JPH058706B2 - - Google Patents

Description

[Detailed description of the invention]

(Technical Field of the Invention) The present invention is a liquid crystal compound suitable for an electro-optical device that utilizes the response of a ferroelectric chiral smectic liquid crystal to an electric field, or a liquid crystal compound that is suitable for use in an electro-optical device that utilizes the response of a ferroelectric chiral smectic liquid crystal to an electric field, or a liquid crystal compound that is suitable for use in an electro-optical device that utilizes the response of a ferroelectric chiral smectic liquid crystal to an electric field. The object of the present invention is to provide a compound useful as a material for providing a liquid crystal composition having a transition temperature on the low temperature side when mixed to form a liquid crystal composition. The present invention also provides a chiral smectic liquid crystal composition containing the compound. Liquid crystals have already been applied as various electro-optical elements and have been put to practical use in displays such as watches and calculators. Most of the liquid crystal display elements currently in practical use utilize the dielectric alignment effect of nematic liquid crystals and cholesteric liquid crystals. However, when applied to display elements with a large number of pixels, which are expected to have a large number of pixels, there are problems in terms of responsiveness, contrast due to the inability to secure a driving margin, viewing angle characteristics, etc. Therefore, on the one hand, MOS panels and TFTs that form switching elements for each pixel
Panel research and development is gaining momentum. (Description of Prior Art) Under these circumstances, Clark et al., in US Pat. No. 4,367,924, disclose a liquid crystal element based on a new display principle using a smectic phase, which eliminates the drawbacks of such liquid crystal elements. Figure 1 shows a schematic diagram of the smectic C* phase or H phase, in which the liquid crystal consists of each molecular layer 1, and in each layer, the average direction of the long axis of the molecules is is shown tilted by an angle Ψ ₀ with a direction perpendicular to . Mayer et al., Le Journal de Physique, Vol. 36, March.
In 1975, in a paper entitled ``Ferroelectric liquid crystals'' published in PPL-69 to L-71, the smectic C* phase or H phase consisting of optically active molecules was published.
Liquid crystal compounds exhibiting a phase generally have an electric dipole density P→
and is ferroelectric. This dipole density P→ acts in a direction perpendicular to the inclination direction n of the molecules and parallel to the layer plane of the smectic phase. The paper states that this is also applicable to the smectic H phase, but the H phase has a greater viscosity with respect to rotation about an axis perpendicular to the layer. Since these chiral smectic liquid crystals have electric dipoles, they are more strongly influenced by electric fields than by dielectric anisotropy. Furthermore, this acting force is polar in the sense that the polarity of P→ points in a direction parallel to the electric field E, so by reversing the direction of the applied electric field, the direction of P→ is reversed. That is, by reversing the electric field, the molecule is transformed into a cone (the angle 2Ψ ₀ of this cone is hereinafter referred to as the cone angle), as shown in Figure 2.
By displacing it along, its direction can be controlled. By detecting the change in the average long axis direction of this molecule using two polarizing plates, it can be used as an electro-optical element. An electro-optical element that utilizes the response of this smectic C* phase or H phase to an electric field has a TN-type Compared to liquid crystal elements, it has excellent high-speed response, and by performing appropriate orientation control, it can have a memory function, and can be used for high-speed optical shutter or displaying a large amount of information. It is expected to be applied to displays, etc. By the way, various compounds have been synthesized as chiral smectic liquid crystal materials having such ferroelectric properties, and the properties of these compounds have been studied. The first ferroelectric liquid crystal synthesized was
It is p-dodecyloxybenzylidene p-amino-2-methylbutyl-cinnamate, which is called DOBAMBC, and various compounds of this Schiff base series liquid crystal have been synthesized and studied in detail as research subjects for ferroelectric liquid crystals. . A compound represented by the following general formula is known as an example of the Schiff base series liquid crystal. (wherein, X is -H, -Cl, or -CN,
Y is -Cl, _-C2H5 , and the * mark represents _an asymmetric carbon atom. ) However, this series of liquid crystal compounds cannot be used at room temperature because they begin to exhibit a chiral smectic phase at a temperature higher than room temperature, and because they are Schiff base compounds, they are decomposed by moisture, so they are unstable in terms of stability. There are drawbacks such as problems. As an evolution of this system, the general formula (2) A chiral smectic liquid crystal compound of a Schiff base, in which a hydroxyl group is introduced into one benzene ring and forms a benzylidene imino bond and an intramolecular hydrogen bond, was described by BI Ostrovskii et al. It was published in Ferroelectrics, vol. 24, p. 309 (1980), and A. Hallsby et al.
