently represent a 1,4-cyclohexylene group or a 1,4-phenylene group, and the above groups are unsubstituted or hydrogen at any position on the ring is substituted by fluorine.

^X1 and ^X2 each independently represent a _C1 - _C5 alkylene group, wherein the alkylene group is unsubstituted or at least one _-CH2- group is substituted by -O-. Preferably, ^X1 and ^X2 each independently represent a _C1 - _C5 alkylene group, wherein the alkylene group is unsubstituted.

^R1 represents hydrogen or fluorine.

m and n represent 0, 1 or 2 respectively, and the sum of m and n is 1 or 2. When m is 2, each ring A is the same or different. When n is 2, each ring B is the same or different.

Based on the total amount of the liquid crystal component being 100 wt%, the content of the liquid crystal compound represented by formula I is in the range of 0.5 wt% to 15 wt%. Preferably, the content of the liquid crystal compound represented by formula I is in the range of 0.9 wt% to 12.5 wt%. More preferably, the content of the liquid crystal compound represented by formula I is in the range of 1.2 wt% to 11 wt%.

Preferably, the liquid crystal compound of formula I is at least one selected from the group consisting of formula I-1, formula I-2 and formula I-3: [Formula I-1] [Formula I-2] [Formula I-3] .

In Formula I-1 to Formula I-3, R ¹ represents hydrogen or fluorine, and X ¹ and X ² each independently represent a C ₁ -C ₅ alkylene group, and the alkylene group is unsubstituted.

Preferably, the liquid crystal compound of formula I-1 is at least one selected from the group consisting of formula I-1a to formula I-1i. Preferably, the liquid crystal compound of formula I-2 is at least one selected from the group consisting of formula I-2a to formula I-2c. Preferably, the liquid crystal compound of formula I-3 is selected from formula I-3a. No. Abbreviation Structure Formula I-1a 3PP1F Formula I-1b 5PP1F Formula I-1c 1PP2F Formula I-1d 3PP2F Formula I-1e 1PP3F Formula I-1f 2PP3F Formula I-1g 3PP3F Formula I-1h 1PP4F Formula I-1i F3PP3F Formula I-2a 1PCC2F Formula I-2b 1PCC3F Formula I-2c 1PCC4F Formula I-3a 3PGP1F

[Liquid crystal compound of formula II] [Formula II]

In the formula II, ring C is represented by 1,4-cyclohexylene, 1,4-phenylene, naphthalene-2,6-diyl, indan-1,5-diyl or indan-2,5-diyl, the above groups are unsubstituted or hydrogen at any position on the ring is substituted by fluorine, linear alkyl or branched alkyl, the above alkyl is unsubstituted or at least one -CH ₂ - is substituted by -O- or -C=C-. Preferably, the ring C is represented by 1,4-cyclohexylene or 1,4-phenylene, the above groups are unsubstituted.

^Z1 represents -COO-, -OCO-, _-OCH2- , _-CH2O- , _-CH2CH2- , or a single bond. Preferably _, ^Z1 represents _-CH2O- or a single bond.

^R2 and ^R3 each independently represent hydrogen, _C1 - _C12 straight chain alkyl, _C3 - _C12 branched chain alkyl, _C1 - _C12 straight chain alkoxy, _C3 - _C12 branched chain alkoxy, C2-C12 straight chain alkenyl, _{C3 - C12} branched chain alkenyl, _C2 - _C12 straight chain oxyalkenyl or _{C3 -C12 branched} chain oxyalkenyl, and the above alkyl, alkoxy, alkenyl or oxyalkenyl are unsubstituted. Preferably, ^R2 and ^R3 each independently represent _C1 - _C12 straight chain alkyl, _C1 - _C12 straight chain alkoxy, and the above alkyl or alkoxy are unsubstituted. More preferably, said R ² and said R ³ each independently represent a C ₁ -C ₅ straight chain alkyl group or a C ₁ -C ₄ straight chain alkoxy group, and said alkyl group or alkoxy group is unsubstituted.

o represents 1, 2 or 3. When o is 2 or 3, each ring C is the same or different, and each Z ¹ is the same or different. Preferably, o represents 1 or 2.

Based on the total amount of the liquid crystal component being 100 wt%, the content of the liquid crystal compound represented by formula II is in the range of 35 wt% to 65 wt%. Preferably, the content of the liquid crystal compound represented by formula II is in the range of 39 wt% to 60 wt%. More preferably, the content of the liquid crystal compound represented by formula II is in the range of 40.5 wt% to 58 wt%.

Preferably, the liquid crystal compound of formula II is at least one selected from the group consisting of formula II-1, formula II-2, formula II-3, formula II-4, formula II-5 and formula II-6: [Formula II-1] [Formula II-2] [Formula II-3] [Formula II-4] [Formula II-5] [Formula II-6] .

In formula II-1 to formula II-6, said ^R2 and said ^R3 each independently represent a _C1 - _C12 straight chain alkyl group or a _C1 - _C12 straight chain alkoxy group, and the above alkyl group or alkoxy group is unsubstituted. More preferably, said ^R2 and said ^R3 each independently represent a _C1 - _C5 straight chain alkyl group or a _C1 - _C4 straight chain alkoxy group, and the above alkyl group or alkoxy group is unsubstituted.

Preferably, the liquid crystal compound of formula II-1 is at least one selected from the group consisting of formula II-1a and formula II-1b. Preferably, the liquid crystal compound of formula II-2 is at least one selected from the group consisting of formula II-2a to formula II-2d. Preferably, the liquid crystal compound of formula II-3 is at least one selected from the group consisting of formula II-3a to formula II-3d. Preferably, the liquid crystal compound of formula II-4 is selected from formula II-4a. Preferably, the liquid crystal compound of formula II-5 is at least one selected from the group consisting of formula II-5a to formula II-5c. Preferably, the liquid crystal compound of formula II-6 is at least one selected from the group consisting of formula II-6a and formula II-6b. No. Abbreviation Structure Formula II-1a 3CYO2 Formula II-1b 5CYO2 Formula II-2a 2CCY1 Formula II-2b 3CCY1 Formula II-2c 3CCYO1 Formula II-2d 3CCYO2 Formula II-3a 2CPYO2 Formula II-3b 3CPYO2 Formula II-3c 3CPYO3 Formula II-3d 3CPYO4 Formula II-4a 3PYO2 Formula II-5a 3C1OYO2 Formula II-5b 2C1OYO2 Formula II-5c 3C1OYO1 Formula II-6a 3CC1OYO2 Formula II-6b 2CC1OYO2

[Liquid crystal compound of formula III] [Formula III]

In the formula III, ring D and ring E each independently represent 1,4-cyclohexylene, 1,4-phenylene, naphthalene-2,6-diyl, indan-1,5-diyl or indan-2,5-diyl, the above groups are unsubstituted or hydrogen at any position on the ring is substituted by fluorine, linear alkyl or branched alkyl, the above alkyl is unsubstituted or at least one -CH ₂ - is substituted by -O- or -C=C-. Preferably, the ring D and the ring E each independently represent 1,4-cyclohexylene, 1,4-phenylene, indan-1,5-diyl or indan-2,5-diyl, the above groups are unsubstituted or hydrogen at any position on the ring is substituted by fluorine.

