JP6601735B2 - Novel liquid crystalline compound, liquid crystal composition, optical element and optical display device - Google Patents

Description

  The present invention relates to a liquid crystal compound, a liquid crystal composition, an optical element, and an optical display device that are useful as materials for optical elements. Specifically, the present invention relates to a novel liquid crystal compound and a liquid crystal composition having a small dielectric anisotropy and a change in birefringence when a voltage is applied. In addition, the present invention relates to an optical element and an optical display device using the liquid crystal composition.

  A liquid crystal display element typified by a liquid crystal display panel, a liquid crystal display module or the like is a liquid crystal compound (in the present invention, a compound having a liquid crystal phase such as a nematic phase or a smectic phase, and a component of a liquid crystal composition that does not have a liquid crystal phase. The optical anisotropy, dielectric anisotropy, etc. of the liquid crystal display element are used as an operation mode of the liquid crystal display element, such as a PC (phase change) mode, TN. (Twisted nematic) mode, STN (super twisted nematic) mode, BTN (bistable twisted nematic) mode, ECB (electrically controlled birefringence) mode, OCB (optics) d bend) mode, IPS (in-plane switching) mode, VA (vertical alignment) mode, a variety of modes such as PSA (Polymer sustained alignment) are known.

  At present, a cyclohexane ring is often used as a compound in a composition having a low Δn, and when it is actually used for a liquid crystal display device, a smectic phase or a crystal is likely to precipitate. For these reasons, development of a liquid crystalline compound having a small Δε and a high clearing point, or a liquid crystalline compound having a small Δε and a wide nematic phase has been demanded.

  For example, the following compound (A) has been reported (for example, Patent Document 1). However, this compound (A) was only confirmed as a by-product of other compounds, and its usefulness as a liquid crystal compound including liquid crystal properties was not confirmed at all.

JP-A-11-255679

The optical display element operating in each mode described above is composed of a liquid crystal compound or a liquid crystal composition. In order to further improve these characteristics, the liquid crystal properties used in the optical display element alone or as a liquid crystal composition are used. It is necessary for the compound to have the following properties (1) to (7). That is,
(1) Chemical stability and physical stability (2) High clearing point (liquid crystal phase-isotropic phase transition temperature) (3) Liquid crystal phase (nematic phase, smectic phase, etc.) ), Especially the nematic phase has a low minimum temperature (4) low viscosity (5) has appropriate optical anisotropy (6) has appropriate elastic constants (7) other liquid crystal properties It is excellent in compatibility with the compound.

When the liquid crystal compound which is chemically and physically stable as in (1) or a composition containing the same is used for an optical display element, the voltage holding ratio can be increased.
In addition, the liquid crystalline compound having a high clearing point or a low minimum temperature of the liquid crystal phase as in (2) and (3) can widen the temperature range of the nematic phase when used alone or as a composition. Thus, it can be used as an optical display element in a wide temperature range.

  Further, when a composition containing a compound having a low viscosity as in (4) and a compound having an appropriate elastic constant as in (7) is used as an optical display element, the response speed can be improved, and (5) In the case of an optical display device using a compound having an appropriate optical anisotropy alone or a composition containing the same, the contrast of the display device can be improved.

  Further, by using a compound having an appropriate elastic constant as in (6) or a composition containing the compound as an optical display element, the driving voltage of the display element can be reduced and the power consumption can be reduced.

  When it is difficult to exhibit a liquid crystal compound with a single compound, it can also be used as a composition prepared by mixing with many other liquid crystal compounds. Therefore, it is also preferable that the liquid crystalline compound used in the display element has good compatibility with other liquid crystalline compounds as in (7). In addition, since the optical display element may be used in a wide temperature range including below freezing point, it may be preferable that the light display element is a compound having good compatibility from a low temperature range.

  The first object of the present invention is to have stability to heat, light, etc., low viscosity, excellent compatibility with other liquid crystal compounds, and nematic phase in a wide temperature range, and suitable optical properties. It is to provide a liquid crystal compound having anisotropy.

  The second object of the present invention is to have stability against heat, light, etc., low viscosity, suitable optical anisotropy, dielectric anisotropy, elastic constant, low threshold voltage, Furthermore, it is to provide a liquid crystal composition containing this compound, having a high nematic phase maximum temperature (nematic phase-isotropic phase transition temperature) and a low nematic phase minimum temperature.

  The third object of the present invention is to provide an optical device containing the above-mentioned compound or composition, which has a short response time, low power consumption and driving voltage, high contrast, and can be used in a wide temperature range. That is.

  As a result of intensive studies to achieve the above object, the inventors of the present invention have excellent properties in the liquid crystal compound represented by the formula (1) and the liquid crystal composition containing the compound. It has been found that excellent optical elements and optical display elements can be obtained by using them.

The present invention includes the following items.
Item 1.
The compound represented by Formula (1).

