JP3538820B2 - (Fluoroalkenyl) cyclohexane derivative and liquid crystal composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel liquid crystal compound which is a (fluoroalkenyl) cyclohexane derivative and a liquid crystal composition containing the same, which are useful as an electro-optical liquid crystal display material.

[0002]

2. Description of the Related Art Liquid crystal display elements have been used in various measuring instruments, such as watches and calculators, automobile panels, word processors, electronic organizers, printers, computers, televisions, and the like. Typical liquid crystal display systems are TN (twisted nematic), STN (super twisted nematic), DS (dynamic light scattering), GH (guest-host), and FLC (ferroelectric liquid crystal). ) Are known, and among them, TN type and STN type are currently most frequently used. As a driving method, a multiplex driving is generally used instead of the conventional static driving, and a simple matrix method, more recently, an active matrix method has been put to practical use. Of these, the active matrix method can display the highest image quality, has a wide viewing angle, is easy to achieve high definition and color, and can display moving images. It is thought to be.

A liquid crystal material used in this active matrix display system is required to have various characteristics as in a normal liquid crystal display, but (1) particularly has a high specific resistance.
It is important that the voltage holding ratio is excellent, (2) the threshold voltage (V _th ) is low, and (3) the temperature range of the liquid crystal phase is wide.

Usually, a threshold voltage (V) in a liquid crystal display is
_th ) is the equation (a)

[0005]

(Equation 1)

(Where k represents a proportional constant, K represents an elastic constant, and Δε represents a dielectric anisotropy.) As can be seen from this equation, the threshold voltage is reduced. For this purpose, it is necessary to reduce the elastic constant of the liquid crystal material or increase the dielectric anisotropy.

However, since a liquid crystal compound having a large dielectric anisotropy has a large polarity, it is very difficult to obtain a high specific resistance and a high voltage holding ratio using such a compound. Therefore, a liquid crystal material having a small elastic constant is required for such a purpose.

However, most bicyclic compounds having a small elastic constant significantly lower the maximum temperature of the liquid crystal phase of the liquid crystal composition when added.

On the other hand, in order to extend the temperature range of the liquid crystal composition to a particularly high temperature range, it is necessary to add a compound having a high maximum temperature of a tricyclic or tetracyclic liquid crystal phase. However, many compounds having such a high maximum temperature have a large elastic constant, and the addition thereof tends to greatly increase the threshold voltage. Therefore, it has been quite difficult to obtain a liquid crystal composition having a small dielectric anisotropy, a wide temperature range of a liquid crystal phase up to a high temperature range, and a low threshold voltage.

[0010]

SUMMARY OF THE INVENTION The problem to be solved by the present invention is to solve the above problems even though the maximum temperature of the liquid crystal phase is higher and the dielectric anisotropy is not so large. Provides a compound that hardly raises the threshold voltage, and contains the compound, the temperature range of the liquid crystal phase is wide up to a high temperature range, the threshold voltage is low, and the dielectric anisotropy is not so large. It is to provide a liquid crystal composition.

[0011]

According to the present invention, there is provided a compound represented by the following general formula (I):

[0012]

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(Where R¹Is hydrogen atom or carbon atom number 1
~ 12 alkyl groups, preferably a hydrogen atom or
Represents a linear alkyl group having 1 to 5 carbon atoms,
Hydrogen atoms are preferred. X¹And X^TwoOne of them is a hydrogen source
And the other represents a fluorine atom, preferably
X¹Represents a fluorine atom, X^TwoRepresents a hydrogen atom. Where X
^TwoIs a fluorine atom, R¹Represents 1 to 12 carbon atoms
Represents an alkyl group. m represents 0 or 1, and is preferably
Is m = 1. Ring A is a 1,4-cyclohexylene group or
Is 1,4-phenyl which may be substituted by a fluorine atom
Represents a nylene group, preferably 1,4-cyclohexyl
Represents a len group. Y¹And Y^TwoAre each independently connected
Or -CH_TwoCH_Two-, Preferably Y¹Is simply
Represents a bond, especially Y¹And Y^TwoAre both single bonds
Is preferred. Z¹Is a fluorine atom, a chlorine atom, a cyano group,
Trifluoromethyl group, trifluoromethoxy group, dif
A fluoromethoxy group, an alkyl group having 1 to 12 carbon atoms,
C1-C12 alkoxyl group, C3-C3
12 alkenyl groups or alkenyl having 3 to 12 carbon atoms
Represents a hydroxy group, preferably a fluorine atom or a chlorine atom.
Represents a trifluoromethoxy group, especially a fluorine atom
Is preferred. Z^TwoAnd Z^ThreeAre each independently a fluorine atom
Represents a hydrogen atom or a hydrogen atom.
The substituents are in the trans configuration. ) (Fluoro
(Alkenyl) cyclohexane derivatives.