CRYSTALS AND LIQUID CRYSTALS,
Letter), volume 82, page 61. This type of compound has attracted attention as a compound that exhibits a smectic C* phase over a wide temperature range including room temperature. Furthermore, since this compound has hydrogen bonds within its molecules, it is less likely to be decomposed by moisture, and is superior in terms of stability compared to ordinary Schiff-type liquid crystals. However, since liquid crystal compounds are generally required for practical use to not crystallize even at temperatures below 0°C, it cannot be said that this type of liquid crystal is still sufficient for practical use in terms of the temperature range in which it can be used as a liquid crystal. do not have. In yet another series, azoxy liquid crystal compounds were developed by P. Keller et al.
Annual Physics Report (ANNALES DE PHYSIQUE) 139
(1978), but this type of compound is also insufficient in terms of the liquid crystal temperature range, exhibits a deep yellow color, and is sensitive to ultraviolet rays, resulting in practical problems such as the need to use a filter. I'm holding it. On the other hand, it is widely used as a TN type liquid crystal material,
Benzoic acid ester-based liquid crystal materials are known, which have a proven track record in terms of stability. As a compound of this series, BI Ostrovsky has given the general formula: (However, n represents an integer of 9 or 10.) It has been reported that a liquid crystal compound represented by the following formula exhibits a chiral smectic phase in a temperature range relatively close to room temperature. In addition, GW Gray etc. are molecular crystals and (MOLECULAR CRYSTALS AND
LIQUID CRYSTALS) Volume 37, Page 189 (1976) and
37 (1978), biphenyl ester materials exhibiting a chiral smectic liquid crystal phase in a temperature range higher than room temperature were reported. (Simplified explanation of the invention) As mentioned above, at present, no liquid crystal compound has yet been found that exhibits a chiral smectic phase in a wide temperature range from below 0°C to above room temperature, including the room temperature where it can be used practically. Furthermore, among the known compounds, even those that exhibit a chiral smectic phase over a relatively wide temperature range have problems in terms of stability or viscosity. Therefore, in order to widen the liquid crystal temperature range of liquid crystal compounds exhibiting the Sc* phase, it is currently necessary to mix various liquid crystal compounds.
Various multi-component mixed liquid crystal compositions are known. In addition, in the known liquid crystal compounds exhibiting the Sc* phase,
Even if the response speed is the fastest, for example (2) above
The response speed of a liquid crystal compound called MBRA8, where m = 1 and n = 8, is 500 microseconds, and a liquid crystal compound with even faster response is required for high-speed response for ferroelectric liquid crystal displays. There is. Here, the present inventors have discovered a promising new liquid crystal compound suitable for obtaining a chiral smek-metal liquid crystal composition that is excellent in stability and has rapid response in a wide temperature range including room temperature. A chiral smectic liquid crystal composition has been found. That is, the present invention provides a chiral smectic liquid crystal composition that is excellent in stability and has a wide liquid crystal temperature range around room temperature, and a novel compound suitable for obtaining the composition. Another object of the present invention is to provide a liquid crystal composition containing the above-mentioned novel compound. Other objects of the invention will become clear from the description below. (Description of the invention) That is, the present invention is based on the formula () (In the formula, m is an integer of 1 to 8, n is an integer of 5 to 14, X is a halogen atom, OH group or CN group,