(In the formula (1), R ¹ , R ² and R ³ are independently a hydrogen atom or an alkyl having 1 to 10 carbon atoms, and in these groups, at least one —CH ₂ — is —O—, —S—, —CO—, or —SiH ₂ — may be substituted, and at least one — (CH ₂ ) ₂ — may be substituted with —CH═CH— or —C≡C—. n is an integer of 0 to 4. m is an integer of 1 or 2. Z ¹ and Z ² are —CH═CH—.

Item 2.
Item 2. The compound according to Item 1, which exhibits a nematic phase.

Item 3.
Item 3. A liquid crystal composition comprising the compound according to item 1 or 2.

Item 4.
Item 4. The liquid crystal composition according to item 3, which exhibits a nematic phase.

Item 5.
Item 5. The liquid crystal composition according to item 3 or 4, containing at least one optically active compound and / or polymerizable compound.

Item 6.
Item 6. The liquid crystal composition according to any one of items 3 to 5, further comprising at least one antioxidant and / or ultraviolet absorber.

Item 7.
Item 7. An optical element using the liquid crystalline compound or liquid crystal composition according to any one of items 1 to 6.

Item 8.
Item 8. An optical display device using the optical element according to Item 7.

  According to the present invention, there are provided a novel liquid crystal compound and a liquid crystal composition which have a responsiveness despite a small dielectric anisotropy and change birefringence by applying a voltage. . Such a liquid crystalline compound and a liquid crystal medium change in color tone due to a change in birefringence according to the magnitude of voltage. For this reason, it is possible to change the color of the liquid crystal directly by changing the voltage. Such a liquid crystal compound can be applied to either a vertical electric field mode or a horizontal electric field mode liquid crystal display device.

The schematic of the electric cell evaluated in the Example is shown. The interference color chart in a vertical electric field about the compound 4 and the figure of the interference color change according to the strength of a voltage are shown. The explanatory view which considers the birefringence change by voltage is shown. The interference color chart in a vertical electric field about the compound 5 and the figure of the interference color change according to the strength of a voltage are shown. The interference color chart in a horizontal electric field about the compound 4 and the figure of the interference color change according to the strength of a voltage are shown.

  Terms used in this specification are as follows. The compound of the present invention has a nematic phase and is a general term for compounds mixed with a composition for the purpose of adjusting the properties such as the temperature range, viscosity, and dielectric anisotropy of the nematic phase alone, or the nematic phase. It is.

  In the present invention, the liquid crystal composition is a general term for a liquid crystal composition and a polymer / liquid crystal composite. A mixture of a plurality of liquid crystal compounds is also included in the liquid crystal composition. The ratio (content) of the liquid crystal compound is expressed as a percentage by weight (% by weight) based on the weight of the liquid crystal composition. If necessary, additives such as an optically active compound, an antioxidant, an ultraviolet absorber, a dye, an antifoaming agent, a polymerizable compound, a polymerization initiator, and a polymerization inhibitor are added to the composition. The ratio (addition amount) of the additive is represented by a weight percentage (% by weight) based on the weight of the liquid crystal composition, similarly to the ratio of the liquid crystal compound. Weight parts per million (ppm) may be used. The ratio of the polymerization initiator and the polymerization inhibitor is exceptionally expressed based on the weight of the polymerizable compound.

  The optical element refers to various elements that perform functions such as light modulation and optical switching by utilizing the electro-optic effect. For example, display elements (liquid crystal display elements), optical communication systems, optical information processing, And a light modulation element used in the sensor system.

Terms used in this specification are as follows. The terms “liquid crystal composition” and “light display element” may be abbreviated as “composition” and “element”, respectively.
The expression “at least one 'A' may be replaced by 'B'” means that the number of 'A' is arbitrary. When the number of “A” is one, the position of “A” is arbitrary, and when the number of “A” is two or more, the positions can be selected without limitation. This rule also applies to the expression “at least one 'A' is replaced by 'B'”.

[Compound]
The compound (1) of the formula (1) of the present invention will be further described.

In formula (1), the line across the benzene ring means that the R ³ group can arbitrarily select the bonding position on the benzene ring. The compound represented by Formula (1) may be abbreviated as Compound (1). This abbreviation also applies to compounds represented by formula (5) and the like. Compound (1) means one compound or two or more compounds represented by formula (1). In the case of compounds, the end groups R ¹ and R ² may be the same or different. Furthermore, in the case of two or more compounds, one of the end groups R ¹ and R ² may be the same or both may be different. Further, when R ³ is bonded, they may be the same as or different from R ¹ and R ² . Further, when a plurality of R ³ are present, they may be the same or different. (In the formula (1), R ¹ , R ² and R ³ are independently a hydrogen atom or an alkyl having 1 to 10 carbon atoms, and in these groups, at least one —CH ₂ — is —O—, —S—, —CO—, or —SiH ₂ — may be substituted, and at least one — (CH ₂ ) ₂ — may be substituted with —CH═CH— or —C≡C—. n is an integer of 0 to 4. m is an integer of 1 or 2. Z ¹ and Z ² are —CH═CH—.

