JPH07224231A - Dichroic coloring matter, and liquid crystal composition and liquid crystal device containing the same - Google Patents

Abstract

PURPOSE:To obtain a liq. crystal compsn. which has improved light resistance and solubility, (esp. in a fluorine-contg. liq. crystal compd.) and exhibits both light and deep colors by incorporating a specific dichroic coloring matter into the compsn. CONSTITUTION:An aniline compd. synthesized by the reaction of formula II is subjected to diazotization and coupling to give a perfluoroalkylsulfonylated dis- or trisazo dichroic coloring matter of formula I (wherein R<1> and R<2> are each alkyl, alkoxyalkyl, fluoroalkylated alkyl, or optionally substd. aralkyl provided they may combine with each other to fqrm a nitrogen-contg. aliph. ring; Rf is 1-12C perfluoroalkyl or omega-H-perfluoroalkyl; Z<1> to Z<9> are each H, halogen, methyl, or methoxy provided Z1, Z<4>, and Z<7> may combine with Z<2>, Z<5>, and Z<8>, respectively, to form a part of an aliph., arom., or nitrogen-contg. arom. ring; m is 1 or 2; and n is 1-8). The coloring matter is mixed with various liq. crystal compds. to give a liq. crystal compsn., which is sandwiched between two substrates with electrodes one of which is transparent, giving a liq. crystal device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel red to blue azo dichroic dye, a liquid crystal composition containing the same and a liquid crystal device.

[0002]

2. Description of the Related Art Currently, liquid crystal displays include twisted nematic (TN) display mode and super twisted (ST).
In addition to the N) mode, various display modes have been proposed. Of these, a guest-host (GH) type display method in which a dye is dissolved in liquid crystal is widely used as a display panel for automobiles and the like because of its characteristics such as a wide viewing angle.

The characteristics of the dichroic dye used in the GH mode are required to be excellent in the following items 1) dichroism 2) solubility 3) light resistance 4) coloring power.

On the other hand, as a red-type dichroic dye necessary for forming a black liquid crystal composition, which has a great demand in the market, conventionally, a dye having an alkyl group, a nitro group or a cyano group at its end is known. It was being done. As the substituent containing a fluorine atom, a trifluoromethyl group has been studied, but other groups are not yet sufficient.

However, conventional dichroic dyes having a nitro group or a cyano group have a great difficulty in light resistance and solubility, and a dye having an alkyl group is apt to have a pale hue such as yellowish red. It has a drawback that it is difficult to obtain a deep hue such as bluish red. Further, there is a problem that these conventional dyes have insufficient affinity such as solubility with respect to a fluorine-based liquid crystal compound used in recent TFT liquid crystal elements and the like.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a red dichroic dye having less of the above problems, a liquid crystal composition and a liquid crystal device containing the same.

[0007]

The present inventors have found that a disazo-based or trisazo-based dye containing a perfluoroalkylalkylsulfonyl group has excellent solubility in a fluorine-based liquid crystal compound and exhibits a deep red color. The invention was reached. That is, the gist of the present invention is the following general formula [I]

[0008]

[Chemical 2]

(In the formula, R ¹ and R ² represent an alkyl group, an alkoxyalkyl group, a fluoroalkyl-substituted alkyl group, or an aralkyl group which may have a substituent, and R ¹ and R ² are linked to each other. To form a nitrogen-containing aliphatic ring, and Rf represents a perfluoroalkyl group having 1 to 12 carbon atoms or a ω-H-perfluoroalkyl group.
Z ^{1 to} Z ⁹ each represent a hydrogen atom, a halogen atom, a methyl group or a methoxy group, and Z ¹ and Z ² , Z ⁴ and Z ⁵ or Z ⁷ and Z ⁸ are linked to each other to form an aliphatic ring or aromatic ring. Alternatively, it may form part of a nitrogen-containing aromatic ring. m is 1 or 2, and n is a number of 1-8. ) In a disazo or trisazo dichroic dye containing a perfluoroalkylalkylsulfonyl group. The disperse or trisazo dichroic dye of the present invention has the following reaction formula

[0010]

[Chemical 3]

It can be synthesized by applying a known diazotization coupling reaction using the anilines having a perfluoroalkylalkylsulfonyl group synthesized by

In the general formula [I] shown above, R ¹ and R ² are each independently C1 to C1 such as methyl, ethyl, linear or branched propyl, butyl, hexyl, octyl and the like.
8 alkyl groups, alkoxyalkyl groups such as ethoxymethyl, butoxymethyl, ethoxyethyl, butoxyethyl, fluoroalkyl-substituted alkyl groups such as perfluoroethylmethyl, perfluorobutylethyl, perfluorohexylethyl, benzyl, phenethyl, 4- Examples thereof include an aralkyl group which may have a substituent (eg, an alkyl group, an alkoxy group, a halogen atom) such as butylbenzyl, 4-butoxyethylbenzyl, 4-pentoxybenzyl, and 4-chlorobenzyl, and R ¹ , R ²
May be linked to each other to form a nitrogen-containing aliphatic ring such as a pyrrolidine ring, a piperidine ring or a morpholine ring.

