JPH072701B2 - Optically active ester compound and liquid crystal composition using the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to an optically active ester compound used for a display element or an electro-optical element, and a ferroelectric smectic liquid crystal composition using the same.

[Prior Art] A liquid crystal display element using a nematic liquid crystal conventionally used for a display unit of a timepiece calculator or the like has a response speed which is much slower than that of another display element, for example, a light emitting diode. Areas where a response is required, eg optical communication,
Applications to liquid crystal display devices for printer heads have been limited.

Recently, as a liquid crystal display device exhibiting high-speed response, a liquid crystal display device using a smectic liquid crystal exhibiting ferroelectricity has been reported (for example, NA, Clark, STLagerwall, Appl.Phys.
Lett. 36 , 899 (1980)) is attracting attention.

Smectic liquid crystals exhibiting ferroelectricity include a chiral smectic C phase and a chiral smectic H phase, which have a layered structure in which liquid crystal molecules are inclined not perpendicular to the stacking direction of layers. This tilt direction is
The liquid crystal molecules are arranged in a spiral around the layer stacking direction, and spontaneous polarization occurs in a direction parallel to the layer and perpendicular to the liquid crystal molecules, and exhibits ferroelectricity. This helical structure is considered to be the cause of the ferroelectricity. A material exhibiting ferroelectricity exhibits responsiveness as a ferroelectric substance to an electric field, and reorients by inverting the direction of spontaneous polarization according to the direction of the electric field.

At this time, it is known that the responsiveness has a large spontaneous polarization, and the lower the viscosity is, the faster the response is for the same electric field strength. In addition, an element using a ferroelectric smectic liquid crystal has a memory property, and researches using this memory property for high-density display are being actively conducted.

[Problems to be Solved by the Invention] As a ferroelectric smectic liquid crystal, conventionally, many compounds of a Schiff base type as shown below have been studied.

p-decyloxybenzylidene-p'-amino-2-methylbutyl-cinnamic acid ester (DOBAMBC) However, such a Schiff base type compound has a problem that its spontaneous response is slow and its response is slow.

Further, as an ester type compound exhibiting a chiral smectic C phase, a compound represented by the following general formula (II) has been known.

(GW Gray et al. Mol.Cryst.Liq.Cryst., 1976, 37 189−211) (R is a linear alkyl group having 5 to 10 carbon atoms) However, this ester compound also has a problem that the spontaneous polarization is small and the response is slow.

[Means for Solving the Problem] The present invention has been made to solve the above-described problems, and has the general formula (In the formula, R represents an alkyl group or an alkoxy group having 1 to 12 carbon atoms, ring A represents trans-1,4-disubstituted cyclohexylene, and ring B represents 1,4-disubstituted phenylene or trans-1. Represents a 4,4-disubstituted cyclohexylene, n represents 0 or 1, and R ′ represents 1 to 1 carbon atoms.
12 alkyl groups or R ″ represents a hydrogen atom, an alkyl group or an alkoxy group having 1 to 12 carbon atoms, a cyano group or a halogen atom, and * represents an optically active center.) Is an optically active ester compound represented by the general formula It is a ferroelectric smectic liquid crystal composition containing at least one optically active ester compound represented by (I).

Since the compound of the general formula (I) has a single bond between the rings, it has a low viscosity and is preferable.

Ring A represents trans-1,4-substituted cyclohexylene, and Ring B represents 1,4-disubstituted phenylene or trans-.
Represents a 1,4-disubstituted cyclohexylene. Transformer
Since 1,4-di-substituted cyclohexylene has a lower viscosity than 1,4-di-substituted phenylene, on the other hand, a compound having a large molecular weight has a higher viscosity, so ring A is changed to trans-1,4-di-substituted cyclohexylene. By doing so, the viscosity can be lowered.

R is an alkyl group having 1 to 12 carbon atoms or 1 to 12 carbon atoms.
Represents 12 alkoxy groups. Further, when the carbon number is small, the melting point is high, and when it is too large, the viscosity is high, so that it is set to 1 to 12, but 2 to 8 is preferable. Further, it may be linear or branched, but in general, a linear one is preferable because it has a higher liquid crystal upper limit temperature showing a smectic C phase when mixed with another compound showing liquid crystallinity.

