JPS6130559A - Fluorine-containing chiral liquid crystal compound - Google Patents

Abstract

NEW MATERIAL:The compound of formula I (R is 1-12C straight-chain alkyl; *is the center of optical activity). EXAMPLE:(+)-4-( 2'-Methylbutyloxy )-3-fluorophenyl-4-pentylbiphenyl-4'-carboxylate. USE:Useful for a ferroelectric smectic liquid crystal display element or electrooptical element. It is mixed with other dielectric smectic liquid crystal or smectic liquid crystal at a ratio to develop chiral smectic C phase within a specific temperature range, and used as a ferroelectric smectic liquid crystal composition. PREPARATION:The compound of formula I can be prepared by treating the 4-n- alkylbiphenyl-4'-carboxylic acid of formula III with a chlorination agent such as thionyl chloride, and reacting the resultant acid chloride of formula IV with the compound of formula V in the presence of a basic substance such as pyridine.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a fluorine-containing chiral liquid crystal compound used in display elements or electro-optical elements.

[Prior Art] Conventionally, liquid crystal display elements using nematic liquid crystals, which are used in the display parts of clock calculators, etc., have a response speed that is extremely slower than that of other display elements, such as light emitting diodes. Applications to fields that require responsiveness, such as optical communications, printer heads, and liquid crystal display elements, have been limited.

Recently, liquid crystal display elements using smectic liquid crystals exhibiting ferroelectricity have been reported as liquid crystal display elements exhibiting high-speed response (for example, N, M, etc.).

Quark, 8. T. Lagervall
, Mpp1. Phya, Lett.

36, 899 (1980)) is attracting attention.

Smectic liquid crystals exhibiting ferroelectricity include chiral smectic C phase and chiral smectic H phase.
These exhibit a layered structure, with liquid crystal molecules tilted rather than perpendicular to the stacking direction of the layers. This direction of inclination is
The liquid crystal molecules are arranged in a spiral fashion in the stacking direction of the layers, and spontaneous polarization occurs in a direction parallel to this layer and perpendicular to the liquid crystal molecules, exhibiting ferroelectricity. The helical structure of the core is thought to be the reason for the ferroelectric property. A material exhibiting ferroelectricity exhibits responsiveness to an electric field as a ferroelectric substance, and reverses the direction of spontaneous polarization and rearranges itself according to the direction of the electric field.

At this time, it is known that the response is larger in spontaneous polarization and the lower the viscosity, the faster the response for the same electric field strength.

[Problem to be solved by the invention]

Conventionally, as ferroelectric liquid crystals, many studies have been conducted on Shipp base type compounds such as those shown below.

p-1 siloxicpenzylidene-p'-amino-2-methylbutyl-cinnamic acid ester (DOBAMBO) However, since such ship base type compounds are easily hydrolyzed, they have the problem of being easily decomposed by moisture.

Further, as an ester compound exhibiting chiral smectic C@, a compound represented by the general formula (II) below was also known.

(G, W, Gray etc. mob, 0ryet, L
iq, Cryst, 1976.

(R is a linear alkyl group having 5 to 10 carbon atoms) However, although this ester compound is resistant to moisture, it has a problem of slow response.

[Means to solve the problem]

The purpose of the present invention is to solve the above problems and provide a stable and fast-responsive ferroelectric smectic liquid crystal composition. An object of the present invention is to provide a fluorine-containing chiral liquid crystal compound used for the composition.

The fluorine-containing chiral liquid crystal compound of the present invention has the general formula (1)
It is a compound represented by, and its general name is (t)-4-(
'2'-Methylbutyloxy)-3-fluorophenyl-4-n-alkylbiphenyl-4'-carboxylic acid ester.

(P represents a linear alkyl group having 1 to 12 carbon atoms, and the buttock represents an optically active center.) The optically active group of the compound (1) of the present invention is a 2-methylbutyl group (→2-methylbutyl or (3)2-methylbutyl group, but (3)2-methylbutyl group, which is synthetically simple, is more preferable.

The number of carbon atoms in the linear alkyl group is preferably from 1 to 12 [5, but more preferably from 2 to 8] since the melting point will be high if it is too small, and the viscosity will be high if it is too large.

In order to use the compound represented by the general formula (I) in a ferroelectric smectic liquid crystal display front X-ray electro-optic device, it must be combined with other ferroelectric compounds so that it has a chiral smectic C phase in a desired temperature range. It is used as a ferroelectric smectic liquid crystal composition by appropriately mixing it with smectic liquid crystal or smectic liquid crystal, and further adding nematic liquid crystal, non-liquid crystal, dichroic dye, etc. in order to adjust the helical pitch and perform color display. It's okay. The content of the compound represented by general formula (1) in the ferroelectric smectic liquid crystal composition of the present invention is 1% by weight or more and 99% by weight or less, preferably t-
! It is preferable that the weight ratio is 5% by weight or more and 90% by weight or less.

Compounds that can be mixed with the compound of general formula (1) of the present invention and used as a ferroelectric liquid crystal include, for example, the following compounds.

(Here, tatami indicates an optically active point, and R1 and u# each indicate a linear or branched alkyl group having 1 to 12 carbon atoms.) Dichroic dyes include so-called guest host dyes such as trisazo dyes and anthraquinone dyes. Examples include dyes used in type liquid crystal display elements.

A ferroelectric liquid crystal display element or an electro-optical element comprises a plurality of substrates, at least one of which is transparent, which is arranged to sandwich a liquid crystal layer and which has electrodes on all or part of the substrate, and a substrate that surrounds the liquid crystal layer. In the liquid crystal display element, the thickness between the substrates is α
5μ to 20μ is preferred. Further, each of the substrates may be subjected to alignment control processing in a parallel direction. As a means for controlling this alignment, an alignment control film may be applied to a part or the entire surface of the electrode substrate.

