JP2663171B2 - Optically active compound and its use - Google Patents

Description

The present invention uses a novel optically active compound, a liquid crystal composition containing the compound, and a liquid crystal composition containing the compound or at least one of the compounds. The present invention relates to an optical switching element configured by:

[Conventional technology]

Liquid crystal display devices currently widely used in practice are the twisted nematic type (TN) and the dynamic scattering type (DS). These are displays using a nematic liquid crystal cell containing a nematic liquid crystal as a main component.One of the disadvantages of the conventional nematic liquid crystal cell is that the response speed is slow, and the response speed is only up to several milliseconds. can give. This is one of the factors that limit the application range of the nematic liquid crystal cell. On the other hand, it has recently become clear that a faster response can be obtained by using a smectic liquid crystal cell.

It is known that some optically active smectic liquid crystals exhibit ferroelectricity, and there is great interest in their applications. Ferroelectric liquid crystal, RB, 1975
It was first synthesized by RB Meyer et al. [J. Phys., 36, L69 (1975)], which is 4- (4-decyloxybenzylideneamino) -2. This is a siso base compound represented by '-methylbutylcinnamate (DOBAMBC), which is characterized by exhibiting ferroelectricity in an optically active state, for example, in a chiral smectic C phase. Later, NA Clark et al. [Appl. Phys. Lett.
Vol. 6, p. 899 (1980)], a high-speed response on the order of microseconds was discovered in a DOBAMBC thin film cell.
This triggered the use of ferroelectric liquid crystals not only for displays such as liquid crystal televisions, but also for optoelectronics-related elements such as optical printer heads, optical Fourier transform elements, and light valves, utilizing their high-speed response and memory properties. It is attracting attention as a material that can be used for parts. In a ferroelectric liquid crystal cell, the use of a material having a high dielectric constant and a large spontaneous polarization is advantageous because the cell can be driven at a high speed, and therefore a material having a large spontaneous polarization is desired.

In practice, it is necessary that the liquid crystal compound or the composition itself be stable and exhibit ferroelectricity in a wide temperature range around room temperature.

[Problems to be solved by the invention]

However, Schiff base-type compounds such as DOBAMBC have drawbacks in terms of stability against water, light, and the like, and have a ferroelectric temperature range of 40 ° C. or higher than room temperature. Did not. Therefore, realization of a material system that is physically and chemically stable and has a large spontaneous polarization is strongly expected as a ferroelectric liquid crystal material.

An object of the present invention is to obtain a novel optically active compound having excellent chemical stability and light stability, a large spontaneous polarization, and a wide temperature range of a chiral smectic C phase. Another object of the present invention is to provide a display element or the like having a high-speed response using such an optically active compound or a liquid crystal composition.

[Means for solving the problem]

In general, the first invention of the present invention relates to an optically active compound and has the following general formula I: (However, Q is a -COO- group, -O- group or a direct bond, R
Is an alkyl or alkyloxy group having 4 or more carbon atoms, m
Is 1 or 2, n is 0 or 1, m + n is 1 or 2,
—CF (CF ₃ ) OC ₃ F ₇ group or at least one of the groups R is an optically active group).

Further, the second invention of the present invention relates to a liquid crystal composition, and at least one of the optically active compounds of the first invention is provided.
It is characterized by containing a seed as a component.

The third invention of the present invention relates to an optical switching element, and is constituted by using the optically active compound of the first invention or a liquid crystal composition containing at least one of these compounds as a component. It is characterized by that.

The compound of the formula (I) has a central skeleton having a phenyl ester or biphenyl ester structure of 3,6-disubstituted pyridine carboxylic acid, and a long-chain substituent (having 4 carbon atoms) at both ends of the molecule. -18 are preferred), which itself exhibits liquid crystallinity. In addition, this compound has a carbonyl group and a CF ₃ group directly bonded to the asymmetric carbon, and the dipole moment of the pyridine ring or the CF ₃ group acts transversely to the molecular long axis, so that high light exposure is obtained. It has nature. In addition, since the presence of a plurality of fluorines lowers the surface energy, it is expected that the resistance to the rotation of the domain will be reduced in a thin cell indispensable for a ferroelectric liquid crystal as compared with a non-fluorinated compound. In addition, when used as a display element, high-speed response can be expected.

(Method for producing compound)

The optically active compound of the general formula (I) in the present invention can be produced, for example, according to the following synthetic route.

However, in the middle of the formula, it is intended to refer to _{-CF (CF 3) OC 3 F} 7 group in Pf.

An outline of the above manufacturing process is as follows.
-Reaction between propyloxypropionic acid chloride and 6-hydroxynicotinic acid in the presence of a basic substance to give 6-
(Perfluoro-1-propyloxyethylcarbonyloxy) nicotinic acid (II) is produced.

Next, compound (II) is converted to acid chloride (III) with a chlorinating agent such as thionyl chloride.

Finally, the desired compound (I) can be produced by reacting the acid chloride (III) with the hydroxy compound (IV) in the presence of a basic substance.

