JPH072721B2 - Pyridazine derivative - Google Patents

Description

The present invention relates to a novel liquid crystal compound and a liquid crystal composition, and particularly to provide a liquid crystal material having ferroelectricity, which has a particularly high response time as compared with a conventional liquid crystal material. The present invention provides a liquid crystal material which has excellent properties and memory properties and is applicable to a liquid crystal display device.

Liquid crystal display elements are widely used as various display elements because of their excellent features such as low voltage operability, low power consumption, thin display capability, and light-receiving type that prevent eye strain.

At present, the most common display system uses nematic liquid crystal called Twisted Nematic type (TV type) as a material. However, while this TN type display device has all of the above-mentioned excellent features, it has a drawback that the response is very slow compared with other light emitting type display systems such as CRT. Therefore, various restrictions have been imposed in application to a display device such as a moving screen of a television set or a head of a high-speed printer which requires a fast response.

In addition to the TN type, guest-host (GH) type, birefringence control (ECB) type, phase transition (PC) type, thermal effect type, etc. have been developed as liquid crystal display elements, and each has its own characteristics. However, in terms of the responsiveness, none of them can be said to be particularly high speed compared with the TN type. For these display devices, a dual-frequency drive type was developed as a display system capable of obtaining a high-speed response, and although the response was considerably improved, it was difficult to say that it was still sufficiently satisfactory. For this reason, attempts have been made to develop a new display system that is more responsive.

Ferroelectric liquid crystals have recently been announced to meet this purpose. (Meyer et al .: Journal de Huisique, 36 L69 (1975)).

The display device using this ferroelectric liquid crystal is capable of 100-1000 times faster response than conventional liquid crystal and memory effect by bistability (Clark et al .: Applied Physics Letters, 36 899). (1980)), and can be expected to be applied to a moving image of a television or the like and a display element on the other side such as a high-speed optical shutter. Ferroelectric liquid crystal belongs to the tilt type chiral smectic phase as a liquid crystal phase, and among them, the chiral smectic C phase (hereinafter abbreviated as SC ^* phase) has the lowest viscosity and is practical. Is desirable for.

Liquid crystal compounds exhibiting the SC ^* phase have been studied so far and many are already known.

A typical example is (s) -2-methylbutyl p-decyloxybenzylidene aminocinnamate (abbreviated as DOBAMBC), which is the first known ferroelectric liquid crystal, and a Schiff base of its homologue. Examples include liquid crystals. This is still one of the most commonly used liquid crystal compounds for studying the physical properties and orientation of ferroelectric liquid crystals, and is one of the important physical property values for ferroelectric liquid crystals such as spontaneous polarization and pitch. I am associated with it. However, DOBAMBC and its series of compounds lack stability to light, lack stability to moisture,
The temperature range showing the SC ^* phase, which is itself colored, is DOBAM
BC, the temperature rise is 17 °, the temperature is narrow at 32 °, and there is a drawback that its temperature range is much higher than room temperature, which is especially fatal for use as a display element. It was not practical.

Many studies have been conducted on ester systems and the like in order to improve these drawbacks, and recently, heterocyclic compounds have been announced in pursuit of further excellent performance (Inukai et al., JP-A-60-92276, JP-A-60-226861). However, the pyrazine derivative or the pyridazine derivative described therein has a narrow temperature range and cannot be said to be sufficient.

The inventors of the present invention focused on a heterocyclic compound as a liquid crystal compound having excellent light and chemical stability, and by combining it alone or in combination, a liquid crystal phase having a ferroelectric property at around room temperature,
In particular, the inventors have made earnest studies as to whether or not a novel liquid crystal compound capable of having a chiral smectic C phase can be obtained, and have reached the present invention.

Further, the present invention is to provide a liquid crystal display device having a fast response by using such a novel liquid crystal compound or composition.

