JPH0742460B2 - Chiral smectic liquid crystal composition - Google Patents

Description

The present invention relates to a liquid crystal composition exhibiting a chiral smectic C phase. More specifically, the present invention relates to a liquid crystal composition exhibiting a chiral smectic C phase, which is suitable for a ferroelectric liquid crystal display suitable for displaying a large capacity and a wide viewing angle.

(B) Conventional technology At present, liquid crystal display devices mainly use the nematic phase of liquid crystal, but in recent years, in addition to this, research on various display modes using the smectic phase has been actively conducted. There is. In particular, a liquid crystal display using a ferroelectric liquid crystal utilizing a chiral smectic C phase is regarded as promising because it can display a large capacity and has a wide viewing angle.

(C) Problems to be solved by the invention However, in the case of a ferroelectric liquid crystal display, a normal TN
Since the memory characteristic in the smectic C phase is utilized unlike the matic) display, it is necessary to improve the response speed as the display capacity increases. For example, if a driving method in which one screen is rewritten in 1/60 sec and four pulses are applied to rewrite one line, the relationship with the number of lines L that can be displayed at the response speed τ is 4 × τ × L = 1. In order to apply it to a large-capacity liquid crystal display device with a large number of lines, which is / 60 sec, the liquid crystal is required to have a significantly high response speed.

Therefore, as a liquid crystal used for a conventional ferroelectric liquid crystal display, a liquid crystal composition in which a plurality of compounds are mixed so as to satisfy various conditions desired for a liquid crystal as in the case of a nematic liquid crystal is used, but at present, the response speed is still low. In terms of, there is no satisfactory result.

Further, the properties desired for the liquid crystal composition used for the ferroelectric liquid crystal display include the following properties in addition to the high speed response as described above. First, of course, it is necessary to exhibit a smectic C phase near room temperature. Further, IAC in order to obtain the orientation of the good liquid crystal (i sotropic-smectic A -smectic
C) or INC (i sotropic- n ematic-smectic A -smec
It is desirable that the liquid crystal composition exhibit a tic C ) phase sequence.

The present invention has been made under such circumstances, and in particular, it is intended to provide a chiral smectic liquid crystal composition having a high response speed, and further exhibits a smectic C phase at around room temperature to exhibit a desired liquid crystal phase series. It is intended to provide a smectic liquid crystal composition.

(D) Means for Solving the Problems As a result of intensive research from the above viewpoint, the inventors of the present invention add a small amount of the compound represented by formula (A) to a liquid crystal compound exhibiting a smectic C phase. As a result, it was found that a chiral smectic liquid crystal composition exhibiting a high-speed response and satisfying the properties desired for a liquid crystal composition used for a ferroelectric liquid crystal display as described above can be obtained, and the present invention provides the same. Arrived

Thus, according to the present invention, a liquid crystal compound exhibiting a smectic C phase has the following formula (A): (In the formula, R ₁ and R ₂ are the same or different and represent a linear or branched alkyl group having 1 to 12 carbon atoms. * Indicates that C is an optically active carbon atom.) There is provided a chiral smectic liquid crystal composition comprising at least one compound represented by

The compound of the above formula (A) used in this invention is a novel compound which has not been described in the literature.

In addition, the terms used in the formula (A) and the formulas described below,
"A straight-chain or branched alkyl group having 1 to 12 carbon atoms" means methyl, ethyl, propyl, i-propyl, butyl, i-butyl, t-butyl, pentyl, 2-methylbutyl, 2,2. -Dimethylpropyl, hexyl, 2 or 3-
Methylpentyl, 2,2-dimethylbutyl, 4-methylhexyl, 6-methyloctyl, n-heptyl, 2,2-dimethylpentyl, 3,3-dimethylpentyl, 2,4-dimethylpentyl, n-octyl, 2 It includes 2,2,3,3-tetramethylbutyl, nonyl, decyl, undecyl, dodecyl and the like. In these alkyl groups, the carbon chain may contain an asymmetric carbon.

Further, the "linear or branched alkoxy group having 1 to 12 carbon atoms" includes an alkoxy group substituted with the above alkyl group. Further, the alkoxycarbonyl group includes a carbonyl group to which such an alkoxy group is bound. The compound of formula (A) has a cis form and a trans form, and both can be used in the present invention.

The compound of the formula (A) is obtained by reacting an optically active epichlorohydrin with a phenol in the presence of a base, and the compound of the formula (I): The compound of formula (II): R ₂ —CH (COOR ₇ ) ₂ (II) (wherein R ₁ and R ₂ have the same meanings as defined in formula (A). R ₇ represents a lower alkyl group such as methyl and ethyl)
Can be obtained by reacting the malonic acid ester in the presence of a base.