^R4 is hydrogen, _C1 - _C12 straight chain alkyl, _C3 - _C12 branched chain alkyl, C1- _C12 straight chain alkoxy, _C3 - _C12 branched chain alkoxy, _C2 - _C12 straight chain alkenyl, _C3 -C12 branched chain alkenyl, _C2 - _C12 straight chain oxyalkylene or _C3 - _C12 branched chain oxyalkylene, wherein the above alkyl, alkoxy, alkenyl or oxyalkylene is unsubstituted or hydrogen on any carbon is substituted by fluorine. Preferably, ^R4 is _{C1 - C12} straight chain alkyl, wherein the above alkyl is unsubstituted. More _preferably , ^R4 is _C2 - _C5 straight chain alkyl, wherein the above alkyl is unsubstituted.

^R5 is hydrogen, fluorine, chlorine, _C1 - _C12 straight chain alkyl, _C3 - _C12 branched chain alkyl, _C1 - _C12 straight chain alkoxy, _C3 - _C12 branched chain alkoxy, C2-C12 straight chain alkenyl, _{C3 - C12} branched chain alkenyl, _C2 - _C12 straight chain oxyalkenyl or _{C3 -C12 branched} chain oxyalkenyl, wherein the above alkyl, alkoxy, alkenyl or oxyalkenyl is unsubstituted or any carbon atom of hydrogen is substituted by fluorine. Preferably, ^R5 is fluorine.

q represents 1, 2 or 3. When q is 2 or 3, each ring E is the same or different. Preferably, q represents 2 or 3.

Based on the total amount of the liquid crystal component being 100 wt%, the content of the liquid crystal compound represented by formula III is in the range of 5 wt% to 18 wt%. Preferably, the content of the liquid crystal compound represented by formula III is in the range of 8 wt% to 15 wt%. More preferably, the content of the liquid crystal compound represented by formula III is in the range of 10 wt% to 12 wt%.

Preferably, the liquid crystal compound of formula III is at least one selected from the group consisting of formula III-1, III-2, III-3, III-4 and III-5: [Formula III-1] [Formula III-2] [Formula III-3] [Formula III-4] [Formula III-5] .

In formula III-1 to formula III-5, the R ⁴ is a C ₁ -C ₁₂ straight chain alkyl group, which is unsubstituted. More preferably, the R ⁴ is a C ₂ -C ₅ straight chain alkyl group, which is unsubstituted. The R ⁵ is fluorine.

Preferably, the liquid crystal compound of formula III-1 is at least one selected from the group consisting of formula III-1a and formula III-1b. Preferably, the liquid crystal compound of formula III-2 is at least one selected from the group consisting of formula III-2a and formula III-2b. Preferably, the liquid crystal compound of formula III-3 is at least one selected from the group consisting of formula III-3a to formula III-3d. Preferably, the liquid crystal compound of formula III-4 is at least one selected from the group consisting of formula III-4a and formula III-4b. Preferably, the liquid crystal compound of formula III-5 is at least one selected from the group consisting of formula III-5a and formula III-5b. No. Abbreviation Structure Formula III-1a 2RIUQUF Formula III-1b 3RIUQUF Formula III-2a 2RIGUQUF Formula III-2b 3RIGUQUF Formula III-3a 2PGUQUF Formula III-3b 3PGUQUF Formula III-3c 4PGUQUF Formula III-3d 5PGUQUF Formula III-4a 2PUQUF Formula III-4b 3PUQUF Formula III-5a 2CUQUF Formula III-5b 3CUQUF

Preferably, in the liquid crystal composition of the present invention, the liquid crystal component further comprises a liquid crystal compound represented by Formula IV. [Formula IV]

In the formula IV, ring F and ring G each independently represent a 1,4-cyclohexylene group or a 1,4-phenylene group, and the above groups are unsubstituted.

R ⁶ represents a C ₁ -C ₅ straight chain alkyl group, a C ₁ -C ₅ straight chain alkoxy group or a C ₂ -C ₅ straight chain alkenyl group, wherein the above alkyl group, alkoxy group or alkenyl group is unsubstituted.

^R7 represents fluorine, _C1 - _C5 straight chain alkyl, _C3 - _C5 branched chain alkyl, _C1 - _C5 straight chain alkoxy, _C3 - _C5 branched chain alkoxy or _C2 - _C5 straight chain alkenyl, and the above alkyl, alkoxy or alkenyl is unsubstituted. Preferably, ^R7 represents fluorine, _C1 - _C5 straight chain alkyl, _C1 - _C5 straight chain alkoxy or _C2 - _C5 straight chain alkenyl, and the above alkyl, alkoxy or alkenyl is unsubstituted.

Z ² represents -COO-, -OCO-, -OCH ₂ -, -CH ₂ O-, -CH=CH-, -C≡C-, -CH ₂ CH ₂ -, or a single bond. Preferably, Z represents -C≡C- or a single bond.

r represents 1 or 2.

Based on the total amount of the liquid crystal component being 100 wt%, the content of the liquid crystal compound represented by formula IV is in the range of 30 wt% to 80 wt%. Preferably, the content of the liquid crystal compound represented by formula IV is in the range of 33 wt% to 77 wt%. More preferably, the content of the liquid crystal compound represented by formula IV is in the range of 35 wt% to 75 wt%.

Preferably, the liquid crystal compound of formula IV is at least one selected from the group consisting of formula IV-1, formula IV-2, formula IV-3, formula IV-4, formula IV-5 and formula IV-6: [Formula IV-1] [Formula IV-2] [Formula IV-3] [Formula IV-4] [Formula IV-5] [Formula IV-6] .

In Formula IV-1 to Formula IV-6, R ⁶ represents C ₁ -C ₅ straight chain alkyl, C ₁ -C ₅ straight chain alkoxy or C ₂ -C ₅ straight chain alkenyl, and the above alkyl, alkoxy or alkenyl is unsubstituted. R ⁷ represents fluorine, C ₁ -C ₅ straight chain alkyl, C ₁ -C ₅ straight chain alkoxy or C ₂ -C ₅ straight chain alkenyl, and the above alkyl, alkoxy or alkenyl is unsubstituted.