The liquid crystal compound in the present invention has the general formula (In the formula, R represents an alkyl group or an alkoxy group having 1 to 20 carbon atoms, n represents an integer of 1 or 2, and Q ^*
Represents an optically active group. Hereinafter, this is referred to as compound (I). ) Is a pyridazine derivative represented by

Ferroelectricity in liquid crystal is when the liquid crystal has a chiral smectic phase of tilt system (SC ^* , SF ^* , SG ^* , SH ^* , SI ^* , SJ ^* , SK ^* , etc. are known). Although appearing, in compound (I), among the chiral smectic phases, most of SC ^* phases, which have low viscosity and are considered to be most practical, can be taken in a low temperature range or a wide temperature range. . Particularly, in the general formula (I), when n is 1, the temperature range is close to room temperature, and when n is 2, the temperature range is high, but the temperature range is wide. In addition, some of the compounds (I) do not have a chiral smectic phase, but these are compounded among the compounds (I), or by compounding with other chiral smectic liquid crystal compounds, It can be used as a liquid crystal composition exhibiting ferroelectricity, and in that case, the temperature range of the chiral smectic phase that was in the high temperature range can be lowered to the low temperature range.

In order for a liquid crystal to show a chiral smectic phase, it is necessary that the molecules are asymmetric and the system is not a racemic body. Therefore, in general, an optically active group is mainly contained in the liquid crystal molecule at the molecular end. Has been introduced to. Also in the compound (I), for example, (s) -2-methylbutanol, which is inexpensively obtained as a main component of natural fusel oil, is used, and the condition is satisfied by connecting a chiral group to the pyridazine ring. , Its introduction is easy as described later.

The compound (I) has no chemical bond unstable to heat, light, moisture, etc. in its molecular skeleton, is chemically sufficient, and is practically usable in that respect as well.

Ferroelectric liquid crystals exhibit high-speed response because they have spontaneous polarization, which interacts directly with the applied electric field. If the viscosity of the liquid crystal is constant, the larger the value of spontaneous polarization, the faster the response speed. Therefore, it is one of the most important physical property values in ferroelectric liquid crystals.

In order to increase the spontaneous polarization, it is desirable that the large intramolecular permanent dipole and the asymmetric carbon exist as close to each other as possible. In the compound (I), a carbonyl bond (C═O) of the ester group and Has a large permanent dipole moment and is close to the asymmetric carbon in the chiral group, so that condition is satisfied.

As described above, the compound (I) may be used alone or as a liquid crystal composition, but the liquid crystal composition in the present invention is composed of a plurality of compounds (I), or the compound (I) as a compounding component thereof. It contains at least one kind and has liquid crystallinity.

Incidentally, the functional groups R and Q ^* in the general formula (I) may have hydrogen substituted with a halogen atom or other substituents as long as the identity of the compound (I) is not impaired. Q ^* is an optically active 2-methylbutyl group, 2-butyl group, 2
-Pentyl group, 2-octyl group and the like are particularly preferable.

Compound (I) has the general formula (In the formula, R represents an alkyl group or an alkoxy group having 1 to 20 carbon atoms, and n represents 1 or 2. Hereinafter, referred to as an acid chloride (II).) (In the formula, Q ^* represents an optically active alkyl group and is hereinafter referred to as a pyridazine derivative (III).) A pyridazine derivative represented by the following is reacted in the presence of a basic physical property such as pyridine to easily obtain. be able to. Here, the acid chloride (II) is a known compound and some of which are commercially available, but it can be easily obtained by treating the corresponding carboxylic acid with a chlorinating agent such as thionyl chloride. is there.

The pyridazine derivative (III) can be synthesized as follows.

First, from the optically active alcohol Q ^* OH and paratoluenesulfonyl chloride, the optically active alcohol O-tosylate
Q ^* OTs (Ts represents para-toluenesulfonyl group) may be replaced with O-tosylate to lead to a halide such as bromide. O-tosylate is more preferable because it easily causes racemization and the like. It is also made from maleic acid and hydrazine and is commercially available 3,6
The target pyridazine derivative (III) can be obtained by reacting with -dihydroxypyridazine in the presence of an alkali.

The liquid crystal compound or composition thus obtained is 2
A uniform thickness (1 μm to 20 μ) between the transparent electrode plates.
By using the thin film of m), it can be used as a liquid crystal display cell.

In the display cell, the liquid crystal molecule needs to be a monodomain having a so-called homogeneous and uniform orientation with the long axis of the molecule parallel to the electrode surface. To this end, the cell surface is subjected to an alignment treatment such as rubbing or vapor deposition, an electric field or a magnetic field is applied, a temperature gradient is applied, or a combination of these means is applied to the liquid crystal from the isotropic liquid phase. A method of gradually cooling to a phase and orienting is generally adopted, and even in the compound or composition of the present invention, uniformly oriented monodomain cells can be obtained by such a method.

