JP2543745B2 - Optically active compound and liquid crystal composition - Google Patents

Description

The present invention relates to a novel optically active compound and a liquid crystal composition containing the optically active compound.

[Conventional technology]

Liquid crystal display elements currently widely used in practice are the twisted nematic type (TN) and the dynamic scattering type (DS). Although these are displays by a nematic liquid crystal cell whose main component is nematic liquid crystal, one of the disadvantages of the conventional nematic liquid crystal cell is that the response speed is slow, and the fact that only a response speed of the order of several milliseconds at the maximum can be obtained. can give. This is one of the factors that limit the application range of nematic liquid crystal cells. 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. [Jiurnal de Huisique (J. Phys.), Vol. 36, L69 (1975)], but it was found to be 4- (4'-n-decyloxybenzylidene). Amino) -2-methylbutyl cinnamate (DOBAMBC) is a typical Schiff base compound, which is characterized by exhibiting ferroelectricity in a specific state, for example, chiral smectic C phase. is there. Then NA Clark et al. [Appl. Phys. Lett. 36th
Vol. 899 (1980)], the fast response of microsecond order was discovered in the thin film cell of DOBAMBC, which triggered the ferroelectric liquid crystal to utilize its fast response and memory property. Not only for displays such as liquid crystal televisions, but also for optical printer heads, optical Fourier transform elements, light valves, and other optoelectronic-related elements, the material is drawing attention. In a ferroelectric liquid crystal cell, the use of a material having a high dielectric constant and large spontaneous polarization is advantageous because the cell can be driven at high speed.
The development of materials with large spontaneous polarization is desired.

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

[Problems to be Solved by the Invention]

However, a Schiff base type compound such as DOBAMBC has a problem in stability against water and light, and has a ferroelectric temperature range of 40 ° C. or more higher than room temperature. Nakatsuta. Therefore, realization of a material system which 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. Further, the present invention intends to provide a display device having a high-speed response using such a novel optically active compound.

[Means for solving the problem]

Briefly describing the present invention, the first invention of the present invention relates to an optically active compound and is characterized by being represented by the following general formula I.

[However, X is an -O- group or a direct bond, and Y is -COO-
Group, —O— group, or direct bond, m and n represent 1 or 2, m + n is 2 or 3, R represents an alkyl group having 4 or more carbon atoms, and C ₃ F ₇ OCF (CF ₃ ) -A group or a group R,
At least one is an optically active group] Further, the second invention of the present invention is an invention relating to a liquid crystal composition, wherein at least one of the optically active compounds of the first invention is
It is characterized by containing a seed as a component.

The compound of the general formula (I) has high optical activity since it has a carbonyl group and a CF ₃ group directly bonded to the asymmetric carbon. Further, the central skeleton has a 1,2-diphenylacetylene structure, and further has a long-chain alkyl group (preferably having 4 to 18 carbon atoms) at both ends of the molecule, so that it itself exhibits liquid crystallinity. Is. In addition, it is expected that the viscosity will be low due to the existence of the 1,2-diphenylacetylene structure, and since the surface energy will decrease due to the presence of a plurality of fluorine atoms, in a thin cell that is essential for a ferroelectric liquid crystal, It is expected that the resistance to domain rotation will be reduced as compared with the non-fluorine-based compound, and when these are unintentionally used as a display element, high-speed response can be expected.

[Compound production method]

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

When the above production process is outlined, first, an acid chloride (III) of optically active perfluoro-2-propyloxypropionic acid (II) is produced by a conventional method, and an iodine compound (I
V). When the bond X in (IV) is a direct bond, it is acylation by the Friedel-Crafts reaction, and -O-
In the case of a group, esterification is carried out, and an iodine compound (V) having a perfluoro-1-propyloxyethylcarbonyl group introduced is obtained. Next, (V) is reacted with propargyl alcohol in the presence of cuprous iodide and a palladium catalyst to produce a hydroxymethylethynyl compound (VI), which is treated with manganese dioxide-potassium hydroxide to give an acetylene compound ( VII) is manufactured. Finally the compound (V
II) can be reacted with an iodine compound (VIII) in the presence of cuprous iodide and a palladium catalyst to produce a compound of general formula I. In the above production process, the target compound is usually produced using optically active perfluoro-2-propyloxypropionic acid (II). However, when a compound in which R is an optically active group is used, the racemic compound (I
The target compound can be similarly produced using I).