* indicates an asymmetric carbon atom, and -S indicates that the alkyl group is linear. ), the compound takes a smectic liquid crystal phase or, when mixed with other liquid crystal compounds, increases the response speed of the mixed composition and further increases the transition speed of the chiral smectic liquid crystal phase. It was discovered that it has the ability to expand to the low temperature side. The present inventor previously discovered that the negative group x in formula ()
We synthesized a compound using a methyl group instead of , and found that this compound has an Sc* phase at around room temperature and has a fast response speed. That is, a short skeleton cyclic group called phenylpyrimidine is used, but it has polarization in the direction of the long axis of the molecule, and the alkyl group and alkoxy group in the side chain are substituted in a direction that strengthens the polarization. . This strong polarizability in the direction of the long axis of the molecule enhances the smectic liquid crystallinity, and the fact that the entire molecule is short and the pyrimidine ring has more lateral extension than the benzene ring, increases the intermolecular distance. I can think of this as having the effect of speeding up the response. Based on this excellent chiral smectic liquid crystal compound, in order to further improve the response, the present inventors added methyl groups bonded to asymmetric carbon atoms to halogens, CN groups, or
As a result of trying to increase the spontaneous polarization by substituting with OH groups, we found that although the chiral smectic property of the compound itself is weak, we found a promising new blend that speeds up the response and expands the Sc* phase toward the low temperature side. We succeeded in obtaining a liquid crystal compound for use in liquid crystals. The method for synthesizing the compounds of the present invention is shown below using chemical formulas. 2 When x represents a CN group or an OH group (In the above reaction formula, m is an integer of 1 to 8, n is 5 to
an integer of 14, p-Ts is p-toluenesulfonyl,
* indicates an asymmetric carbon atom. ) The present invention will be explained below with reference to Examples. In the examples, Cry represents a crystal phase, SA represents a smectic A phase, and Sc* represents a chiral smectic C phase.
phase, Iso means isotropic liquid phase. Example 1 (m=2, n=8, X=Cl) Optically active 5-n-octyl-2-[4-(3'-
Synthesis of chloropentyloxy)phenylpyrimidine Sodium hydride (approx.
% suspension in oil) and 3 ml of dry N,N-dimethylformamide were added. Then dry it N,N-
4-(5-
n-octyl-2-pyrimidinyl)phenol
0.38g was added dropwise under ice cooling. After reacting for 30 minutes at room temperature, add 1 ml of dry N,N-dimethylformamide.
Optically active 3-chloropentyl-p- dissolved in
0.37 g of toluenesulfonic acid ester (this compound was synthesized from L(+)-β-hydroxyvaleric acid methyl ester [[α] ²⁰ _D = +28.1, (C = 1, CHCl ₃ )] by a conventional method.) was dripped. 100 in oil bath after dripping
The reaction was carried out at ℃ for 8 hours. After the reaction was completed, it was cooled, poured into ice water, and extracted with ethyl acetate. The ethyl acetate layer was washed with 5% NaOH and water, dried, and the organic solvent was distilled off. The residual oil was purified by silica gel column chromatography and repeated recrystallization to obtain optically active 5-n-octyl-
0.19 g of 2-[4-(3'-chloropentyloxy)phenyl]pyrimidine was obtained. IRν ^film _nax(cn-1) 1610, 1585, 1430, 1250, 1170
，
1110, 800, 750'H-NMR (60MHz, CDCl ₃ /TMS int) δ (ppm) 8.62 (S, 2H, Pyrimidine H) 8.42 (d, 2H, Aromatic H) 7.02 (d, 2H, Aromatic H) 4.03 (t, 2H, -CH ₂ -O-) 2.60 (t, 2H, -CH ₂ -pyr) Transition temperature (℃) Cry 15.0 ---→ ← --- *13.5S _A 42.6 --- → Iso (However, * indicates supercooling.) Example 2 (m=2, n=11, x=OH) Optically active 5-n-undecyl-2-[4-
(3'-hydroxy-pentyloxy)phenyl]
Synthesis of pyrimidine 1 Optically active 5-n-undecyl-2-[4-
Synthesis of (3'-tetrahydropyranyloxy-pentyloxy)phenyl]pyrimidine In a 30 ml three-necked flask equipped with a condenser, thermometer, dropping funnel, and calcium chloride tube, sodium hydride (approximately 50% suspension in oil) was added. turbid liquid) 0.76g, dry N, N
- Added 5 ml of dimethylformamide. Then 4 was dissolved in 5 ml of dry N,N-dimethylformamide.
