JPH0629222B2 - Novel compound, method for producing the same, and liquid crystal composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a display device, an optical device, and
The present invention relates to a liquid crystal compound and a liquid crystal composition that can be used for various sensors and the like, and particularly to provide a liquid crystal material exhibiting ferroelectricity, and to provide a liquid crystal display device having a faster response speed than conventional liquid crystal materials. A liquid crystal material having utility value is provided.

<Prior Art> Liquid crystal display devices have many excellent features such as low voltage operability, low power consumption, thin display capability, and light-receiving type that do not cause eye strain. It is used for many purposes. At present, the display method is generally mainly Twisted Nematic (T
A nematic liquid crystal called N) type is used as a material. However, this TN type display element has a drawback that the response is very slow compared to other light emitting type display elements (for example, CRT), and is subject to application restrictions such as not suitable for moving images. Was there. Other liquid crystal display methods are guest-host (GH) type, dynamic scattering (DS)
Type, birefringence control (ECB) type, phase transition (PC) type, thermal effect type, etc. have been developed, and all have their characteristics, but there is no significant difference in response from the TN type. Therefore, development of a new liquid crystal display system with excellent response speed has been tried in various fields.

Ferroelectric liquid crystal was first announced by RB Meyer in France in 1975 (RB Meyer et al., Journal de Physique (RBMeye).
r et al. J. Physique 36 L-69 (1975)), the display element using this is very fast, about 1000 times faster than the conventional liquid crystal, and memory because of the ferroelectricity of liquid crystal. It has an excellent feature that it has both properties and can be expected to be applied to various fields as a display device including use for moving images such as television screens.

Ferroelectric liquid crystal has a tilted chiral smectic phase as a liquid crystal phase, that is, chiral smectic C (SmC ^* ).
Phase, chiral smectic F (SmF ^* ) phase, chiral smectic G (SmG ^* ) phase, chiral smectic H (SmH ^* ) phase,
It belongs to the chiral smectic I (SmI ^* ) phase, the chiral smectic J (SmJ ^* ) phase, and the chiral smectic K (SmK ^* ) phase. Fast response has been experimentally confirmed for some of these phases, but at present, the chiral smectic C (SmC ^* ) phase is considered to be the most preferable in a practical sense.

Some liquid crystal compounds exhibiting a chiral smectic (SmC ^* ) phase are already known. A typical example is (S) -2-methylbutyl p, which was first synthesized as a ferroelectric liquid crystal.
-Decyloxybenzylidene aminocinnamate (DOBA
MBC) and a series of Schiff base liquid crystals.

(1) P. Keller and others, Journal de Physique, PK
eller et al. J. de Physique 37 C3 (1976); 2) Ibid.
Academy de Science Paris, idem, Acad.Sc.Par
is 282 C639 (1976); 3) B. I. Ostrovsky et al., Ferroelectrics, BIOstrouskii et al F
erroelectrics 24 309 (1980); 4) K. Yoshino et al.,
Japanese Journal of Applied Physics, K. Yoshino et al. Japanese J. of Appl. Physics 2
3 L175 (1984); 5) Isogai et al., JP-A-59-98051) However, all of them have problems in chemical stability against water, light, etc. and are not suitable for practical use.

Some are known for azoxy liquid crystals (P. Keller et a, P. Keller et al., Anale de physique.
l, Ann.Phys. 3 139 (1978)) Its liquid crystal temperature range and strong coloring property make it unsuitable for practical use.

Ester-based chiral smectic liquid crystals have already
Some reports by odby et al. (Goodbye et al., Liquid.
Crystals and Ordered Fluids, go
odby et al Liquid Crystals & Ordered Fluids Vol 4
However, the appearance of the chiral smectic phase is monotropic, the temperature range is high, and the process of introducing the chiral group is complicated, which is not satisfactory.

<Problems to be Solved by the Invention> The inventors have found that an ester compound as a liquid crystal compound is
Focusing on the point that it is excellent in chemical stability and photostability, the inventors have earnestly studied whether a new liquid crystal compound having a chiral smectic phase can be obtained at around room temperature, and arrived at the present invention.