〔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 Compound (A) 4-Iodobiphenyl 14 g was dissolved in 180 ml of carbon disulfide, 7 g of crushed anhydrous aluminum chloride was added, and a solution of 17.6 g of optically active perfluoro-2-propyloxypropionic acid chloride / 30 ml of carbon disulfide was added while stirring. The mixture was added dropwise at 5 ° C or lower, then heated under reflux for 7 hours, cooled, poured into dilute hydrochloric acid, extracted with chloroform, washed with water, dried over anhydrous aluminum sulfate, the solvent was distilled off, the residue was dissolved in toluene, and silica gel was used. Purified through a short column of 4-iodo-4 ′-(perfluoro-1-propyloxyethylcarbonyl) biphenyl (V, where X =
A direct bond, m = 2) was prepared.

(B) 11.8 g of the above compound and 1.4 of propargyl alcohol
g dissolved in 22 ml triethylamine, 0.1 g cuprous iodide
And 0.16 g of dichlorobis (triphenylphosphine) palladium (divalent) were added and stirred at room temperature for 30 hours, then water, toluene and dilute hydrochloric acid were added, and the mixture was washed with water, an aqueous solution of sodium hydrogencarbonate and water in this order, and Purify through a short column of silica gel, 4- (2-hydroxymethyl) ethynyl-4 ′-(perfluoro-1-propyloxyethylcarbonyl) biphenyl (VI, where X =
A direct bond, m = 2) was prepared.

(C) 8.3 g of the above compound (VI) was dissolved in 100 ml of benzene, 4.9 g of manganese dioxide and 2.2 g of potassium hydroxide were added, and the mixture was heated under reflux for 7 hours with stirring. Inorganic residue is removed by filtration, the residue is washed with benzene three times, the benzene solution is washed with water, dried and passed through a short column of silica gel, and the solvent is distilled off to remove 4-ethynyl-4 '-(perfluoro). -1-Propyloxyethylcarbonyl) biphenyl (VII, where X = direct bond, m = 2) was prepared.

(D) 1.65 g of the above compound (VII) and 1.2 g of decyl 4-iodobenzoate were dissolved in 10 ml of triethylamine, and 15 mg of cuprous iodide and dichlorobis (triphenylphosphine) were dissolved.
Palladium (divalent) 20 mg was added, the reaction and post-treatment were carried out in the same manner as in (b), column chromatography was performed on silica gel using hexane-toluene as a solvent, and recrystallization was performed using hexane to give the compound (general compound). X = a direct bond in formula I, Y = -COO- _{group, R = C 10 H 21,} m = 2, n = 1 compounds) were prepared.

(E) This compound was enclosed in a glass cell having a transparent electrode having an electrode gap of about 3 μm and observed with a polarizing microscope.
SC * phase was exhibited in the range of ° C. In this temperature range, for example ±
When a 5V, 1Hz electric field was applied, domain inversion was observed along with the electric field polarity reversal. Other phase transition temperatures are shown in Table 1 below together with other examples. Here, Cry indicates a crystalline state, SC * indicates a chiral smectic C phase, SA indicates a smectic A phase, Ch indicates a cholesteric phase, and I indicates an isotropic liquid phase. Indicates that the phase exists. In addition, this compound was enclosed in a cell with an electrode gap of 115 μm, and the triangular wave method reported by Miyazato et al. [K. Miyasato, S. Abe, H. Takezoe, A. Fukada and E. Kuse, Japanese.
Journal of Applied Physics (Jpn.J.Ap
pl. Phys.), 1983, Vol. 22, L661, the spontaneous polarization was measured and found to be 182 nC / cm ² .

