JPH0466276B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to a liquid crystal compound whose molecular structure is easily changeable and which is an optically active lactic acid derivative, a liquid crystal composition containing the same, and a liquid crystal element using the liquid crystal composition. BACKGROUND ART Conventional liquid crystal elements include, for example, M. Schadt and W. Helfrich.
Helfrich), “Applied Physics Letters”, Volume 18, No. 4 (“Applied Physics Letters”,
Vol.18, No.．． 4) (1971.2.15), P.127-128 "Voltage-dependent optical behavior of twisted nematic liquid crystals"
(“Voltage-Dependent Optical Activity of a
A device using a TN (Twisted Nematic Liquid Crystal) liquid crystal described in “Twisted Nematic Liquid Crystal” is known.
TN liquid crystals have a problem in that crosstalk occurs during time-division driving using a matrix electrode structure with high pixel density, so the number of pixels has been limited. Furthermore, its use as a display has been limited due to its slow electric field response and poor viewing angle characteristics. Furthermore, a display element is known in which a switching element using a thin film transistor is connected to each pixel and switching is performed for each pixel, but the process of forming the thin film transistor on the substrate is extremely complicated, and it is difficult to use a display element with a large area. There are some problems that make it difficult to create. In order to improve the drawbacks of conventional liquid crystal devices, the use of bistable liquid crystal devices was proposed by Clark and Lagerwall (Japanese Patent Laid-Open No. 1983-1973).
-107216, US Pat. No. 4,367,924, etc.). In general, liquid crystals with bistability include:
A ferroelectric liquid crystal having a chiral smectic C phase (SmC ^* ) or H phase (SmH ^* ) is used. Because this ferroelectric liquid crystal has spontaneous polarization, it has an extremely fast response speed, can develop a bistable state with memory properties, and has excellent viewing angle characteristics, so it can be used for large-capacity, large-screen displays. It is suitable as Liquid crystal compounds used in ferroelectric liquid crystals have asymmetric carbon, so in addition to being used as ferroelectric liquid crystals using their chiral smectic phase, they can also be used for the following optical elements: It can also be used. (1) Those that utilize the cholesteric-nematic phase transition effect in the liquid crystal state (JJWysoki,
A.Adams and W.Haas; Phys.Rev.Lett., 20,
1024 (1968)), (2) one that utilizes the White-Taylor type guest-host effect in the liquid crystal state (DLWhite
and GNTaylor; J.Appl.Phys., 45 , 4718
(1974)), (3) By fixing a substance with a cholesteric phase in the liquid crystal state into a matrix, its selective scattering properties can be utilized and used as a notch filter or bandpass filter (F.
J. Kahn, Appl. Phys. Lett., 18, 231 (1971)),
Products used as circularly polarized beam splitters that utilize circularly polarized light characteristics (SDJacobs, SPIE,
37, 98 (1981)); etc. Although a detailed explanation of each method will be omitted, all of them are important as display elements and modulation elements. Conventionally, optically active intermediates for synthesizing functional materials required for optical elements characterized by having optical activity include 2-methylbutanol, secondary octyl alcohol, secondary butyl alcohol, and p-(chloride). Known examples include 2-methylbutylbenzoic acid, secondary phenethyl alcohol, amino acid derivatives, synthetic derivatives, and cholesterol derivatives. However, these have the following drawbacks. It is difficult to change the structure of optically active chain hydrocarbon derivatives and, with the exception of some, they are very expensive. Amino acid derivatives are relatively inexpensive and their structures can be easily changed, but the hydrogen groups of amines are chemically active and easily cause hydrogen bonds and chemical reactions, which tends to limit the properties of functional materials. . It is difficult to change the structure of chemical derivatives and cholesterol derivatives, and they tend to adversely affect the properties of functional materials due to steric hindrance. Furthermore, among optical elements characterized by having optical activity, polar groups have been introduced in order to improve responsiveness in methods using electro-responsive optical effects in a liquid crystal state. Most of the optically active intermediates had low polarity or were unable to utilize polar groups effectively. Particularly in ferroelectric liquid crystals, it is known that the response speed is proportional to the spontaneous polarization, and it is desired to increase the spontaneous polarization in order to increase the speed. From this point of view, P.keller et al. showed that it is possible to increase spontaneous polarization and speed up the response by introducing a chlorine group into an asymmetric carbon (CRAcad.Sc.