  The following preferred embodiments of the compound (1) of the present invention are preferable because they have a nematic phase, a small dielectric anisotropy, and a characteristic that birefringence changes when a voltage is applied. The compound (1) having such a nematic phase is physically and chemically stable under conditions in which the device is usually used, and can be used as a compound alone or as a component of a liquid crystal composition. The compound (1) has good compatibility with other liquid crystal compounds. In addition, the liquid crystal composition containing the compound (1) is stable under conditions where the device is usually used. When this liquid crystal composition is stored at a low temperature, even if a large amount of compound (1) is added, it does not precipitate as crystals.

Next, the preferable form of a compound (1) is demonstrated. In the formula (1), R ¹ and R ² are alkyl having 1 to 10 carbon atoms, and in this alkyl, at least one —CH ₂ — is —O—, —S—, —CO—, or —SiH. ₂ — may be substituted, and at least one — (CH ₂ ) ₂ — may be substituted with —CH═CH— or —C≡C—.

  Preferred alkyl is methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, or octyl. More preferred alkyl is ethyl, propyl, butyl, pentyl, or heptyl.

R ³ is alkyl having 1 to 10 carbons, in which at least one —CH ₂ — may be replaced by —O—, —S—, —CO—, or —SiH ₂ —; At least one — (CH ₂ ) ₂ — may be replaced by —CH═CH— or —C≡C—. Preferred alkyl is methyl or ethyl for decreasing the phase transition temperature. The binding site of R ³ is not particularly limited. In addition, n is an integer of 0-4, Preferably it is 0. When alkyl is bonded to R ³ , n may preferably be 0 because liquid crystallinity may not be exhibited. m is 1.

The preferred configuration of —CH═CH— constituting Z ¹ and Z ² may be either cis or trans, but is preferably a trans isomer.
Preferred compounds (1) are the compounds (1-1) and (1-2) shown below.

A method for synthesizing compound (1) will be described. Compound (1) is synthesized by appropriately combining techniques in organic synthetic chemistry. Methods for introducing the desired end groups, rings and linking groups into the starting materials are Organic Syntheses (John Wiley & Sons, Inc), Organic Reactions (John Wiley & Sons, Inc), Comprehensive・ It is described in books such as Organic Synthesis (Pergamon Press) and New Experimental Chemistry Course (Maruzen).

  An example of a method for synthesizing the compound (1) of the present invention is shown in the following scheme. However, the synthesis method of these compounds is not limited to the following scheme.

For example, first, 1,4-di (bromomethyl) benzene compound (2-1) is reacted with triethyl phosphite. Separately, after reacting the corresponding cyclohexanecarboxylic acid compound (3-1) with ethanol, the cyclohexanecarbaldehyde compound (3-3) was synthesized in the presence of sodium diisobutyl tert-butoxyaluminum hydride (SDBBA), and the compound (2 Compound (1) can be synthesized by reacting -2) with compound (3-3).
In addition, the compound (1) of the present invention may not have a nematic phase. The composition containing this compound and another component should just have a nematic phase. Examples of such compounds include the following.

[Liquid crystal composition]
The liquid crystal composition according to the present invention will be described. The liquid crystal composition of the present invention contains compound (1). The liquid crystal composition may be composed of the compound (1) alone or may contain other components. When other components are contained, it is preferable to contain the compound (1) in a proportion of 0.1 to 99% by weight in order to develop excellent characteristics.
A preferred embodiment of the liquid crystal composition according to the present invention is a liquid crystal composition that has a nematic phase in a wide temperature range and has appropriate optical anisotropy.

The liquid crystal composition of the present invention is generally prepared by a known method, for example, a method of dissolving necessary components at a high temperature.
In the preparation of the liquid crystal composition of the present invention, additives well known to those skilled in the art are added depending on the application. For example, the liquid crystal composition desirably contains an optically active compound and / or a polymerizable compound. Furthermore, it is desirable that the liquid crystal composition of the present invention contains at least one antioxidant and / or ultraviolet absorber.

  Examples of the optically active compound include known chiral dopants. This chiral dopant has the effect of inducing the helical structure of the liquid crystal to adjust the necessary twist angle and preventing reverse twist. Examples of the chiral dopant include the following optically active compounds (Op-1) to (Op-14). In these formulas, * represents an asymmetric carbon.

The liquid crystal composition of the present invention can adjust the pitch of twist by adding these optically active compounds. The twist pitch is preferably adjusted in the range of 40 to 200 μm in the case of a liquid crystal composition for TFT and TN. If it is the liquid crystal composition for STN, it is preferable to adjust to the range of 6-20 micrometers. In the case of the bistable TN (Bistable TN) mode, it is preferably adjusted to a range of 1.5 to 4 μm. Two or more optically active compounds may be added for the purpose of adjusting the temperature dependence of the pitch.