In the above production process, the target compound (I) is usually produced by using optically active perfluoro-2-propyloxypropionic acid, but when a compound in which R is an optically active group is used, the compound is racemic. The target compound can be produced in the same manner by using the above acid.

〔Example〕

Hereinafter, the present invention will be described more specifically with reference to Examples, but the scope of the present invention is not limited to these Examples.

Example 1 4.0 g of 6-hydroxynicotinic acid was dissolved in 80 ml of pyridine, a solution of 8.8 g of optically active perfluoro-2-propyloxypropionic acid chloride in 20 ml of chloroform was gradually added, and the mixture was heated at 55 to 60 ° C. for 5 hours. After cooling, water was added and the aqueous layer was extracted with chloroform. The organic layer was washed with water, dried over anhydrous magnesium sulfate, the solvent was distilled off, and the residue was recrystallized from water-ethanol to give 6- (par Fluoro-1-propyloxyethylcarbonyloxy) nicotinic acid (II) was prepared.

1.1 g of the above compound was heated under reflux with 5 ml of thionyl chloride for 4 hours, and the residue obtained by distilling off the thionyl chloride and the solvent under reduced pressure was dissolved in chloroform.
0.9 g of 4'-decyloxybiphenyl and 0.8 ml of triethylamine were added, reacted at 60 ± 5 ° C. for 5 hours, left overnight, poured into water and extracted with chloroform, washed with a dilute sodium hydroxide aqueous solution and then with water, and dried. The extract was dried over magnesium sulfate, purified by column chromatography on silica gel using chloroform-ethyl acetate as a solvent, the solvent was distilled off, and the residue was recrystallized from ethanol to give compound 6-.
(Perfluoro-1-propyloxyethylcarbonyloxy) pyridine-3-carboxylic acid-4'-decyloxy-4-biphenyl ester was produced.

When this compound is sealed in a glass cell with a gap of about 3 μm between transparent electrodes and observed with a polarizing microscope while applying an electric field of ± 5 V and 1 Hz, when the temperature drops, the domain is also inverted with the reversal of the electric field from 56 ° C. Was observed. Other phase transition temperatures are shown in Table 1 below together with other examples. Cry is a crystalline state and SC * is a ferroelectric chiral smectic C phase, which is a phase at least partially responding to the above-mentioned electric field. SA is smectic A phase, Ch is cholesteric phase,
I indicates an isotropic liquid phase. Indicates that the phase exists. () Indicates that the phase is monotropic.

This compound was prepared by the triangular wave method reported by Miyazato et al. (K. Miyazato,
H. Takezoe, A. Fukuda, and Japanese Journal of Applied Physics (Jpn.J. Appl. Phy
s.), 1983, vol. 22, p. L661], and the value was 152 nC / cm ² .

Example 2 Compound: 6- (perfluoro-1-propyl) in the same manner as in Example 1 except that octyl 4-hydroxy-4'-biphenylcarboxylate was used in place of 4-hydroxy-4'-decyloxybiphenyl. (Oxyethylcarbonyloxy) pyridine-3-carboxylic acid-4'-octyloxycarbonyl-4-biphenyl ester was prepared.

The phase transition temperature of this compound is as shown in Table 1. However,-indicates that the existence of the phase is not clear.

The value of spontaneous polarization measured in the same manner as in Example 1 was 11
It was 8 nC / cm ² .

Example 3 Compound: 6- (perfluoro-1-propyloxyethylcarbonyloxy) pyridine-3 in the same manner as in Example 1 using compound (II) and 4-hydroxybenzoic acid-4'-hexyloxyphenyl ester. -Carboxylic acid-4 '-(4-hexyloxyphenyloxycarbonyl) phenyl ester was prepared. The phase transition temperature of this compound is as shown in Table 1.

Example 4 Using the compound (II) and 4-hydroxybenzoic acid-4'-decylphenyl ester in the same manner as in Example 1, compound: 6- (perfluoro-1-propyloxyethylcarbonyloxy) pyridine-3- Carboxylic acid-4'-
(4-decylphenyloxycarbonyl) phenyl ester was produced. The phase transition temperature of this compound is as shown in Table 1.

Example 5 Compound: 6- (perfluoro-1-propyloxyethylcarbonyloxy) pyridine-3-carboxylic acid-4'-octyl in the same manner as in Example 1 using compound (II) and 4-octyloxyphenol. An oxyphenyl ester was prepared. The phase transition temperature of this compound is as shown in Table 1.

Example 6 Compound: 6- (perfluoro-1-propyloxyethylcarbonyloxy) pyridine-3-carboxylic acid-4 'in the same manner as in Example 1 using compound (II) and hexyl 4-hydroxybenzoate. -Hexyloxycarbonyl phenyl ester was prepared. The phase transition temperature of this compound is as shown in Table 1.