Paris, 282 C, 639 (1976)). However, chlorine groups introduced into asymmetric carbons are chemically unstable and have the disadvantage of decreasing the stability of the liquid crystal phase due to their large atomic radius, so improvements are desired. ing. The above-mentioned drawbacks have been a major constraint on the development of various materials. Purpose of the Invention In view of the above circumstances, the main object of the present invention is to provide a liquid crystal composition containing an optically active liquid crystal compound useful for controlling the liquid crystal state, and a liquid crystal element using the liquid crystal composition. be. The present invention also provides a liquid crystal composition containing a compound that produces large spontaneous polarization when used as a ferroelectric liquid crystal due to the presence of an oxygen atom adjacent to an asymmetric carbon atom, and a liquid crystal element using the liquid crystal composition. The purpose is to provide In addition, in the present invention, it is easy to change the length of the alkyl group, and this allows H.Arnold, Z.Phys.
Chem., 226 , 146 (1964), liquid crystal compositions containing at least one liquid crystal compound as a compounding component, which can control the type and temperature range of the liquid crystal phase developed in the liquid crystal state; An object of the present invention is to provide a liquid crystal element using a liquid crystal composition. Summary of the Invention The present invention is based on the general formula () (In the above general formula, R ¹ represents an alkyl group having 4 to 16 carbon atoms, R represents an alkyl group having 1 to 16 carbon atoms, respectively. Also, m and n are integers of 1 or 2, and k is 0 The present invention provides a liquid crystal composition containing at least one type of lactic acid derivative represented by (or 1, c ^* represents an optically active asymmetric carbon atom) and a liquid crystal element using the same. DETAILED DESCRIPTION OF THE INVENTION In the general formula () representing the above-mentioned optically active lactic acid derivative, R is an alkyl group having 1 to 16 carbon atoms. If the number of carbon atoms is 17 or more, the viscosity and molar volume of the final functional material will increase, which is undesirable. Further, the preferable number of carbon atoms of R is 2 to
It is 14. R ¹ is an alkyl group having 4 to 16 carbon atoms, and preferably R ¹ has 6 to 14 carbon atoms.
n=1 or 2 and k=0 or 1. An example of the method for synthesizing the optically active lactic acid derivative represented by the general formula () of the present invention is shown below using a reaction scheme. The optically active lactic acid derivative of the present invention is preferably 4-(2-alkoxypropyloxy)benzoic acid, 4'-(2-alkoxypropyloxy)biphenylcarboxylic acid, etc. shown in Japanese Patent Application No. 60-245709. It is synthesized via an optically active intermediate (compound of formula (f) below). That is, the compound in which R is an alkyl group [the compound of formula (a) above] can be synthesized by reacting a lactic acid ester and a hydrocarbon iodide in the presence of Ag ₂ O. In this case, it is preferable to mix the lactic acid ester and the hydrocarbon in a container, and then add Ag ₂ O to the mixture. Furthermore, in order to synthesize the compound of the above formula (b), a method is used in which the compound of the above formula (a) is treated with a reducing agent such as LiAlH ₄ . Furthermore, in the case of substituting an OH group with a halogen atom, a method is employed in which a halogenating agent such as PBr ₃ , SOCl ₂ or PCl ₅ is allowed to act on the compound of formula (b). In addition, in the case of tosylation, a method is used in which p-toluenesulfonic acid chloride is allowed to act on the compound of formula (b). By reacting the thus obtained compounds of formulas (c), (d), and (e) with p-hydroxybenzoic acid and p-hydroxybiphenylcarboxylic acid under alkaline conditions, formula (f) is obtained. It is possible to obtain a compound of Furthermore, the optically active liquid crystalline lactic acid derivative of the present invention can be obtained by converting the compound of formula (f) into an acid chloride with thionyl chloride and then reacting it with a compound represented by general formula (g). RI in the above reaction formula can be selected from a wide range of carbon numbers, and specifically includes iodobutane, iodopentane, iodohexane, iodoheptane, iodooctane, iodononane, iododecane, iodoundecane, iododecane, Iodotridecane, iodotetradecane, iodobentadecane, iodohexadecane,
Linear saturated hydrocarbon iodides such as iodoheptadecane, iodooctadecane, iodononadecane, iodoeicosane; branched saturated hydrocarbons such as 2-iodobutane, 1-iodo-2-methylpropane, 1-iodo-3-methylbutane, etc. There is iodide. Optically active lactic acid derivatives can be obtained by freely selecting from the above iodides. Table 1 shows the phase transition temperature and optical rotation of the optically active liquid crystalline lactic acid derivative thus obtained.

