JP2822550B2 - Azulene derivative, liquid crystal composition and liquid crystal device using the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a novel azulene derivative, a liquid crystal composition and a liquid crystal device using the same, and more particularly to a blue-based negative or low positive useful for liquid crystal display and the like. The present invention relates to an azulene derivative having dichroism, a liquid crystal composition, and a liquid crystal device containing the same.

[Problems to be Solved by Conventional Techniques and Inventions] Currently, various display modes other than a twisted nematic (TN) type display mode and a super twist (STN) mode have been proposed as a liquid crystal display, and a liquid crystal has a dye. A guest-host (GH) type display system using a solution of GaN is widely used as a display panel of an automobile or the like because of its features such as a wide viewing angle.

The GH mode is also characterized in that it can be used in combination with other modes such as a TN type combined mode (TN-GH) mode, and therefore, the dye used has various hues and secondary colors depending on the intended use and display mode. There is a demand for color.

Of these, dyes having negative dichroism are useful for positive guest host display or hue correction of compound colors, and dyes having low positive dichroism are useful for hue correction of compound colors, etc. Little is known about blue dyes having the above properties.

In addition, dyes generally have low solubility in liquid crystals, and in particular, have a problem that they are easily precipitated because of low solubility stability at low temperatures.

An object of the present invention is to provide a dye having excellent dissolution stability and having a negative or low dichroic color of blue, which is hardly known hitherto, a liquid crystal composition containing the same, and a liquid crystal element using the same. I do.

[Means for Solving the Problems] The object of the present invention is to provide the following general formula [I] (Wherein, R represents an alkyl group.) An azulene derivative represented by the following formula, a liquid crystal composition containing at least one of the azulene derivative, and a liquid crystal element in which at least one of the compositions is sandwiched between transparent substrates with electrodes. Achieved.

Examples of R in the azulene derivative represented by the general formula [I] of the present invention include a methyl group, an ethyl group, a branched or linear propyl group, a butyl group, a hexal group, an alkyl group such as an octyl group. . The azulene derivative [I] of the present invention is a novel colored liquid crystal compound and can be synthesized via 2-hydroxy-6-cyanoazulene by the following reaction route.

The liquid crystal composition containing the azulene derivative of the present invention has a low dichroism near negative or close to zero, while ordinary anthraquinone-based and azo-based dyes exhibit positive dichroism having an order parameter of 0.5 or more. It has a distinctive feature in terms of its properties.

The liquid crystal composition of the present invention can be obtained by converting the azulene derivative represented by the above general formula [I] into various liquid crystal compounds such as biphenyl, phenylcyclohexane, phenylpyrimidine, cyclohexylcyclohexane and the like, which exhibit a nematic or smectic phase. It can be easily prepared by mixing the product with a known method.

In this case, since the azulene derivative of the present invention is a liquid crystal compound having a wide liquid crystal temperature range, a liquid crystal composition having excellent dissolution stability can be prepared.

Further, the liquid crystal composition of the present invention may contain an optically active compound which may or may not show a liquid crystal phase such as cholesteryl nonanoate, or may contain various additives such as an ultraviolet absorber and an antioxidant. May be contained.

An element utilizing the guest-host effect by sandwiching the liquid crystal composition obtained in this way between substrates with at least one transparent electrode [Shoichi Matsumoto, Ichiyoshi Kakuda “Latest technology of liquid crystal” Association, 34 (1983); JLFergason, SI
D85Digest, 69 (1985), etc.].

[Effects of the Invention] The present invention relates to an azulene derivative having negative to low positive dichroism, a liquid crystal composition containing the same, and a liquid crystal element using the same, and used for hue correction in a guest-host mode. Thus, a liquid crystal element with a higher display effect can be realized.

[Examples] Next, the present invention will be described specifically with reference to Examples.
The present invention is not limited by these examples.

Example 1 The following structural formula Is dissolved in 10 ml of trifluoroacetic acid, 20 ml of hydrobromic acid is added thereto, and the mixture is heated and reacted at 100 ° C. for 2 hours. The reaction solution is added to 300 ml of ice water and extracted with chloroform. The chloroform solution was washed with water and dried over anhydrous sodium sulfate.
-Hydroxy-6-bromoazulene was obtained.