Preferably, the compound of formula IV-1 is at least one selected from the group consisting of formula IV-1a to formula IV-1h. Preferably, the compound of formula IV-2 is at least one selected from the group consisting of formula IV-2a and formula IV-2b. Preferably, the compound of formula IV-3 is at least one selected from the group consisting of formula IV-3a and formula IV-3b. Preferably, the compound of formula IV-4 is at least one selected from the group consisting of formula IV-4a to formula IV-4c. Preferably, the compound of formula IV-5 is at least one selected from the group consisting of formula IV-5a to formula IV-5d. Preferably, the compound of formula IV-6 is selected from formula IV-6a. No. Abbreviation Structure Formula IV-1a 3CC2 Formula IV-1b 3CC3 Formula IV-1c 3CC4 Formula IV-1d 3CC5 Formula IV-1e 5CC2 Formula IV-1f 3CCO1 Formula IV-1g 3CCV1 Formula IV-1h 3CCV Formula IV-2a 3CPO1 Formula IV-2b 3CPO2 Formula IV-3a 3PPO2 Formula IV-3b 1V2PPO1 Formula IV-4a 3CCP1 Formula IV-4b 3CCPO1 Formula IV-4c VCCP1 Formula IV-5a 3CPP1 Formula IV-5b 3CPP2 Formula IV-5c 3CPPF Formula IV-5d 2CPPF Formula IV-6a 3CPTP2

Preferably, in the liquid crystal composition of the present invention, the liquid crystal component further comprises a liquid crystal compound represented by Formula V. [Formula V]

In the formula V, Ring J and Ring I each independently represent 1,4-cyclohexylene, 1,4-phenylene, naphthalene-2,6-diyl, indan-1,5-diyl or indan-2,5-diyl, and the above groups are unsubstituted or hydrogen at any position on the ring is substituted by fluorine.

^R8 represents hydrogen, _C1 - _C12 straight chain alkyl, _C3 - _C12 branched chain alkyl, C1- _C12 straight chain alkoxy, _C3 - _C12 branched chain alkoxy, _C2 - _C12 straight chain alkenyl, _{C3 - C12} branched chain alkenyl, _C2 - _C12 straight chain oxyalkenyl or _C3 - _C12 branched chain oxyalkenyl, wherein the above alkyl, alkoxy, alkenyl or oxyalkenyl is unsubstituted or hydrogen on any carbon is substituted by fluorine.

s represents 1 or 2. When s is 2, each ring I is the same or different.

Based on 100 wt% of the total amount of the liquid crystal component, the content of the liquid crystal compound represented by formula V is in a range of 2 wt% to 15 wt%. Preferably, the content of the liquid crystal compound represented by formula V is in a range of 3 wt% to 10 wt%. More preferably, the content of the liquid crystal compound represented by formula V is in a range of 5 wt% to 8 wt%.

Preferably, the liquid crystal compound of formula V is selected from formula V-1: [Formula V-1]

In formula V-1, ^R8 represents hydrogen, _C1 - _C12 straight-chain alkyl, _C3 - _C12 branched-chain alkyl, _C1 - _C12 straight-chain alkoxy, _C3 - _C12 branched-chain alkoxy, _C2 - _C12 straight-chain alkenyl, _C3 - _C12 branched-chain alkenyl, _C2 - _C12 straight-chain oxyalkenyl or _C3 - _C12 branched-chain oxyalkenyl, and the above alkyl, alkoxy, alkenyl or oxyalkenyl is unsubstituted or has hydrogen on any carbon substituted by fluorine.

Preferably, the liquid crystal compound of formula V-1 is at least one selected from the group consisting of formula V-1a to formula V-1c. No. Abbreviation Structure Formula V-1a 1RIGUO2F Formula V-1b 2RIGUO2F Formula V-1c 3RIGUO2F

Preferably, the liquid crystal composition of the present invention further comprises an additive, wherein the additive comprises a compound represented by Formula VI. [Formula VI]

In the formula VI, ring K represents 1,4-phenylene or indan-2,5-diyl, and the above groups are unsubstituted or hydrogen at any position on the ring is substituted by fluorine.

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

t and u represent 1 or 2 respectively, and the sum of t and u is 2, 3 or 4. When u is 2, each ring K is the same or different.

Based on 100 wt% of the total amount of the liquid crystal composition, the content of the compound represented by formula VI ranges from 0.1 wt% to 1 wt%. Preferably, the content of the compound represented by formula VI ranges from 0.2 wt% to 0.7 wt%.

Preferably, the compound of formula VI is at least one selected from the group consisting of formula VI-1, formula VI-2 and formula VI-3: [Formula VI-1] [Formula VI-2] [Formula VI-3]

In Formula VI-1 to Formula VI-3, Z ³ represents -OCH ₂ -, -CH ₂ O-, -CH ₂ CH ₂ - or a single bond.

Preferably, the compound of formula VI-1 is selected from formula VI-1a. Preferably, the compound of formula VI-2 is selected from formula VI-2a. Preferably, the compound of formula VI-3 is selected from formula VI-3a. No. Abbreviation Structure Formula VI-1a BMA Formula VI-2a PG1OGPMA Formula VI-3a PGRIMA

The present invention will be further described with respect to the following embodiments, but it should be understood that the embodiments are only for illustrative purposes and should not be interpreted as limitations on the implementation of the present invention.

[Synthesis Example 1] Liquid crystal compound represented by formula I-1e

(1) Synthesis of Compound A1: 4-bromophenylpropanol (15 g, 69.8 mmol), p-toluenesulfonyl chloride (12.6 g, 66.3 mmol, TsCl), triethylamine (9.6 mL, 69.8 mmol, TEA) and dichloromethane (280 mL, DCM) were mixed to obtain a mixture. The mixture was heated to 30°C for reaction. The reaction was followed by silica gel thin layer chromatography (eluent: ethyl acetate/n-hexane, volume ratio = 3/7) until the TsCl reaction was complete. Then, a small amount of 1N hydrochloric acid was added to terminate the reaction to obtain a crude product. The crude product was extracted with distilled water and ethyl acetate and the organic layer was collected. Thereafter, the organic layer was first dehydrated with magnesium sulfate, filtered, and then concentrated under reduced pressure to remove the residual organic solvent to obtain Compound A1.

(2) Synthesis of Compound A2: Compound A1, tetra-n-butylammonium fluoride·1M tetrahydrofuran solution (140 mL, 139.6 mmol, abbreviated as TBAF) and tetrahydrofuran (270 mL, abbreviated as THF) were mixed and reacted. The reaction was followed by silica gel thin layer chromatography (eluent: ethyl acetate/n-hexane volume ratio = 1/19) until the reaction of Compound A1 was completed to obtain a crude product. Then, the organic solvent in the crude product was removed by concentration under reduced pressure, and then purified by silica gel column chromatography (eluent: ethyl acetate/n-hexane volume ratio = 1/19) to obtain Compound A2.