[Table] The liquid crystal composition of the present invention contains at least one optically active substance or a liquid crystal lactic acid derivative represented by the above general formula () as a compounding component. Among the above compositions, those containing ferroelectric liquid crystals as represented by the following formulas (1) to (13) can increase spontaneous polarization and further reduce viscosity. It is preferable that the response speed can be improved in combination with the effect of In such a case, it is preferable to use the liquid crystalline lactic acid derivative of the present invention represented by the general formula () in a proportion of 0.1 to 99% by weight, particularly preferably 1 to 90% by weight.
Used in % by weight.

【table】

【table】

【table】

[Table] In addition, by blending the liquid crystalline lactic acid derivative of the above general formula () with a smectic liquid crystal that is not chiral itself as shown in the following formulas (1) to (5), it can be used as a ferroelectric liquid crystal. A usable composition is obtained. In such cases, the liquid crystalline lactic acid derivative of the present invention represented by the general formula () can be used in a proportion of 1.0 to 99% by weight.

【table】

[Table] Furthermore, the nematic liquid crystal containing at least one lactic acid derivative of the present invention as a compounding component is preferable because it can prevent the occurrence of reverse domains when used in a twisted-machine (TN) type cell. Effects of the Invention As described above, the optically active liquid crystalline lactic acid derivative of the present invention combines an optically active lactic acid derivative with a functional material intermediate having appropriate intermolecular force and shape without impairing optical activity. This allows for free molecular design.
In particular, by selecting the length of the alkyl group, it is possible to control the type and temperature range of the liquid crystal phase developed in the liquid crystal state. Furthermore, the liquid crystal composition containing at least one type of optically active lactic acid derivative and optically active liquid crystalline lactic acid derivative of the present invention as a compounding component can be used as a chiral nematic liquid crystal or a chiral smectic liquid crystal. By increasing spontaneous polarization, adjusting viscosity, etc., it is possible to improve performance such as increasing response speed and preventing the occurrence of reverse domains. EXAMPLES Hereinafter, the liquid crystal optically active substance that is a lactic acid derivative, the liquid crystal composition, and the liquid crystal element of the present invention will be explained in detail with reference to Examples. Example 1 4-(2-ethoxypropyloxy)benzoic acid 4'-octyloxyphenyl ester 4-(2-ethoxypropyloxy)benzoic acid
5.1 ml of thionyl chloride was added to 1.5 g and refluxed for 2 hours. After thionyl chloride was distilled off and toluene was added, a solution of 1.5 g of p-octyloxyphenol in 7.7 ml of dry pyridine was added dropwise at a temperature below 5°C. After stirring at room temperature for 3.5 hours and standing overnight, cold water was added and the ether extracted mixture was diluted with 5%
After washing with an HCI aqueous solution and a 5% NaOH aqueous solution, it was further washed with water. When the solvent was distilled off and purified by silica gel column chromatography, 1.2 g of 4-(2
-ethoxypropyloxy)benzoic acid 4'-octyloxyphenyl ester was obtained. The following infrared absorption peaks were obtained for the product. IR (cm ^-1 ): 2940, 1735, 1605, 1510, 1250, 1190, 1165,
1070. The infrared absorption chart is shown in Figure 1. Example 2 4-(2-octyloxypropyloxy) was prepared in the same manner as in Example 1 using 4-(2-octyloxypropyloxy)benzoic acid instead of 4-(2-ethoxypropyloxy)benzoic acid. )
Benzoic acid 4'-octyloxyphenyl ester was obtained. The following infrared absorption peaks were obtained for the product. IR (cm ^-1 ): 2930, 1715, 1600, 1510, 1470, 1270, 1190,
1175, 1100, 1075. The infrared absorption chart is shown in Figure 2. Example 3 4-(2-dodecyloxypropyloxy)biphenylcarboxylic acid octyloxyphenyl ester To 2.0g of 4-(2-dodecyloxypropyloxy)biphenylcarboxylic acid, 0.8g of phosphorus pentachloride was added, and further oxyphenyl ester 3.9 ml of phosphorus chloride was added and the mixture was refluxed for 2 hours. Phosphorus oxychloride was distilled off from the reaction mixture, toluene was added, and 1.0 g of 4-octyloxyphenol dissolved in 6.1 ml of pyridine was added.
was added dropwise, stirred at room temperature for 2.5 hours, and left overnight.
