JPS63211291A - Liquid crystal material - Google Patents

Abstract

NEW MATERIAL:An 2-(4'-alkoxyphenyl)-5-alkyl-1,3,2-dioxaborinane expressed by formula I (R is 1-18C alkyl; m is 1 or 5; n is 0-5; the star mark is asymme tric carbon atom). USE:A display element. The compound expressed by formula I shows chiral smectic C phase, has ferroelectricity and is useful in obtaining chiral smectic liquid crystal composition having wide temperature range. PREPARATION:For example, an optically active alkyl-p-toluene sulfonic ester is reacted with bromophenol in the presence of sodium hydroxide in anhydrous ethanol at room temperature to provide a 4-alkoxybromobenzene expressed by formula II (R having the star mark is formula III), which is then reacted with a 4-alkoxyphenylmagnesium bromide in a solvent such as THF at -60 deg.C to afford a compound expressed by formula IV, which is further reacted with a 2-alkyl-1,3-propanediol in a solvent such as toluene, under reflux to provide the aimed compound.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a ferroelectric liquid crystal compound useful as a display element with excellent responsiveness for two-image display, and a liquid crystal composition containing the same.

Currently, display elements made of liquid crystal materials are of a light-receiving type and are in widespread practical use because of their low power consumption and the ability to create thin display devices. On the other hand, EL (electroluminescence) and plasma displays, which are light-emitting display systems and feature high-speed response, are being actively developed.

[Conventional technology]

Most of the liquid crystals that have been used in display devices so far have been nematic liquid crystals, and the mainstream is TN (twisted nematic).
Twisted Nematic) ) type. Although this TN type display system has advantages such as small size and low power consumption, it also has the disadvantage that the response speed of two-image display is slow. Various attempts have been made to improve this point, but
Molecular Crystals and Rixo HD Crystals
Liquid Crystal Volume 94, Volume 15
The results demonstrate the theoretical limits shown on pages 5-165.

It appears that the development of materials for TN type displays has almost reached its limit.

Therefore, in order to overcome the above-mentioned drawbacks, interest has shifted to the development of chiral liquid crystals in place of nematic liquid crystals in recent years, and considerable progress has been made in particular with respect to ferroelectric liquid crystals.

What was the first ferroelectric liquid crystal developed?

A compound represented by CH3 -CH2C1 (C2H5 * (in the formula, * indicates an asymmetric carbon atom) (
(hereinafter abbreviated as DOBAMBC), its liquid crystal phase series and phase transition temperature (° C.) are as follows.

(In the formula, C represents a crystalline phase, SA represents a smectic A phase, SC* represents a chiral smectic C phase, SH represents a chiral smectic H phase, and H represents an isotropic liquid).

Ferroelectricity is found in chiral smectic C phase (hereinafter abbreviated as SC) or chiral smectic H phase (hereinafter abbreviated as SH), which are classified and named based on their molecular arrangement, and when used, displays that can respond up to 1 μs. The possibility of obtaining devices such as R, B, Meyer, etc.
France (Journal of Physics
Rance, Vol. 36, p. 69 (1975).

Since then, various analogs of DOBAMBC have been synthesized,
Because the lower limit of the temperature range belonging to Sc or SH is higher than room temperature, and the compound itself is unstable to moisture and light, research is currently focused on ester-based ferroelectric liquid crystal compounds shown in Table 1 below. The center of has shifted [Liquid Crystals and Ordered 7A/-is (::rystalsand 0r
Dered Fluids, 4, 1-32
(1982)].

The symbols in Table 4 indicate the following.

C: i-crystalline phase, SA: smectic physiognomy, Sc*: chiral smectic ca, ch: cholesteric phase, I: isotropic liquid.

CH3 2MO: -CH2C) (C6H13,*: Asymmetric carbon atom* [Problems to be solved by the invention] As a result, chemically stable compounds were obtained, but as shown in Table 1, these liquid crystals The temperature range in which the compound alone exhibits 9 ferroelectricity is higher than room temperature.

Not practical. Furthermore, since the two molecules of the mixtures of the compounds shown in Table 1 have similar structures, no large melting point drop was found as shown in Table 2.

Table 2 - ff12': Compounds with a structure in which 4M)1 is used as Q in 2MB in the compound of patient 2.

Therefore, in the nematic liquid crystal material used in the TN type display system, this problem was solved by mixing two or more types of liquid crystal compounds with significantly different molecular structures.

Therefore, there is a strong desire to develop a ferroelectric liquid crystal compound that is significantly different from these Entel-based ferroelectric liquid crystal compounds in terms of its bimolecular structure.