That is, the present invention intends to provide a novel ferroelectric compound which is excellent in light and chemical stability and is colorless and capable of operating at room temperature, a composition, and a liquid crystal compound as a compounding component of the composition. Is.

The present invention also aims to provide a method for industrially easily producing such a novel compound.

<Means for Solving the Problem> The compound of the present invention is characterized by being represented by the following general formula (I).

(In the formula, R represents an alkyl or alkoxy group having 1 to 20 carbon atoms, R ^* represents an optically active alkyl group, and X, Y
Represents hydrogen, chlorine, or fluorine,
X and Y do not represent hydrogen at the same time. ) In order to exhibit ferroelectricity, it is necessary for the liquid crystal to have a tilt type chiral smectic phase, preferably a chiral smectic C (SmC ^* ) phase. In order to take a chiral smectic phase, it is necessary to select a liquid crystal molecular skeleton that has a smectic phase easily.

The compound of the general formula (I) in the present invention (hereinafter referred to as compound I) has the following structure as the core of the molecular skeleton, (Where X and Y are as described above) Those having the structure of (3) are characterized in that they easily take a smectic phase, and due to the presence of halogen atoms, the liquid crystal temperature range is in the low temperature range.

In order for a liquid crystal molecule to exhibit a chiral smectic phase, it is necessary that the molecule be asymmetric and optically active. Therefore, it is necessary to introduce an optically active alkyl group having an asymmetric carbon atom as a substituent. ing. The compound I of the present invention is, for example, commercially available (S)-(-)
By linking 2-methylbutanol, 2-octanol or the like to one end of the molecule through an ester bond, the condition can be satisfied, and the introduction thereof is very easy. Ferroelectric liquid crystals need to have large spontaneous polarization for practical purposes, but in compound (I), they are permanent dipoles in the molecule near their asymmetric carbons. It has a bond and C-halogen (fluorine or chlorine), and is advantageous in that respect.

Compound I has only stable ester bond, ether bond, and aromatic ring-halogen bond as a functional group in its molecular skeleton, and thus is stable to thermal, chemical, and light, and is sufficiently practical. It is profitable.

In compound I alone, chiral smectic C (SmC
^* ) Those which do not show a phase (in compound I, X = Cl, Y = H
Although the case, etc.) are present, they by blending with other species of compound I showing a chiral smectic C (SmC ^*) phase, shows a chiral smectic C (SmC ^*) phase, and a liquid crystal composition obtained by the formulation It has the effect of lowering the melting point of the product and the temperature range of liquid crystal.

The liquid crystal composition referred to in the present invention is composed of a plurality of compounds belonging to compound I, or compound I as a compounding component thereof.
Is contained in at least one kind and is characterized by having liquid crystallinity.

Next, a method for producing compound I will be described. The compound of the present invention can be synthesized by the general formula (II) (In the formula, R represents an alkyl or alkoxy group having 1 to 20 carbon atoms.)
II) and the general formula (III) (In the formula, R ^* represents an optically active alkyl group, and X,
Y represents hydrogen, fluorine, or chlorine, but X and Y do not represent hydrogen at the same time. ) And a phenol derivative (hereinafter referred to as “phenol derivative III”) represented by (1) are reacted in an organic solvent.
Acid chloride II is not suitable for storage because it is not easy to purify and decomposes in moisture. (Wherein R is the same as acid chloride II) is reacted with a chlorinating agent such as thionyl chloride in the presence of a basic substance (which may also serve as a solvent) in an organic solvent. A suitable method is to synthesize the compound I by adding the phenol derivative III and reacting it with the acid chloride II, without isolation and purification, and removing only the chlorinating agent.
Pyridine is mainly used as the basic substance, but other tertiary amines such as triethylamine can also be used. As the chlorinating agent, inorganic acid chlorides such as thionyl chloride, phosphorus trichloride, phosphorus pentachloride and phosphorus oxychloride can be used, but thionyl chloride is most suitable. As the solvent, almost all organic solvents except alcohols, carboxylic acids, primary and secondary amines can be used, but usually aromatic hydrocarbons such as benzene and toluene, halogen-based solvents such as methylene chloride and carbon tetrachloride. Esters such as hydrocarbons and ethyl acetate are used. Alternatively, pyridine or the like used as a base may be used in excess and used as a solvent.