Example 2 Compound 4-Methoxybiphenyl 27.6 g, acetic acid 160 ml and sulfuric acid 4 m
It was dissolved in l, an aqueous solution of 51.3 g of periodic acid was added, and further 20 g of iodine was added little by little. Agitate at 62-73 ° C for 1
The reaction was allowed for 0 hours. After cooling, water was added, and the mixture was extracted with chloroform, washed with an aqueous sodium hydrogen sulfite solution to remove excess iodine, washed with water, dried, passed through a short silica gel column and then the solvent was removed, and 4-methoxy-4 ′ was used. -Iodobiphenyl was prepared.

Next, 15.5 g of the above compound was mixed with 8.2 g of anhydrous aluminum chloride. After standing for 2 hours, 50 ml of cyclohexane was added and kept at 60 to 70 ° C for 5 hours. After cooling, 50 ml of dilute hydrochloric acid was added, stirred and washed with water, the solvent was distilled off, and the residue was recrystallized from ethanol. -Hydroxy-4'-iodobiphenyl (IV, X = -O- group, m = 2) was prepared.

The above compound (IV) (1.5 g) was dissolved in pyridine (30 ml), and a solution of optically active perfluoro-2-propyloxypropionic acid chloride (1.8 g) in toluene was gradually added to the solution at 55 to 62 ° C.
After stirring for 5 hours at room temperature, the mixture was left standing overnight, water was added to the mixture, and the mixture was extracted with toluene.
After drying over anhydrous magnesium sulfate, it was passed through a silica gel column and recrystallized from heptane to give 4- (perfluoro-1).
-Propyloxyethylcarbonyloxy) -4-iodobiphenyl (V, where X = -O- group, m = 2) was prepared.

From the compound (V) above, 4-ethynyl-4 ′-(perfluoro-1) was prepared in the same manner as in Examples 1 (b) and (c).
-Propyloxyethylcarbonyloxy) biphenyl (VII, where X = -O- group, m = 2) was prepared. Finally, using the above compound (VII) and decyl 4-iodobenzoate, the compound (in the general formula I, X = -O- group, Y = -COO- group, R = was used) in the same manner as in Example 1 (d). C ₁₀ H
₂₁ , a compound of m = 2 and n = 1) was produced.

The phase transition temperature of this compound is as shown in Table 1. Note that () indicates that the phase is monotropic. The spontaneous polarization value measured in the same manner as in Example 1 was 131 nC / cm ² .

Example 3 Compound The compound was prepared in the same manner as in Example 1 except that 4-dodecyloxyiodobenzene was used in place of decyl 4-iodobenzoate (X = direct bond, Y = -O in general formula I).
- _{group, R = C 12 H 25,} m = 2, n = 1 compounds) were prepared.

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

Example 4 Compound 4- (Perfluoro-1-propyloxyethylcarbonyloxy) iodobenzene (V, where X = -O is obtained in the same manner as in Example 2 except that 4-iodophenol is used in place of 4-hydroxy-4'-iodobiphenyl.
Group, m = 1) was prepared, and this compound was added to 4-iodo-
The compound was prepared in the same manner as in Example 1 except that 4′-dodecylbiphenyl was used (in the general formula I, X═—O— group, Y
= Direct bond, R = C ₁₂ H ₂₅ , m = 1, n = 2). The phase transition temperature of this compound is as shown in Table 1.

Example 5 Compound Iodobenzene instead of 4-iodobiphenyl
4'-iodo-instead of octyl 4-iodobenzoate
4- Biff enyl carboxylic except for using acid decyl in the same manner as in Example 1 compound (Formula X = a direct bond in I, Y = -COO- _{group, R = C 10 H 21,} m = 1, n = 2 Compound) was produced.