R'represents an alkyl group having 1 to 12 carbon atoms or a phenyl group having a substituent at the p-position. When it is not an alkyl group, it is an ester of benzyl alcohol and is chemically unstable. Is preferred. Further, in the case of an alkyl group, it may be linear or branched,
In general, a straight-chain compound is preferable because it has a higher maximum liquid crystal temperature that exhibits a smectic C phase when mixed with another compound exhibiting liquid crystallinity.

Therefore, the preferred embodiments of the present invention are as follows.

An optically active ester compound represented by the formula (I) in which R and R'represent a linear alkyl group having 1 to 12 carbon atoms, a ring B represents a 1,4-disubstituted phenylene, and n represents 1. .

The optical rotatory power of the compound represented by the general formula (I) may be levorotatory or dextrorotatory.

The compound represented by the general formula (I) is used for a ferroelectric smectic liquid crystal display device or an electro-optical device, so that it has another chiral smectic C phase in a desired temperature range. , A smectic liquid crystal or other optically active substance, and used as a ferroelectric smectic liquid crystal composition. Further, nematic liquid crystals, non-liquid crystals, dichroic dyes, etc. may be added for adjusting the helical pitch and for displaying colors. When the content of the compound represented by formula (I) in the ferroelectric smectic liquid crystal composition of the present invention is too large, the ferroelectric smectic maximum temperature tends to be lowered, and when it is too small. The effect of increasing the spontaneous polarization is small, so it is set to 1 to 90 wt%, preferably 2 to 50%.
wt% is good.

Examples of the counterpart compound used as a ferroelectric smectic liquid crystal composition by mixing with the compound of the general formula (I) of the present invention include the following.

In the following examples, R ^* represents an optically active alkyl group or alkoxy group, R has no relation to R of the present invention, and represents a linear or branched alkyl group or alkoxy group, which is identical to one compound. R ^* and R are not necessarily the same groups.

In addition to these, various known liquid crystal or non-liquid crystal liquid crystal additives can be used in combination, and examples thereof include the following.

And compounds obtained by substituting a part of hydrogen atoms of these benzene ring, cyclohexane ring and the like with halogen, cyano group, methyl group and the like.

Examples of this are compounds such as the following compounds having a negative dielectric anisotropy. In the following examples, R has nothing to do with R of the present invention and represents a linear or branched alkyl group having 1 to 12 carbon atoms, and even if the same R is shown in one compound, They are not necessarily the same groups.

Examples of the dichroic dye include dyes used in so-called guest-host type liquid crystal display elements such as trisazo type and anthraquinone type.

The ferroelectric liquid crystal display element or the electro-optical element is arranged so as to sandwich the liquid crystal layer, and at least one substrate is transparent and has a plurality of substrates having electrodes on the whole surface or a part thereof, and surrounds the liquid crystal layer. And a seal member formed between the electrode substrates. In the liquid crystal display element, the thickness between the substrates is 0.
5 to 20 μm is preferable. Further, the substrates may be subjected to alignment control processing parallel to each other. As a means for controlling the orientation, an orientation control film may be applied partially or entirely on the electrode substrate. As the orientation control film, a polymer material such as polyimide having a refractive index of 1.5 or more is preferable. Further, it is preferable that at least one polarizer is attached to the liquid crystal element. At least two electrode substrates are required, but a larger number of electrode substrates may be stacked and used.

The compound of the present invention can be synthesized, for example, by the route shown below.

(In the formula, R, R ', ring A, ring B, n and * have the above meanings.) That is, carboxylic acid (III) is treated with a chlorinating agent such as thionyl chloride or phosphorus oxychloride to form an acid chloride ( IV), and in the presence of a basic substance such as pyridine,
-Reaction with cyano alcohol (V), extraction, recrystallization,
Pure (I) can be synthesized by performing a series of purification treatments such as distillation and column chromatography.

[Examples] Next, the present invention will be specifically described with reference to Examples.

Example 1 After heating 3.50 g (0.01 mol) of the compound of Example 3 with 10 ml of thionyl chloride and 40 ml of carbon tetrachloride at reflux temperature for 4 hours, the low boiling point substances were removed by an evaporator. Was obtained as a yellow oil. This is toluene
Dissolve it in 15 ml and add it to the method of Elliott et al. (JDElliott,
VMFChoi and WSJohnson, J.Org.Chem., 48 , 2294 (19
83)) 1.69 g (0.01 mol) of the compound of 1 was dissolved in 10 ml of toluene, 4 ml of pyridine was added, and the mixture was stirred at room temperature for 4 hours. The mixture was poured into 100 ml of water and extracted with toluene. The toluene layer was washed with water and dried over anhydrous magnesium sulfate, and then the solvent was distilled off. The remaining oily substance was subjected to alumina column chromatography using toluene as a developing solvent,
Further, recrystallize twice from 20 ml of ethanol to obtain the target. Was obtained. Yield 2.2 g (0.0044 mol), yield 44%,
Melting point 75.5 ° C.