When R ¹ is an alkyl group, the cyclohexane ring and R ¹ may be in the trans or cis configuration, but the trans configuration is preferred because of excellent liquid crystallinity.

The compound represented by the general formula (I) of the present invention can be produced, for example, as follows.

[0016]

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(Wherein R ¹ , Y ¹ , m, ring A, Y ² , Z ¹ ,
Z ² and Z ³ have the same meanings as in formula (I). ) By reacting the corresponding 1-alkenylcyclohexane derivative of the general formula (II) with N-iodosuccinimide (NIS) and hydrogen fluoride-pyridine, Iodoalkyl)
A cyclohexane derivative and a compound represented by the general formula (IIIb):
A (fluoro-1-iodoalkyl) cyclohexane derivative is obtained.

[0018] Here, when R ¹ is a hydrogen atom, primarily compounds of general formula (IIIa) is obtained, R ¹
Is an alkyl group, the general formulas (IIIa) and (I
The compound of IIb) is obtained approximately in half. However, these can be separated by an ordinary purification method, or they can be used in the form of a mixture without separation.

Formulas (IIIa) and (IIIb)
With 1,8-diazabicyclo- [5,4,0]
By reacting with a base such as -7-undecene (DBU), (1-fluoroalkenyl) of the general formula (Ia)
Cyclohexane derivatives and (2-fluoroalkenyl) cyclohexane derivatives of the general formula (Ib) can be obtained.

In the general formula (I), when R ¹ is an alkyl group, from the compound of the general formula (II) in which the terminal alkenyl group is in a trans configuration, in the fluoroalkenyl group of the general formula (I), R ¹ And a compound having a cyclohexane ring in cis configuration is obtained, and a compound in general formula (I) in trans configuration is obtained from a compound of general formula (II) in cis configuration. As described above, R ¹ and the cyclohexane ring in the fluoroalkenyl group of the general formula (I) preferably have a trans configuration, and therefore, the compound of the general formula (II) used as a raw material is preferably a cis form.

Representative examples of the compound represented by the general formula (I) thus produced are shown in Table 1.

[0022]

[Table 1]

(In the table, Cr represents a crystal phase, N represents a nematic phase, and I represents an isotropic liquid phase.) From Table 1, the compound represented by the general formula (I) represents the upper limit of the nematic phase. Since the temperature is considerably high, it is possible to expand the liquid crystal phase to a high temperature range by adding it to a general-purpose base liquid crystal.

As shown in the examples described later, the compound represented by the general formula (I) of the present invention is in the form of a mixture with another nematic liquid crystal compound, particularly, TN type or ST type.
It can be used as a material for an N-type field-effect display cell, and is particularly suitable as a component of an active matrix driving liquid crystal material.

Preferred examples of the nematic liquid crystal compound which can be used by mixing with the compound represented by formula (I) of the present invention include, for example, 4-nematic liquid crystal compounds.
Substituted benzoic acid 4-substituted phenyl ester, 4-substituted cyclohexanecarboxylic acid 4-substituted phenyl ester, 4-substituted
Substituted cyclohexanecarboxylic acid 4'-substituted biphenylyl ester, 4- (4-substituted cyclohexanecarbonyloxy) benzoic acid 4-substituted phenyl ester, 4- (4-
4-substituted cyclohexyl) benzoic acid phenyl ester, 4- (4-substituted cyclohexyl) benzoic acid 4-substituted cyclohexyl ester, 4,4′-substituted biphenyl,
1- (4-substituted phenyl) -4-substituted cyclohexane,
4,4 "-substituted terphenyl, 1- (4'-substituted biphenylyl) -4-substituted cyclohexane, 1- (4-substituted cyclohexyl) -4- (4-substituted phenyl) cyclohexane, 2- (4-substituted phenyl) ) -5-substituted pyrimidine, 2- (4'-substituted biphenylyl) -5-substituted pyrimidine and the like.