 The phase transition temperature of this compound is as shown in Table 1.

The spontaneous polarization value measured in the same manner as in Example 1 is 16
It was 4 nC / cm ² .

Example 6 Compound A compound was prepared in the same manner as in Example 2 except that 4- (perfluoro-1-propyloxyethylcarbonyloxy) iodobenzene (V) obtained in Example 4 and 4-iodo-4′-decyloxybiphenyl were used. (in the general formula I X = Y = -O- _{group, R = C 10 H 21,} m = 1,
n = 2 compounds) were prepared. The phase transition temperature of this compound is as shown in Table 1.

Example 7 Compound In the same manner as in Example 1 except that iodobenzene was used instead of 4-iodobiphenyl, the compound (general formula I
X = a direct bond at, Y = -COO- _{group, R = C 8 H 17,} m
= N = 1 compound) was produced.

 The phase transition temperature of this compound is as shown in Table 1.

Example 8 Compound The compound was prepared in the same manner as in Example 1 except that racemic perfluoro-2-propyloxypropionic acid and optically active-4-iodobenzoic acid-1-methylheptyl ester were used (X in formula I: direct bond, Y = -COO-
The group R = CH * (CH ₃ ) C ₆ H ₁₃ , m = 2, n = 1) was prepared.

 The phase transition temperature of this compound is as shown in Table 1.

The value of spontaneous polarization measured in the same manner as in Example 1 was 11
It was 7 nC / cm ² .

-In the columns of X and Y-is a direct bond, and-in the column of Ch
Indicates that this phase does not exist or its existence is unclear. 1 MH represents an optically active 1-methylheptyl group.

Example 9 [Liquid Crystal Composition] 4′-of the following structural formula, which is a non-chiral smectic liquid crystal, is added to 18 parts by weight of the compound of Example 7.
(2-Methylbutyl) -4-biphenylcarboxylic acid (4
-Hexyloxyphenyl) ester 29 parts by weight, and 4'-octyloxy-4-biphenylcarboxylic acid (4
A liquid crystal composition was prepared by mixing 53 parts by weight of -pentyloxyphenyl) ester.

This liquid crystal composition responded to the electric field of Example 1 (e) in the range of 4 to 49 ° C. and showed the SC * phase. The response time obtained from the change in transmitted light intensity when a square wave of ± 20 V and 10 Hz was applied was 35 μsec, indicating a high-speed response.

Example 10 [Liquid Crystal Composition] Compounds of Examples 3 to 5
A liquid crystal composition was prepared by mixing 32 and 33 parts by weight of the non-chiral smectic liquid crystal of Example 9 with 2 and 14 parts by weight, respectively. This liquid crystal composition is 2 to 59 ℃
The SC * phase was shown in the range. Moreover, the response time measured in the same manner as in Example 9 was 48 μsec, which showed a high-speed response.

Thus, by mixing liquid crystal compounds having different structures, a liquid crystal composition exhibiting a chiral smectic C liquid crystal phase can be obtained in a wider temperature range than when used alone and above and below room temperature.

〔The invention's effect〕

As described above, according to the present invention, by using 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, the spontaneous polarization is large and the viscosity is low. Therefore, not only a material capable of high-speed response when used as a display element can be provided, but also a material system exhibiting a chiral smectic phase in a wide temperature range can be provided.

Claims (2)

(57) [Claims] (1) The following general formula (I): [However, X is an -O- group or a direct bond, and Y is -COO-
Group, —O— group, or direct bond, m and n represent 1 or 2, m + n is 2 or 3, R represents an alkyl group having 4 or more carbon atoms, and C ₃ F ₇ OCF (CF ₃ ) -Group or R is at least one is an optically active group]. 2. A liquid crystal composition comprising at least one optically active compound according to claim 1 as a component.