[Α] _D ²⁵ = 5.9 ° (C = 0.82, CHCl ₃ , 1 = 10 mm) The ¹ H NMR spectrum of this compound was as follows.

(CDCl ₃ solvent TMS internal standard) δ 8.2 to 7.2 complex m 8H δ 5.60 t J = 7Hz 1H δ 2.8 to 0.8 complex m 38H The IR spectrum diagram of this compound is shown in FIG.

Examples 2, 3 and Reference Examples 1, 2 In the same manner as in Example 1, the corresponding carboxylic acid and optically active α
-The compound shown in Table 1 was obtained from cyano alcohol. In addition, Table 1 also shows the ¹ H NMR spectrum of the obtained compound.

Example 4 The compound of Example 1 was treated with 4-n-octyloxybenzoic acid-
5.2 wt% was mixed with 4'-n-hexyloxyphenyl. This mixture is a hot stage (FP-Metra, FP
-51) When observed under a polarized light microscope, a chiral smectic C phase was shown at 54.1 ° C or lower, a smectic A phase was shown at 54.1 ° C to 83.7 ° C, and a cholesteric phase was shown at 83.3 ° C to 93.3 ° C. The above shows an isotropic liquid phase. In addition, this mixture was sandwiched with 3μ spacers and enclosed in a cell with an electrode area of 1 cm ^{2, and} at a temperature 10 ° C lower than the upper limit temperature (Ts) indicating the smectic C phase.
Method such as Miyasato's method of applying 20Hz, 10V triangular wave (K.Miy
Its spontaneous polarization was measured according to Asato et al., Japan. J. Appl. Phys., 22 , L 661 (1983), and was 3.7 nC / cm ² .

The magnitude of spontaneous polarization depends on the ferroelectric liquid crystal that has been studied in the past. Considering that (DOBAMBC) is 3.7 nC / cm ² alone, the mixture is a mixture obtained by diluting the compound of Example 1 to 5.2 wt%, which is extremely large.

EFFECTS OF THE INVENTION The present invention provides an optically active ester compound represented by the general formula (I) which has large spontaneous polarization and is chemically stable, and a ferroelectric smectic liquid crystal composition containing at least one of the compounds. By providing, it has an excellent effect that a display element or an electro-optical element capable of high-speed response can be configured.

[Brief description of drawings]

FIG. 1 is an IR spectrum diagram of the compound of Example 1 of the present invention.

Claims (5)

[Claims] 1. A general formula (In the formula, R represents an alkyl group or an alkoxy group having 1 to 12 carbon atoms, ring A represents trans-1,4-disubstituted cyclohexylene, and ring B represents 1,4-disubstituted phenylene or trans-1. Represents a 4,4-disubstituted cyclohexylene, n represents 0 or 1, and R ′ represents 1 to 1 carbon atoms.
12 alkyl groups or R ″ represents a hydrogen atom, an alkyl or alkoxy group having 1 to 12 carbon atoms, a cyano group or a halogen atom, and * represents an optically active center). 2. The compound according to claim 1, wherein R in the general formula (I) is a linear group. 3. A compound represented by the formula (I), wherein R is a linear alkyl group, ring B represents 1,4-disubstituted phenylene, and n represents 1. The described compound. 4. The compound according to claim 1, 2, or 3, wherein R'in the general formula (I) represents a linear alkyl group. 5. A general formula (In the formula, R represents an alkyl group or an alkoxy group having 1 to 12 carbon atoms, ring A represents trans-1,4-disubstituted cyclohexylene, and ring B represents 1,4-disubstituted phenylene or trans-1. Represents a 4,4-disubstituted cyclohexylene, n represents 0 or 1, and R ′ represents 1 to 1 carbon atoms.
12 alkyl groups or R ″ represents a hydrogen atom, an alkyl group or an alkoxy group having 1 to 12 carbon atoms, a cyano group or a halogen atom, and * represents an optically active center). Ferroelectric smectic liquid crystal composition.