Although the present invention is as described above, the compound I of the present invention is
Was previously known as a representative ferroelectric liquid crystal compound
Compared with DOBAMBC, as shown in the examples described later, it can be easily produced industrially, is colorless in itself, and has chemical stability against light. Further, in the composition of the present invention, as in the case of a general liquid crystal composition, the melting point is lowered as compared with a single compound, and the composition can be used at room temperature.

Furthermore, the ferroelectric liquid crystal compound and composition of the present invention have a response speed of a nematic liquid crystal as in the conventional ferroelectric liquid crystal.
Extremely large, over 100 times. Therefore, it is extremely promising as a light switching element for display.

Hereinafter, the present invention will be specifically described with reference to examples.
Of course, the spirit and scope of the present invention are not limited by these examples.

The transition temperature was measured using a polarizing microscope equipped with a temperature adjustment stage and a differential scanning calorimeter (DSC).
There is some variation depending on the measuring method and the purity of the compound.

Example 1 [6-((s) -2-methylbutyloxy) pyridazin-3-yl 4-decyloxybenzoate Synthesis of 1-a.6-((s) -2-methylbutyloxy) -3-
Hydroxypyridazine Synthesis of 17.9 g of 3,6-dihydroxypyridazine (maleic acid hydrazide), and (s) -2-methylbutyl tosylate 5
8.3 g and 9.0 g of sodium hydroxide were heated and refluxed in 100 ml of water for 20 hours. On the way, 14 g of (s) -2-methylbutyl tosylate was added. After cooling, it was made weakly acidic with dilute hydrochloric acid and extracted twice with methylene chloride. The organic phase was concentrated, dissolved in ether, and then extracted with 20% aqueous sodium hydroxide solution.
Hydrochloric acid was added to weakly acidify, and the mixture was extracted twice with methylene chloride. The crude crystals obtained by distilling the solvent off were recrystallized twice from n-hexane to obtain 8.5 g of white crystals of 6-((s) -2-methylbutyloxy) -3-hydroxypyridazine.

IR: 3200, 3070, 1680, 1600, 1555, 1440, 1390, 132
0, 1280, 1230, 995, 920, 850, 810, 620, 585, 520
Synthesis of (cm ^-1 ) I-b.6-((s) -2-methylbutyloxy) pyridazin-3-yl 4-decyloxybenzoate 4-decyloxybenzoic acid chloride obtained from 4-decyloxybenzoic acid 6-obtained with 296 mg and Ia
182 mg of ((s) -2-methylbutyloxy) -3-hydroxypyridazine was reacted in 5 ml of pyrinodine at 80 to 90 ° C. for 4 hours. After cooling, add methylene chloride and dilute hydrochloric acid,
The organic layer was further washed with diluted hydrochloric acid, saturated sodium bicarbonate water, and saturated aqueous sodium chloride solution. After dehydration over anhydrous sodium sulfate and drying, the solvent was distilled off to obtain 395 mg of crude crystals.

Purify by silica gel column chromatography (developing solvent: chloroform / hexane = 1/1) to give 6-((s)
-2-Methylbutyloxy) pyridazin-3-yl 4-
305 mg of white crystals of decyloxybenzoate were obtained.

The structure was confirmed by nuclear magnetic resonance spectrum (NMR), infrared absorption spectrum (IR) and mass spectrum (MS). The spectrum data is shown below.

IR: 3100, 1740, 1615, 1520, 1445, 1390, 1320, 128
0, 1230, 1170, 1110, 1060, 1000, 880, 850, 770, 69
5,605,520 (cm ⁻¹ ) MS: m / e = 442 (P ⁺ ) (d, dd, t and m in NMR are double lines and 2
Represents double doublet, triplet, and multiplet, P ^{+ in} MS
Represents the parent peak. This shows a liquid crystal phase and has an SC ^* phase. The phase transition temperature is described below.

C → SC ^* (melting point) 49 ° C. SC ^* I 54 ° C. (where C represents a crystalline phase and I represents an isotropic liquid phase) Examples 2 to 5 In Example 1, 4-decyl benzoate formation In place of 4-octyloxybenzoic acid chloride (Example 2),
4-dodecyloxybenzoic acid chloride (Example 3), 4-
Tetradecyloxybenzoic acid chloride (Example 4) or 4
Using hexadecyloxybenzoic acid chloride (Example 5), reaction and purification were carried out in the same manner, and 6-((s)-
2-Methylbutyloxy) pyridazin-3-yl 4-octyloxybenzoate, 6-((s) -2-methylbutyloxy) pyridazin-3-yl 4-dodecyloxybenzoate, 6-((s) -2- Methylbutyloxy) pyridazin-3-yl 4-tetradecyloxybenzoate or 6-((s) -2-methylbutyloxy)
Pyridazin-3-yl 4-hexadecyloxybenzoate was obtained. These NMR and IR give charts that differ only in the intensity ratio of the absorptions corresponding to the methylene chains compared to those in Example 1, and MS is the respective parent peak m / e = 414, 470, 498 and 526 were given.