(3) Synthesis of Compound I-1e: Compound A2, 4-methylphenylboronic acid (14.2 g, 104.7 mmol), tetrakis(triphenylphosphine)palladium (2 g, 1.73 mmol, referred to as Pd(PPh ₃ ) ₄ ), aqueous potassium carbonate solution (3M, 115 mL) and tetrahydrofuran (450 mL) were mixed to obtain a mixture. The mixture was heated to the reflux temperature of tetrahydrofuran in a reflux apparatus filled with dry nitrogen and reacted. The reaction was followed by silica gel thin layer chromatography (the eluent was n-hexane) until the reaction of Compound A2 was completed to obtain a crude product. After the temperature of the crude product returns to room temperature, the crude product is extracted with distilled water and ethyl acetate and the organic layer is collected. Thereafter, the organic layer is first dehydrated with magnesium sulfate, filtered, concentrated under reduced pressure to remove residual organic solvents, and purified by silica gel column chromatography (the eluent is n-hexane) to obtain a liquid crystal compound represented by formula I-1e.

The liquid crystal compound represented by formula I-1e was identified using a nuclear magnetic resonance spectrometer. The results were: ¹ H-NMR (400 MHz, CDCl ₃ ): δ7.51-7.46 (m, 4H), δ7.23-7.22 (m, 4H), δ4.48 (dt, 2H), δ2.77 (t, 2H), δ2.38 (s, 3H), δ2.03 (dtt, 2H).

[Synthesis Example 2] Liquid crystal compound represented by formula I-1h

(1) Synthesis of compound B2: Compound B1 (2 g, 9 mmol) was first mixed with borane dimethyl sulfide (4.5 mL, 9 mmol, referred to as BH ₃ -SMe ₂ ) at 0°C to obtain a mixture, and the mixture was slowly returned to room temperature under a nitrogen atmosphere and reacted for 3 hours. Then, distilled water (10 mL), 30% sodium hydroxide (NaOH) aqueous solution (5 mL) and 30% hydrogen peroxide (H ₂ O ₂ ) aqueous solution (5 mL, 44 mmol) and reacted for 30 minutes. After the reaction temperature returned to room temperature, a small amount of saturated potassium carbonate aqueous solution was added and stirred until the white suspended solid disappeared to obtain a crude product. The crude product was extracted with distilled water and ethyl acetate and the organic layer was collected. Thereafter, the organic layer was first dehydrated with magnesium sulfate, filtered, and then concentrated under reduced pressure to remove the residual organic solvent to obtain compound B2.

(2) Synthesis of compound I-1h: Compound B2, diethylaminosulfur trifluoride (1.9 g, 11.7 mmol, referred to as DAST) and dichloromethane (80 mL, referred to as DCM) were mixed at -60°C and reacted. The reaction was followed by silica gel thin layer chromatography (eluent: ethyl acetate/n-hexane volume ratio = 1/4) until the reaction of compound B2 was completed to obtain a mixture. After the temperature of the mixture returns to room temperature, a saturated aqueous sodium bicarbonate solution is added to terminate the reaction to obtain a crude product. The crude product is extracted with distilled water and ethyl acetate and the organic layer is collected. Thereafter, the organic layer is first dehydrated with magnesium sulfate, filtered, concentrated under reduced pressure to remove residual organic solvents, and purified by silica gel column chromatography (the eluent is n-hexane) to obtain a liquid crystal compound represented by formula I-1h.

The liquid crystal compound represented by formula I-1h was identified using a nuclear magnetic resonance spectrometer. The results were: ¹ H-NMR (400 MHz, CDCl ₃ ): δ7.50-7.46 (m, 4H), δ7.26-7.22 (m, 4H), δ4.47 (dt, 2H), δ2.69 (t, 2H), δ2.38 (s, 3H), δ1.82-1.70 (m, 4H).

[Synthesis Example 3] Liquid crystal compound represented by formula I-2a

(1) Synthesis of Compound C2: Compound C1 (15 g, 56.08 mmol) and borane dimethyl sulfide (28.1 mL, 56.08 mmol, referred to as BH ₃ -SMe ₂ ) were mixed at 0°C and slowly returned to room temperature for reaction for 3 hours under a nitrogen atmosphere. Then, distilled water (9 mL), 30% sodium hydroxide (NaOH) aqueous solution (22.5 mL) and 30% hydrogen peroxide (H ₂ O ₂ ) aqueous solution (22.5 mL, 198 mmol) and reacted for 30 minutes to obtain a mixture. After the temperature of the mixture returned to room temperature, a small amount of saturated aqueous potassium carbonate solution was added and stirred until the white suspended solid disappeared to obtain a crude product. The crude product was extracted with distilled water and ethyl acetate and the organic layer was collected. Thereafter, the organic layer was first dehydrated with magnesium sulfate, filtered, and then concentrated under reduced pressure to remove the residual organic solvent to obtain compound C2.

(2) Synthesis of Compound C3: Compound C2, p-toluenesulfonyl chloride (16 g, 84.12 mmol, abbreviated as TsCl), triethylamine (11.7 mL, 84.12 mmol, abbreviated as TEA), 4-dimethylaminopyridine (1.7 g, 14.02 mmol, abbreviated as DMAP) and dichloromethane (275 mL, referred to as DCM) was mixed to obtain a mixture, the mixture was heated to 30°C for reaction, and the reaction was followed by silica gel thin layer chromatography (eluent: ethyl acetate/n-hexane volume ratio = 3/17) until the TsCl reaction was completed. Then, a small amount of 1N hydrochloric acid was added to terminate the reaction to obtain a crude product, which was extracted with distilled water and ethyl acetate and the organic layer was collected. Thereafter, the organic layer was first dehydrated with magnesium sulfate, filtered, concentrated under reduced pressure to remove the residual organic solvent, and then purified by silica gel column chromatography (eluent: ethyl acetate/n-hexane volume ratio = 1/9) to obtain compound C3.

(3) Synthesis of Compound I-2a: Compound C3, tetrabutylammonium fluoride·1M tetrahydrofuran solution (112.16 mL, 112.16 mmol, abbreviated as TBAF) and tetrahydrofuran (110 mL, abbreviated as THF) was mixed and reacted for 12 hours to obtain a mixture, which was concentrated under reduced pressure to remove the organic solvent in the mixture to obtain a crude product, and the crude product was extracted with distilled water and ethyl acetate and the organic layer was collected. Thereafter, the organic layer was first dehydrated with magnesium sulfate, filtered, concentrated under reduced pressure to remove the residual organic solvent, and then purified by silica gel column chromatography (eluent: ethyl acetate/n-hexane volume ratio = 1/9) to obtain a liquid crystal compound represented by formula I-2a.