The liquid crystal composition of the present invention can also be used as a PSA (Polymer Sustained Alignment) type liquid crystal composition by adding a polymerizable compound.
Examples of the polymerizable compound include at least one polymerizable compound selected from the group of compounds represented by formula (5).

In formula (5), ring K and ring M are independently cyclohexyl, cyclohexenyl, phenyl, 1-naphthyl, 2-naphthyl, tetrahydropyran-2-yl, 1,3-dioxane-2-yl, pyrimidine- 2-yl or pyridin-2-yl, and in these rings, at least one hydrogen is halogen, alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, or at least one hydrogen being halogen. May be substituted with substituted alkyl having 1 to 12 carbons; ring L is 1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene, naphthalene-1,2-diyl Naphthalene-1,3-diyl, naphthalene-1,4-diyl, naphthalene-1,5-diyl, naphthalene-1,6-diyl, Phthalene-1,7-diyl, naphthalene-1,8-diyl, naphthalene-2,3-diyl, naphthalene-2,6-diyl, naphthalene-2,7-diyl, tetrahydropyran-2,5-diyl, 1 , 3-dioxane-2,5-diyl, pyrimidine-2,5-diyl, or pyridine-2,5-diyl, in which at least one hydrogen is halogen, alkyl having 1 to 12 carbons , Alkoxy having 1 to 12 carbons, or alkyl having 1 to 12 carbons in which at least one hydrogen is replaced by halogen, and when a plurality of rings L are present, they may be the same, Or it may be different. Z ⁴ and Z ⁵ are each independently a single bond or alkylene having 1 to 10 carbons, in which at least one —CH ₂ — is —O—, —CO—, —COO—, or It may be replaced by -OCO-, at least one -CH ₂ -CH ₂ - is, -CH = CH -, - C (CH 3) = CH -, - CH = C (CH 3) -, or - C (CH ₃ ) ═C (CH ₃ ) — may be replaced, and in these groups, at least one hydrogen may be replaced by fluorine or chlorine, and the same when a plurality of Z ⁵ are present. May be different or different. P ¹ , P ² , and P ³ are each independently a polymerizable group, and when there are a plurality of P ¹ , P ² , and P ³ , they may be the same or different; Sp ² , Sp ³ , and Sp ⁴ are each independently a single bond or alkylene having 1 to 10 carbons, in which at least one —CH ₂ — is —O—, — COO—, —OCO—, or —OCOO— may be replaced, and at least one —CH ₂ —CH ₂ — may be replaced with —CH═CH— or —C≡C— In the group, at least one hydrogen may be replaced by fluorine or chlorine; g is 0, 1, or 2; h, j, and k are independently 0, 1, 2, 3, Or 4; and h, j, and the sum of k is 1 or more, Sp ^2, Sp ^3, and if Sp ⁴ is present in plural may be may be the same or different.

In Formula (5), P ¹ , P ² , and P ³ are each independently a polymerizable group selected from the group of groups represented by Formula (P-1) to Formula (P-6). It is preferable.

In formula (P-1) to formula (P-6), M ¹ , M ² , and M ³ are independently hydrogen, fluorine, alkyl having 1 to 5 carbons, or at least one hydrogen is replaced by halogen In formula (5), when all of h P ¹ and k P ³ are groups represented by formula (P-4), At least one of Sp ¹ and k Sp ^{3 is} a group in which at least one —CH ₂ — is replaced by —O—, —COO—, —OCO—, or —OCOO—.
As the polymerizable compound, compounds represented by the formulas (5-1) to (5-27) are preferable.

In formula (5-1) to formula (5-27), P ⁴ , P ⁵ and P ⁶ are independently from the group of groups represented by formula (P-1) to formula (P-3). A selected polymerizable group;

In formula (P-1) to formula (P-3), M ¹ , M ² , and M ³ are independently hydrogen, fluorine, alkyl having 1 to 5 carbons, or at least one hydrogen is replaced by halogen In formulas (5-1) to (5-27), Sp ² , Sp ³ , and Sp ⁴ are each independently a single bond or a carbon number of 1 to 10 In which at least one —CH ₂ — may be replaced by —O—, —COO—, —OCO—, or —OCOO—, and at least one —CH ₂ —CH ₂ -May be replaced by -CH = CH- or -C≡C-, in which at least one hydrogen may be replaced by fluorine or chlorine.

  The amount of the polymerizable compound used is about 0.03% by weight or more based on the weight of the liquid crystal composition, and about 10% by weight or less to prevent display defects of the device. A more preferred addition ratio is in the range of approximately 0.1% by weight to approximately 2% by weight. A particularly preferred addition ratio is in the range of about 0.2% by weight to about 1.0% by weight.