The respective phase transition temperatures are summarized in Table 1.

Example 6 [6-((s) -2-methylbutyloxy) pyridazin-3-yl 4'-decyloxybiphenyl-4
-Synthesis of Carboxylate] 373 mg of 4'-decyloxybiphenyl-4-carboxylic acid chloride obtained from 4'-decyloxybiphenyl-4-carboxylic acid and 6-((s ) -2-
Methylbutyloxy) -3-hydroxypyridazine 182m
g was reacted in the same manner as in Example 1 in 5 ml of pyridine and purified in the same manner as in Example 1 to obtain 6-((s) -2-methylbutyloxy) pyridazin-3-yl 4'-decyloxybiphenyl-4. -180 mg of carboxylate are obtained. The spectrum data is shown below.

IR: 3100, 1745, 1610, 1510, 1445, 1390, 1245, 120
0, 1075, 1000, 875, 830, 765, 725, 690 (cm ⁻¹ ) MS: m / e = 442 (P ⁺ ), which showed the SC ^* phase. The phase transfer temperature is shown below.

SC ^* -I 139 [deg.] C. SX-SC ^* 95 [deg.] C. Melting point 101 [deg.] C. (SX represents a chiral smectic phase closer to other crystalline phases.) Examples 7 to 9 In Example 6, 4'- Decyloxybiphenyl-4
-In place of the carboxylic acid chloride, 4'-octyloxybiphenyl-4-carboxylic acid chloride, 4'-dodecyloxybiphenyl-4-carboxylic acid chloride (Example 8) or 4'-tetradecyloxy Reaction purification was carried out in the same manner using biphenyl-4-carboxylic acid chloride (Example 9),
6-((s) -2-methylbutyloxy) pyridazin-3-yl 4'-octyloxybiphenyl-
4-carboxylate, 6-((s) -2-methylbutyloxy) pyridazin-3-yl 4'-dodecyloxybiphenyl-4-carboxylate or 6-((s)-
2-Methylbutyloxy) pyridazin-3-yl 4'-
Obtained tetradecyloxybiphenyl-4-carboxylate. These NMR and IR give charts which differ only in the intensity ratio of the absorptions corresponding to the methylene chains compared to those in Example 6, and the MS shows the respective parent peaks, m / e = 490,546. , 574 was given.

These phase transition temperatures are summarized in Table 1.

Example 10 [Synthesis of 6-((s) -2-methylbutyloxy) pyridazin-3-yl 4-decylbenzoete] In Example 1, the 4-decyloxybenzoic acid chloride was replaced with 4-decylbenzoic acid. Reaction purification was carried out in the same manner using acid chloride, and 6-((s) -2-methylbutyloxy)
White crystals of pyridazin-3-yl 4-decylbenzoate were obtained. The spectrum data is shown below.

IR: 3100, 1745, 1615, 1600, 1450, 1390, 1325, 127
5, 1240, 1180, 1070, 1020, 880, 765, 705 (cm ^-1 ) This phase transition temperature is described below.

Melting point 56 ° (SC ^* phase can be confirmed under rapid cooling, but transition temperature is unknown due to crystallization.) Example 11 [6-((s) -2-methylbutyloxy) pyridazin-3-yl 4 ′ -Synthesis of Octylbiphenyl-4-carboxylate] In Example 1, 4'-octylbiphenyl-4 was synthesized from 4'-octylbiphenyl-4-carboxylic acid instead of 4-decyloxybenzoyl chloride. -Reaction purification was carried out in the same manner using carboxylic acid chloride to give 6-((s)
-2-Methylbutyloxy) pyridazin-3-yl 4 '
White crystals of -octylbiphenyl-4-carboxylate were obtained. The spectrum data is shown below.