4.33 g of -(5-n-undecyl-2-pyrimidinyl)phenol was slowly added dropwise. At 80℃, 30
After reacting for a minute, p-trienesulfonic acid-3-
Tetrahydropyranyloxypentyl ester
4.3g (This compound is L(+)-β-hydroxyvaleric acid methyl ester [[α] ²⁰ _D = +28.1, (C = 1,
CHCl ₃ )] by a conventional method. ) drying N,
A solution in 5 ml of N-dimethylformamide was added dropwise. The mixture was reacted at 80-85°C for 8 hours, then cooled.
It was poured into ice water and extracted with ether. The ether layer was washed with 10% NaOH and water, dried, the ether was distilled off, and the optically active 5-n-undecyl-2
6.39 g of crude product -[4-(3'-tetrahydropyranyloxy-pentyloxy)phenyl]pyrimidine was obtained. This compound was used in the next reaction without purification. IRν ^neat _nax(cn-1) : 1610, 1590, 1430, 1253,
1170, 1135, 1125, 800 2 Optically active 5-n-undecyl-2-[4-
(3'-hydroxy-pentyloxy)phenyl]
Pyrimidine In a 300 ml flask equipped with a condenser, 6.39 g of the optically active 5-n-undecyl-2-[4-(3'-tetrahydropyranyloxy-pentyloxy)phenyl]pyrimidine obtained in 1), 100 g of ethyl alcohol
ml, and 0.3 g of p-toluenesulfonic acid were added thereto, and the mixture was reacted for 1 hour under heating and reflux. After the reaction was completed, ethyl alcohol was distilled off, water and ethyl acetate were added to the residue to dissolve it, and the organic layer was separated. The organic layer was washed with an aqueous sodium bicarbonate solution and water, then dried, and the organic medium was distilled off. The obtained crude product was purified by silica gel column chromatography and repeated recrystallization to obtain 2.85 g of optically active 5-n-undecyl-2-[4-(3'-hydroxy-pentyloxy)].
phenyl]pyrimidine was obtained. Melting point 80-86℃ [[α] ²⁵ _D = +3.89° (C = 2, CHCl ₃ )] IRν ^nujol _nax(cn-1) 3400, 1610, 1590, 1435, 1255
，
1177, 800′H-NMR (60MHz, CDCl ₃ /TMS int) δ (ppm) 8.53 (S, 2H, Pyrimidine H) 8.32 (d, 2H, Aromatic H) 6.95 (d, 2H, Aromatic H) 4.18 (t , 2H, -CH ₂ -O-) 3.43~4.03 (m, 1H,

[Formula]) 2.60 (t, 2H, −CH ₂ −pyr) 1.73 (S, 1H, −OH) 0.6 to 2.4 (m, 28H) Transition temperature (°C) Cry77.5°C ――――→ ←―― --- *Sc*88.8 ----→ S _A 84.0 -----> Iso (However, * indicates supercooling.) Example 3 (m=2, n=11, x=CN) Optical activity 5-n-undecyl-2-[4-
Synthesis of (3'-cyanopentyloxy)phenyl]pyrimidine 1 Optically active 5-n-undecyl-2-[4-
Synthesis of (3'-methanesulfonyloxy-pentyloxy)phenyl]pyrimidine Optically active 5-n-undecyl-2-[4-
(3'-hydroxy-pentyloxy)phenyl]
2.5 g of pyrimidine was dissolved in 25 ml of dry pyridine.