  In order to adapt to a polymer support alignment (PSA) type device, a polymerizable compound different from the compound (5) may be added to the composition together with the polymerizable compound (5). Preferable examples of such a polymerizable compound are compounds such as acrylate, methacrylate, vinyl compound, vinyloxy compound, propenyl ether, epoxy compound (oxirane, oxetane), vinyl ketone and the like. Further preferred examples are acrylate or methacrylate derivatives. A desirable ratio of compound (5) is 10% by weight or more based on the total weight of the polymerizable compound. A more desirable ratio is 50% by weight or more. A particularly desirable ratio is 80% by weight or more. The most preferred ratio is 100% by weight.

  A polymerizable compound such as compound (5) is polymerized by ultraviolet irradiation. The polymerization may be performed in the presence of a suitable initiator such as a photopolymerization initiator. Appropriate conditions for polymerization, the appropriate type of initiator, and the appropriate amount are known to those skilled in the art and are described in the literature. For example, Irgacure 651 (registered trademark; BASF), Irgacure 184 (registered trademark; BASF), or Darocur 1173 (registered trademark; BASF), which are photoinitiators, are suitable for radical polymerization. A desirable ratio of the photopolymerization initiator is in the range of approximately 0.1% by weight to approximately 5% by weight based on the total weight of the polymerizable compound. A more desirable ratio is in the range of approximately 1% by weight to approximately 3% by weight.

  In order to prevent a decrease in specific resistance due to heating in the atmosphere or to maintain a large voltage holding ratio not only at room temperature but also at a temperature close to the upper limit temperature after using the device for a long time, an antioxidant is composed. Added to the product. A preferred example of the antioxidant is a compound (7) wherein n is an integer of 1 to 9.

  In the compound (7), preferred n is 1, 3, 5, 7, or 9. Further preferred n is 7. Since the compound (7) in which n is 7 has low volatility, it is effective for maintaining a large voltage holding ratio not only at room temperature but also at a temperature close to the upper limit temperature after the device has been used for a long time. A desirable ratio of the antioxidant is approximately 50 ppm or more for achieving its effect, and is approximately 600 ppm or less for avoiding a decrease in the maximum temperature or avoiding an increase in the minimum temperature. A more desirable ratio is in the range of approximately 100 ppm to approximately 300 ppm.

  Preferred examples of the ultraviolet absorber include benzophenone derivatives, benzoate derivatives, triazole derivatives and the like. Also preferred are light stabilizers such as sterically hindered amines. A desirable ratio of the absorbent and the stabilizer is approximately 50 ppm or more for achieving the effect thereof, and approximately 10,000 ppm or less for avoiding a decrease in the maximum temperature or avoiding an increase in the minimum temperature. A more desirable ratio is in the range of approximately 100 ppm to approximately 10,000 ppm.

  The liquid crystal composition of the present invention can be obtained as a GH type liquid crystal composition by adding a dichroic dye such as merocyanine, styryl, azo, azomethine, azoxy, quinophthalone, anthraquinone, and tetrazine. It can also be used.

  The liquid crystal composition of the present invention includes NCAP produced by microencapsulating nematic liquid crystal, polymer dispersed liquid crystal display device (PDLCD) produced by forming a three-dimensional network polymer in liquid crystal, for example, polymer network liquid crystal display It can also be used as a liquid crystal composition for birefringence control (ECB) type and DS type as well as element (PNLCD).

  In the liquid crystal composition according to the present invention, for example, when the compound constituting each component is a liquid, by mixing each compound, and when the compound includes a solid, the respective compounds are mixed and dissolved by heating. By mixing them with each other and mixing them. The liquid crystal composition according to the present invention can also be prepared by other known methods.

[Optical element]
The optical element according to the present invention is characterized by using the liquid crystal compound or the liquid crystal composition.
Specifically, an electrode is disposed on one or both surfaces, and a liquid crystal compound or liquid crystal composition disposed between the substrates, and an electric field applying unit that applies an electric field to the liquid crystal compound or liquid crystal composition via the electrode It is an optical element provided with.

  When no electric field is applied, the liquid crystalline compound or liquid crystal composition is optically isotropic. However, when an electric field is applied, the liquid crystalline compound or liquid crystal composition exhibits optical anisotropy and can be modulated by an electric field. Become.

It is also an embodiment of the optical element of the present invention that the electrodes are arranged in a matrix to form a pixel electrode, each pixel includes an active element, and the active element is a thin film transistor (TFT).
Such an optical element can be used for an optical display device such as a liquid crystal display device, an organic EL display device, or a PDP.

Evaluation in the present invention was performed as follows.
[ ¹ H-NMR, ¹³ C-NMR analysis]
¹ H-NMR spectrum (abbreviated as ¹ H-NMR) and ¹³ C-NMR spectrum (abbreviated as ¹³ C-NMR)
Measured using a Bruker DPX300 NMR. When CDCl ₃ was used as the solvent, Tetramethylsilane (TMS) was used as the internal standard substance. Chemical shifts were expressed in δ values (ppm), and the following abbreviations were used for peak splitting. s (single line), d (double line), t (triple line), q (quadruple line), quin (quintet line), sext (hexet line), hept (seven line), m (multiple line) ), Br (broad).

[IR measurement]
IR spectra were measured with a PerkinElmer Spectrum Two Fourier transform infrared absorption spectrometer using KBr pellets or KBr plates.

[MS spectrum measurement]
Mass (MS) spectra were measured with Thermo Fisher Scientific's Active Mass Spectrometer.

[Phase structure and transition temperature (℃)]
The phase structure and the transition temperature were measured by the following methods (1) and (2).
(1) Phase identification with a polarizing microscope (Nikon ECLIPSE E400 POL) was performed by placing a sample on a hot cool stage (Hot Cool Stage HCS400 manufactured by Instec Corporation) and observing changes in the state while heating.
(2) DSC 3100 S was used as a differential scanning calorimeter manufactured by Mac Science Co., Ltd., and the transition temperature was determined from the endothermic peak or exothermic peak accompanying the phase change of the sample by raising and lowering the temperature of the sample.

[Observation of optical response behavior by voltage application]
The device is a cell (eetch cell) that is coated with a polyimide alignment film on an ITO electrode glass substrate with antiparallel horizontal alignment and then rubbed and assembled so that the distance between the two glass substrates is 15 μm or 5 μm. The liquid crystalline compound was heated to a nematic or liquid state and then introduced between the electrodes by capillary action.

  A hot-cool stage of the melting point measurement device (Hot-cool stage by Instec Co., Ltd.) so that the rubbing direction and the polarizer or analyzer are at an angle of 20 to 45 ° to a polarizing microscope in which the polarizer and the analyzer are orthogonal to each other. HCS400).

  The voltage is applied to Yokogawa Electric's function generator FG110, Keyence oscillograph NR-2000, and FLC electronics high-speed amplifier F10A. .15 Hz, triangular wave) was applied, and the change in color tone accompanying voltage application was observed with a polarizing microscope.

[Synthesis example]
Compounds 1 to 6 were synthesized by the following synthesis method.

Compound 50 Synthesis Oven-dried 50 mL three-necked flask equipped with Dimroth and calcium chloride tubes, NaH (0.12 grams, 3.2 mmol, 60% dispersion in mineral oil) and dry THF (7 mL) under N ₂ atmosphere It was. Subsequently, when compound 7 (0.30 grams, 0.79 mmol) was added and gently heated at about 50 ° C., the solution gradually turned pale yellow. A solution of cyclohexanecarbaldehyde (0.23 mL, 1.9 mmol) in THF (5 mL) was added dropwise via a 25 mL addition funnel over 1 hour.

After completion of the dropwise addition, the reaction was completed by heating and holding at about 50 ° C. with stirring for 3 hours. After cooling to room temperature and carefully decomposing and neutralizing a small amount of unreacted NaH by adding 1N HCl, the reaction solution was extracted three times with CHCl ₃ . The organic layer was washed with saturated brine, and then dried over anhydrous MgSO ₄ . The solution was filtered and the solvent was removed by vacuum distillation. The crude product was purified by silica gel column chromatography using hexane as the eluent. Compounds 2, 3, 4, 5 and 6 were synthesized by the same synthesis method using the corresponding aldehyde and phosphonium salt, respectively.

Synthesis scheme of compound 1

Compound 1: Yield 57%; White solid; Rf = 0.31 (n-hexane only);
IR (KBr) 2925, 2853, 1705, 1512, 1449, 967, 803 cm ^-1 ;
¹ H-NMR (CDCl ₃ , 300 MHz) δ; 1.15 − 1.34 (m, 10H), 1.66-1.81 (m, 10H), 2.10 −2.13 (m, 2H), 6.15 (dd, J = 15.9, 3.4 Hz, 2H), 6.31 (dd, J = 15.9, 0.8 Hz, 2H), 7.26 (s, 4H);
¹³ C-NMR (CDCl ₃ , 75 MHz) δ; 25.96, 26.08, 32.87, 41.09, 125.93, 126.87, 136.18, 136.46;
HRMS (APPI) calcd for C ₂₂ H ₃₀ [M ⁺ ] 294.2342, found 294.2337.