IR: 3100, 1745, 1610, 1600, 1445, 1325, 1280, 124
0, 1215, 1190, 1110, 1070, 1005, 875, 820, 765, 70
0,670 (cm ⁻¹ ) MS: m / e = 474 (P ⁺ ) This showed an SC ^* phase. The phase transition temperature is shown below.

SC ^* -I 114 ℃ SX-SC ^* 95 ℃ Melting point 106 ℃ In the table, -represents that the phase exists, -represents that the phase does not exist, and the number on the right side of-represents the phase transition temperature from the phase to a higher phase in the temperature range.
2MB ^* represents (s) -2-methylbutyl group. The parentheses indicate that the phase is monotropic that appears only when the temperature drops. Also, ^{* *} is the phase can be confirmed at the time of rapid cooling, for crystallization, indicating that transition temperature can not be measured.

Example 12 [Expansion of temperature range of SC ^* phase by mixing] 6-((s) -2-methylbutyloxy) pyridazin-3-yl 4-dodecyloxybenzoate obtained in Example 3 and SC ^* alone 4-decyloxyphenyl 4-octyloxybenzoate, a known liquid crystal compound exhibiting no phase And 4-octyloxyphenyl 4-decyloxybenzoate A composition was prepared using the above three components in equal amounts.

This composition exhibited an SC ^* phase between 53.5 ° C and 78.0 ° C, and changed to an isotropic liquid phase at higher temperatures and to other chiral smectic phases at lower temperatures. As a result, the temperature range of the SC ^* phase was expanded considerably.

Comparative Example 1 In Example 12, which is the compound of Example 3 of the present invention 6
-((S) -2-Methylbutyloxy) pyridazine-3
In place of the -yl 4-dodecyloxybenzoate, the compound described in JP-A-60-226861 has a pyridazine ring and an optically active group bonded to it in the molecule, but 3-(( S) -2-Methylbutyloxy) -6- (4-octyloxyphenyl) pyridazine with 4-decyloxyphenyl 4-octyloxybenzoate and 4-octyloxyphenyl, 4-decyloxybenzoate A composition was prepared using the above three components in equal amounts.

This composition showed a chiral smectic C (SC ^* ) phase at a temperature of 80 ° C or lower when the temperature was lowered from the isotropic liquid (I) phase,
Precipitation of crystals occurred at 0 ° C, and when left as it was, it was completely crystallized. From this, it is clear that the compound of the general formula (I) of the present invention can greatly expand the temperature range of the SC ^* phase of the liquid crystal composition.

Example 13 [Preparation of liquid crystal composition exhibiting SC ^* phase at room temperature] 6-((s) -2-methylbutyloxy) pyridazin-3-yl 4-dodecyloxybenzoate and 3-obtained in Example 3 A composition was prepared consisting of an equal amount of chloro-4- (s) -2-methylbutyloxycarbonyl) phenyl 4'-decyloxybiphenyl-4-carboxylate. This composition exhibited the SC ^* phase at a temperature of 67 ° C. or lower, and did not crystallize even when left standing at 20 ° C. for a long time. At temperatures above 67 ℃, SA phase was shown, and at above 93 ℃, isotropic liquid phase was shown.

The helical pitch of this composition was 10 μm or more.

This composition was filled in a cell having a thickness of 2 to 3 μm, and 10 V, 1
A rapid response was observed when an electric field of 00 Hz was applied, and the intensity of the transmitted light was detected by a photomultiplier, and it was less than 1 msec at 50 °.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masashi Osawa 5-12-23 Akatsuka, Itabashi-ku, Tokyo (72) Inventor Tadao Tokaibayashi 3-13-6 Oizumi-cho, Nerima-ku, Tokyo

Claims (5)

[Claims] 1. A general formula (In the formula, R represents an alkyl group or an alkoxy group having 1 to 20 carbon atoms, n represents an integer of 1 or 2, and Q ^*
Represents an optically active alkyl group. ] The novel pyridazine derivative shown by these. 2. In the general formula (I), Q ^* is (s) -2-
The compound according to claim 1, which is a methylbutyl group. 3. General formula (In the formula, R represents an alkyl group or an alkoxy group having 1 to 20 carbon atoms, n represents an integer of 1 or 2, and Q ^*
Represents an optically active alkyl group. ) A liquid crystal composition containing at least one pyridazine derivative represented by 4. A liquid crystal composition according to claim 3, which contains two or more compounds of the formula (I). 5. The liquid crystal composition according to claim 3, which has a chiral smectic phase.