JPS59118744A - Liquid crystal substance and liquid crystal composition - Google Patents

Abstract

NEW MATERIAL:The compound of formula (R is alkyl; R* is optically active group having asymmetric carbon atom). EXAMPLE:4-Octyloxy-4-biphenylcarboxylic acid 2-methylbutyl ester. USE:A ferroelectric liquid crystal component having photochemical and chemical stability. When mixed with other liquid crystal compound, the temperature range of the composition exhibiting ferroelectricity can be lowered near to room temperature. The ferroelectric composition can be utilized for a display device taking advantage of the photo-switching phenomenon of ferroelectric liquid crystal, and a high-speed photo-switching having a response time of about 1 m-sec can be attained. PROCESS:The compound of formula I can be prepared by converting 4-alkyloxy- 4'-biphenylcarboxylic acid to an acid halide with a halogenation agent such as thionyl chloride, phosphorus pentachloride, etc., and reacting the halide with an optically active alcohol in e.g. pyridine.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel liquid crystal material and a liquid crystal composition containing the liquid crystal, particularly a smectic liquid crystal composition.

In this specification, the term "liquid crystalline substance" refers to a substance that exhibits a liquid crystal phase by itself, and a substance that is useful as a component of a liquid crystal composition even if it is not detected to exhibit a liquid crystal phase by itself.

Currently, liquid crystals are becoming widely used as display materials, but most of the liquid crystal display elements using them are T
N (Twist Nematic) type display method (
For example, see Japanese Patent Laid-Open No. 11737/1983). The TN type display system is light-receiving type, so your eyes won't get tired.1. Although it has excellent features such as extremely low power consumption,
There are drawbacks such as slow response and the display not being visible depending on the viewing angle. Recent demands for display devices include particularly high-speed response, and in order to meet these demands, various improvements have been made in the field of liquid crystal materials. However, when compared with other light-emitting display elements (EL (electroluminescence) displays, plasma displays, etc.), there is still a large difference in response time K. T
It is essential to develop a new liquid crystal display system to replace the N-type display system. One such attempt is a display device that utilizes the optical switching phenomenon of ferroelectric liquid crystals (for example, the
No. 6-107216, N, A, Cjark, S
, T. Lagerwau; Appt., Phys.
Lett., 86.899 (1980), etc.). Ferroelectric liquid crystal was developed by R,B in 1975.

Its existence was first announced by Meyer et al. (R, B, Meyer et al.
e, 86. (see L-69 (1975)), from a crystal structure point of view it is chiral smectic C phase (hereinafter abbreviated as SmC phase) or chiral smectic H phase (hereinafter abbreviated as SmC phase).
It is said to belong to the SmH* phase).

Currently, the compounds shown in Table 1 are known as ferroelectric liquid crystal compounds (Ph, Martinot-Lagar
de; J, Physique, 37. CB-1
29 (1976)).

However, as can be seen from Table 1, the temperature range in which existing ferroelectric liquid crystal compounds exhibit ferroelectricity (temperature range in which they exhibit SmC* phase or SmH* phase) is often higher than room temperature, and both compounds , the carbon-carbon double bond attached to the benzene ring easily undergoes isomerization in a short period of time when exposed to light, resulting in instability in which it becomes a cis form and no longer exhibits a liquid crystal phase, making it unsuitable for use in display devices. . Therefore, as a result of earnestly pursuing a molecular structure that eliminates such unstable factors and exhibits ferroelectricity in the temperature range near room temperature, we have arrived at the compound of the present invention and a liquid crystal composition containing it as a compounding ingredient. did.

That is, the present invention provides a liquid crystalline 4-alkyloxy-4'-biphenylcarboxylic acid ester represented by the general formula (in the above formula, R represents an alkyl group and R* represents an optically active group having an asymmetric carbon atom). and a liquid crystal composition containing the compound ' as a constituent component.

Comparing the compound of formula (1) of the present invention with the existing ferroelectric liquid crystal compounds shown in Table 1, it is found that first of all, it lacks a carbon-carbon double bond, which is a factor of instability against light, and furthermore, it lacks a factor of instability against water. Certain azomethine bonds are missing, resulting in an extremely stable substance. Furthermore, although this compound exhibits ferroelectricity in a preferable temperature range around room temperature, such a fact cannot be easily deduced from known experimental facts. G as a compound related to the compound of the present invention
, W. Gray et al. (Mob, Cryst.

Liq, Cryst, , , 37.157 (197
6)) The following three series of compounds have been reported, and their liquid crystal phase transition temperatures have been shown.