As the liquid crystal compound exhibiting the smectic C phase in the present invention, various smectic liquid crystals known in the art can be used. As a specific example, the following formula (II
Examples thereof include compounds represented by I), (IV) and (V).

(In the formula, A and B are each a single bond or -COO-,
-OCO-, -CH = CH-COO-, -OCO-CH = CH-, -O
A-, -S-, -OCOO- or -CO- group is shown. D and E are each a single bond or -COO-, -OCO-, -CH =
N-, -N = CH-, -CH = CH-, -C≡C-, -CH = CH
-COO -, - OCO-CH = CH -, - CH 2 CH 2 -, - OCH 2 -, CH
_{2 represents an} O-, -COS- or -SCO- group.

Are each independently a benzene ring, a pyridine ring, a pyrimidine ring, a pyrazine ring, a pyridazine ring, a piperazine ring,
6-membered rings such as cyclohexane ring, pyran ring, dioxacyclohexane ring, thiapyran ring, dithian ring, thiadiazine ring, bicyclo [2.2.2] octane ring, and tetrazine ring are shown, and the hydrogen atom in these 6-membered rings is It may be substituted with a fluorine atom, chlorine atom, bromine atom, cyano group, nitro group, lower alkyl group, lower alkoxy group or deuterium (D). R ₈ and R ₉ each independently represent a linear or branched alkyl or alkoxy group having 1 to 12 carbon atoms. p represents an integer of 1 or 2. ) Of course, these can be used as a mixture of two or more kinds.

Among the smectic liquid crystal compounds as described above, the following formula (B): (In the formula, R ₃ represents a linear or branched alkyl group or alkoxy group having 1 to 12 carbon atoms, and R ₄ represents a linear or branched alkyl group having 1 to 12 carbon atoms) Since the compound has a dipole moment in the direction perpendicular to the molecular axis, it is preferable because it improves the thermal stability of the obtained chiral smectic liquid crystal composition and sufficiently secures the temperature stability of the smectic C phase. Further, a compound of formula (B) and the following formula (C): (In the formula, R ₅ is a linear or branched C 1-12 alkyl group or alkoxy group, R ₆ is a linear or branched C 1-12 alkoxy group or an alkoxy group thereof. X represents -COO-, -OCO-, or a single bond, and m and n are each an integer of 1 or 2) in combination with one or more compounds. The use of a smectic liquid crystal compound is more preferable because the above-mentioned thermal stability is further improved and a chiral smectic liquid crystal composition exhibiting a smectic C phase at room temperature is obtained. In this case, the mixing ratio of the compounds of the formulas (B) and (C) is usually 10: 1 to 1: 3 (polymerization ratio).

The chiral smectic liquid crystal composition of the present invention can be obtained by mixing the above-mentioned optically active compound of the formula (A) with a liquid crystal compound exhibiting a smectic C phase. In this case, the amount of the compound of the formula (A) mixed is 0.5 in the liquid crystal composition.
It is suitable to be 20 to 20% by weight, preferably 1 to 10% by weight. If it is less than 0.5% by weight, the effect of improving the response of the smectic liquid crystal compound is insufficient, and if it exceeds 20% by weight, the thermal stability of the smectic C phase is insufficient, which is not suitable.

The chiral smectic liquid crystal composition of the present invention may contain various additives such as a pitch adjusting chiral compound and a compound having a large Ps as long as the effect of the present invention is not impaired.

(E) Operation The compound of formula (A) has two optically active carbons, and these optically active carbons are incorporated in a rigid five-membered ring structure, so that the free rotation of the molecule is suppressed. It is considered that when mixed with a liquid crystal compound exhibiting a smectic phase, spontaneous polarization as a liquid crystal composition is increased and the response speed is greatly improved. By selecting a smectic liquid crystal compound to be combined and a mixing ratio, a liquid crystal composition exhibiting a smectic C phase at around room temperature and having a high response speed having a phase series such as IAC or INAC can be obtained.

(F) Examples The liquid crystal compositions having a chiral smectic C phase of the present invention will be described in detail below with reference to Examples, but the present invention is not limited thereto.

In each of the following examples, the R and S indications of the optically activated product (A) of the present invention were based on the position numbers of the following compound formulas.