[Means for solving problems]

The present inventors have conducted intensive research from the above viewpoint.

The inventors discovered a ferroelectric liquid crystal compound whose temperature range is around room temperature and a liquid crystal composition containing the same, and arrived at the present invention.

That is, 2 the present invention is based on the general formula [I] (wherein R is an alkyl group having 1 to 18 carbon atoms, 2m is 1 or 5, n is an integer of O to 5, and * is an asymmetric carbon atom). (respectively).

The present invention also provides a chiral smectic liquid crystal composition containing at least one compound represented by the general formula CI).

In the general formula [E], the boron-containing skeleton is named as follows.

In general formula [I), R represents an alkyl group having 1 to 18 carbon atoms, preferably a linear alkyl group having 8 to 16 carbon atoms. Therefore, the compound represented by the above general formula [E] is 2-(4'-alkoxyphenyl)-5
-alkyl/l'-1,3,2-dioxaborinane.

The method for producing the compound represented by the general formula CI) will be described in detail below, and an optically active alcohol is used as one of the raw materials for production. Optically active alcohols include 2-methylbutanol, 3-methylpentanol, 4-methylhexanol, 5-methylhegtanol, and 6-methyloctatool, which are available at low cost for industrial versatility. , 1-methylglopano-p, etc. are often used.

An outline of the method for producing the compound represented by the general formula CI) is as shown in the following formula.

3) H3''U represents an alkyl group having 1 to 18 carbon atoms, Ts represents a tosyl group, X represents a chlorine atom or a bromine atom (and THF represents tetrahydrofuran, respectively) [Function] The compound of the present invention has the following properties. Indicates the function and features of

First, a group that can be decomposed into two in a moisture-containing atmosphere, such as a carboxylic acid ester group (-C-0-), is very stable. Next, as in the case of the dioxaneborinane ring, the bc phase stably exists due to the interaction between molecules with large polarization of the long axis of the molecule.

Furthermore, sterically, the dioxaborinane ring has a slightly bent structure and does not exist on the same plane as the benzene ring, so it can form an Sc phase in a low temperature range.

However, when the compound of the present invention is mixed with other liquid crystals having a planar structure such as ester liquid crystals, biphenyl liquid crystals, or phenylpyrimidine liquid crystals, backing between molecules becomes worse, and the melting point of the thermally stable phase decreases. is significantly reduced, giving the liquid crystal composition of the present invention having an Sc phase over a wide temperature range, including temperatures near room temperature.

〔Example〕

The present invention will be explained below by way of examples.

In the examples, ``chi'' indicates weight % @'R Example 1
4-Flukoxybrobenzene was added to a 300 CC four-way flask equipped with a stirrer, a thermometer, and a reflux condenser. (0,
206 mol), sodium hydroxide 8.24 t (0,20
6mo/L/) and anhydrous ethanol/L'2007! Prepare.

Stir to form a solution, and add to this solution an optically active alkyl/vP-toluenesulfonic acid ester prepared in advance from an optically active alcohol and p-)/l/enesulfonic acid.
．． 206 mol was added dropwise at room temperature. After the dropwise addition, the mixture was further reacted under reflux for 10 hours, and after the precipitate was separated, the ethanol was distilled off, and the residue was extracted with ether.

The organic layer was washed with saturated brine, dried over anhydrous sodium sulfate, and then the organic solvent was distilled off. The resulting oil? Distillation under reduced pressure or silica gel column chromatography (developing solvent:
4-alkoxybromobenzene shown in Table 3 was obtained in a yield of 87 to 94%. Its structure was confirmed by IR and NMR spectra.

The results are shown in Table 3.

Table 3: Into a 300 CH three-piece flask equipped with a stirrer, a thermometer, 9 dropping funnels, and a nitrogen gas introduction tube, under a nitrogen stream, trimethyl boric acid/vol. Stir to form a solution, keep the internal temperature below -60°C in a dry ice bath, and add 0.0% of 4-alcoquinphenylmagnesium bromide prepared from 4-alkoxybromobenzene synthesized in Production Example 1 and magnesium to this solution. A solution of 70 mmol of anhydrous tetrahydrofuran containing 0.09 mol was added dropwise over about 10 minutes without stirring.

After stirring at -60°C for 2 hours, water IO- was added dropwise and using the heat of reaction, the internal temperature was gradually raised to -30°C.

Next, the dry ice bath was removed, and while an aqueous solution 55- containing concentrated sulfuric acid 3- was added dropwise, the temperature was raised to room temperature to complete the reaction. Tetrahydrofuran was distilled off under reduced pressure.