Example 7 Compound (II) prepared in the same manner as in Example 1 from racemic perfluoro-2-propyloxypropionic acid
And using 4-hydroxy-4 '-(1-methylheptyloxy) biphenyl in the same manner as in Example 1.
: 6- (perfluoro-1-propyloxyethylcarbonyloxy) pyridine-3-carboxylic acid-4 '-(1
-Methylheptyloxy) -4-biphenyl ester was prepared. The phase transition temperature of this compound is as shown in Table 1.

The value of the spontaneous polarization measured in the same manner as in Example 1 was 75.
It was nC / cm ² .

Example 8 Compound (II) prepared in the same manner as in Example 1 from racemic perfluoro-2-propyloxypropionic acid
Compound: 6- (perfluoro-1-propyloxyethylcarbonyloxy) pyridine-3-carboxylic acid-4'- and 4-hydroxy-4 '-(2-methylbutyl) biphenyl in the same manner as in Example 1. (2-Methylbutyl) -4-biphenyl ester was produced. The phase transition temperature of this compound is as shown in Table 1.

Example 9 Compound (II) prepared in the same manner as in Example 1 from racemic perfluoro-2-propyloxypropionic acid
Compound: 6- (perfluoro-1-propyloxyethylcarbonyloxy) pyridine-3-carboxylic acid in the same manner as in Example 1 and using 4-hydroxybenzoic acid-4 ′-(1-methylheptyloxy) phenyl -4'-
[4- (1-Methylheptyloxy) phenyloxycarbonyl] phenyl ester was produced. The phase transition temperature of this compound is as shown in Table 1.

Example 10 {Liquid crystal composition} 20 parts by weight of the compound in Example 2 were mixed with a non-chiral smectic liquid crystal of 4-
(2-methylbutyl) -4'-biphenylcarboxylic acid-
30 parts by weight of 4 "-hexyloxyphenyl ester and 4-octyloxy-4'-biphenylcarboxylic acid
A liquid crystal composition was prepared by mixing 50 parts by weight of 4 ″ -pentyloxyphenyl ester.

This liquid crystal composition exhibited an SC * phase in the range of 17 to 57 ° C., and the temperature range was significantly expanded as compared with the single compound.

Example 11 {Liquid crystal composition} 30 parts by weight of the non-chiral smectic liquid crystal compound of Example 10 and 10 parts by weight of the compound of Examples 3 and 4, respectively, and 4-
A liquid crystal composition was prepared by mixing 20 parts by weight of octyloxybenzoic acid-4 '-(2-methylbutyloxy) phenyl ester.

This liquid crystal composition exhibited an SC * phase in the range of 8 to 58 ° C., and the temperature range was remarkably expanded as compared with the case where each was alone.

Example 12 {Liquid Crystal Composition} To the compounds of Examples 5, 6 and 8, and 10 parts by weight of each, the three non-chiral smectic liquid crystal compounds of Example 11 were mixed in an amount of 20 parts by weight, respectively. Was prepared. This liquid crystal composition is 4 to 62 ° C
And the temperature range was remarkably expanded as compared with the case of the single compound.

As shown in the above three examples, by mixing a liquid crystal compound having a different structure with the compound of the present invention, a liquid crystal composition that becomes a chiral smectic C liquid crystal in a wider temperature range than when used alone, and above and below room temperature. Can be obtained.

Example 13 << Optical Switching Element >> The polyimide film formed on the glass surface with a transparent electrode was subjected to a rubbing alignment treatment, and the compound obtained in Example 1 was placed in a glass cell in which the gap between the transparent electrodes was kept at 3 μm with alumina powder. It was heated and filled as an isotropic liquid to produce a thin film liquid crystal cell. Cool the cell slowly to 52 ° C
Of the transmitted light intensity when a ± 20 V, 10 Hz square wave was applied, measured with a photomultiplier tube. The response time due to a 0-90% change in the light intensity was 57 μsec. Was observed.

Example 14 << Optical Switching Element >> Using the liquid crystal compositions prepared in Examples 10 to 12, a liquid crystal cell was produced in the same manner as in Example 13. Measurement temperature 41 ° C
The response times obtained under the same conditions as in Example 13 were 60, 82, and 44 μsec, respectively, and it was confirmed that high-speed response was exhibited.

〔The invention's effect〕

As described above, according to the present invention, since the optically active compound represented by the general formula I or the liquid crystal composition containing at least one of the optically active compounds as a component is used, the spontaneous polarization is large and the display is performed. When used as an element, not only high-speed response is possible, but also a material system and an optical switching element exhibiting a chiral smectic phase in a wide temperature range can be provided.

Claims (3)

(57) [Claims] (1) The following general formula (I): (However, Q is a -COO- group, -O- group or a direct bond, R
Is an alkyl or alkyloxy group having 4 or more carbon atoms, m
Is 1 or 2, n is 0 or 1, m + n is 1 or 2,
An optically active compound represented by —CF (CF ₃ ) OC ₃ F ₇ group or at least one of the groups R is an optically active group. 2. A liquid crystal composition comprising at least one optically active compound according to claim 1 as a component. 3. An optical switching element comprising the optically active compound according to claim 1, or a liquid crystal composition containing at least one of the compounds as a component.