Preparation of optically active compound (A) Example 1-a R-(-)-epichlorohydrin (chemical purity 98.5% or more, optical purity 99% or more) 5.55 g and 4- (trans-4-n) represented by the following chemical formula: -Pentylcyclohexyl)
2.46 g phenol, A mixture of 0.04 g of benzyltriethylammonium chloride and 60 ° C. with stirring was added dropwise with an aqueous solution of sodium hydroxide (0.45 g of NaOH, 15 ml of water) over 20 minutes.
Refluxed for hours. The reaction solution was cooled to room temperature, extracted twice with ether, washed once with saturated brine, and the solvent was evaporated under reduced pressure. The residue was purified by silica gel chromatography to obtain 1.8 g of (S) -2,3-epoxypropyl-4- (trans-4-n-pentylcyclohexyl) phenyl ether represented by the following chemical formula (A ′).

The physical properties of this compound (A ') are shown below.

▲ [α] ²⁵ _D ▼ + 4.44 ° (c = 1.36, CH ₂ Cl ₂ ) NMR (CDCl ₃ ) δ: 0.45 to 2.50 (21H, m) 2.50 to 3.00 (2H, m) 3.15 to 3.50 (1H, m) 3.70 to 4.30 (2H, m) 6.79 (2H, d, J = 9.0Hz) 7.09 (2H, d, J = 9.0Hz) Next, 50 wt% sodium hydride suspended in mineral oil 224m
After washing g twice with dry ether, 10 ml of dry tetrahydrofuran was added. While stirring this suspension at 40 ° C, n-
130 mg of dimethyl butylmalonate was added dropwise and stirred for 5 minutes, and then (S) -2,3-epoxypropyl-4- (trans-4-n-pentylcyclohexyl) obtained above was obtained.
1.41 g of phenyl ether (A ') was added dropwise, and the mixture was stirred under reflux for 20 hours. After the reaction solution was returned to room temperature, 4N hydrochloric acid was added dropwise until pH = 1, extracted twice with ether, washed once with saturated saline solution, and the solvent was distilled off under reduced pressure. The residue is separated and purified by silica gel chromatography, and the optically active compound represented by the following chemical formula, (2S, 4S) body (A ₁ ) and (2R, 4
S) form (A ₂ ) of γ-lactone derivative of 50 mg and 4 respectively
0 mg was obtained.

The chemical formulas, physical properties and elemental analysis results of the optically active compound and (2S, 4S) body are shown below.

▲ [α] ²³ _D ▼ + 33.45 ° (c = 0.658, CH ₂ Cl ₂ ) NMR (CDCl ₃ ) δ: 0.88 to 1.98 (30H, m) 2.38 to 2.67 (3H, m) 4.07 to 4.13 (2H, m) 4.67~4.73 (1H, m) 6.83 (2H, d, as J = 8.3Hz) 7.12 (2H, d, J = 8.3Hz) IR (KBr) 1762cm -1 Elementary analysis (C ₂₆ H ₄₀ O ₃₎ CH theoretical value (%) 77.95 10.07 Actual value (%) 77.91 10.12 The chemical formula and physical properties of the optically active compound and the (2R, 4S) compound are shown below.

▲ [α] ²⁴ _D ▼ + 20.37 ° (c = 1.05, CH ₂ Cl ₂ ) NMR (CDCl ₃ ) δ: 0.70 to 2.95 (33H, m) 4.00 to 4.25 (2H, m) 4.50 to 4.95 (1H, m) 6.77 (2H, d, J = 8.4Hz) 7.11 (2H, d, J = 8.4Hz) IR (KBr) 1762cm ^-1 Example 1-b 50% sodium hydride 163mg dry 1,2-dimethoxyethane 716 mg of dimethyl-n-heptyl malonate in suspension
1,2-dimethoxyethane solution was added and reacted for 5 minutes under stirring, and then (S) -2,3-epoxypropyl-4-
A solution of 940 mg of (trans-4-n-pentylcyclohexyl) phenyl ether in 1,2-dimethoxyethane was added,
The mixture was heated and stirred for 2 hours and a half. The reaction mixture was acidified with hydrochloric acid, extracted with ether, evaporated to remove the solvent, and purified by silica gel column chromatography to obtain the γ-lactone of the optically active compound (2S, 4S) represented by the following chemical formula (A ₃ ). The derivative was obtained.

The physical properties of the above optically active compound (A ₃ ) are shown below.

▲ [α] ²³ _D ▼ + 27.61 ° (c = 0.04, CH ₂ Cl ₂ ) NMR (CDCl ₃ ) δ: 0.88 to 1.98 (36H, m) 2.10 to 2.83 (3H, m) 3.96 to 4.16 (2H, m) 4.67 to 4.73 (1H, m) 6.75 (2H, d, J = 8.3Hz) 7.10 (2H, d, J = 8.3Hz) IR (KBr) 1765cm ^-1 Preparation of chiral smectic liquid crystal composition A liquid crystal composition having a chiral smectic C phase having a composition shown in Table 1 was prepared. The phase transition temperature is also shown.

