KR950011236B1 - Liquid crystal material - Google Patents

Abstract

a relation expression as following drawing, wherein, R1 and R2 are alkyl of C1-18, Z represents single combination or O, and X1, X2 and X3 respectively represent four substitution positions of phenyl and hydrogen and 2 to 4 fluorines.

Description

Liquid crystal material

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to ferroelectric fluoro-terphenyls liquid crystal materials, and more particularly, to liquid crystal materials having enhanced smectic properties by introducing vinyl groups into molecules.

Recently, interest in fluorine-substituted biphenyls (-biphenyls) and / or terphenyls (-terphenyls) has been increasing. In particular, ferroelectric display devices have used S _C * based (chiral smectic C phase) liquid crystal materials. There is a great deal of research into their use as the main substance to provide.

Early research has shown that fluorine-substituted terphenyl-based materials have two advantages: That is, it lowers the melting point of the parent system to provide a more ordered Smetic phase, and is tilted such as S _C (Small C phase), S ₁ (Small I phase) and S _F (Small F phase). It provides a compound that tends to form a smetic phase.

However, they generally have high refractive index, weak positive dielectric anisotropy, and ordered smectic phases still exist as enantiomers or monotropic phases. This indicates that the above-described fluorine-substituted terphenyl-based materials need to be improved in their physical properties in order to be substantially employed as the S _C * mixture.

Following further studies, it has been found that o-difluoro substituents exhibit very improved physical properties. They exhibit excellent properties, especially in ferroelectric fields, among which they have a low dielectric anisotropy (negative value). This is explained by the fact that such an arrangement of fluorine atoms fixes the molecule to one side and provides a molecule that is not wider than a monocyclic ring.

An object of the present invention is to provide a novel liquid crystal material having improved liquid crystal properties in the o-difluoro substituted terphenyl-based liquid crystal material by introducing a vinyl group between the phenyl group and the alkyl group in the molecule.

In order to achieve the above object, the present invention provides a liquid crystal material represented by the following relationship (XIV).

Wherein R ¹ , R ² are alkyl groups of C _1-18 , Z represents a single bond or O, X ¹ , X ² and X ³ each represent four substitution positions for a phenyl group and hydrogen and 2-4 fluorine to be.

In particular, it is preferred that in the above formula Z is O and X ¹ , X ² and X ³ consist of hydrogen and two parallel fluorine (O-fluoro).

Hereinafter, an experimental method for preparing a liquid crystal material of the present invention is 4 "-heptyloxy-1- (1-octenyl) -2,3-difluoroterphenyl (XIII; 4" -heptyloxy-1- (1-octenyl) ) -2,3-difluoroterphenyl) will be described in detail by way of example.

[Step 1]

Dissolve 12 g (0.1 mole) of o-difluorobenzene (I) in 80 ml of THF at -78 ° C and nitrogen atmosphere, and 65.7 ml (n-BuLi) of 1.6 M in hexane. Mole) is added dropwise and stirred for 2 hours. Thereafter, 13.4 g (0.1 mol) of octyl aldehyde (II; octyl aldehyde) was dissolved in 50 ml of THF, and slowly added at -78 ° C. Then, the temperature was gradually raised to room temperature and stirred overnight.

The reaction is quenched with aqueous NH ₄ Cl solution, the organics are extracted twice with ether, washed three times with distilled water and dried over magnesium sulfate (MgSO ₄ ). The solvent is removed under reduced pressure followed by vacuum distillation (100-102 ° C./0.2 mmHg) to afford compound (III).

The chemical shift on the ¹ H-NMR spectrum of the obtained compound (III) is as follows.

δ (CDCl ₃ ); 0.9 ppm (t, 3H), 1.0-1.4 ppm (m, 10H), 1.6-1.8 ppm (m, 2H), 2.1 ppm (s, 1H), 5.0 ppm (t, 1H), 7.0-7.3 ppm (m , 3H)

[Step 2]

8 g (0.04 mol) of Compound (III) is dissolved in 50 ml of pentane, and then 17.1 g (0.12 mol) of phosphorus pentoxide (PO ₂ ) ₅ is slowly added thereto. After stirring at room temperature overnight, P ₂ O ₅ was filtered off and immediately vacuum distilled (72-75 ° C./0.5 mmHg) to afford unsaturated compound (IV).

The chemical shift on the ¹ H-NMR spectrum of the obtained compound (IV) is as follows.

δ (CDCl ₃ ); 0.9 ppm (t, 3H), 1.0-1.4 ppm (m, 8H), 2.2-2.4 ppm (q, 2H), 6.2-6.6 ppm (m, 2H), 7.0-7.3 ppm (m, 3H)

[Step 3]

4.9 g (0.027 mol) of Compound (IV) was dissolved in 40 ml of THF at -78 ° C under a nitrogen atmosphere. Then, 16.9 ml (0.027 mol) of 1.6 M n-BuLi dissolved therein was added and stirred for 2 hours. Dissolve 10.5 g (0.056 mol) of triisopropyl borate (V) in 25 ml of THF and slowly dropwise, raise the temperature of the reaction to room temperature and stir overnight. After hydrolyzing the reaction with 10% aqueous HCl solution, the organics were extracted with ether and recrystallized with pentane to obtain compound (VI).