As the alignment control film, a polymer material such as polyimide having a refractive index of 1.5 or more is preferable. Furthermore, it is preferable that at least one polarizer is provided with a liquid crystal element trap. At least two electrode substrates are required, but more electrode substrates may be stacked and used.

The compound of the present invention can be synthesized, for example, by the route shown below.

(In the formula, R represents a linear alkyl group having 1 to 12 carbon atoms,
Tatami indicates an optically active center. ) Ab 4-n-alkylbiphenyl-4'-carboxylic acid @) is reacted with a chlorinating agent such as thionyl chloride or phosphorus oxychloride to form an acid chloride QV), and then (t)-4-(
2'-Methylbutyloxy)-6 fluorophenol is trapped in the presence of a basic substance such as pyridine, and then subjected to a series of purification treatments such as extraction, recrystallization, and column chromatography to obtain pure (1) 1. can be synthesized into

Next, the present invention will be specifically explained using examples.

〔Example〕

Example 1 2. Of (7.5 mmol) and 5-thionyl chloride were mixed in 20-carbon tetrachloride, heated and stirred at reflux temperature for 8 hours, and then the solvent and unreacted thionyl chloride were distilled off using an evaporator. . To the remaining yellow oily substance, 5- toluene was added and dissolved, and 1.5-
A solution of t (75 mmol) dissolved in toluene 5- was added dropwise, pyridine 1- was further added, and the mixture was stirred at room temperature for 3 hours. The mixture was poured into water, extracted with toluene, dried over anhydrous magnesium sulfate, and then the solvent was distilled off using an evaporator. The remaining crude product was recrystallized from ethanol 50, subjected to alumina column chromatography using toluene as a developing solvent, and further recrystallized from ethanol 20 to obtain the desired (+)-4-(2' 1.4 g (52 mmol) of -methylbutyloxy)-3-fluorophenyl-4-n-pentylbiphenyl-4'-carboxylic acid ester were obtained. (Yield: 42) Observation using a polarizing microscope equipped with a hot stage revealed that this compound transitioned from a crystalline phase to a smectic phase at 92.5°C and to an isotropic liquid phase at 1655°C.

Specific optical rotation [α] of this compound in chloroform solution
It was Amaseke 5346.

The R spectrum of this compound is shown in FIG.

The 1i17 and IH NMR spectra of this compound were as follows.

1'F NMR (0DO1, solvent OFO: L, internal standard) Φ' 13 L Oppm (multiplet
') IH loss dR (CD (31, solvent, TM8 internal standard) δα8~2..OComplex m, 18H62
, 55t, J-6H22H δ580 憇X pattern JA) 3-14
Hz JAX-JBz -6Hsg 2H δ 45-43 Complex m 11B00
Compound 2.1 f (7.5 mmol) denoted by 0H
By performing the same operations as in Example 1 using ! l
y(t)-4-(2'-methylbutyloxy)-3-fluorophenyl 4-n-hexylbiphenyl-4'-carvone jp 1.8? (&\9 mmol) was obtained.

Observation of the 52-chi hot-staged product under a polarizing microscope revealed that this compound transitioned from a crystalline to a smectic A phase at 565°C and to an isotropic liquid phase at 16 [L1°C.

The IR spectrum of this compound is shown in FIG.

The 11'F and IH NMR spectrum lines of this compound were below.

"F NMR (CDCl, solvent, CFCl, internal standard)
Φ" 1311 ppm "HNMR (CDCl, solvent, TMS internal standard) δ α
8-2. Ocomplex m 20H62,5
5tJ-6Hg 2HδA80 ABX
pattern JAB -14Hz, ,TA
X-JB! -6Hz 2H δ &5-a3 complex Examples 3 to 7 Using the carboxylic acids shown below in place of the compounds shown below, the same treatment was performed below.Fluorine-containing chiral liquid crystal compounds shown in Table 1 I got it.

Example 8 The compound of Example 2 was converted into n-hexyloxy722n-
The mixture was mixed with octyloxybenzoic acid at a concentration of 20 vt% (hereinafter referred to as mixture A), and its responsiveness as a ferroelectric smectic liquid crystal was completely measured. On the other hand, as a comparative example, a compound ((+)-n-hexyloxyphenyl-4-(2
'-Methylbutyl)biphenyl-4'-carboxylic acid ester) was also measured.

The mixture exhibited a chiral smectic C phase even at room temperature in a supercooled state, transformed to a smectic human phase at 6a5°C, transformed to a cholesteric phase at 89.6°C, and further transformed to a niote isotropic liquid phase at 9a5°C.

Mixture A and the comparative example compound were sealed in a cell with a 3 μm spacer sandwiched between two glass substrates treated with a polyimide overcoat, and the response was measured by applying a DC voltage at 60°C. The result is the second
Shown in the table.

〔Effect of the invention〕

As can be seen from Example 8, the compound of the present invention is an extremely useful compound for constructing a ferroelectric chiral smectic composition that operates even at room temperature, is stable, and has high-speed response.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 are R spectra of the compounds of Example 1 and Example 2 of the present invention.

Claims (1)

[Claims] (1) Fluorine-containing chiral liquid crystal compound represented by the general formula (I) ▲ Numerical formulas, chemical formulas, tables, etc. are available ▼ (I) (Here, R is a linear alkyl group having 1 to 12 carbon atoms, or *
indicates an optically active center)