Particularly, for active matrices, 4,4′-substituted biphenyl, 1- (4-substituted phenyl) -4-substituted cyclohexane, 4,4 ″ -substituted terphenyl, 1- (4′-substituted) Biphenylyl) -4-substituted cyclohexane, 1- (4-substituted cyclohexyl) -4
-(4-Substituted phenyl) cyclohexane and the like are preferred.

The effect of the compound of the general formula (I) of the present invention is as follows:
For example, it is clear from the following example. Base liquid crystal (A), which is currently widely used as a nematic liquid crystal material

[0028]

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(Wherein the cyclohexane ring represents the trans configuration, and “%” means “% by weight”).
Shows a nematic phase at 5 ° C or less and dielectric anisotropy (Δε)
Was +6.7, and the threshold voltage (V _th ) of the TN cell manufactured using the same was 1.60 V.

A liquid crystal composition (M-1) comprising 80% by weight of the base liquid crystal (A) and 20% by weight of the compound (No. 1) in Table 1 was prepared. The maximum temperature of the nematic phase of (M-1) was greatly increased to 60.1 ° C. Also, Δ
ε was slightly reduced to +5.8. Next, a cell was prepared in the same manner using this composition, and V _th was measured. As a result, although the upper limit temperature of the nematic phase was increased and Δε was decreased, the increase was 1.64 V and the increase was 1.64 V. It was slight. This is considered to be because the elastic constant (K) of the compound (No. 1) was relatively small.

From the above results, the compound represented by the general formula (I) can be added to a base liquid crystal exhibiting a nematic liquid crystal phase to increase the temperature range of the liquid crystal phase in a high temperature range without substantially increasing the threshold voltage. It is clear that it can be expanded to:

Next, a base liquid crystal (B) particularly suitable for an active matrix

[0033]

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(Wherein the cyclohexane ring represents a trans configuration), a nematic phase was obtained at 116.7 ° C. or less, and the dielectric anisotropy (Δε) was +4.7. The threshold voltage (V _th ) of the TN cell manufactured as described above is 2.43 V.

The parent liquid crystal (B) 80% by weight and (N
o. A liquid crystal composition (M-
When 2) was prepared, the maximum temperature of the nematic phase was 11
The temperature dropped slightly to 2 ° C. Δε was very small at +3.7. However, when V _th was measured in the same manner, despite the fact that Δε decreased, 2.
There was almost no change to 44V. Therefore, (No.
Since the compound of 1) can suppress the dielectric anisotropy (Δε) to be low, it can be understood that the compound is also suitable as a liquid crystal material for an active matrix that requires a high specific resistance and a high voltage holding ratio.

[0036]

EXAMPLES Examples of the present invention are shown below to further explain the present invention. However, the invention is not limited to these examples.

The measurement of the phase transition temperature was carried out using a polarizing microscope equipped with a temperature control stage and a differential scanning calorimeter (DSC). The structure of the compound is represented by a nuclear magnetic resonance spectrum ( ¹ H-NMR) and an infrared absorption spectrum (I
R), mass spectrum (MS) and the like. IR
In (KBr) represents the measurement by tablet molding. N
CDCl _{3 in} MR represents a solvent, and J represents a coupling constant. s represents a singlet, d represents a doublet, t represents a triplet, q represents a quadruple, quintet represents a quintuple, and m represents a multiplet. For example, dd represents a double double line.
M ^{+ in} MS represents a parent peak, and the value in parentheses represents the relative intensity of the peak. “%” In the composition means “% by weight”. (Example 1) 3,4-difluoro-1- [trans-
Synthesis of 4- [trans-4- (1-fluoroethenyl) cyclohexyl] cyclohexyl] benzene (Compound No. 1) (1-a) 3,4-difluoro-1- [trans-4
Synthesis of-[trans-4- (1-fluoro-2-iodoethyl) cyclohexyl] cyclohexyl] benzene