The chemical shift on the ¹ H-NMR spectrum of the obtained compound (VI) is as follows.

δ (CDCl ₃ ); 0.9 ppm (t, 3H), 1.0-1.4 ppm (m, 8H), 2.2-2.4 ppm (q, 2H), 5.0 ppm (q, 2H), 6.5-6.7 ppm (m, 2H), 7.0-7.5 ppm (m, 2H)

A solution of 35 g (0.2 mol) of p-bromophenol and 60 g of K ₂ CO ₃ was dissolved in 300 ml of acetone, and 30 g (0.16 mol) of heptyl bromide was dissolved in 60 ml of acetone. It was added dropwise to reflux for 40 hours. The organics are extracted with ether and washed with 5% aqueous NaOH solution. After drying over MgSO ₄ , vacuum distillation (100-110 ° C./0.1 mmHg) gave the compound (iii).

[Step 5]

12.75 g (0.04 mol) of compound (iii) was dissolved in 80 ml of THF, and 31.3 ml (0.04 mol) of n-BuLi at 1.6M concentration under -78 ° C and nitrogen gas were added and stirred for 2 hours. 19.0 g (0.01 mol) of triisopropyl borate (V) is dripped gradually here. After stirring at room temperature overnight, hydrolysis was performed by adding 10% HCl, and then the organics were extracted with ether and recrystallized with pentane to obtain compound (VII).

[Step 6]

3.3 g (0.01 mol) of compound (iii) was dissolved in 15 ml of ethanol, and 3.4 g (0.01 mol) of 1-bromo-4-iodobenzene (XI) was added thereto, followed by tetrakistriphenylphosphine palladium (0). (tetrakistriphenylphosphine palladium (0); Pd (0) ｛P (C ₆ H ₅ ) ₃ ｝ ₄ ) 0.65 g (0.56 mmol) of catalyst was added dropwise to 30 ml of benzene. 30 ml of Na ₂ CO ₃ 2M aqueous solution is added and refluxed for 5 hours. Recrystallization with ethanol affords compound (XII).

The chemical shift on <^1> H-NMR spectrum with respect to obtained compound (XII) is as follows.

δ (CDCl ₃ ); 0,9ppm (t, 3H), 1.1-1.6ppm (m, 8H), 1.8-2.0ppm (s, 2H), 4.0-4.1ppm (t, 2H), 7.0-7.5ppm (m, 8H)

1.32 g (0.005 mol) of Compound (VI) and 1.34 g (0.004 mol) of (XII) were dissolved in 15 ml of ethanol, and tetrakistriphenyl phosphine palladium (0); Pd (0) 0P (C ₆ H ₅ ) ₃ ｝ ₄ ) 0.23 g (0.2 mmol) of the catalyst is dissolved in 10 ml of benzene and added dropwise thereto. 10 ml of Na ₂ CO ₃ 2M aqueous solution is added and refluxed for 20 hours. The starting material and catalyst were removed by column chromatography (silica gel, pet.ether: methylene chloride = 3: 1) and recrystallized from a solvent having a ethanol: ethyl acetate of 10: 1 to obtain a compound (XIII).

The chemical shift on <^1> H-NMR spectrum with respect to obtained compound (XIII) is as follows.

δ (CDCl ₃ ); 0.9 ppm (t, 6H), 1.0-1.4 ppm (m, 16H), 1.8-1.9 m (s, 2H), 2.2-2.4 ppm (q, 2H), 4.0 ppm (t, 2H), 6.4-6.8 ppm (m, 2H), 6.9-6.8 ppm (m, 2H), 6.9-7.8 ppm (m, 10H)

The phase transition of the vinylene-terphenyl liquid crystal compound (XIII) prepared according to the above process is as follows.

Where C is a solid state and I is an isotropic liquid state.

In other words, it can be seen that the smectic phase appears over a wide temperature range and the nematic phase does not appear. This phase change temperature is stronger than that of the liquid crystal material of a similar kind of simple alkyl chains, it can be seen that the phase transition temperature range is much wider.

The vinylene-terphenyl-based liquid crystal material of the present invention can be applied not only to the compounds exemplified in the present invention but also to all compounds prepared according to the same original and without departing from the scope of the claims.

Claims (3)

Liquid crystal substance represented by the following relational formula (XIV) Wherein R ¹ , R ² are alkyl groups of C _1-18 , Z represents a single bond or O, X ¹ , X ² and X ³ each represent four substitution positions for a phenyl group and hydrogen and 2-4 fluorine to be. The liquid crystal material according to claim 1, wherein Z in formula (XIV) is O, and X ¹ , X ² and X ³ are hydrogen and two parallel fluorine. The liquid crystal material of claim 1, wherein the liquid crystal material is represented by the following Formula (XIII).