The liquid crystal compound represented by formula I-2a was identified using a nuclear magnetic resonance spectrometer. The results were: ¹ H-NMR (400 MHz, CDCl ₃ ): δ7.08 (s, 4H), δ4.49 (dt, 2H), δ2.39 (tt, 1H), δ2.30 (t, 3H), δ1.90-1.73 (m, 8H), δ1.58 (dtt, 2H), δ1.45-1.34 (m, 3H), δ1.15-0.87 (m, 8H).

[Synthesis Example 4] Liquid crystal compound represented by formula I-2b

(1) Synthesis of Compound D1: Ethylenediyl chloride (3.6 mL, 41.69 mmol, referred to as (COCl) ₂ ) and tetrahydrofuran (190 mL, referred to as THF) were mixed and cooled to -78°C under a dry nitrogen atmosphere. Then, dimethyl sulfoxide (3.9 mL, referred to as DMSO) was slowly added and stirred for 30 minutes. Compound C2 (8.35 g, 27.79 mmol) and tetrahydrofuran (190 mL, referred to as THF) were slowly added and stirred for 45 minutes. Then, triethylamine (18 mL, 111.16 mmol, referred to as TEA) to obtain a mixture, and stirred for 2 hours to allow the mixture to slowly return to room temperature, then a saturated aqueous ammonium chloride solution was added to terminate the reaction to obtain a crude product, which was extracted with distilled water and ethyl acetate and the organic layer was collected. Thereafter, the organic layer was first dehydrated with magnesium sulfate, filtered, concentrated under reduced pressure to remove residual organic solvents, and then purified by silica gel column chromatography (eluent: ethyl acetate/n-hexane volume ratio = 1/4) to obtain compound D1.

(2) Synthesis of Compound D2: Methyltriphenylphosphonium bromide (11.8 g, 33.05 mmol, Ph ₃ PCH ₃ Br) and tetrahydrofuran (60 mL, THF) were mixed and cooled to 0°C, and then n-butyl lithium (n-BuLi) · 2.5 M n-hexane solution (9.9 mL, 24.75 mmol) was slowly added and stirred for 2 hours. Compound D1 and tetrahydrofuran (40 mL, abbreviated as THF) was reacted to obtain a mixture, the mixture was stirred for 2 hours, the temperature of the mixture was returned to room temperature and then stirred for 10 hours, then a saturated aqueous ammonium chloride solution was added to terminate the reaction to obtain a crude product, the crude product was extracted with distilled water and ethyl acetate and the organic layer was collected, then the organic layer was first dehydrated with magnesium sulfate, filtered, concentrated under reduced pressure to remove the residual organic solvent, and then purified by silica gel column chromatography (eluent: ethyl acetate/n-hexane volume ratio = 1/19) to obtain compound D2.

(3) Synthesis of Compound D3: The synthesis method of Compound D3 is similar to that of Compound C2, except that, in the synthesis method of Compound D3, Compound C1 is replaced by Compound D2 to obtain Compound D3.

(4) Synthesis of Compound D4: The synthesis method of Compound D4 is similar to that of Compound C3, except that in the synthesis method of Compound D4, Compound C2 is replaced by Compound D3 to obtain Compound D4.

(5) Synthesis of Compound I-2b: The synthesis method of Compound I-2b is similar to that of Compound I-2a, except that, in the synthesis method of Compound I-2b, Compound C3 is replaced by Compound D4 to obtain the liquid crystal compound represented by Formula I-2b.

The liquid crystal compound represented by formula I-2b was identified using a nuclear magnetic resonance spectrometer. The results were: ¹ H-NMR (400 MHz, CDCl ₃ ): δ7.08 (s, 4H), δ4.41 (dt, 2H), δ2.39 (tt, 1H), δ2.30 (t, 3H), δ1.90-0.84 (m, 23H).

[Synthesis Example 5] Liquid crystal compound represented by formula I-2c

(1) Synthesis of Compound E2: The synthesis method of Compound E2 is similar to that of Compound B2, except that in the synthesis of Compound E2, Compound B1 is replaced by Compound E1 to obtain Compound E2.

(2) Synthesis of Compound I-2c: The synthesis method of Compound I-2c is similar to that of Compound I-1h, except that, in the synthesis method of Compound I-2c, Compound B2 is replaced by Compound E2 to obtain the liquid crystal compound represented by Formula I-2c.

The liquid crystal compound represented by formula I-2c was identified using a nuclear magnetic resonance spectrometer. The results were: ¹ H-NMR (400 MHz, CDCl ₃ ): δ7.08 (s, 4H), δ4.43 (dt, 2H), δ2.39 (tt, 1H), δ2.30 (t, 3H), δ1.90-0.81 (m, 25H).

Examples 1 to 16 and Comparative Examples 1 to 2

[Preparation of Liquid Crystal Composition]

The liquid crystal compositions of Examples 1 to 16 and the liquid crystal compositions of Comparative Examples 1 to 2 were prepared according to the types and amounts of the components listed in Tables 1 to 3 below.

The main difference between Comparative Examples 1 and 2 and Examples 1 to 16 is that Comparative Examples 1 and 2 do not use the liquid crystal compound represented by Formula I, but use the liquid crystal compound of 3CC1F. Abbreviation Structure 3CC1F

[LCD Display]

The liquid crystal display device of Example 1 is prepared using the liquid crystal composition of Example 1. The liquid crystal display device is prepared by spacing two substrates containing an indium tin oxide layer (hereinafter referred to as ITO substrates) (spacing is 3.5 mm), then injecting the liquid crystal composition of Example 1 into the gap between the two ITO substrates, and sealing according to the liquid crystal box manufacturing method to form a liquid crystal box. A 12V DC voltage is applied to the liquid crystal box, and ultraviolet light (peak wavelength 313 nm) is irradiated at the same time for curing to form a liquid crystal display device. The liquid crystal display devices of Examples 2 to 16 and Comparative Examples 1 to 2 are obtained by the same preparation method as Example 1, and the difference is that Examples 2 to 16 and Comparative Examples 1 to 2 use the liquid crystal compositions of Examples 2 to 16 and Comparative Examples 1 to 2, respectively.