[0038]

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3,4-difluoro-1- [trans-4
9.8 g (43.5 mmol) of N-iodosuccinimide (NIS) was added to a solution of 8.82 g (29 mmol) of-(trans-4-ethenylcyclohexyl) cyclohexyl] benzene in dichloromethane (80 ml). At 25 ° C., 2.5 ml of a hydrogen fluoride-pyridine solution was added,
Stir for 3 hours. The reaction solution is a saturated aqueous sodium hydrogen carbonate solution and a sodium hydrogen sulfite aqueous solution (1/1) 300 ml
The reaction product was extracted three times with 60 ml of dichloromethane, and the extract was washed with 50 ml of saturated saline and dried over anhydrous sodium sulfate. After concentration under reduced pressure, the obtained residue was subjected to column chromatography (Kieselgel).
60, hexane / ethyl acetate = 80/1) to give 3,4-difluoro-1- [trans-4-.
[Trans-4- (1-fluoro-2-iodoethyl)
8.26 g of [cyclohexyl] cyclohexyl] benzene
(Yield: 64%) and 1.12 g of 3,4-difluoro-1- [trans-4- [trans-4- (2-fluoro-1-iodoethyl) cyclohexyl] cyclohexyl] benzene (yield: 9% ) Got. 3,4-difluoro-1- [trans-4- [trans-4- (1-fluoro-2-iodoethyl) cyclohexyl] cyclohexyl] benzene colorless plate crystal phase transition temperature (° C.): Cr87N105I IR (KBr) : 2950, 2880, 1610, 15
20, 1450, 1280, 1120, 830, 780
_{^{cm -1 1 H NMR (CDCl 3}} ): δ = 0.95~1.22
(M, 8H), 1.36 (quintet, J = 12.
4Hz, 2H), 1.60 to 2.03 (m, 9H),
2.41 (tt, J = 12.2 and 3.5 Hz, 1
H), 3.31 (ddd, J = 21.7, 11.1an
d6.5 Hz, 1H), 3.40 (ddd, J = 23.
6, 11.1 and 3.9 Hz, 1H), 4.15 (d
td, J = 47.2, 6.4 and 3.9 Hz, 1
H), 6.89 (ddt, J = 6.3, 4.3and)
2.1Hz, 1H), 6.99 (ddd, J = 11.
9, 7.7 and 2.1 Hz, 1H), 7.05 (d
t, J = 10.4 and 8.4 Hz, 1H) MS: m / z 450 (M ⁺ , 100), 140 (5
5), 127 (62) Elemental analysis: C ₂₀ H ₂₆ F ₃ I Calculated: C, 53.34%; H, 5.82% Found: C, 53.11%; H, 5.71% 3,4-difluoro-1- [trans-4- [trans-4- (2-fluoro-1-iodoethyl) cyclohexyl] cyclohexyl] benzene melting point 69 ° C. IR (KBr): 2950, 2880, 1520, 12
_{^{90,980cm -1 1 H NMR (CDCl 3}} ): δ = 1.05~1.30
(M, 9H), 1.36 (quintet, J = 12.
2Hz, 2H), 1.72-1.94 (m, 8H),
2.41 (tt, J = 12.4 and 3.6 Hz, 1
H), 4.22 to 4.31 (m, 1H), 4.59 (d
dd, J = 47.6, 9.6 and 8.5 Hz, 1
H), 4.65 (ddd, J = 47.1, 9.7 and
5.7 Hz, 1 H), 6.89 (ddt, J = 6.3,
4.3 and 2.1 Hz, 1H), 6.98 (ddd,
J = 11.9, 7.7 and 2.1 Hz, 1H), 7.
04 (dt, J = 10.4 and 8.4 Hz, 1H) MS: m / z 450 (M ⁺ , 21), 323 (4
6), 127 (100) Elementary analysis: C ₂₀ H ₂₆ F ₃ I Calculated: C, 53.34%; H, 5.82% Found: C, 53.16%; H, 5.71% (1-b) 3,4-difluoro-1- [trans-4
Synthesis of-[trans-4- (1-fluoroethenyl) cyclohexyl] cyclohexyl] benzene