Synthesis scheme of compound 2

Compound 2: Yield 27%; white solid; Rf = 0.31 (n-hexane only);
IR (KBr) 2961, 2874, 1496, 1449, 969, 804 cm ^-1 ;
¹ H-NMR (CDCl ₃ , 300 MHz) δ; 0.93 (t, J = 7.3 Hz, 6H), 1.44 (sext, J = 7.4 Hz, 4H), 2.11 (q, J = 7.1 Hz, 4H), 5.80 − 5.87 (m, 2H), 6.16 − 6.25 (m, 2H), 6.43 (d, J = 15.8 Hz, 2H), 6.75 (dd, J = 15.6, 10.5 Hz, 2H), 7.31 (s, 4H);
¹³ C-NMR (CDCl ₃ , 75 MHz) δ; 13.64, 22.40, 34.88, 126.21, 129.03, 129.56, 130.64, 135.64, 136.42;
HRMS (APPI) calcd for C ₂₀ H ₂₇ [M ⁺ ] 267.2107, found 267.2104.

Synthesis scheme of compound 3

Compound 3: yield 35%; white solid; Rf = 0.29 (n-hexane only);
IR (KBr) 2924, 2851, 1705, 1512, 1496, 1449, 969, 804 cm ^-1 ;
¹ H-NMR (CDCl ₃ , 300 MHz) δ; 1.12 − 1.31 (m, 10H), 1.75-1.80 (m, 10H), 2.16 (m, 2H), 6.21 (dd, J = 16.1, 6.9 Hz, 2H) , 6.31 (d, J = 15.9 Hz, 2H), 7.40 (d, J = 8.1 Hz, 4H), 7.53 (d, J = 8.4 Hz, 4H);
¹³ C-NMR (CDCl ₃ , 75 MHz) δ; 25.96, 26.07, 32.86, 41.14, 126.22, 126.66, 126.76,136.89, 139.02; (Two peaks at 136.89 ppm cannot be separated)
HRMS (APPI) calcd for C ₂₈ H ₃₄ [M ⁺ ] 370.2655, found 370.2647.

Synthesis scheme of compound 4

Compound 4: Yield 8.5%; white solid; Rf = 0.40 (n-hexane only);
IR (KBr) 2923, 2846, 1651, 1511, 1448, 963, 803 cm ^-1 ;
¹ H-NMR (CDCl ₃ , 300 MHz) δ; 0.88 (t, J = 7.2 Hz, 6H), 0.92-1.00 (m, 4H), 1.21-1.36 (m, 14H), 1.80 (m, 8H), 2.04 (m, 2H), 6.14 (dd, J = 16.0, 6.9 Hz, 2H), 6.31 (dd, J = 16.9, 0.96 Hz, 2H), 7.26 (s, 4H);
¹³ C-NMR (CDCl ₃ , 75 MHz) δ; 14.34, 19.93, 29.64, 32.84, 36.92, 39.67, 41.40, 125.80, 125.94, 126.93, 136.11, 136.46;
HRMS (APPI) calcd for C ₂₈ H ₄₂ [M ⁺ ] 378.3281, found 378.3270.

Synthesis scheme of compound 5

Compound 5: Yield 14%; White solid; Rf = 0.34 (n-hexane only);
IR (KBr) 2953, 2921, 2844, 1488, 960, 799 cm ^-1 ;
¹ H-NMR (CDCl ₃ , 300 MHz) δ; 0.89 (t, J = 6.9 Hz, 6H), 0.96 (br, 2H), 1.12 − 1.27 (m, 24H), 1.79 − 1.82 (m, 8H), 2.04 -2.06 (m, 2H), 6.14 (dd, J = 15.8, 6.81 Hz, 2H), 6.31 (d, J = 16.5 Hz, 2H), 7.26 (s, 4H);
¹³ C-NMR (CDCl ₃ , 75 MHz) δ; 14.05, 22.63, 32.12, 32.82, 32.86, 37.19, 37.32, 41.40, 125.92, 126.88, 136.14, 136.43;
HRMS (APPI) calcd for C ₃₂ H ₅₀ [M ⁺ ] 434.3907, found 434.3894.

Synthesis scheme of compound 6

Compound 6: Yield 29%; White solid; Rf = 0.34 (n-hexane only);
IR (KBr) cm ^-1 ; 2914, 2848, 1645, 1446, 973, 890 cm ^-1 ;
¹ H-NMR (CDCl ₃ , 300 MHz) δ; 0.89 (t, J = 7.2 Hz, 6H), 0.93 − 1.01 (m, 4H), 1.13- 1.39 (m, 14H), 1.78 − 1.84 (m, 8H) , 2.06 − 2.08 (m, 2H), 2.28 (s, 6H), 6.01 (dd, J = 15.8, 7.1 Hz, 2H), 6.48 (d, J = 15.8 Hz, 2H), 7.18 (s, 2H);
¹³ C-NMR (CDCl ₃ , 75 MHz) δ; 14.33, 19.29, 19.92, 32.84, 32.99, 36.90, 39.67, 41.75, 124.63, 126.80, 132.32, 135.26, 137.26;
HRMS (APPI) calcd for C ₃₀ H ₄₆ [M ⁺ ] 406.3594, found 406.3584.

