JPH0196155A - 1-(substituted phenyl)ethanol derivative - Google Patents

Abstract

NEW MATERIAL:An optically active compound expressed by formula I (R<1> and R<2> are 1-20C alkyl, alkoxy or H; l, m and n are 0 or 1; X is F, Cl, Br or cyano; rings A, B and C are formulas IV, V and VI; Y is H, halogen or cyano). EXAMPLE:1-(2-Bromophenyl)ethyl R-4-pentyloxybiphenyl-4'-carboxylate. USE:Usable as a component of liquid crystal compositions, having negative temperature characteristics and high twisting ability and useful as electrooptical elements. This compound is capable of inducing a highly twisted structure by a small amount thereof added in using as a doping agent for the liquid crystal compositions and miscible with many kinds of liquid crystal substances and providing chiral compositions having flat temperature characteristics of pitch by blending with a compound having positive temperature characteristics. PREPARATION:For example, an optically active alcohol expressed by formula II is reacted with carboxylic acids expressed by formula III to afford the aimed compound expressed by formula I.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a novel organic chemical compound and a liquid crystal composition containing the same, and more particularly to an organic compound having an optically active group and a liquid crystal composition containing the same. Regarding.

[Prior Art] The applications of liquid crystal display elements have rapidly expanded due to improvements in circuits, drive methods, and cell manufacturing technology, and especially improvements in the characteristics of liquid crystal compositions sealed in the elements. However, liquid crystal display elements have many points to be improved as will be described later.

For example, the viewing angle is narrow, the contrast is poor, the response speed is slow, the display capacity is still small,
Another problem is a decrease in display quality due to changes in ambient temperature. Among these, deterioration in display quality due to changes in ambient temperature is caused by temperature changes in threshold voltage vth.

As a means commonly used in recent years, by adding a small amount of optically active substance to the liquid crystal composition, the reverse twist of the liquid crystal molecules is suppressed and the liquid crystal molecules are given a clockwise or counterclockwise helical structure, thereby maintaining display quality. There is a method 0 for example τ
N (twisted nes+atic) type display element,
and the recently proposed SBE (supertwiste
This can have an advantageous effect on, for example, a display device of the d birefrigence select type.

However, if the twisting ability of the optically active material added as a dopant is too low, it becomes necessary to add the dopant at a relatively high concentration to obtain the required pitch, which may be detrimental to other material parameters. It is clear that this will have an impact. For this reason, there has been a long-awaited need for an optically active substance that has a high twisting ability, that is, the ability to develop a shorter pitch when added to a liquid crystal in the same amount.

For example, the CB-15 made by BDH and the recently reported Japanese Patent Application Publication No. 8
The compounds described in No. 2-81354 and JP-A No. 82-81355 have the ability to develop a pitch of around 10 pi+ just by adding 1% by weight to a nematic liquid crystal composition.
In a sense, it can be said to be a practical optically active substance.

However, numerically known optically active substances, including the compounds mentioned above, often have an undesirable effect, increasing the pitch of the liquid crystal material to which they are added as the temperature increases. For example, in the SBE method, the characteristic pitch P of the liquid crystal composition changes due to temperature change, and this changes the cell thickness d of the display element and the characteristic pitch P of the liquid crystal composition.
The value of the ratio P/d also changes. 0 Normally P/d is less than 2, but if it becomes more than 2 due to temperature change, it becomes 27.
A 0 degree twist turns into a 30 degree twist.

In addition, in terms of improvement for increasing display capacity, it is necessary to improve the steepness of the change in transmittance when voltage is applied to the display element. G. Bauer and W. Fehrenbach reported calculation results at the 15th Freiburg Liquid Crystal Conference (1985) that the steepness was greatly improved by twisting 270 degrees. It becomes necessary to eliminate change.

As a way to solve this problem, in recent years optically active compounds with negative temperature characteristics, that is, substances whose intrinsic pitch decreases as the temperature rises, have been discovered. By mixing an appropriate amount with a suitable amount, a composition whose characteristic pitch does not change due to temperature can be obtained (Japanese Patent Application No. 81-179194, Emoto et al.).

However, all of the currently reported substances with negative temperature characteristics have a low twisting ability for liquid crystal materials and must be added at a fairly high concentration to obtain the necessary pitch, resulting in various adverse effects. It is thought that it is bringing about In order to solve these problems, a material with a short pitch and negative temperature characteristics is desired.

[Problems to be Solved by the Invention] The present inventors have developed an optically active compound that has the characteristics necessary to realize a liquid crystal composition having suitable characteristics, namely, negative temperature characteristics and high twisting ability. As a result of intensive efforts to develop the present invention, the present invention has been achieved.

An object of the present invention is to provide an optically active compound that has the properties necessary for realizing a liquid crystal composition having suitable properties, particularly negative temperature properties, and extremely high twisting ability.

[Means for Solving the Problems] The present invention is based on the following: -Mathical formula (in the above formula, R1 and R2 represent an alkyl group, an alkoxy group, or a hydrogen atom having 1 to 20 carbon atoms, and 1, m,
n each represents 0 or l, X represents a fluorine atom (Y represents either a hydrogen atom, a halogen atom, or a cyano group,
), a liquid crystal composition containing at least one thereof, and an electro-optical element using the liquid crystal composition.

[Method for producing compound] Next, the method for producing the compound of formula (1) of the present invention will be described. The compound of formula (I) can be suitably produced, for example, by the following route.

(a) When X=F, CI, Br (7) (However, in the above formula, R1, R2, 1, m, n, A, B
.

(C indicates the same meaning as above, X indicates any one of F, CI, Br, etc.) That is, the optically active alcohol represented by the formula (II) (
A compound of formula (I) can be obtained by reacting various carboxylic acids represented by formula (m).

(b) In the case of X-ON, by cyanating the compound obtained in the above (a) where X=Br, a compound where X-ON in formula CI) can be obtained.

[Operations and Effects of the Invention] The first feature of the compound of the present invention is that when it is used as a doping agent for a liquid crystal composition, it induces a highly twisted structure in a small amount added. As shown in Example 3 below, the pitch when 1% by weight was added to a liquid crystal composition without a twisted structure was as short as 7.41L at 25°C, and it was optimized by adding a smaller amount. It is possible to prepare a liquid crystal composition having a twisted structure, that is, a chiral liquid crystal composition.

This means that optically active compounds currently known as doping agents, such as C-15 (trade name, manufactured by BDH), are 83u
, ■ Considering that even the product name CB-15 is only a 10JL layer, this is a surprising characteristic.

Furthermore, a second feature of the compounds of the present invention is that they have negative temperature characteristics. As shown in Example 3, the temperature characteristics δP are -0 at tl-20°C, -0 at t2-40°C,
189, which exhibits negative characteristics, and by mixing an appropriate M with a compound arbitrarily selected from the numerically known group of compounds with positive temperature characteristics, the temperature characteristics of the pitch can be flattened. It becomes possible to easily provide a chiral composition in which δP=O.

All of these excellent properties of the compounds of the present invention are due to the skeleton, and the above properties cannot be expressed without this skeleton.In other words, if the compound contains the above skeleton in its molecular structure, It goes without saying that various structures can be substituted for parts A and 8 in the above formula. An application has been filed.

Furthermore, due to their high twisting ability, the compounds of the present invention require only a small amount of addition to obtain chiral liquid crystal compositions with an optimized twisting structure, and are therefore compatible with various types of liquid crystal materials. Liquid crystal substances that can be mixed with and can be used include Schiff bases,
Biphenyls, phenylcyclohexanes, phenylpyridines, phenylpyrimidines, phenyldioxanes, cyclohexylbiphenyls, cinnamic acid esters,
Examples include phenyl esters, or a liquid crystal composition formed by arbitrarily selecting and combining them.

Furthermore, the chiral liquid crystal composition produced by adding the compound of the present invention, that is, the liquid crystal composition having a twisted structure, is not limited to only a chiral nematic composition, but also a chiral liquid crystal composition in which a smectic phase, particularly a smectic C phase, has a twisted structure. It also refers to m-acids having a smectic C phase.

In recent years, research has been actively conducted on new drive systems using chiral smectic C phase (Clark et al.: Applied Phys, Iett, 3).
8,889 (1980)), a chiral smectic C phase can be induced by adding the compound of the present invention to a compound or composition having a smectic C phase. In this case, it is said that the larger the spontaneous polarization, the faster the response speed, and as shown in Example 4 below, it is possible to obtain a composition that exhibits a large spontaneous polarization of 1 G, 4 nc/cm'.

[Examples] The compounds of the present invention will be explained in more detail with reference to Examples below.

Example 1 R-4-pentyloxybiphenyl-4°-carboxylic acid 1-(2-bromophenyl)ethyl ester (in formula (I), m=1. n=o, R'-CsHr+O-
.

Production of: R-1-(2-bromophenyl)ethanol [α) o
"33.5CC-3,52ClCl5) 4g,
4-pentyloxybiphenyl-4°-carvone m6
g, dicyclohexylcarbodiimide 7 g, dimethylamine/pyridine 0.4 g, and dichloromethane 1 (losM) were stirred at room temperature for 2 hours, and the insoluble matter was filtered off. The filtrate was washed with acid, alkali, and water, and the solvent was distilled off, and the residue was recrystallized from a mixed solvent of ethanol and ethyl acetate to obtain R-4-pentyloxybiphenyl-4'=carboxylic acid 1-(2-'lomonenyl)ethyl ester at 7.68 °C. The substance corresponds to the title compound according to elemental analysis, N) IR-spectrum, and IR-spectrum.

Example 2 R-4-pentyloxybiphenyl-4-carboxylic acid 1
-(2-cyanophenyl)ethyl ester ((I
) in the formula I-m-1, n=0, R'=CsHzO
−.

Production: R-4-pentyloxybiphenyl-4''-carboxylic acid 1-(2-'7'romophenyl) prepared in Example 1
A mixture of 6 g of ethyl ester, 2.1 g of cupric cyanide, and 40 layers of dimethylformamide was heated at 150°C.
Stir for hours. After cooling, a mixture of 6.4 g of ferrous chloride and 7 parts of 20% hydrochloric acid was added and stirred at 80 to 70°C for 20 minutes. After adding toluene and washing with water, the solvent was distilled off and the residue was recrystallized from ethanol to obtain R-4 of 2.88.
-pentyloxybiphenyl-4'-carboxylic acid 1-(
2-cyanophenyl)ethyl ester was obtained.

Oboro p 112.5-112.8℃. Also, this thing is
Elemental analysis, NMR-spectrum and IR-spectrum correspond to the title compound.

Example 3 (Usage Example 1) Nematic liquid crystal composition (commercially available ZLI-1 manufactured by Merck & Co., Ltd.)
132) was added with 1% by weight of the compounds of Examples 1 and 2 of the present invention to prepare a chiral nematic liquid crystal composition. When this chiral nematic liquid crystal composition was injected into a parallel-treated wedge-shaped cell and observed under a polarizing microscope, the helical pitch was observed to be similar to that of the vestibule.

However, the above-mentioned δP2Q#T is a parameter expressing temperature characteristics and is defined by the following equation.

P(t); Pitch length at t'c: The pitch that appears above the temperature is extremely short, and the pitch length shortens as the temperature rises. The compound was found to be an excellent pitch modifier for liquid crystal compositions.

Example 4 (Use Example 2) A chiral smectic C liquid crystal composition was prepared by adding 20% by weight of the compound of Example 2 to 80% by weight of a racemic compound having the following phase transition point.

The phase transition point was as follows.

The spontaneous polarization value of this composition was measured and was 1G, 4nc.
/am” It happened.

that's all

Claims (3)

[Claims] (1) General formula▲There are mathematical formulas, chemical formulas, tables, etc.▼…(I) (However, in the above formula, R^1 and R^2 are alkyl groups with 1 to 20 carbon atoms, alkoxy groups, or hydrogen atoms. indicate, l, m
, n each represents 0 or 1, X represents a fluorine atom, chlorine atom, bromine atom, or cyano group, ▲ mathematical formula, chemical formula,
There are tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼
, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ are each independently, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (Y represents either a hydrogen atom, a halogen atom, or a cyano group.) An optically active compound represented by the following. (2) General formula▲There are mathematical formulas, chemical formulas, tables, etc.▼…(I) (However, in the above formula, R^1 and R^2 are alkyl groups with 1 to 20 carbon atoms, alkoxy groups, or hydrogen atoms. indicate, l, m
, n each represents 0 or 1, X represents a fluorine atom, chlorine atom, bromine atom, or cyano group, ▲ mathematical formula, chemical formula,
There are tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼
, ▲There are mathematical formulas, chemical formulas, tables, etc.▼ are each independently, ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (Y represents either a hydrogen atom, a halogen atom, or a cyano group.) Contains at least one kind,
A liquid crystal composition comprising at least two components. (3) General formula▲There are mathematical formulas, chemical formulas, tables, etc.▼…(I) (However, in the above formula, R^1 and R^2 are alkyl groups with 1 to 20 carbon atoms, alkoxy groups, or hydrogen atoms. indicate, l, m
, n each represents 0 or 1, X represents a fluorine atom, chlorine atom, bromine atom, or cyano group, ▲ mathematical formula, chemical formula,
There are tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼
, ▲There are mathematical formulas, chemical formulas, tables, etc.▼ are each independently, ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (Y represents either a hydrogen atom, a halogen atom, or a cyano group.) Contains at least one kind,
An electro-optical element using a liquid crystal composition comprising at least two components.