The phenol derivative III used as a starting material, that is, an alkyl ester of halogen-substituted hydroxybenzoic acid, such as (S) -2-methylbutyl ester, has the corresponding general formula V (In the formula, X and Y are the same as the phenol derivative III.) And a halogen-substituted hydroxybenzoic acid represented by (S)-
Acid-catalyzed dehydration ester condensation with 2-methylbutanol, or the corresponding general formula VI (In the formula, X and Y are the same as the phenol derivative III.) Easily by heating the halogen-substituted cyanophenol in (S) -2-methylbutanol under acid catalyst in the presence of a trace amount of water. Can be obtained. Other alkyl esters can be synthesized in much the same way.

The obtained liquid crystal compound or composition can be used as a liquid crystal display cell by forming a thin film having a uniform thickness (1 μm to 20 μm) between two transparent electrode plates. In the cell, the liquid crystal molecules are required to have a so-called homogeneous uniform alignment parallel to the electrode surface. For this purpose, a method in which a uniformly oriented monodomain is obtained by gradually cooling to a smectic phase under the condition of applying an electric field or magnetic field, or with a temperature gradient, is used. In the same manner as above, a monodomain can be formed by the same method and used as a display element.

<Effects of the Invention> The present invention is as described above.
Is, as compared with DOBAMBC which is conventionally known as a chiral smectic liquid crystal compound, can be easily produced industrially as shown in Examples described later, is colorless in itself, and is resistant to light, water, etc. It excels in chemical stability and emerges a chiral smectic phase at lower temperatures. Moreover, in the composition of the present invention, like the general liquid crystal composition, the temperature range of the liquid crystal is lower than that of a single compound, and it is expected that the composition can be used at room temperature. Further, the liquid crystal compound and the liquid crystal composition of the present invention have an extremely high response speed of 10 μsec, which is about 1000 times that of a nematic liquid crystal, like the conventional ferroelectric liquid crystal. Therefore, it is extremely promising as an optical switching element for display.

<Examples> The present invention will be specifically described below with reference to Examples, but of course the gist and scope of the present invention are not limited to these Examples.

Example 1 Synthesis and physical properties of (abbreviated as IAn) 4.38 g of 4'-n-hexadecyloxybiphenyl-4
-Carboxylic acid (IV) _{n = 16} was stirred in 50 ml of pyridine under nitrogen atmosphere at room temperature, and then thionyl chloride 3.0 m under ice cooling.
l was added dropwise. After heating to 60 ° and stirring for 5 hours, the temperature was returned to room temperature, and excess thionyl chloride and most of the remaining pyridine were distilled off under reduced pressure. Most of the residual viscous yellow oil was 4'-n-hexadecyloxybiphenyl-4-.
Carboxylic acid chloride (II) _{n = 16} , but this was not isolated and purified, and the (S) -2-methylbutyl-2-fluoro-4-hydroxybenzoate (III) was directly added to the reaction system.
2.26 g (X = H, Y = F) dissolved in 30 ml carbon tetrachloride were added. The mixture was heated to 50 to 60 °, reacted for 4 hours and then left to cool. 200 ml of ethyl acetate was added to the reaction product,
Then, the mixture was washed successively with 50 ml each of 5% hydrochloric acid, 5% aqueous sodium hydrogen carbonate solution, water and saturated saline solution, and then dried over anhydrous sodium sulfate. The oily substance obtained by distilling off the solvent under reduced pressure was purified by silica gel column chromatography (developing solvent: n-hexane-ethyl acetate mixed system) and recrystallized from ethanol to give 4-((S)).
-2'-methylbutyloxycarbonyl) -3-fluorophenyl 4'-n-hexadecyloxybiphenyl-
5.42 g of white crystals of 4-carboxylate (IA16) were obtained. (Yield 84%) Confirmation of the structure of the product was confirmed by nuclear magnetic resonance spectrum (NMR),
Based on infrared absorption spectrum (IR) and mass spectrum (MS). The results are shown below.