Rf is a perfluoroalkyl group having 1 to 12 carbon atoms such as trifluoromethyl group, pentafluoroethyl group, heptafluoropropyl group, nonafluorobutyl group, undecafluoropentyl group, heptadecafluorooctyl group or 3H. -Perfluoropropyl group,
4H-perfluorobutyl group, 6H-perfluorohexyl group, 8H-perfluorooctyl group and the like are ω-H-perfluoroalkyl groups having 1 to 12 carbon atoms and containing one hydrogen atom at the terminal.

Z ^{1 to} Z ⁹ each represent a hydrogen atom, a halogen atom, a methyl group or a methoxy group, and Z ¹ and Z
² , when Z ⁴ and Z ⁵ or Z ⁷ and Z ⁸ are linked to each other, they may form an aliphatic ring portion of a tetralin ring, an aromatic ring portion of a naphthalene ring or a nitrogen-containing aromatic ring portion of a quinoline ring, R ¹ and Z ⁸ or R ² and Z ⁹ may be linked to each other to form a nitrogen-containing aliphatic ring portion of a julolidine ring or a tetrahydroquinoline ring.

Among the dichroic dyes of the present invention, disazo dyes are particularly useful as a component of a black liquid crystal composition because they have a deep-bluish hue of bluish red to magenta even in a reddish color.

The liquid crystal composition of the present invention comprises an azo dichroic dye represented by the general formula [I] shown above in [Liquid Crystal Device Handbook: Japan Society for the Promotion of Science, 142nd Committee (1989);
p154 to p192, p715 to p722], and easily mixed by a known method with various liquid crystal compounds or liquid crystal compositions such as biphenyl type, phenylcyclohexane type, phenylpyrimidine type and cyclohexylcyclohexane type exhibiting a nematic or smectic phase. Can be prepared. Examples of such liquid crystal compounds include the compounds described in JP-A-3-14892. In addition to this, a fluorine-based liquid crystal used for a TFT liquid crystal element can also be preferably used.

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

By sandwiching the liquid crystal composition thus obtained between substrates having electrodes, at least one of which is transparent, a device applying the guest-host effect [Shoichi Matsumoto, Ryo Tsunoda “Latest Liquid Crystal Technology” "Industrial Research Council, 34 (198
3); L. Fergason, SID85Dige
st, 68 (1985)] and the like. The substrate is usually a glass plate or acrylic resin,
Various synthetic resin plates such as polycarbonate resin and epoxy resin are listed, and the electrode layer is formed on the substrate. As the transparent electrode layer, a layer made of a metal oxide such as indium oxide, indium tin oxide (ITO) or tin oxide is usually used. The surface of the transparent electrode layer which is in contact with the liquid crystal is subjected to an alignment treatment, if necessary. As the method of the alignment treatment, for example, a method of applying polyimide for parallel alignment, SiO
A method of vapor-depositing from an oblique angle to obtain parallel alignment is appropriately used.

Usually, the substrates are integrated with each other with a spacer or the like so that the surfaces of the alignment treatment layers face each other, and the substrate is 1 to 50 μm.
Preferably, a liquid crystal element is prepared by forming elements having an element interval of 1 to 15 μ and enclosing a liquid crystal in this element interval.

[0020]

The liquid crystal element such as a display element excellent in contrast and durability is obtained by the red dichroic dye having high dichroism and high coloring power of the present invention and the fluorine-based liquid crystal composition containing the same. Can be configured.

[0021]

EXAMPLES Next, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

Example 1 To 20 ml of dimethylformamide was added 30 mmol of P-nitrothiophenol, 50 mmol of sodium hydride was added with stirring, and the mixture was stirred at room temperature for 3 hours, and then 2- (perfluorobutyl) ethyl iodide 3 was added.
5 mmol was added, and the reaction was carried out by stirring overnight at room temperature under a nitrogen atmosphere. Then, the reaction mixture was discharged into 150 ml of water, the yellow precipitate was collected by filtration, and recrystallized from hexane to obtain the desired product having the following structure.

[0023]

[Chemical 4]

The physical properties of this compound are shown below. bp 136 ° C./1.0 mmHg; ¹ HNMR (CDCl ₃ ) δ2.50 (tt, J = 1)
6.5 and 8.2 Hz, 2H), 3.29 (tt, J
= 8.2 and 2.4 Hz, 2H), 7.38 (d, J
= 8.9 Hz, 2H), 8.18 (d, J = 8.9H)
z, 2H); EIMS (70 eV) m / z (rel intensi)
ty) 401 (M ⁺ , 100), 371 (18), 16
8 (25).

4 mmol of this compound was added to 10 ml of acetic acid, 75 ml of water containing 10 mmol of potassium permanganate was added with stirring at 40 ° C., and 15 minutes later, the reaction product was discharged into excess water containing sodium hydrosulfite to give a white mixture. The precipitate was collected by filtration and recrystallized from hexane to obtain the following target product.

[0026]

[Chemical 5]

The physical properties of this compound are shown below. mp121 to 123 ° C .; ¹ HNMR (CDCl ₃ ) δ2.06 (tt, J = 1)
7.1 and 8.2 Hz, 2H), 2.81 (tt, J
= 8.2 and 4.0 Hz, 2H), 7.59 (d, J
= 8.5 Hz, 2H), 7.90 (d, J = 8.5H
z, 2H); EIMS (70 eV) m / z (rel intensi)
ty) 433 (M ⁺ , 6), 186 (100), 122
(74), 77 (38).

2 mmol of this compound, 12 mmo of concentrated hydrochloric acid
1 ml was heated to reflux with 25 ml of methanol, and 12 mmol of iron powder was gradually added to this and stirred, and after confirming the disappearance of the raw material by thin layer chromatography, it was discharged into excess water containing caustic soda to precipitate the precipitate. Separated, then it was Soclat extracted with methanol. After concentrating this extract, column chromatography purification was performed using dichloromethane to obtain the following target product.

[0029]

[Chemical 6]

The physical properties of this compound are shown below. ¹ HNMR (CDCl ₃ ) δ2.56 (tt, J = 1
7.7 and 8.4 Hz, 2H), 3.27 (tt, J
= 8.4 and 3.7 Hz, 2H), 4.30 (br
s, 2H), 6.74 (d, J = 8.7Hz, 2H),
7.68 (d, J = 8.7 Hz, 2H); EIMS (70 eV) m / z (rel intensi)
ty) 403 (M ⁺ , 64), 156 (100), 10
8 (69), 92 (79), 65 (59). 0.5 ml of concentrated hydrochloric acid was added to 20 ml of an acetone-dimethylformamide mixed solution (mixing ratio 1: 1) containing 0.8 g (2 mmol) of this compound, and the mixture was cooled to 0 ° C. to contain 0.14 g (2 mmol) of sodium nitrite. 5 ml of an aqueous solution was added. After 15 minutes, the following compound was added to this mixed solution.

[0031]

[Chemical 7]

Aqueous solution 1 containing 0.42 g (2 mmol)
0 ml was added at 0 ° C., and the mixture was stirred at the same temperature for 1 hour for reaction, then the reaction mixture was discharged into excess water and the precipitate was collected by filtration. The obtained product was refluxed in an aqueous solution containing 4 g of sodium hydroxide for 6 hours, cooled, extracted with dichloromethane, and then purified by column chromatography using a 4: 1 mixture of dichloromethane: acetone to purify the product. 0.5 g (yield 50%) of a monoazo compound having a structure was obtained.

[0033]

[Chemical 8]

The physical properties of this compound are shown below. mp197-198 ° C .; ¹ HNMR (CDCl ₃ ) δ2.62 (tt, J = 1)
8.0 and 8.2 Hz, 2H), 3.37 (tt, J
= 8.2 and 4.8 Hz, 2H), 4.22 (br)
s, 2H), 6.76 (d, J = 8.8Hz, 2H),
7.86 (d, J = 8.8Hz, 2H), 8.02
(D, J = 3.0 Hz, 4 H); EIMS (70 eV) m / z (rel intensi)
ty) 507 (M ⁺ , 18), 120 (42), 92
(100); UV (EtOH) 424 nm (19800).

0.5 g of a monoazo compound having a perfluoroalkylalkylsulfonyl group represented by the above structural formula was added to acetone or dimethylformamide (DM).
F), a water mixture (acetone: DMF: water = 2: 0.5:
0.5) After dissolving in 25 ml of concentrated hydrochloric acid and 0.25 ml of concentrated hydrochloric acid,
After cooling to 0 ° C., an aqueous solution containing 0.07 g of sodium nitrite was added, and 15 minutes later, 5 ml of acetone containing 0.3 g of N, N-diethylaniline was added to this diazo solution at 0 ° C. with stirring. After reacting for 1 hour at temperature, the reaction product was discharged into excess water, the precipitate was collected by filtration and purified by column chromatography using dichloromethane to obtain a dye having the following structural formula.

[0036]

[Chemical 9]

The physical properties of this dye are shown below. λmax (EtOH): 505 nm ¹ HNMR (CDCl ₃ ) δ 1.26 (t, J = 7.0)
Hz, 6H), 2.64 (tt, J = 18.0 and
8.4 Hz, 2H), 3.39 (tt, J = 8.4an
d4.0 Hz, 2H, 3.49 (q, J = 7.0H
z, 4H), 6.75 (d, J = 9.2Hz, 2H),
7.91 (d, J = 9.2 Hz, 2H), 7.99
(D, J = 8.7 Hz, 2H), 8.10 (d, J =
8.7 Hz, 2H), 8.11 (s, 4H); EIMS (70 eV) m / z (rel intensi)
ty) 667 (M ⁺ , 23), 148 (100);

This azo dye is called as ZLI-1565 under the trade name.
A red guest-host type liquid crystal composition was prepared by dissolving it in a phenylcyclohexane liquid crystal mixture commercially available as (E, MERCK) at a concentration of 1 wt%. This was coated with a polyimide resin, cured, and rubbed to face a glass substrate with a transparent electrode, and the glass substrate was sealed in a cell having a gap of 9 μm configured so that liquid crystals were aligned in parallel.

The absorbance (A //) of linearly polarized light parallel to the orientation direction of this red-colored cell and the absorbance (A⊥) of linearly polarized light perpendicular to the orientation direction were measured, and the absorption peak (λmax: 512 nm) was measured. The order parameter (S) in

## EQU1 ## S = 0.76 was obtained as a result of obtaining from S = (A // − A⊥) / (A / ++ 2A⊥).

The trade name Z instead of the above ZLI-1565
Using a fluorine-based liquid crystal mixture commercially available as LI-4792 (manufactured by E. MERCK), the order parameter was determined in the same manner. As a result, S = 0.76 (λma)
x: 506 nm).

Example 2 Monoazo compound containing perfluoroalkylalkylsulfonyl group represented by the following structural formula

[0042]

[Chemical 10]

A dye having the following structural formula was obtained in the same manner as in Example 1.

[0044]

[Chemical 11]

The physical properties of this dye are shown below. λmax (EtOH): 491 nm ¹ HNMR (CDCl ₃ ) δ 1.26 (t, J = 7.0)
Hz, 6H), 2.64 (tt, J = 16.5 and
8.8 Hz, 2H), 3.39 (tt, J = 8.8an
d2.0 Hz, 2H), 3.49 (q, J = 7.0H
z, 4H), 6.75 (d, J = 8.8Hz, 2H),
7.78 (d, J = 8.8 Hz, 2H), 7.91
(D, J = 8.9 Hz, 2H), 7.99 (d, J =
8.9 Hz, 2H), 8.05-8.13 (m, 4
H); EIMS (70 eV) m / z (rel intensi)
ty) 767 (M ⁺ , 1), 148 (100);

A liquid crystal composition was prepared by dissolving this azo dye in a phenylcyclohexane liquid crystal mixture marketed under the trade name ZLI-1565 (manufactured by E. MERCK) in the same manner as in Example 1 to prepare a liquid crystal composition. Enclosed in. The order parameter (S) at the absorption peak (λmax: 506 nm) was 0.65.

Trade name Z instead of the above ZLI-1565
The order parameter (S) was determined in the same manner using a fluorine-based liquid crystal mixture commercially available as LI-4792 (manufactured by E. MERCK), and as a result, S = 0.65 (λ
max: 504 nm).

Example 3 Fluorine-based liquid crystal mixture of azo dye obtained by the method according to Examples 1 and 2 above: trade name ZLI-4792
Table 1 shows the order parameter (S) and hue in (E. MERCK).

[0049]

[Table 1]

[0050]

[Table 2]

Claims (3)

[Claims] 1. The following general formula [I]:(In the formula, R¹, R²Is an alkyl group, alkoxyalkyl
A group, a fluoroalkyl-substituted alkyl group, or a substituent
Represents an aralkyl group which may have, and R ¹And R
²May be linked to each other to form a nitrogen-containing aliphatic ring.
Rf is a perfluoroalkyl group having 1 to 12 carbon atoms or
Represents an ω-H-perfluoroalkyl group. Z¹~ Z⁹
Is a hydrogen atom, halogen atom, methyl group or
Represents a toxy group, Z¹And Z², Z^FourAnd Z^FiveOr Z⁷When
Z⁸Are linked to each other by an aliphatic ring, aromatic ring or nitrogen-containing
It may form part of an aromatic ring. m is 1 or 2, n
Indicates a number from 1 to 8. ) Perfluoroal
A disazo type containing a alkylalkylsulfonyl group, or
Trisazo type dichroic dye. 2. A liquid crystal composition comprising a liquid crystal compound and the disazo or trisazo dichroic dye having the perfluoroalkylalkylsulfonyl group according to claim 1. 3. A liquid crystal device having the liquid crystal composition according to claim 2 sandwiched between two substrates with electrodes, at least one of which is transparent.