The above 2-hydroxy-6-bromoazulene was added with 20 ml of acetic anhydride and a catalytic amount of pyridine and reacted overnight, then the reaction solution was added to 100 ml of water, stirred at room temperature for 4 hours, and extracted with benzene. . The extract was washed with brine, dried over anhydrous sodium sulfate, and the solvent was distilled off. The resulting product was purified by column chromatography (silica gel) and recrystallized from methanol to give a compound represented by the following structural formula 2. -Acetoxy-6-bromoazulene was obtained (melting point: 112)
° C).

0.56 g of 2-acetoxy-6-bromoazulene synthesized by the above reaction was dissolved in 5 ml of anhydrous DMF, 0.33 g of cuprous cyanide was added at 120 ° C., and the mixture was heated at 150 ° C. for 40 minutes. In addition, it was extracted with benzene. After the extract was washed with saturated brine and dried over anhydrous sodium sulfate, the target product was separated and purified by column chromatography, and recrystallized from methanol to obtain the following 2-acetoxy-6-cyanoazulene (melting point: 129 ° C) ).

0.17 g of 2-acetoxy-6-cyanoazulene synthesized by the above reaction was added to 5 ml of 100% phosphoric acid, followed by stirring at room temperature for 90 minutes. The reaction solution was added to 40 ml of water, and extracted with ethyl acetate. The extract was washed with saturated saline and dried over magnesium sulfate, and then the solvent was distilled off to obtain the following 2-hydroxy-6-cyanoazulene.

Next, 1 ml of thionyl chloride was added to 0.06 g of pn-pentylbenzoic acid, and the mixture was refluxed for 3 hours. After the reaction, excess thionyl chloride was distilled off under reduced pressure. To this, 0.034 g of 2-hydroxy-6-cyanoazulene synthesized by the above reaction,
1 ml of benzene and 3 drops of pyridine were added, and the mixture was stirred at room temperature overnight.

After washing with 0.1N hydrochloric acid and saturated saline and drying over anhydrous sodium sulfate, the solvent was distilled off. The residue was purified by column chromatography to give the following compound.

 This compound is a blue-violet crystal showing a liquid crystal region at 117-194 ° C
This is marketed under the trade name ZLI-1132 (Merck).
10 for phenylcyclohexane-based liquid crystal compositions sold
The liquid crystal composition obtained by blending wt% is used as a transparent substrate with electrodes.
Is subjected to a homogeneous alignment treatment so that the electrodes face each other.
A liquid crystal element was fabricated by enclosing it in a 50μ thick cell.
Was. Absorption of polarized light parallel to the alignment direction of this liquid crystal element
Sepector (A ) And polarized light perpendicular to the alignment direction
Absorption spectrum (A_⊥) Was measured. S = (A -A_⊥) / (2_⊥+ A ) When the order parameter (S) was calculated, it was 450
Low positive value or wavelength in the wavelength range over 690nm
It showed a negative value.

Example 2 Instead of pn-pentylbenzoic acid of Example 1, p-
The following compounds were synthesized in the same manner as in Example 1 except that n-hexylbenzoic acid was used.

This compound is a blue-violet liquid crystal exhibiting a liquid crystal region at 105 ° C. to 181 ° C. A liquid crystal device was prepared in the same manner as in Example 1, and the order parameter (S) was determined.
And the same results were obtained.

Example 3 Instead of pn-pentylbenzoic acid in Example 1, p-
The following compounds were synthesized in the same manner as in Example 1 except that n-octylbenzoic acid was used.

This compound is a blue-violet liquid crystal exhibiting a liquid crystal region at 101 ° C. to 177 ° C. A liquid crystal device was prepared in the same manner as in Example 1, and the order parameter (S) was determined.
And the same results were obtained.

[Brief description of the drawings]

 FIG. 1 shows a liquid crystal composition containing the azulene derivative of Example 1.
Into a cell with a transparent electrode that has been subjected to a homogeneous alignment treatment.
Drawing showing the absorption spectrum of the liquid crystal device fabricated by encapsulation
And A Is absorption for linearly polarized light parallel to the alignment direction
Spectrum, A_⊥Is linearly polarized light perpendicular to the alignment direction.
3 shows an absorption spectrum for the same.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C07C 255/47 C09K 19/60 G02F 1/13 CA (STN) CAOLD (STN) REGISTRY (STN)

Claims (3)

(57) [Claims] 1. A compound represented by the following general formula [I] (In the formula, R represents an alkyl group.) 2. A liquid crystal composition comprising at least one azulene derivative according to claim 1. 3. A liquid crystal device characterized in that at least one of the liquid crystal compositions according to claim 2 is sandwiched between transparent substrates with electrodes.