Cold water was added to extract the ether. After washing with water, the solvent was distilled off and the residue was purified by silica gel column chromatography to obtain 1.3 g of 4-(2-dodecyloxypropyloxy)biphenylcarboxylic acid octyloxyphenyl ester. The infrared absorption chart is shown in Figure 3. Example 4 4-(2-ethoxypropyloxy)benzoic acid 4'-(decyloxy) was prepared from 4-(2-ethoxypropyloxy)benzoic acid and 4-hydroxybenzoic acid decyl ester by the same method as in Example 1. Carbonyl) phenyl ester was obtained. The following infrared absorption peaks were obtained for the product. IR (cm ^-1 ): 3930, 3855, 1735, 1720, 1600, 1510, 1250,
1200, 1160, 1105, 1060, 760. The infrared absorption chart is shown in Figure 4. Example 5 4-(2-octyloxypropyloxy)benzoic acid 4'-(decyloxycarbonyl)biphenyl ester 4-(2-octyloxypropyloxybenzoic acid and 4'- From hydroxybiphenylcarboxylic acid decyl ester, 4-(2-octyloxypropyloxy)
Benzoic acid 4'-(decyloxycarbonyl)biphenyl ester was synthesized. The following infrared absorption peaks were obtained for the product. IR (cm ^-1 ): 3930, 3850, 1730, 1710, 1600, 1510, 1280,
1170, 1110, 770. The infrared absorption chart is shown in FIG. Example 6 A liquid crystal composition having the following composition was prepared. In the cooling process, this liquid crystal composition has a
It exhibits an SmC ^* phase in a temperature range of 15°C, and by blending the liquid crystalline lactic acid derivative of the present invention, it was possible to lower the temperature to a range that covers room temperature without narrowing the temperature range of SmC*. Note that it does not contain the lactic acid derivative of the present invention. SmC ^* temperature range alone was 134-41°C. Example 7 Liquid crystal element using the liquid crystal compound produced in Example 6 A film of about 1000 Å was applied to a 10 x 20 mm glass plate with high precision polishing.
An ITO film was provided as an electrode, and an approximately 1000Å
SiO ₂ was deposited by ion beam method. The liquid crystal composition produced in Example 6 was dropped onto a glass substrate that had been processed in the same manner, and the glass substrates were stacked facing each other. While holding the board at 115℃,
When the upper and lower substrates were moved in parallel while maintaining the distance between them under a polarizing microscope, horizontally aligned monodomains were obtained. The liquid crystal layer thickness at that time was 1.0 μm, and when a pulse of ±20 V was applied in the chiral smectic C phase, room temperature (25
Switching was performed at a response speed of approximately 500 μsec at 50°C and 45 μsec at 50°C. Examples 8 to 11 The following liquid crystal compound (A) also used in Example 6 On the other hand, for the lactic acid derivative compounds of Examples 1 to 4, and for the Example 3 compound of the resulting liquid crystal composition,
Liquid crystal compositions of Examples 8 to 11 were obtained by mixing 40% by weight and 20% by weight of the others. The composition ratio, SmC _* phase temperature range, and response speed at 50°C when the device was fabricated and tested in the same manner as in Example 7 were determined for the composition of Example 6 and the liquid crystal compound (A) alone for these liquid crystal compositions. The data are summarized in Table 2 below.

[Table] In all examples, it is observed that the addition of the lactic acid derivative of the present invention lowers the lower limit of the SmC _* phase temperature range and improves the response speed.

[Brief explanation of the drawing]

FIG. 1 to FIG. 5 each show Example 1 of the present invention.
The infrared absorption chart of the liquid crystalline compound obtained in 5 to 5 is shown. Representative figure: Figure 1.

Claims (1)

[Claims] 1 General formula () (In the above general formula, R ¹ represents an alkyl group having 4 to 16 carbon atoms, R represents an alkyl group having 1 to 16 carbon atoms, respectively. Also, m and n are integers of 1 or 2, and k is 0 or 1, c ^* represents an optically active asymmetric carbon atom.) A liquid crystal composition comprising at least one lactic acid derivative represented by the following. 2 General formula () (In the above general formula, R ¹ represents an alkyl group having 4 to 16 carbon atoms, R represents an alkyl group having 1 to 16 carbon atoms, respectively. Also, m and n are integers of 1 or 2, and k is 0 or 1, c ^* represents an optically active asymmetric carbon atom.) A liquid crystal element comprising a liquid crystal composition containing at least one lactic acid derivative represented by the following.