Aether/l/20G- was added to extract the target product. A white solid was obtained after distilling off the nityl. This is 20-3
It was dissolved in n-hexane at a temperature of 0°C, cooled to -30°C, recrystallized, and air-dried to obtain the 4-alkoxyphenylboronic acids shown in Table 4 below. Its structure was confirmed by IR and NMR spectroscopy.

The results are shown in Table 4.

2t equipped with stirrer, thermometer 2 dropper and reflux condenser
Lithium aluminum hydride 15 was added to the Mitsuro flask.
A solution of 0.2 mole of 2-alkylmalonic acid dissolved in anhydrous ether (20) was heated to an internal temperature of It was added dropwise at 5°C. After the dropwise addition was completed, the reaction was kept at reflux temperature for 6 hours. After the completion of the reaction, the reaction product was cooled on ice,
To decompose the excess lithium aluminum hydride, a water-saturated ether/L'50 ml 1. Then, 10 aqueous solutions of 5% sodium hydroxide were added dropwise, and the mixture was stirred at 25°C overnight. The produced white inorganic matter was removed and the mother liquor was concentrated to obtain a white solid. Recrystallization was performed with n-hexane to obtain 2-alk IV-1,3-propanediol shown in Table 5 below.

Table 5 R-CH (C) 120f () 2 2 equipped with a stirrer, thermometer and azeotropic dehydrator with reflux condenser
0.01 mole of 4-alkoxyphenylporonic acid obtained in Production Example 2 and 0.01 mole of 2-alkyl-1,3-propanediol obtained in Production Example 3 were charged into a 00 CC four-tube flask together with toluene 5o-. Azeotropic dehydration was carried out at reflux temperature. The reaction was completed in about 1 to 2 hours, toluene was distilled off under reduced pressure, and the residue was subjected to silica gel column chromatography (200 mesh silica gel/l/40 S',
Isolate and purify using dichloromethane (developing solvent),
2-(4'-Flucoxypheny#)-5-alkyl-1,3,2-dioxaborinane shown in Table 6 was obtained in a yield of 90-96%. A compound with even higher purity can be obtained by recrystallization from petroleum ether.

The results are shown in Tables 6-1 and 6-2 together with the phase transition temperature of each compound obtained.

The symbols in the table below represent the following:

C: crystalline phase, SC: chiral smectic C phase.

SA: Smectic physiognomy, isotropic liquid phase (to) The symbols in the table indicate the following.

C: Crystal phase, SA: Smectic A phase, I: Tokichi phase, S
c: chiral smectic C phase (the same applies to the following examples) Example 2 Using the compound of the present invention obtained in Example 1, liquid crystal compositions shown in Table 7 below were prepared, and their phase transition temperatures were determined. The measurement results were as shown in Table 7.

Table 7 When this liquid crystal composition was applied with a polyimide film and subjected to parallel alignment treatment by rubbing the two surfaces, and injected into a cell having a transparent electrode with a cell thickness controlled to 2 μm, a uniformly aligned cell was obtained by SC. was gotten. Also at a temperature of 30℃ ±10
When a camellia wave voltage of V was applied, a display element with a response time of 1.4 ms and a contrast of 10 was obtained.

Example 3 A liquid crystal composition was prepared by mixing and dissolving 70% of the liquid crystal composition of the present invention obtained in Example 2 and 30% of the known ester-based liquid crystal composition listed in Table 2, and its phase transition was evaluated. The temperature was measured and the results were as follows.

5℃ 51℃ 60℃ 64℃C--5cm
(2)-SAMMPMIIMPCh-2 (2) When this liquid crystal composition was injected into a cell similar to the cell used in Example 2, a cell with uniform orientation could be obtained by SC. The response time of this cell at 25° C. was 1.3 ms, and the contrast was 13. It was possible to expand the range of esters.

〔Effect of the invention〕

As shown in Example 1 above, the compound of the present invention is a compound that exhibits an SC phase near room temperature and has ferroelectricity.
Still, from the results of Examples 2 and 3, it is clear that it is an effective component in obtaining a chiral smectic liquid crystal composition over a wide temperature range including room temperature. Such effects are achieved for the first time by the present invention.

Claims (2)

[Claims] (1) General formula ▲ Numerical formula, chemical formula, table, etc. A compound represented by (respectively indicating a carbon atom). (2) General formulas ▲ Numerical formulas, chemical formulas, tables, etc. At least one compound represented by
A chiral smectic liquid crystal composition characterized by containing seeds.