JP2735263B2 - Liquid crystal material and liquid crystal display device using the same - Google Patents

Description

The present invention relates to a novel liquid crystal material and a liquid crystal display device using the same, particularly to a ferroelectric liquid crystal having a chiral smectic C phase.

[Conventional technology]

2. Description of the Related Art Liquid crystals have been widely used in calculators, watches and the like as a favorite of small flat panel displays. Also,
Recently, it has been used as a display for automobiles and a display for personal computers. Furthermore, it has begun to be applied to moving picture displays such as small liquid crystal televisions.

By the way, conventionally, twisted nematic liquid crystals are known as liquid crystals used in calculators, watches and the like. However, the display system using the liquid crystal has problems such as insufficient response speed and occurrence of crosstalk. For this reason, it has been difficult to apply the present invention to a device requiring a high response speed, such as a large-screen display for a moving image of the liquid crystal.

To solve these problems, thin film transist
Although a method such as an active matrix using or (TFT) has been developed, there are problems such as a high manufacturing cost.

For this reason, a display method using a ferroelectric liquid crystal has attracted attention as an alternative to a display method using a twisted nematic liquid crystal. This method was adopted in 1975 by RBMayer
It has features such as a faster response speed and a memory effect as compared with the conventional method. The ferroelectric liquid crystal has a liquid crystal form of a chiral smectic C phase. Many materials have been known as such ferroelectric liquid crystal materials.

However, the conventional ferroelectric liquid crystal material has a problem that it is unstable with respect to moisture and light in the air, has a narrow temperature range in which a chiral smectic C phase is obtained, and has a large restriction in use.

(Problems to be Solved by the Invention) The present invention has been made to solve the above problems, and can expand the temperature range of the chiral smectic C phase.
It is another object of the present invention to provide a liquid crystal material having excellent thermodynamic stability and a liquid crystal display device using the same.

[Configuration of the invention]

(Means and Action for Solving the Problems) The liquid crystal material of the present invention has a general formula Optically active 7-alkoxy-2-fluorenonecarboxylic acid 4-alkoxyphenyl ester represented by the formula: wherein R in the formulas (A) and (B) is an alkyl group, R ^*
Represents an optically active group having an asymmetric carbon atom].

Further, the present invention is a liquid crystal display element using a liquid crystal material represented by the above general formula (A) or (B).

The liquid crystal material of the present invention comprises a 7-alkoxy-2-fluorenonecarboxylic acid 4- represented by the general formulas (A) and (B).
A mixture of two or more of the alkoxyphenyl esters, or a mixture of these with another compound exhibiting a chiral smectic C phase may be used.

As R in the above general formulas (A) and (B), a linear alkyl group having 3 to 18 carbon atoms is selected from the viewpoint of expanding the temperature range of the chiral smectic C phase.
It is more preferable to select a linear alkyl group of

As R ^* in the above general formulas (A) and (B), from the viewpoint of expanding the temperature range of the chiral smectic C phase, the following general formula: [However, R _{1 to} R ₃ in the general formula (C) are any of an alkyl group, a halogen group, a cyano group, a trifluoroalkyl group, and a hydrogen atom, and R ₁ ≠ R ₂ , R ₂ ≠ R ₃ , R ₃ ≠ R ₁ is satisfied, and n is an integer of 0 to 15 (preferably an integer of 0 to 8).] It is preferable to use an alkyl group having an asymmetric carbon atom represented by the following formula: Among these, it is more preferable to use a 2-methylbutyl group or a 2-octyl group.

Optically active 7-alkoxy-2 to be a liquid crystal material of the present invention
-Fluorenonecarboxylic acid 4-alkoxyphenyl ester can be produced according to the following reaction.

First, from commercially available fluorene, for example, Org.Synth., 1
After a three-stage reaction disclosed in 933, 13 , 74, 7-
Synthesize hydroxyfluorene (I). Next, CHCo
According to the method disclosed in Ak et al., J. Org. Chem., 1954, 19 , 626, the reactions (I) to (II) are carried out. Furthermore, GWGr
ay et al., J. Chem. Soc., 1957, 3228,
The reactions (II) to (III) are performed.

On the other hand, an optically active alcohol is reacted with p-toluenesulfonic acid chloride in pyridine to form a p-toluenesulfonic acid salt of the optically active alcohol, and then reacted with hydroquinone to synthesize a hydroquinone ester (IV) of the optically active alcohol. I do.