Table 1 Dosage(wt%) Embodiment 1 2 3 4 5 6 Liquid crystal components Formula I 1PP3F 4 8 -- -- 9 4.4 3PP3F -- -- 1.5 5 -- -- F2CCP1 -- -- -- -- -- -- F3CCP1 -- -- -- -- -- -- Formula II 3CYO2 18.5 19 19 19 -- 18.5 5CYO2 -- -- 6.5 3 -- -- 2CCY1 -- -- -- -- -- 2 3CCY1 -- -- 10 10 -- -- 3CCYO1 5 -- -- -- -- -- 3CCYO2 8 10 8 -- -- 12.5 2CPYO2 -- -- -- -- -- -- 3CPYO2 17 15 13 13 -- 16.5 3CPYO3 -- -- -- -- -- -- 3CPYO4 1 -- -- 8 -- -- Formula III 2RIGUQUF -- -- -- -- 7 -- 3RIGUQUF -- -- -- -- 4 -- Formula IV 3CC2 9.5 20 20 20 -- 9.9 3CC3 2.5 -- -- -- -- 2 3CC4 13.5 -- 6 6 -- 14.1 3CC5 -- -- -- -- -- 5.8 5CC2 2.5 -- -- -- -- 1.3 3CCO1 -- -- -- -- 5 0.5 3CCV1 -- -- -- -- 5 -- 3CCV -- -- -- -- 35 -- 3CPO1 -- -- -- -- -- 2 3CPO2 8 10 -- -- -- -- 3PPO2 6 -- -- -- -- 6 1V2PPO1 -- -- -- -- -- -- 3CCP1 -- 8 9 8 -- -- VCCP1 -- -- -- -- -- -- 3CPP1 4.5 -- -- -- -- 4.5 3CPP2 -- 10 7 8 9 -- 2CPPF -- -- -- -- 4 -- 3CPPF -- -- -- -- 5 -- 3CPTP2 -- -- -- -- 11 -- Formula V 3RIGUO2F -- -- -- -- 6 -- Additives Formula VI BMA -- -- -- -- -- -- 3CC1F -- -- -- -- -- --

Table 2 Dosage(wt%) Embodiment 7 8 9 10 11 12 Liquid crystal components Formula I 1PP3F 10.5 3.5 4 -- 9.5 8.5 3PP3F -- -- -- 4 -- -- F2CCP1 -- 7 1 -- -- -- F3CCP1 -- -- -- -- -- -- Formula II 3CYO2 12 20 19 18 15 15 5CYO2 1 -- 3 -- -- -- 2CCY1 -- -- -- 2 -- -- 3CCY1 5.5 3.9 -- -- 7.5 5 3CCYO1 -- -- -- -- 8 8 3CCYO2 4 4 12 12 4.5 4 2CPYO2 2.5 -- -- -- 3 2.5 3CPYO2 16.5 17 16 17 16 16.5 3CPYO3 -- 4.5 -- -- -- -- 3CPYO4 -- -- -- -- -- -- Formula III 2RIGUQUF -- -- -- -- -- -- 3RIGUQUF -- -- -- -- -- -- Formula IV 3CC2 15.5 15.5 15.5 10 15.5 15.5 3CC3 2.5 3 2.5 2.5 -- 2 3CC4 12.5 8 10 13.5 12.5 12.5 3CC5 3 4.4 -- 7 -- -- 5CC2 -- -- 4 3.5 -- -- 3CCO1 -- -- -- -- -- -- 3CCV1 -- -- -- -- -- -- 3CCV -- -- -- -- -- -- 3CPO1 8 -- -- -- -- -- 3CPO2 -- -- -- -- 4 4 3PPO2 2.5 5.2 -- 6 2 2 1V2PPO1 -- -- 6.5 -- -- -- 3CCP1 -- -- -- -- -- -- VCCP1 -- -- -- -- -- -- 3CPP1 4 4 6 4.5 2.5 4.5 3CPP2 -- -- 0.5 -- -- -- 2CPPF -- -- -- -- -- -- 3CPPF -- -- -- -- -- -- 3CPTP2 -- -- -- -- -- -- Formula V 3RIGUO2F -- -- -- -- -- -- Additives Formula VI BMA -- -- -- -- -- -- 3CC1F -- -- -- -- -- --

Table 3 Dosage(wt%) Embodiment Comparison Example 13 14 15 16 1 2 Liquid crystal components Formula I 1PP3F -- -- 1.7 2 -- -- 3PP3F -- 9.5 -- -- -- -- F2CCP1 6 -- -- 6 -- -- F3CCP1 -- -- 4 -- -- -- Formula II 3CYO2 24.4 15 twenty one 20 19 -- 5CYO2 -- -- 3.4 -- -- -- 2CCY1 -- -- -- -- -- -- 3CCY1 -- 7.5 -- 4.4 -- -- 3CCYO1 -- 8 -- -- -- -- 3CCYO2 4 4.5 9 4 10 -- 2CPYO2 -- 3 -- -- -- -- 3CPYO2 17 16 17 17 15.5 -- 3CPYO3 4.5 -- -- 4.5 -- -- 3CPYO4 -- -- -- -- -- -- Formula III 2RIGUQUF -- -- -- -- -- 7 3RIGUQUF -- -- -- -- -- 4 Formula IV 3CC2 15.5 15.5 15.5 15.5 20 -- 3CC3 3 -- 2.5 3 -- -- 3CC4 8 12.5 8 8 -- -- 3CC5 -- -- -- 6.4 -- -- 5CC2 -- -- -- -- -- -- 3CCO1 -- -- -- -- 1.5 7 3CCV1 -- -- -- -- -- 3 3CCV -- -- -- -- -- 35 3CPO1 -- -- -- -- -- -- 3CPO2 6.4 4 5.4 -- 10 -- 3PPO2 5.2 2 5.5 5.2 -- -- 1V2PPO1 -- -- -- -- -- -- 3CCP1 -- -- -- -- 6 -- VCCP1 -- -- 2 -- -- -- 3CPP1 6 2.5 5 4 -- -- 3CPP2 -- -- -- -- 10 7 2CPPF -- -- -- -- -- 4 3CPPF -- -- -- -- -- 5 3CPTP2 -- -- -- -- -- 11 Formula V 3RIGUO2F -- -- -- -- -- 6 Additives Formula VI BMA -- -- -- 0.3 -- -- 3CC1F -- -- -- -- 8 11

[Quality Test]

The following methods were used to test the properties of the liquid crystal compositions of the embodiments and comparative examples. The test results are summarized in Tables 4 to 6 below:

Clearing point temperature (T _ni , °C): Using a differential scanning calorimeter (DSC) system, place the liquid crystal composition on an aluminum plate and accurately weigh 0.5 to 10 mg. The phase transition temperature is determined by the starting points of the endothermic peak and the exothermic peak due to the phase transition of the liquid crystal composition. The phase transition is represented by: crystalline phase is marked as C, smectic phase is marked as S, nematic phase is marked as N, and liquid is marked as I. Among them, the phase transition temperature from nematic phase to liquid is the clearing point temperature (T _ni ).