NMR: δ6.8 to 8.3 (m ^* .11H, aromatic), δ4.17 (d
_{^{d **. 2H, COOCH 2)}} , δ3.98 (t ***. 2H, _{^{δ1.6~1.9 (m *. 3H),}} δ1.2~1.5 (m *. 28H), δ0.8
_{^{5~1.1 (m *. 9H, -CH}} 3) IR: 1740,1725,1610,1300,1260,1210,1140,1080,840,775
(cm ^-1 ) MS: M / e = 646 (P ⁺ ) ^**** Represents the parent peak. (IA16) is a liquid crystal compound having a smectic A (SmA) phase and a chiral smectic C (SmC ^* ) phase, and isotropic liquid phase (I
So) to SmA phase transition temperature (Iso-SmA) is 155 ° (hereinafter all temperatures mean ° C), SmA to SmC ^* phase transition temperature (SmA-SmC ^* ) is 82.5 °, melting point is It was 76 °.

Example 2 Instead of (IV) _{n = 16} in Example 1, 4'-n-
Tetradecyloxybiphenyl-4-carboxylic acid (IV)
_{n = 14} , 4'-n-dodecyloxybiphenyl-4-
Carboxylic acid (IV) _{n = 12} , 4'-n-decyloxybiphenyl-4-carboxylic acid (IV) _{n = 10} was used to carry out the same reaction and purification in the same manner as in 4-((S) -2'- Methylbutyloxycarbonyl) -3-fluorophenyl 4'-n-tetradecyloxybiphenyl-4-carboxylate (I
A14), 4-((S) -2'-methylbutyloxycarbonyl) -3-fluorophenyl-4'-n-dodecyloxybiphenyl-4-carboxylate (IA12), 4 ((S)
2'-Methylbutyloxycarbonyl) -3-fluorophenyl-4'-n-decyloxy-4-carboxylate (IA10) was synthesized. All IRs are (IA1
It showed absorption similar to that of 6), and NMR showed a pattern in which only the intensity of the proton of the saturated methylene chain at δ1.2 to 1.5 changed. All MS showed a parent peak. The transition temperatures are shown below. (Sm ^* indicates other chiral smectic phases) Example 3 (Synthesis and physical properties of IBn) 10.98 g of 4'-n-dodecyloxybiphenyl-4-
Carboxylic acid (IV) _{n = 12} was dissolved in 50 ml of carbon tetrachloride, 10 ml of pyridine was added and stirred. Under cooling with water, 10.0 ml of thionyl chloride was added dropwise, and the mixture was heated at the reflux temperature of the solvent for 2 hours for reaction. Excess thionyl chloride and most of the solvent were distilled off under reduced pressure, and 6.78 g of (S) -2-methylbutyl 3-fluoro-4-hydroxybenzoate (III) (X = F, Y
= H) was added as 50 ml of methylene chloride solution, and the mixture was heated under reflux for 1 hour.

The solvent was distilled off under reduced pressure, 200 ml of ethyl acetate was added, and 5%
It was washed successively with 50 ml each of hydrochloric acid, 5% aqueous sodium hydrogen carbonate solution, water and saturated brine, and dried over anhydrous magnesium sulfate. The solvent was distilled off, and the obtained crude crystals were added to ethanol-
Recrystallization from hexane was repeated twice to obtain 14.0 g of 4-((S) -2'-methylbutyloxycarbonyl) -2fluorophenyl 4'-n-dodecyloxybiphenyl-4-carboxylate (IB12). (Yield 81.3%) Each spectrum data and transition temperature are as follows.

NMR: δ6.9 to 8.2 (m.11H, aromatic), δ4.15 (dd.2H, CO
OCH _2- ), δ4.00 (t.2H, δ1.6 to 2.0 (m.3H), δ1.2 to 1.5 (m.20H), δ0.85 to 1.1
_{(m.9H, -CH 3) IR:} 1735,1720,1600,1295,1190,1110,1070,830,760 (cm
^-1 ) MS: M / e = 590 (P ⁺ ) Transition temperature Example 4 In place of 4′-n-dodecyloxybiphenyl-4-carboxylic acid (IV) _{n = 12} in Example 3, 4′-n-octyloxybiphenyl-4-carboxylic acid (IV) _{n = 8} ,
4'-n-hexadecyloxybiphenyl-4-carboxylic acid (IV) _{n = 16} was used to carry out the same reaction to give 4-
((S) -2'-methylbutyloxycarbonyl) -2-
Fluorophenyl 4'-n-octyloxybiphenyl-4-carboxylate (IB8) and 4-((S) -2'-
Methylbutyloxycarbonyl) -2-fluorophenyl 4'-n-hexadecyloxybiphenyl-4-carboxylate (IB16) was obtained. NMR and IR show the same spectrum pattern as IB12, MS shows M / e = 534 (IB8),
630 (IB16) (all P ⁺ ) was shown. The transition temperatures are shown below.

Example 5 (Synthesis and physical properties of ICn) 4'-n-decyloxyphenyl-4-carboxylic acid (IV)
_{n = 10} 3.54 g and (S) -2-methylbutyl 2-chloro-4-hydroxybenzoate (III)
Reaction and purification were carried out in the same manner as in Example 1 using _{x = H and Y = cl} , and 4- (2'-methylbutylcarbonyl) -3-chlorophenyl 4'-n-decyloxybiphenyl-4- was used.
4.45 g of carboxylate (IC10) was obtained. (Yield 77%)
The structure was confirmed by NMR, IR and MS. The spectrum data and transition temperature are shown below.

NMR: δ6.9 to 8.2 (m.11H, aromaticH), δ4.16 (dd.2H, COO
CH _2- ), δ3.96 (t.2H, δ1.6 to 2.0 (m.3H), δ1.2 to 1.6 (m.16H), δ0.85 to 1.05
(m.9H, CH ₃ ) IR: 1725,1605,1400,1295,1205,1120,1075,835,775,700
(cm ^-1 ) MS: M / e = 578,580 (P ⁺ ) Example 6 (Synthesis and physical properties of IDn) 4'-n-hexadecyloxybiphenyl-4-carboxylic acid (IV) _{n = 16} 2.76 g and (S) -2-methylbutyl 3
-Chloro-4-hydroxybenzoate (III)
_The reaction and purification were carried out in the same manner as in Example 3 using 2.43 g of _{x = cl and Y = H} to give 4- (2'-methylbutyloxycarbonyl) -2-chlorophenyl 4'-n-hexadecyloxybiphenyl-4. -Carboxylate (ID16) 5.50g
Got (Yield 83%) The structure was confirmed by NMR, IR and MS. The spectrum data and transition temperature are shown below.

NMR: δ6.9 to 8.3 (m.11H, aromatic), δ4.15 (dd.2H, COOC
H ₂ ), δ3.96 (t.2H, δ1.6 to 1.9 (m.3H), δ1.2 to 1.5 (m.28H), δ0.85 to 1.05
_{(m.9H, -CH 3) IR:} 1745,1720,1608,1280,1255,1200,1115,1075,840,77
0cm ^-1 MS: M / e = 662 (P ⁺ ) Example 7 4'-n-dodecyloxybiphenyl-4-carboxylic acid
(IV) Using _{n = 12} , the reaction and purification were carried out in the same manner as in Example 6 to give 4-((S) -2′-methylbutyloxycarbonyl) -2-chlorophenyl 4′-n-dodecyloxybiphenyl-4. -Carboxylate (ID12) was obtained. NMR, IR
Shows the same spectrum pattern as (ID16), MS has M / e = 6
It showed 06 (P ⁺ ). The transition temperatures are shown below.

Example 8 (Composition of Liquid Crystal Composition Showing SmC ^* Phase) 40 parts of (IA16) was mixed with 10 parts of (ID12) and (ID16) to prepare a liquid crystal composition A. The composition A showed the SmC ^* phase, and its temperature range was 65 ° to 78 °, which was considerably lower than that of (IA16) alone, and the enantiotropic stable state was exhibited. The transition temperatures are shown below.

Example 9 A liquid crystal composition B was prepared by mixing 20 parts (ID16) with 27 parts DOBAMBC. Composition B showed the SmC ^* phase whose temperature range was 41 ° to 53 °, which was considerably lower than that of DOBAMBC alone. The transition temperatures are shown below.

Example 10 (Preparation of Liquid Crystal Display Device) Isotropic phase (IA16) was filled between two glass transparent electrode plates with a spacer having a thickness of 3 μm interposed therebetween to prepare a thin film cell. Gradually cooling with a temperature gradient, the SmA phase was oriented and a uniform monodomain was obtained. When this cell was cooled to the SmC ^* phase and an electric field (5 V, 0.1 Hz rectangular wave) was applied between 63 ° and 73 °, a clear switching operation was confirmed. Further, when a rectangular wave of 15 V and 20 kHz was applied and an optical switching operation was detected by a photomultiplier, a clear switching operation was also confirmed. As a result, a liquid crystal display device having a high response speed was obtained.

Example 11 Instead of carboxylic acid (IV) _n = 16 as in Example 2,
4'-n-octyloxybiphenyl-4-carboxylic acid
Compound (IA8) was synthesized using (IV) _n = 8. The physical properties of this product are shown in Table 1 (a).

Example 12 Compound IF12 was synthesized using a carboxylic acid in which the substituent R was an n-octyl group instead of the carboxylic acid (IV) _n = 12 in Example 2. The physical properties of this product are shown in Table 1 (a).

Example 13 From the five carboxylic acids used in Examples 2, 11 and 12 and the phenol derivative III having the substituents X = H and Y = cl, five compounds IG8 and IG1 were prepared in the same manner as in Example 3.
0, IG12, IG14, and IH12 were synthesized. The physical properties of these are shown in Table 1 (a).

Example 14 Carboxylic acid (IV) _n = 10 in Example 2 and Example 1
Substituents R ^* are each, instead of the phenol derivative in the s
Two kinds of compounds IJ10 and IK10 were synthesized from the two kinds of phenol derivatives substituted with the (R) -1-methylpropyl group and the (R) -1-methylheptyl group. The physical properties of these are shown in Table 1 (b).

Claims (7)

[Claims] 1. A compound represented by the general formula I: (In the formula, R represents an alkyl or alkoxy group having 1 to 20 carbon atoms, R ^* represents an optically active alkyl group, and X and Y each represent hydrogen, fluorine, or chlorine. , Y does not represent hydrogen at the same time.) 2. General formula II (In the formula, R represents an alkyl or alkoxy group having 1 to 20 carbon atoms.) And a general formula III (In the formula, R ^* represents an optically active alkyl group, and X and Y each represent hydrogen, fluorine, or chlorine, but X and Y do not represent hydrogen at the same time.) Of the general formula I, characterized in that it is reacted with a phenol derivative (The symbols in the formula are as described above). 3. The general formula I (In the formula, R represents an alkyl or alkoxy group having 1 to 20 carbon atoms, R ^* represents an optically active alkyl group,
X and Y each represent hydrogen, fluorine or chlorine, but X and Y do not represent hydrogen at the same time. ) A liquid crystal composition containing at least one compound I represented by the formula (1) as a compounding component. 4. The liquid crystal composition according to claim 3, which contains two or more compounds I. 5. A liquid crystal composition according to claim 3, which contains at least one compound I and a liquid crystal compound other than compound I. 6. The liquid crystal composition according to claim 3, 4 or 5, which has a chiral smectic phase. 7. The liquid crystal composition according to claim 6, which can be used as an optical switching element for display.