Further, the above (III) is oxidized with sodium dichromate or ammonium dichromate in acetic acid to form 7-alkoxyfluorenone-2-carboxylic acid (V), and converted into an acid chloride with thionyl chloride, and then in pyridine. By reacting with (IV), optically active 7-alkoxy-2-fluorenonecarboxylic acid 4-alkoxyphenyl ester (A) is produced.

In addition, the optically active 7-alkoxy-2-fluorenonecarboxylic acid 4-alkoxyphenyl ester represented by the general formula (B) is obtained by changing R-Br to R ^* -Br and R ^*
It can be produced in exactly the same manner except that -OH is changed to R-OH.

General formulas (A) and (B) constituting the liquid crystal material of the present invention.
The optically active 7-alkoxy-2-fluorenonecarboxylic acid 4-alkoxyphenyl ester represented by the formula (1) has a wide temperature range of the chiral smectic C phase and excellent thermodynamic stability. Or a mixture thereof with another compound exhibiting a chiral smectic C phase to provide a liquid crystal display device such as a display with less restrictions on use.

(Examples) Hereinafter, the present invention will be described in detail based on examples.

Synthesis Example 1 First, 7-octyloxyfluorenone-2-carboxylic acid was synthesized by a known method. 4.00 g of this 7-octyloxyfluorenone-2-carboxylic acid (0.0118 mol
l) was dissolved in 1 of acetic acid, and 20.0 g of sodium dichromate was added thereto. After heating this solution under reflux for 3 hours,
Cooled to room temperature. The deposited precipitate was collected by filtration and recrystallized twice with acetic acid and twice with xylene to give 1.99 g (yield 48
%) Of yellow crystals.

When the IR spectrum and the NMR spectrum of this crystal were measured, it was confirmed to be 7-octyloxyfluorenone-2-carboxylic acid.

Next, 1.75 g (0.005 mol) of 7-octyloxyfluorenone-2-carboxylic acid obtained as described above and 10 ml of thionyl chloride were refluxed for 1 hour while stirring. Subsequently, after excess thionyl chloride was distilled off, the residue was recrystallized from n-hexane to obtain 1.76 g (yield: 75%) of yellowish white crystals (acid chloride).

Subsequently, 1.39 g (3.75 × 10 ⁻³ mol) of the above acid chloride was added to 10
A solution prepared by dissolving 0.947 g (5.26 × 10 ⁻³ mol) of 4-(+)-2-methylbutoxyphenol in 5 ml of pyridine was added dropwise to the solution dissolved in pyridine of 5 ml over 5 minutes. And heated at 90 ° C. for 4 hours using an oil bath. After cooling the pyridine solution to room temperature, it was poured into 500 ml of ion-exchanged water to precipitate a product, and the precipitate was collected by filtration. The obtained product was recrystallized three times with ethanol to obtain 1.55 g (3.01 × 10 ⁻³ mol, 80%) of yellow needles. Elemental analysis of the crystal showed C: 77.1H: 7.5O: 1.52 (calculated values C: 77.04, H: 7.39, O: 15.56). FIG. 1 shows an NMR spectrum of a heavy chloroform solution of the crystals.

These NMR spectrum, elemental analysis, and IR spectrum M
From the S spectrum, it can be seen that this yellow crystal is represented by R of the general formula (A)
As C ₈ H ₁₇ and as R ^* Was confirmed to be 7-octyloxyfluorenone-2-carboxylic acid 4-(+)-2-methylbutylphenyl ester, respectively.

Synthesis Examples 2 to 67 7-hexyloxyfluorenone-2-carboxylic acid,
7-nonyloxyfluorenone-2-carboxylic acid, 7-
Decyloxyfluorenone-2-carboxylic acid, 7-dodecyloxyfluorenone-2-carboxylic acid, and 7-tetradecyloxyfluorenone-2-carboxylic acid, respectively.
0.1 mol was prepared and the same reaction as in Synthesis Example 1 was carried out to give 7-hexyloxyfluorenone-2-carboxylic acid 4-(+)-
2-methylbutoxyphenyl ester, 7-nonyloxyfluorenone-2-carboxylic acid 4-(+)-2-methylbutoxyphenyl ester, 7-decyloxyfluorenone-2-carboxylic acid 4-(+)-2-methylbutoxy Phenyl ester, 7-dodecyloxyfluorenone-2-
Carboxylic acid 4-(+)-2-methylbutoxyphenyl ester, 7-tetradecyloxyfluorenone-2-carboxylic acid 4-(+)-2-methylbutoxyphenyl ester were synthesized. These compounds are represented by the general formula (A) based on NMR spectrum, elemental analysis IR spectrum, and mass spectrum.
It was confirmed that the structure was represented by

 Table 1 shows these phase transition temperatures.