Dielectric anisotropy (Δε): A liquid crystal composition is placed in a liquid crystal box and a voltage ranging from 0 V to 20 V is applied to the liquid crystal box at 25°C. The average dielectric constant measured in a direction parallel to the long axis of the liquid crystal molecules is ε‖, and the average dielectric constant measured perpendicular to the long axis of the liquid crystal molecules is ε⊥. Dielectric anisotropy (Δε) = ε‖ - ε⊥.

Rotational viscosity (γ1, mPa•S): The liquid crystal composition is placed in a liquid crystal box, and a voltage of 20 V is applied to the liquid crystal box at a temperature of 25°C. The rotational viscosity γ1 can be obtained by converting the dielectric anisotropy (Δε) factor added by the instrument.

Refractive index anisotropy (Δn): The liquid crystal composition is measured using an Abbe refractometer (manufacturer: ATAGO; model: DR-M2) with a polarizing plate mounted on an eyepiece. First, wipe the main prism surface of the Abbe refractometer in a single direction, then drop a small amount of liquid crystal composition on the main prism, and then measure the refractive index anisotropy at a test temperature of 25°C using a filter with a wavelength of 589 nm. When the polarization direction is parallel to the wiping direction, the measured refractive index is n‖; when the polarization direction is perpendicular to the wiping direction, the measured refractive index is n⊥; refractive index anisotropy (Δn) = n‖-n⊥.

Transmittance (T@5V): The liquid crystal composition is placed in a liquid crystal box, and a voltage of 5 V is applied to the liquid crystal box at a temperature of 25°C. The intensity of the light transmitted through the liquid crystal box is measured using a light sensing module (manufacturer: HAMAMATSU; model: H10721-20). The transmittance of the liquid crystal composition is calculated based on the intensity of the light transmitted through the liquid crystal box measured before the voltage of 5 V is applied to the liquid crystal box.

Transmittance difference (ΔT): The liquid crystal composition is placed in a liquid crystal box, and a voltage of 6 V is applied to the liquid crystal box at a temperature of 25°C. A light sensing module (manufacturer: HAMAMATSU; model: H10721-20) is used to measure the intensity of the light transmitted through the liquid crystal box. Afterwards, the intensity of the light transmitted through the liquid crystal box is measured without applying voltage. Finally, the transmittance difference is obtained by subtracting the intensity of the light transmitted through the liquid crystal composition when the voltage is 6V from the intensity of the light transmitted through the liquid crystal composition when no voltage is applied.

Table 4 _T Δε γ1 Δn T@5V Embodiment 2 74.2 -2.45 102 0.1058 4749 3 82.7 -2.85 112 0.0944 4417 4 79.3 -2.57 110 0.1014 4738 Comparison Example 1 74.8 -2.45 102 0.0944 4299

Table 5 _T Δε γ1 Δn ΔT Embodiment 5 77.1 3.34 53.3 0.1098 580 Comparison Example 2 78.1 3.39 54.0 0.1237 493

Table 6 _T Δε γ1 Δn Embodiment 1 74.0 -2.76 105.6 0.1043 6 73.0 -2.69 110.4 0.1032 7 75.2 -2.56 100.1 0.1033 8 73.7 -2.65 105.5 0.1038 9 74.6 -2.72 106.1 0.1024 10 74.4 -2.64 100.6 0.1022 11 73.4 -2.83 103.8 0.1015 12 75.3 -2.67 100.8 0.1025 13 72.6 -2.79 98.8 0.1026 14 74.2 -2.77 110.4 0.1012 15 73.8 -2.88 109.3 0.1021 16 74.3 -2.66 99.5 0.1026

From the compositions of the liquid crystal compositions in Tables 1 to 3 and the property test results in Table 4, it can be seen that when the liquid crystal composition has negative dielectric anisotropy, compared with Comparative Example 1 which does not use the liquid crystal compound of Formula I, Examples 2 to 4 have higher transmittance due to the liquid crystal compound of Formula I.

From the compositions of the liquid crystal compositions in Tables 1 to 3 and the property test results in Table 5, it can be seen that when the liquid crystal composition has positive dielectric anisotropy, compared with Comparative Example 2 which does not use the liquid crystal compound of Formula I, Example 5 has a higher transmittance difference due to the liquid crystal compound of Formula I, indicating that the liquid crystal composition of Example 5 has a higher transmittance.

In summary, the liquid crystal composition of the present invention has high transmittance through the cooperation of the liquid crystal compound of formula I with a specific structural design and one of the liquid crystal compounds of formula II and formula III, which is beneficial for the subsequent application of the liquid crystal composition to a liquid crystal display device, so that the liquid crystal display device has a better contrast, and the liquid crystal display device can achieve a certain brightness at a lower voltage and has the effect of saving power, so the purpose of the present invention can be achieved.

However, the above is only an embodiment of the present invention and should not be used to limit the scope of implementation of the present invention. All simple equivalent changes and modifications made according to the scope of the patent application of the present invention and the content of the patent specification are still within the scope of the present patent.

Claims (11)

A liquid crystal composition comprises: a liquid crystal component, comprising a liquid crystal compound represented by formula I-1, and a liquid crystal compound represented by one of formulas II and III,