Both Compositions 1 and 2 show a smectic C phase around room temperature, Composition 1 shows an IAC phase series, and Composition 2 shows an INAC phase series.

In addition, a nematic (N) phase, a smectic A (S _A ) phase,
The liquid crystal phase such as the smectic C (S _C ) phase was identified by observing the structure with a polarizing microscope equipped with a hot stage and preparing a phase diagram of a binary system for confirming the compatibility of the known liquid crystal compound with the liquid crystal phase.

Further, among the compounds in the table, 2M4, 3M5, 4M6 and 6M8 are respectively optically active 2-methyl-butyl group and 3-methyl-
A pentyl group, a 4-methyl-hexyl group, and a 6-methyl-octyl group are shown.

Example 3 A liquid crystal display device was produced using the liquid crystal composition prepared in Example 2. An ITO film is formed on two glass substrates, a nylon film is applied, and rubbing is performed. Next, the two glass substrates are made to have the same Rabink direction, and the cell thickness is 2 μm.
Stick together. The liquid crystal composition shown in Table 1 in this cell 1,
Injected 2. This liquid crystal element was placed between two orthogonal polarizers, an electric field was applied, and changes in transmitted light intensity were observed. Table 1 also shows the response speed obtained from the change in transmitted light intensity when an electric field of Vp-p = 20 V was applied at 25 ° C.

As shown in Table 1, in the liquid crystal display device using the liquid crystal composition exhibiting the chiral smectic C phase, good orientation and high-speed response were obtained.

Example 4 The n-pentyl group of 4- (trans-4-n-pentylcyclohexyl) phenol of Example 1-a was converted into the following second
Other than using a phenol prepared by substituting one of the substituents represented by R ₁ in the table and a malonic ester prepared by substituting by one of the substituents represented by R ₂ in the same table In the same manner as in Example 1-a and Example 1-b, compound A ₄ ~
A ₁₃ was prepared. The physical properties of these compounds are also shown in Table 2.

Example 5 Various liquid crystal compositions exhibiting a chiral smectic C phase were prepared.
Each composition shown in Table 3 was prepared. The table also shows the phase transition temperature and the response speed measured in the same manner as in Example 3 for each liquid crystal composition.

(G) Effect of the Invention According to the present invention, a chiral smectic liquid crystal composition having a high-speed response suitable for a large capacity, wide viewing angle ferroelectric liquid crystal display can be obtained. In addition, it is possible to obtain a liquid crystal composition that exhibits a smectic C phase at around room temperature and an ideal liquid crystal phase series.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Fumiaki Funada 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (72) Inventor Kazuhiko Sakaguchi, 2-7-1, Minami-Sakurazuka, Toyonaka-shi, Osaka (72) Inventor Naoya Kasai 2-35-1 Oshima, Amagasaki City, Hyogo Prefecture (72) Inventor Yoshikazu Takehira 5-5-4 Suzuhara Town, Itami City, Hyogo Prefecture (56) References Japanese Patent Publication No. 5-39955 B2)

Claims (4)

[Claims] 1. A liquid crystal compound exhibiting a smectic C phase has the following formula (A): (In the formula, R ₁ and R ₂ are the same or different and represent a linear or branched alkyl group having 1 to 12 carbon atoms. * Indicates that C is an optically active carbon atom.) A chiral smectic liquid crystal composition obtained by adding at least one compound represented by: 2. A liquid crystal compound exhibiting a smectic C phase has the following formula (B): (In the formula, R ₃ represents a linear or branched alkyl group or alkoxy group having 1 to 12 carbon atoms, and R ₄ represents a linear or branched alkyl group having 1 to 12 carbon atoms) The liquid crystal composition according to claim 1, which comprises one kind or two or more kinds of the represented compounds. 3. A liquid crystal compound exhibiting a smectic C phase, which is one or more compounds represented by the formula (B),
Formula (C): (In the formula, R ₅ is a linear or branched C 1-12 alkyl group or alkoxy group, R ₆ is a linear or branched C 1-12 alkoxy group or an alkoxy group thereof. X represents -COO-, -OCO- or a single bond, and m and n are each an integer of 1 or 2.) from one or more compounds represented by The liquid crystal composition according to claim 2, wherein 4. A liquid crystal display device comprising the chiral smectic liquid crystal composition according to claim 1.