[0040]

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7.07 g (15) of 3,4-difluoro-1- [trans-4- [trans-4- (1-fluoro-2-iodoethyl) cyclohexyl] cyclohexyl] benzene obtained in the above (1-a) 1.7 mmol) in dichloromethane (30 ml), 1,8-diazabicyclo [5,4,0] -7-undecene (DBU) 11.75.
ml (78.5 mmol) was added, and the mixture was heated under reflux for 8 hours. The reaction solution was saturated aqueous sodium hydrogen carbonate solution (100 ml).
The reaction product was extracted three times with 30 ml of dichloromethane, and the extract was washed with 30 ml of a saturated saline solution and dried over anhydrous sodium sulfate. After concentration under reduced pressure, the obtained residue was subjected to column chromatography (Kieselgel).
60, hexane / ethyl acetate = 80/1) to give 3,4-difluoro-1- [trans-4-.
3.38 g of [trans-4- (1-fluoroethenyl) cyclohexyl] cyclohexyl] benzene (yield: 6
7%). Recrystallization from ethanol gave 2.26 g of a purified product (yield: 53%). Colorless plate crystal phase transition temperature (° C): Cr60N101I IR (KBr): 2950, 2880, 1675, 15
_{^{20,1285,1220,870cm -1 1 H NMR (CDCl 3}} ): δ = 1.00~1.31
(M, 8H), 1.37 (q, J = 12.2 Hz, 2
H), 1.58-2.11 (m, 9H), 2.41 (t
t, J = 12.1 and 3.4 Hz, 1H), 4.17
(Ddd, J = 51.6, 2.8 and 0.8 Hz, 1
H), 4.44 (dd, J = 18.6 and 2.8H)
z, 1H), 6.89 (ddt, J = 6.3, 4.3a)
nd2.1 Hz, 1H), 6.98 (ddd, J = 1)
1.9, 7.8 and 2.1 Hz, 1H), 7.05
(Dt, J = 10.4 and 8.4 Hz, 1H) MS: m / z 322 (M ⁺ , 37), 179 (3
3), 140 (59), 127 (100), 79 (4
1), 67 (53), 55 (49), 41 (49) Elemental analysis: Calculated _{C 20 H 25 F 3: C} , 74.51%; H, 7.82% Found: C, 74. H, 7.79% (Example 2) Preparation of liquid crystal composition (1) Base liquid crystal (A) having the following composition

[0042]

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(Wherein the cyclohexane ring represents a trans configuration) showed a nematic (N) phase at 54.5 ° C. or lower. The physical properties and the threshold voltage (V _th ) of the TN cell manufactured using the same were as follows.

Dielectric anisotropy (Δε) +6.7 Refractive index anisotropy (Δn) 0.092 Threshold voltage (V _th ) 1.60 V 80% of the parent liquid crystal (A) and ( No. 1)
A liquid crystal composition (M-1) consisting of 20% of the compound of the formula (1) was prepared. The maximum temperature (T _NI ) of the N phase of (M-1) and the physical properties thereof were as follows.

Maximum temperature of N phase (T _NI ) 60.1 ° C. Dielectric anisotropy (Δε) +5.0 Refractive index anisotropy (Δn) 0.093 Threshold voltage (V _th ) 1.64 V As described above, although the maximum temperature of the nematic phase increases and the dielectric anisotropy decreases, the threshold voltage does not increase so much. Considering the above formula (a), it is considered that the elastic constant of the compound of (No. 1) is relatively small. (Example 3) Preparation of liquid crystal composition (2) Fluorine-based base liquid crystal (B) particularly suitable for active matrix

[0046]

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When a cyclohexane ring represented a trans configuration, a nematic (N) phase was exhibited at 116.7 ° C. or lower. The physical properties and the threshold voltage (V _th ) of the TN cell manufactured using the same were as follows.

Dielectric anisotropy (Δε) +4.7 Refractive index anisotropy (Δn) 0.090 Threshold voltage (V _th ) 2.43 V 80% of the base liquid crystal (B) and ( No. 1)
A liquid crystal composition (M-2) consisting of 20% of the compound of the formula (1) was prepared. The maximum temperature (T _NI ) of the N phase of (M-2) and the physical properties thereof were as follows.