[Evaluation example]
Table 1 shows the phase transition behavior of the synthesized compounds 1-6. Among the synthesized compounds 1 to 6, compounds 2, 4 and 5 exhibited liquid crystal, and compounds 4 and 5 exhibited a nematic phase. Cr represents a crystalline phase, Sm represents a smectic phase, N represents a nematic phase, Iso represents an isotropic liquid, G represents a glass state, and X represents an unidentified phase (a phase that is a liquid crystal phase but whose type cannot be specified).

The reason why only the smectic phase was expressed in the compound 2 is considered to be that the molecular mobility decreased due to the increase in the number of double bonds, and the layer ordered structure was stabilized.
Comparison of compounds 1 and 3 and compound 4 revealed that the liquid crystallinity was sufficiently affected not only by the influence of the core part but also by the presence or absence of alkyl chains R ¹ and R ² .

In compound 5, a smectic phase was newly developed by extending the alkyl chain. This is considered that a smectic phase with improved stability appears. Further, in compounds 4 and 5, a nematic phase was developed. This is thought to be due to the balance between the R ¹ and R ² alkyl chains and the interaction of the core (aromatic ring and double bond), steric hindrance in the cyclohexane moiety, and molecular mobility.

  Compound 6 was obtained by introducing a methyl group into compound 4, and was synthesized with the aim of reducing the interaction and bringing the phase transition temperature closer to room temperature. As a result, the compound 6 did not exhibit liquid crystallinity. It is considered that by introducing a methyl group in each uniaxial direction of the aromatic ring, the interaction was reduced too much and liquid crystal properties were not exhibited.

[Example 1]
The following voltage application experiment was performed on the compound 4 expressing the nematic phase.
An electric cell (ITO area: 1 cm × 1 cm, cell gap is 5 and 15 μm, respectively) shown in FIG. 1 is filled with compound 4, and DC voltage (cell spacing: 15 μm) or AC voltage ( A change in interference color was evaluated by applying a cell spacing of 5 μm. The results are shown in FIG.

When voltage was applied perpendicularly to the major axis direction of the liquid crystal molecules, it was confirmed that the interference color changes depending on the strength of the voltage.
Further, this change is in accordance with the interference color chart shown on the left of FIG. 2, and when the applied voltage is increased, the color is shifted downward. It is conceivable that the birefringence (Δn) is small. Considering the change in birefringence, as shown in FIG. 3, the inclination of the molecule due to the bias of electrons occurs in the long axis direction of the molecule, and the change in birefringence occurs according to the strength of the voltage. It is thought that there is not.

[Example 2]
The following voltage application experiment was performed on the compound 5 expressing the nematic phase.
An electric cell (ITO area: 1 cm × 1 cm, each cell gap is 5 μm) was filled with compound 5, and an alternating voltage was applied at 180 ° C. at which a nematic phase was developed to evaluate the change in interference color. The results are shown in FIG.

  When voltage was applied perpendicularly to the major axis direction of the liquid crystal molecules, it was confirmed that the interference color changes depending on the strength of the voltage.

[Example 3]
A voltage application experiment was conducted on the compound 4 expressing a nematic phase in order to examine the optical response in a transverse electric field as shown below.
Fringe Field Switching cell capable of applying lateral electric field (alignment treatment: anti-parallel, electrode area: 1 cm ² , cell gap: 3.5 μm, pixel electrode width: 3.5 μm, pixel electrode spacing: 7.0 μm, line and space: 10.5 μm ) Was filled with compound 4, and an alternating voltage was applied at 160 ° C. at which a nematic phase was developed, and the change in interference color was evaluated. The results are shown in FIG.

  Similar to the behavior in the vertical electric field in Examples 1 and 2, it was confirmed that the interference color changes depending on the voltage strength with respect to the horizontal electric field.

Claims (8)

The compound represented by Formula (1).
(In the formula (1), R ¹ , R ² and R ³ are independently a hydrogen atom or an alkyl having 1 to 10 carbon atoms, and in these groups, at least one —CH ₂ — is —O—, —S—, —CO—, or —SiH ₂ — may be substituted, and at least one — (CH ₂ ) ₂ — may be substituted with —CH═CH— or —C≡C—. n is an integer of 0 to 4. m is an integer of 1 or 2. Z ¹ and Z ² are —CH═CH—.   2. A compound according to claim 1 exhibiting a nematic phase.   A liquid crystal composition containing the compound according to claim 1.   The liquid crystal composition according to claim 3, which exhibits a nematic phase.   The liquid crystal composition according to claim 3 or 4, comprising at least one optically active compound and / or polymerizable compound.   Furthermore, the liquid-crystal composition of any one of Claims 3-5 containing an at least 1 antioxidant and / or a ultraviolet absorber.   The optical element using the liquid crystalline compound or liquid crystal composition of any one of Claims 1-6.   An optical display device using the optical element according to claim 7.