In the formulae I-1 to III, Ring C, Ring D and Ring E each independently represent 1,4-cyclohexylene, 1,4-phenylene, naphthalene-2,6-diyl, indane-1,5-diyl or indane-2,5-diyl, the above groups are unsubstituted or hydrogen at any position on the ring is substituted by fluorine, linear alkyl or branched alkyl, the above alkyl is unsubstituted or at least one -CH ₂ - is substituted by -O- or -C=C-, Z ¹ represents -COO-, -OCO-, -OCH ₂ -, -CH ₂ O-, -CH ₂ CH ₂ - or a single bond, X ¹ and X ² each independently represent C ₁ -C ₅ alkylene, the above alkylene is unsubstituted or at least one -CH ₂ - is substituted by -O-; R wherein ^R1 represents hydrogen or fluorine, ^R2 and ^R3 each independently represent hydrogen, _C1 - _C12 straight-chain alkyl, _C3 - _C12 branched-chain alkyl, _C1 - _C12 straight-chain alkoxy, _C3 - _C12 branched-chain alkoxy, _C2 - _C12 straight-chain alkenyl, _C3 - _C12 branched-chain alkenyl, _C2 - _C12 straight-chain oxyalkylene or _C3 - _C12 branched-chain oxyalkylene, and the above alkyl, alkoxy, alkenyl or oxyalkylene is unsubstituted, and ^R4 represents hydrogen, _C1 - _C12 straight-chain alkyl, C3-C12 branched-chain alkyl, _C1 - _C12 straight-chain alkoxy, _C3 - _C12 branched-chain alkoxy, _C2 - _C12 straight-chain alkenyl, _C3 - _C12 branched-chain the alkyl, alkoxy, alkenyl or oxyalkenyl groups are unsubstituted or any hydrogen on carbon is substituted by fluorine, and R5 is hydrogen, fluorine, chlorine, _{C1 -} C12 straight-chain alkyl, _C3 - _C12 branched-chain alkyl, C1- _C12 straight-chain alkoxy, C3 _{- C12} branched-chain alkoxy, C2- _C12 straight-chain alkenyl, C3 _{- C12} branched-chain alkenyl, C2-C12 straight-chain oxyalkenyl or _C3 -C12 branched-chain alkenyl; the alkyl, alkoxy, alkenyl or oxyalkenyl groups are unsubstituted or any hydrogen on carbon is substituted by fluorine, and ^R5 is hydrogen, fluorine, chlorine, C1- _C12 straight-chain alkyl, _C3 - _C12 branched-chain alkyl, _C1 - _C12 straight-chain alkoxy, C3-C12 branched-chain alkoxy, _C2 - _C12 straight-chain alkenyl, _C3 - _C12 branched-chain alkenyl, C2-C12 straight-chain oxyalkenyl or _C3 -C ₁₂ -branched oxyalkenyl groups, the above alkyl, alkoxy, alkenyl or oxyalkenyl groups are unsubstituted or hydrogen on any carbon is substituted by fluorine, o represents 1, 2 or 3, when o is 2 or 3, each ring C is the same or different, each ^Z1 is the same or different, q represents 1, 2 or 3, when q is 2 or 3, each ring E is the same or different. The liquid crystal composition according to claim 1, wherein ^X1 and ^X2 each independently represent a _C1 - _C5 alkylene group, and the alkylene group is unsubstituted. The liquid crystal composition as claimed in claim 1, wherein the liquid crystal compound of formula II is at least one selected from the group consisting of formula II-1, formula II-2, formula II-3, formula II-4, formula II-5 and formula II-6:

In Formula II-1 to Formula II-6, the groups represented by R ² and R ³ are respectively as defined in claim 1. The liquid crystal composition according to claim 1 or 3, wherein R ² and R ³ each independently represent a C ₁ -C ₁₂ straight-chain alkyl group or a C ₁ -C ₁₂ straight-chain alkoxy group, and the alkyl group or alkoxy group is unsubstituted. The liquid crystal composition of claim 1, wherein the liquid crystal compound of formula III is at least one selected from the group consisting of formula III-1, formula III-2, formula III-3, formula III-4 and formula III-5:

In Formula III-1 to Formula III-5, the groups represented by R ⁴ and R ⁵ are respectively as defined in claim 1. The liquid crystal composition according to claim 1 or 5, wherein R ⁴ represents a C ₁ -C ₁₂ straight chain alkyl group, the alkyl group is unsubstituted, and R ⁵ represents fluorine. The liquid crystal composition as described in claim 1 further comprises a liquid crystal compound represented by formula IV

In Formula IV, Ring F and Ring G each independently represent 1,4-cyclohexylene or 1,4-phenylene, and the above groups are unsubstituted, ^R6 represents _C1 - _C5 straight-chain alkyl, _C1 - _C5 straight-chain alkoxy or _C2 - _C5 straight-chain alkenyl, and the above alkyl, alkoxy or alkenyl are unsubstituted, ^R7 represents fluorine, _C1 - _C5 straight-chain alkyl, _C3 - _C5 branched-chain alkyl, _C1 - _C5 straight-chain alkoxy, _C3 - _C5 branched-chain alkoxy or C2 _{- C5} straight-chain alkenyl, and the above alkyl, alkoxy or _alkenyl are unsubstituted, and ^Z2 represents -COO-, -OCO-, _-OCH2- , _-CH2O- , -CH=CH-, -C≡C-, _-CH2CH2 - or single key; r means 1 or 2. The liquid crystal composition of claim 7, wherein the liquid crystal compound of formula IV is at least one selected from the group consisting of formula IV-1, formula IV-2, formula IV-3, formula IV-4, formula IV-5 and formula IV-6:

In formula IV-1 to formula IV-6, R ⁶ represents a C ₁ -C ₅ straight-chain alkyl group, a C ₁ -C ₅ straight-chain alkoxy group or a C ₂ -C ₅ straight-chain alkenyl group, and the above alkyl group, alkoxy group or alkenyl group is unsubstituted; R ⁷ represents fluorine, a C ₁ -C ₅ straight-chain alkyl group, a C ₁ -C ₅ straight-chain alkoxy group or a C ₂ -C ₅ straight-chain alkenyl group, and the above alkyl group, alkoxy group or alkenyl group is unsubstituted. The liquid crystal composition as described in claim 1 further comprises a liquid crystal compound represented by formula V

In Formula V, Ring J and Ring I each independently represent 1,4-cyclohexylene, 1,4-phenylene, naphthalene-2,6-diyl, indan-1,5-diyl or indan-2,5-diyl, the above groups are unsubstituted or hydrogen at any position on the ring is substituted by fluorine, ^R8 represents hydrogen, _C1 - _C12 straight-chain alkyl, _C3 - _C12 branched-chain alkyl, _C1 - _C12 straight-chain alkoxy, _C3 - _C12 branched-chain alkoxy, _C2 - _C12 straight-chain alkenyl, _C3 - _C12 branched-chain alkenyl, _C2 - _C12 straight-chain oxyalkylene or _C3 -C12 _12- branched oxyalkylene groups, wherein the above alkyl, alkoxy, alkenyl or oxyalkylene groups are unsubstituted or hydrogen on any carbon is substituted by fluorine, s represents 1 or 2, when s is 2, each ring I is the same or different. The liquid crystal composition as described in claim 1 further comprises an additive, wherein the additive comprises a compound represented by formula VI

In the formula VI, ring K represents 1,4-phenylene or indane-2,5-diyl, the above groups are unsubstituted or hydrogen at any position on the ring is substituted by fluorine, Z ³ represents -OCH ₂ -, -CH ₂ O-, -CH ₂ CH ₂ - or a single bond, t and u represent 1 or 2 respectively, and the sum of t and u is 2, 3 or 4. When u is 2, each ring K is the same or different. A liquid crystal display device comprising a liquid crystal composition as described in any one of claims 1 to 10.