Maximum temperature of N phase (T _NI ) 112.0 ° C. Dielectric anisotropy (Δε) +3.7 Refractive index anisotropy (Δn) 0.089 Threshold voltage (V _th ) 2.44 V As described above, although the dielectric anisotropy is small, the threshold voltage is hardly changed.

The composition (M-2) has a specific resistance of 10 ¹³ Ω.
Cm or more, and the voltage holding ratio of the cell manufactured using this was as high as 98% or more. From the above results, it was found that the compound of the general formula (I) of the present invention, when added to the base liquid crystal, has a dielectric anisotropy with almost no change in its maximum nematic phase temperature and its threshold voltage (V _th ). It is clear that the characteristics can be reduced. (Example 3) Thermal stability test The compound of (No. 1) obtained in Example 1 was sealed in an ampoule, and left in a 100 ° C incubator for 24 hours. After cooling, the content was dissolved in hexane at 10%, and the specific resistance was measured. As a result, there was no change from the specific resistance similarly measured using the sample before the heating test. When the purity was measured by a capillary gas chromatograph, no impurities were generated.

[0051]

The liquid crystal compound represented by the general formula (I) of the present invention can be easily produced industrially as shown in the Examples, and chemically reacts with heat, light, water and the like. It is very stable and has excellent compatibility with the base liquid crystal which is currently widely used as a nematic liquid crystal. In addition, the upper limit temperature of the nematic phase is high, and the threshold voltage (V _th ) of the obtained liquid crystal cell hardly increases even if it is added to the base liquid crystal. Therefore, it can be used as a material for various liquid crystal display elements that require a wide temperature range of the liquid crystal phase and low voltage driving. Further, since the dielectric anisotropy is not so large, it is very useful as a liquid crystal material for driving an active matrix which requires a high specific resistance and a high voltage holding ratio.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Tetsuo Kusumoto 1-9-2-102 Minamidai, Sagamihara City, Kanagawa Prefecture (72) Inventor Kenichi Sato 35-11 Kamimizo, Sagamihara City, Kanagawa Prefecture (56) References JP2 -184642 (JP, A) Patent table 6-500343 (JP, A) German Patent Application Publication No. 4113054 (DE, A1) German Patent Application Publication 4113309 (DE, A1) German Patent Application Publication 4314085 (DE) , A 1) (58) Fields surveyed (Int. Cl. ⁷ , DB name) CA (STN) CAOLD (STN) REGISTRY (STN)

Claims (4)

(57) [Claims] 1. A compound of the general formula (I) (Wherein, R ¹ represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, and ^one of X ¹ and X ² represents a hydrogen atom and the other represents a fluorine atom, but X ² represents a fluorine atom In the formula, R ¹ represents an alkyl group having 1 to 12 carbon atoms, m represents 0 or 1, and ring A is 1,4-cyclohexylene group or 1,4 which may be substituted by a fluorine atom. Y ¹ and Y ² each independently represent a single bond or —CH ₂ CH ₂ —;
¹ is a fluorine atom, a chlorine atom, a cyano group, a trifluoromethyl group, a trifluoromethoxy group, a difluoromethoxy group, an alkyl group having 1 to 12 carbon atoms,
12 represents an alkoxyl group, an alkenyl group having 3 to 12 carbon atoms or an alkenyloxy group having 3 to 12 carbon atoms, Z ² and Z ³ each independently represent a fluorine atom or a hydrogen atom, and a cyclohexane ring The two substituents are in the trans configuration. ). 2. The compound according to claim ¹ , wherein in the formula (I), R ¹ represents a hydrogen atom, X ¹ represents a fluorine atom, and X ² represents a hydrogen atom. 3. In the general formula (I), m represents 1, ring A represents a 1,4-cyclohexylene group, and Y ^1
3. The compound according to claim 2, wherein Y ² and Y ² both represent a single bond, Z ¹ and Z ² both represent a fluorine atom, and Z ³ represents a hydrogen atom. 4. A liquid crystal composition containing the compound represented by the general formula (I) according to claim 1.