Examples 1-2 Among the six compounds synthesized in Synthesis Examples 1-6 above,
As shown in Table 2, the three compounds were mixed at the mixing ratios (weight ratios) shown in Table 2, and the C of the obtained liquid crystal material was adjusted.
→ SmC ^* , SmC ^* → SmA, SmA → I Each phase transition temperature was measured. The results are shown in Table 2.

Synthesis Examples 7 to 9 7-decyloxyfluorenone-2-carboxylic acid, 7
-Dodecyloxyfluorenone-2-carboxylic acid, 7-
0.1 mol of tetradecyloxyfluorenone-2-carboxylic acid was prepared, and reacted with optically active S4- (2-octyloxy) phenol in the same manner as in Synthesis Examples 1 to 6 to obtain optically active S7-decyl. Oxyfluorenone-2
-Carboxylic acid 4- (2-octyloxy) phenyl ester, S7-dodecyloxyfluorenone-2-carboxylic acid 4- (2-octyloxy) phenyl ester, S7-
Tetradecyloxyfluorenone-2-carboxylic acid 4-
(2-Octyloxy) phenyl ester was synthesized.

The structures of these compounds were confirmed by NMR spectrum, elemental analysis, IR spectrum and mass spectrum.

Table 3 shows the phase transition temperatures of the compounds thus obtained. The temperature change of the spontaneous polarization is shown in the characteristic diagram of FIG. 2, and the temperature change of the tilt angle is shown in the characteristic diagram of FIG.

Example 6 As shown in Table 4, 10
The liquid crystal material was prepared by mixing the kinds of compounds in the proportions shown in the table.

The temperature range showing the SmC ^* phase of this liquid crystal material is -5 ° C to 90 ° C
° C.

Next, the liquid crystal material obtained as described above was injected into a cell of a liquid crystal display element, and its response speed was measured.

FIG. 4 is a schematic longitudinal sectional view showing a cell structure of the liquid crystal display device. Here, a glass substrate (11a, 12a) transparent electrodes (12b, 12b) formed on the polyimide alignment film (11c, 12c) on the is formed to constitute the substrate 11, 12. The two substrates are arranged so that the example in which the alignment film is formed is opposed to each other, and after injecting the liquid crystal material 14 according to the present invention,
The periphery is hermetically sealed by a sealing material 13 to form a display element. Here, these two substrates are connected to a gap material 15.
At a predetermined interval. The figure also shows the external electrodes 16 for driving the liquid crystal display element.

As a result of measuring this display element at room temperature (25 ° C.),
The response speed was 245 μs.

〔The invention's effect〕

As described in detail above, according to the liquid crystal material of the present invention, the temperature range of the chiral smectic C phase is wide and the stability is excellent. Is played.

[Brief description of the drawings]

FIG. 1 is a diagram showing an NMR spectrum of 7-octyloxyfluorenone-2-carboxylic acid-2-methylbutyl ester synthesized in Synthesis Example 1, and FIG. 2 is a diagram illustrating Synthesis Examples 7 to 9.
Characteristic diagram showing the temperature change of spontaneous polarization of the compound synthesized in
FIG. 3 is a characteristic diagram showing the temperature change of the tilt angle of the compounds synthesized in Synthesis Examples 7 to 9, and FIG. 4 is a schematic longitudinal sectional view showing the cell structure of the liquid crystal display element used in Example 6. 11 , 12 … substrate, 13… sealing material 14… liquid crystal material, 15… gap material 16… external electrode

Claims (5)

(57) [Claims] (1) General formula Optically active 7-alkoxy-2-fluorenonecarboxylic acid 4-alkoxyphenyl ester represented by the formula: wherein R in the formulas (A) and (B) is an alkyl group, R ^*
Represents an optically active group having an asymmetric carbon atom. ] A liquid crystal material comprising: (2) R in the general formulas (A) and (B) has 3 to 3 carbon atoms.
The liquid crystal material according to claim 1, wherein the liquid crystal material has 18 linear alkyl groups. 3. The method according to claim 1, wherein R ^{* in} formulas (A) and (B) is an optically active 2-methylbutyl group.
The liquid crystal material as described. 4. The liquid crystal material according to claim 1, wherein R ^{* in} formulas (A) and (B) is an optically active 2-octyl group. 5. A liquid crystal display device comprising the liquid crystal material according to claim 1.