C5H170+ C00Cn H2n+1C+oH21
0% C00Cn H2n+ 1C8HI70 + C
00CH(CH3) Cn H2n+1 (Cn in the above formula
(H2n+ 1 represents a linear alkyl group) In contrast, the compound (I) of the present invention all has a branched alkyl group and is an optically active substance, and its *5rnC phase exhibits ferroelectricity. was completely unknown until now. Furthermore, it should be noted that a compound of the following formula having a chemical structure similar to that of the compound of the present invention is disclosed in Japanese Unexamined Patent Publication No. 57
-11944.

? H3 R yoke) -@-Coo-CH2-CH-C2H! .

* (R represents an alkyl group having 1 to 10 carbon atoms) However, these do not show any smectic phase.

It only shows a cholesteric phase at low temperatures.

The chemical structure of the liquid crystalline compound of the present invention is characterized by having a biphenyl skeleton, as is clear from formula (1), and having an alkyl group at the 4-position and C0OR* at the 4'-position. . The alkyloxy group at the 4-position is an alkyloxy group having 1 to 18 carbon atoms, preferably an alkyloxy group having 4 to 14 carbon atoms. In the C0OR group at the 4'-position, R is an optically active group and has the structure shown by the following formula.

1 "-(CHz)n CH-R2 Here, R1 and R2 are either an alkyl group, an alkyloxy group, a cyano group, or a halogen atom, but R1, R2
are different, and cases where R, R, and R2 are both halogen atoms are excluded.

In the father formula, n is an integer from 0 to 8. Among the compounds of formula (1), those particularly suitable for practical production are those where n = 1, R
4=CH3, R2=C2H5, i.e. *R is 2-methylbutyl group and n=0°R+=
CH3, R2=C6H13, that is, a compound in which R is a 2-octyl group.

By the way, as mentioned earlier, ferroelectric liquid crystals belong to *5rrlCJapanese 1i SmH, but the characteristics of these two liquid crystal phases are that the molecules are distributed and arranged in a layered manner, and the surface of the layer is The reason is that the molecules are arranged tilted in a certain direction, and the direction of the tilt is slightly shifted from layer to layer, resulting in a liquid crystal structure with a spiral structure as a whole (R, B. Meyer: Mot.
Cryst, Liq, Cryst, .

40, 88 (1977)). The spontaneous polarization points in a direction perpendicular to the helical axis (direction perpendicular to the layer plane) and the alignment direction of the liquid crystal molecules. Now, in order to induce such a liquid crystal structure and spontaneous polarization, it is thought that the following two elements are necessary in the molecular structure. That is, in order to induce a helical structure, the terminal group must have an asymmetric structure, and in order to induce spontaneous polarization, the terminal group must have a permanent dipole in a direction approximately perpendicular to the long sleeve direction of the liquid crystal molecules. That's true. The compound of formula (1) satisfies all of these two conditions and has photochemical stability and chemical stability not found in existing ferroelectric liquid crystal compounds. Furthermore, as shown in the Examples below, when blended with other liquid crystal compounds, it also exhibits the effect of lowering the temperature range in which the liquid crystal composition exhibits ferroelectricity to around room temperature.

Compound (1) is produced by reacting 4-alkyloxy-47-biphenylcarboxylic acid with a halogenating agent such as thionyl chloride or phosphorus pentachloride to form a cyano-rhodanide, which is then converted into a cyano-rhodanide in a basic solvent such as pyridine. Although it is most preferably synthesized by reacting with an optically active alcohol, other commonly known esterification methods may also be used.

Next, Table 2 shows the phase transition temperature of compound (1) obtained as described above.

Table 2 In the above table, C represents the crystalline phase, SmA represents the smectic A phase, and ■ represents the isotropic liquid phase (transparent phase). The phase transition temperature to the phase on the right is shown, and - indicates that the phase is not shown.

Also, () indicates the monotropic phase transition temperature.

Moreover, (#1) indicates the presence of a smectic phase of unknown origin.

Among the compounds shown in Table 2, the SmC* phase is observed as a single compound for those with n = 7 to 12, but crystallization occurs during the phase transition measurement for the other compounds, and SmC* as a single compound is observed.
No phase could be detected.

These compounds exhibit ferroelectricity in their SmC* phase, and the relationship between their spontaneous polarization values and temperature is shown in FIG. In Figure 1, A(@) is 4- which is one of the compounds of formula (1).
Octyloxy-4'-biphenylcarboxylic acid 2-methylbutyl ester' (r, B (○) is also 4-hebutyloxy-4'-biphenylcarboxylic acid 2-.7' methylbutyl ester, C (0) is 4-octyloxy-4
'-Biphenylcarboxylic acid-2-methylbutylphenyl ester and p-octyloxydibenzylidene-p-(2-methylbutyloxycarbonyl), which is one of the ferroelectric liquid crystal compounds for which the applicants previously applied for a patent. Shows an equimolar mixture with aniline. The spontaneous polarization value of the compound of formula (1) shown here is, for example, p-alkoxybenzylidene-p'-amino-2-methyl, which is one of the known ferroelectric liquid crystal compounds shown in Table 1. This is almost twice as high as that of butyl cinnamate.

The compound of formula (I) of the present invention is preferably used as a composition of 92 or more types rather than as a single compound. This is because mixing lowers the melting point and produces an SmC phase that is thermodynamically stable in a temperature range including around room temperature. Such a liquid crystal composition can be obtained by mixing the compounds of the formula (1) of the present invention with each other, and can also be obtained by mixing with known ferroelectric liquid crystal substances as shown in Table 1, both of which are ferroelectric. have sex. Furthermore, p-alkoxybenzylidene-p-(2-methylbutyloxycarbonyl)anilines (Japanese Patent Application No. 1983), which are ferroelectric liquid crystal compounds discovered by the present inventors and for which a patent application was filed )
A composition obtained by mixing with is also a useful ferroelectric liquid crystal composition. These ferroelectric liquid crystal compositions can be used in display devices that utilize the optical switching phenomenon of ferroelectric liquid crystals, as described above, and can achieve high-speed response optical switching with a response time of about 1 millisecond, as shown in the examples below. It can be carried out.

Hereinafter, the compounds of the present invention will be explained in more detail with reference to Examples.

Example 1 [4-octyloxy-47-biphenylcal (C2H
5) Production of 4-octyloxy-47-biphenylcarboxylic acid 20
9 and 50 ml of thionyl chloride were heated under reflux for 2 hours, excess thionyl chloride was distilled off, and 4-octyloxy-47
- Obtain biphenylcarboxylic acid chloride. This product is not particularly purified and is used as a toluene solution in the next step.

On the other hand, a solution of (-)2-methyl-1-bukunol (manufactured by Eastman Kodak) 16N in pyridine 501 was cooled in water, and a toluene solution of the above acid chloride was added thereto for about 30 minutes with stirring. Add it in water and then take a 90°C hot water bath.”
Stir for 30 minutes. After cooling, add 6N hydrochloric acid and ice to make acidic, separate the layers, remove the organic layer, wash with water, wash with 2N sodium hydroxide solution, wash with water, and then distill off toluene to obtain the target product (crude product). .

This was dissolved in about 70ml of heptane and alumina/
After passing through a heptane chromatography column and recrystallizing twice from ethanol, 8 x colorless needle crystals were obtained. oy
was gotten. Its NMR spectrum and elemental analysis were consistent with it being the desired compound, 4-octyloxy-4'-biphenylcarboxylic acid-2-methylbutyl ester. In addition, the degree of light absorption [α] in a chloroform solution was +3.5°. The phase transition temperatures are shown in Table 2 above along with those of other compounds of the (1) formula.

The raw materials 4-octyloxy-47- and phenylcarboxylic acid are known substances obtained by alkaline hydrolysis of commercially available 4-octyloxy-4'-cyanobiphenyl (M-24 manufactured by BDH).

Example 2 [4-octyloxy-47- and phenylcarboxylic acid-
2-octyl ester ((1) 2〇 * R is C5Hrr, R is -CH(CH3)(C6H
1:l) Production] First, in the same manner as in Example 1, 4-octyloxy-41
-Biphenylcarboxylic acid chloride was produced. Part 19
．． 8F toluene solution I and 10g (-)2-octyl alcohol (manufactured by Fururikisha) were dissolved in pyridine 40Ilvt and added dropwise with stirring to a water-cooled solution, and further 90
Stir for 3 hours on a 'C water bath. After cooling, the mixture was acidified with 6N hydrochloric acid and separated, and the organic layer was washed with water, 2N sodium hydroxide solution, and water, and the toluene was distilled off to obtain the desired residue. This was recrystallized twice with ethanol to obtain scaly crystals 17.21.

The melting point of this product was 74.5-75° C0, the NMR spectrum and elemental analysis values were consistent with the chemical structure of the target product, and the degree of light absorption [α]6 in chloroform solution was -33.2°.

Similarly, (-)2-octyl alcohol was replaced with (±
) The antipode of the same substance was obtained using octyl alcohol (manufactured by Fluka). Melting point 74.5-75°C1 Light intensity (a)
B=+a3. Oo (in chloroform solution).

Similarly, 4-pentyloxy-4'-biphenylcarboxylic acid chloride, (-)2-octyl alcohol and 4-pentyloxy-4'-biphenylcarboxylic acid-
2-octyl ester was obtained. Melting point 61.8°c0 Example 3 4-hebutyloxy-4'-biphenylcarboxylic acid-2
-Methyl butyl ester and 4-octyloxy-4'-
An equimolar mixture of biphenylcarboxylic acid-2-methylbutyl ester (all compounds of formula (1) listed in Table 2) has a melting point (CSmC* point) of 33°C and an SmC*-SmA point of 42.2°C9SmA -I point is 65°C, indicating that the compound has characteristics more suitable for display elements than a single compound.

Example 4 In formula (1), R is respectively C7H]5, C8H17, CJ
L9. ClOH2+ ICl2) 1.25, R* is a 14:11:6:10:9 mixture C of -CI (2-old H-C2H5 compound (IsaH3, both listed in Table 2)
M-jk ratio) is 34.6°C at the SmC* point and 63.2°C at the SmA-1 point, which has characteristics suitable for display devices.

Example 5 4-octyloxy-47-biphenylcarboxylic acid-2
- Methyl butyl ester (listed in Table 2) and p-octyloxybenzylidene-p, which is one of the strong g-electroconductive liquid crystal compounds previously discovered by the present inventors and for which a patent application has been filed.
The equimolar mixture of -(2-methylbutyloxycarbonyl)aniline is C-5rnC* point 20-21°C, 5r
nC*-SmA point 33.6°C, SmA-I point 62°C
The value of the spontaneous polarization of this mixture is indicated by C in FIG.

Example 6 A liquid crystal display element having the liquid crystal composition of Example 5 as a liquid crystal phase was manufactured, and its response characteristics were evaluated. For liquid crystal display elements, a polyimide polymer film is provided on a glass substrate provided with an indium oxide transparent electrode, and after rubbing with a gauze layer in a certain direction, the glass is placed so that the rubbing directions of the two substrates are parallel to each other. A liquid crystal cell was assembled using fibers as spacers, and the liquid crystal composition of Example 5 was vacuum-sealed into the cell. The cell spacing is 5.4 μm. This liquid crystal display element was placed between two orthogonal polarizers, and when an electric field was applied, the intensity change at the point where the liquid crystal was transmitted was measured. 2
The response waveform measured at 4°C is shown in Figure 2, and as is clear from it, the response time of this liquid crystal display element is very short, about 1 millisecond, and this liquid crystal display element has excellent high-speed response. It shows that you have it.

[Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between the spontaneous polarization value of liquid crystal and temperature.
0) is 4-hebutyloxy-4'-biphenylcarboxylic acid-2-methylbutyl ester, C(0) is Example 5
2 is a graph showing the response characteristics of the liquid crystal display element of Example 6. Engraving of the above drawings (no changes to the contents) 1 Figure 1 Ton J ('c) Figure 2 9 Takumi m (mil rz) 3-1-1 Saiwai-cho, Hitachi City Stock% formula 3-1 Saiwai-cho, Hitachi City No. 1 Hitachi, Ltd., Hitachi Research Institute 0 Applicant: Hitachi Ltd., 5-5 Marunouchi, Chiyoda-ku, Tokyo No. 1 Procedural Amendment Commissioner Kazuo Wakasugi Patent Application No. 234561 of 1982 No. 2, Name of the invention Liquid crystal substance and liquid crystal composition 3 Relationship with the amended case Patent applicant 3-6-32 Nakanoshima, Kita-ku, Osaka-shi, Osaka Prefecture (530)
(207) Chisso Corporation Representative Sadao Nogi (and 1 other person) 4. Agent 2-8-1 Shinjuku, Shinjuku-ku, Tokyo (160) (and 1 other person)
Name) No increase in the number of inventions due to the Tomoe amendment Drawings subject to the I amendment Contents of the amendment (a) As shown in the appendix α Catalog drawings of attached documents (Figure, □11) 1 or more copies

Claims (1)

[Scope of Claims] (1) A liquid crystalline 4-alkyloxy-4'-biphenylcarboxylic acid ester having a molecular structure represented by general formula (1). (In the above formula, R represents an alkyl group, R% represents an optically active group having an asymmetric carbon atom.) (2) - in formula (i) represents an optically active 2-methyloctyl group (?H3 CH2CHC2H5 (* is The liquid crystalline compound according to claim 1, which is an asymmetric carbon atom) * in which R in formula (3) (I) is an optically active 2-octyl group CH:
. ' The liquid crystalline metal compound according to claim 1, which is a CHC6HI3 (* indicates an asymmetric carbon atom) powder. (4) A liquid crystal composition comprising at least one liquid crystalline 4-alkyloxy-4'-biphenylcarboxylic acid ester having a molecular structure represented by the general formula (I). RO (Hyc-o-R” (I) (in the above formula, R represents an alkyl group, R* represents an optically active group having an asymmetric carbon atom) (5) R* in formula (1) is optically active The liquid crystal composition according to claim 4, which is a 2-methylbutyl group or a 2-methyloctyl group having a 2-methylbutyl group or a 2-methyloctyl group. The liquid crystal composition according to claim 4 or 5, comprising: -methylsthyloxycarbonyl)anisones and/or p-alkyloxybenzylidene-p'-amino-2-methylbutylcinnamates. thing.