To this mixture, 0.76 g of methanesulfonyl chloride was slowly added dropwise at 5° C. under ice cooling. After the dropwise addition, the reaction was further continued for 2 hours, and then at room temperature for 2 hours. After the reaction was completed, the mixture was poured into ice water and extracted with ether. The ether layer was washed with diluted hydrochloric acid and water, dried, and the ether was distilled off to obtain an oil. This oil was crystallized and separated, and 2.63 g of optically active 5-n
-undecyl-2-[4-(3'-methanesulfonyloxy-pentyloxy)phenyl]pyrimidine was obtained. IRν ^nujol _nax(cn-1) : 1610, 1590, 1435, 1337,
1183, 1173, 910, 800 2 Optically active 5-n-undecyl-2-[4-
Synthesis of (3'-cyanopentyloxy)phenyl]pyrimidine In a 30 ml flask equipped with a cooling tube and a calcium chloride tube, the optically active 5-n-undecyl-2-[4-(3'- 2.63 g of methanesulfonyloxy-pentyloxy)phenyl]pyrimidine and 10 ml of dry dimethyl sulfoxide were added and dissolved, and then 0.32 g of sodium cyanide was added and stirred at room temperature for 15 hours. Furthermore, the reaction mixture is 80-90
After heating at °C for 4 hours, the mixture was allowed to cool, poured into ice water, and the reaction product was extracted with ether. The ether layer was washed with water, dried, filtered, and the ether was distilled off. The obtained crude product was purified by silica gel column chromatography and repeated recrystallization to obtain 1.0 g of optically active 5-n-undecyl-2-[4-(3'-cyanopentyloxy)phenyl]pyrimidine. Obtained. The specific optical power was [α] ²⁵ _D = -28.57° (C = 2, CHCl ₃ ), but the optical purity was not investigated. IRν ^nujol _nax(cn-1) : 2240, 1605, 1585, 1430,
1245, 1165, 797'H-NMR (60MHz, CDCl ₃ /TMS int) δ (ppm) 8.60 (S, 2H, Pyrimidine H) 8.40 (d, 2H, Aromatic H) 7.00 (d, 2H, Aromatic H) 4.20 (t, 2H, _-CH2 -O-) 0.65-3.15 (m, 31H) The transition temperature of the obtained compound was measured and the following results were obtained. Transition temperature (℃): 60.6℃ Cry ――――→ ←―――― *53Iso (However, * indicates supercooling.) Test example 1 Compound (1) Compound (2) Compound (1) and compound (2) of Example 3 in a weight ratio of 3:1
The liquid crystal composition obtained by mixing exhibited the following transition temperature and response speed. Transition temperature (℃): Cry2℃ ――――→ ←―――― −1℃Sc＊39.6 ――――→ S _A 49.7 ――――→ Iso response speed 180μs (30.0℃) Here, the compound ( 1) showed the following transition temperature and response speed. Transition temperature (℃): Cry3℃ ―――→ ←―――― 3℃Sb14.2℃ ――――→ ←―――― *Sc＊48.6 ――――→ S _A 56.3 ――――→ Iso Response speed :600μs The transition temperature (°C) of compound (2) is as shown in Example 3. Transition temperature: Cry60.6℃ ――――→ ←―――― *53.0Iso (However, * indicates supercooling.) The addition of the compound (2) of the present invention significantly changes the liquid crystallinity. I was able to speed up the response. Test Example 2 Same as Test Example 1 Compound (1) and compound (3) (compound of Example 1) The transition temperature and response speed of a liquid crystal composition obtained by mixing the following in a ratio of 3:1 were as follows. Transition temperature: Cry10.5 ――――→ ←―――― ＊3℃Sc＊27.2 ――――→ S _A 51.7 ――――→ Iso Response speed: 220μs (25.0℃) Transition of compound (3) The temperatures are as follows as shown in Example 1. Transition temperature (℃): Cry15.0℃ ――――→ ←―――― *13.5S _A 42.5 ――――→ Iso (However, the * mark indicates supercooling.) As described above, according to the present invention The new liquid crystal compound is
It is particularly effective as a blending agent suitable for obtaining a composition that exhibits a liquid crystal temperature near room temperature and as a blending agent that increases response speed, and is excellent for obtaining a practical Sc* liquid crystal composition that can be used in a wide temperature range including room temperature. This liquid crystal material will greatly contribute to the practical application of ferroelectric liquid crystal displays.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a smectic C* phase or H phase, and FIG. 2 is a schematic diagram showing the movement of liquid crystal molecules in a chiral smectic phase along a cone due to an electric field.

Claims (1)

[Claims] 1 formula (In the formula, m is an integer of 1 to 8, n is an integer of 5 to 14, X is a halogen atom, OH group, or CN group, S is a straight-chain alkyl, and * is an asymmetric carbon atom. ) An optically active pyrimidine compound represented by 2 formulas (In the formula, m is an integer from 1 to 8, n is an integer from 5 to 14, X is a halogen atom or a CN group, S is a straight-chain alkyl, and * represents an asymmetric carbon atom) A ferroelectric chiral smectic liquid crystal composition comprising an optically active pyrimidine compound represented by: