DD262032A1 - CRYSTALLINE-LIQUID SUBSTANCES - Google Patents

Abstract

The aim of the invention are modified crystalline liquid mixtures which can be used in optoelectronic arrangements at low operating voltages. According to the invention, new crystalline liquid 5-subst.-2- (4-subst.-benzoylmethylene) -1,3-dithiane of the general formula in mixtures with one another and in mixtures with other crystalline-liquid or non-kirstallin-liquid substances in optoelectronic components used. formula

Description

= -C _n H _2n ,,, - (O> - ^S -. Λ ^H> - ^R

R - "C _n H _{2n +} 1, -OC _n H _{2n +} 1, R = C _n H _{2n + 1}

n = 1 to 14 mean

be used in mixtures with each other and in mixtures with other crystalline liquid or non-crystalline substances.

Field of application of the invention

The invention relates to novel crystalline liquid substances for use in optoelectronic components for modulation of the incident or transmitted light as well as for the representation of numerals, characters and images. The optoelectronic components using liquid crystals are z. B. used as displays in electronic watches, computers and devices with digital displays.

Characteristic of the known state of the art

There are already well over 12000 crystalline-liquid compounds.

[D. Demus, H. Demus, H. Zaschke: Liquid Crystals in Tables, Leipzig 1974; D. Demus, H. Zaschke: Liquid Crystals in Tables II, Leipzig 1984],

some of which are also suitable for use in optoelectronic displays. However, there is no pure connection, which even approximately corresponds to the properties required for displays. Therefore, mixtures of several, often 10 to 15 different and very different substance classes belonging substances are always used for applications

[B.Bahadur, Mol. Crystal. Liq. Cryst. 89, 345 (1983)]

Depending on the intended use, the displays must have different properties, which necessitates changes in the requirements for melting and clarifying temperature, threshold voltage, turn-on and turn-off times, optical anisotropy, dielectric anisotropy, elastic constants and other properties.

In order to be able to adapt the mixtures to such requirements, there is a constant search for new substances which specifically influence the required properties of mixtures.

Object of the invention

The aim of the invention are modified crystalline liquid mixtures which can be used in optoelectronic components at low operating voltages.

Explanation of the essence of the invention

The object of the invention are novel crystalline liquid substances for lowering the threshold voltage and modifying the properties of mixtures intended for use in optoelectronic displays.

According to the invention, new crystalline liquid 5-Subst.-2- {4-subst.-benzoylmethylene) -1,3-dithiane of the general formula

where R ¹ = -C _n H _{2n + 11} -OC _n H _{2n + 17} -SC _n H _{2n +} OO-C _n H _{2n + 1} ,

-CN, -halogen,

R ² =

-C _n H _{2n + 1} , - / Q \ -R

R - "C _n H _2n -H ₁ -OC _n H _{2n +}

R = -C _n H _{2n +}

n = Ibis

mean, used in mixtures with each other and in IVlischungen with other crystalline-liquid or non-crystalline liquid substances in optoelectronic devices.

The substances according to the invention are colorless, stable and have low threshold voltages in the presence of polar groups. They are very easy to mix with other crystalline-liquid substances.

The invention will be elucidated in four examples.

embodiments example 1

Table 1 below shows the transformation temperatures of substances according to the invention.

Where:

K = crystalline solid state Sa = smectic A phase N = nematic is = isotropic liquid The numbers between the phase designations mean the transformation temperatures in ⁰ C.

Table 1 R ^ R P> "'s. _y- ^C n ^H 2n + 1 NC -C-CH = / NC η O ^S " Sa N C ₆ H ₁₃ - 4 K - - (96.5) No. CsH ₁₁ - 8th , 121.5 , 96 1.1 C ₆ H ₁₃ - 4 68 - _ - - 1.2 CsH ₁₁ - 8th 64.5 , 81 3.1 C ₆ H ₁₃ - 8th 73.5 , 84.5 1.4 4 65 1.5 5 63 - - - - 1.6 67 1.7

IS

Example 2

The following physical properties were measured on two substances according to the invention.

Table 2 Δ _F H Δε Π substance kJ / mol (66 ⁰ C) cP 24.2 - - 1.1 42.6 '' 14.3 50 (68 ⁰ C) 1.2 1876 (extrapolated to 25 ⁰ C) = Enthalpy of fusion Δ _Ρ Η = theische.Anisotropie Δε = Viscosity η

Example 3

The addition of substances according to the invention alters the properties of mixtures. This will be shown using the example of the following basic mixture Mi 24.

Composition of Mi 24: "mol%

4-n-butylcyclohexanecarboxylic acid - (4-ethoxyphenyl ester) 13.3

4-n-butylcyclohexanecarboxylic acid - (4-n-hexyloxy-ester) 21,7

4-n-Propylcyclohexanecarboxylic acid (4-cyanoester) 22,4

4-n-butylcyclohexanecarboxylic acid (4-cyanoester) 20.2

4-n-pentylcyclohexanecarboxylic acid (4-cyanoester) 22,4

Table 3

Mi24 No. 1/2 Klärp. U ₀ τ | ° τ _Α ⁵⁰ η ₂₀

mol% mol% CV ⁰ ms ms cP

100 - 68 2,14 39 64

90 10 71 1.11 49 86

Where:

U ₀ '= threshold voltage at 25 ^o C ^and AC 500Hz

"τΐ ⁰ = switch-on time at 50% intensity change

"Ca ⁰ = cooldown at 50% intensity change

η ₂₀ = viscosity at 20 ° C

The measurement of the electro-optical properties took place in a twisted layer (cell of the Schadt-Helfrich type).

Example 4

The synthesis of the substances according to the invention is described using the example of 5-octyl-2- (4-cyano-benzoylmethylene) 1,3-dithiane:

0.02 mol (2.9 g) of 4-cyanacetophenone are dissolved in 50 ml of anhydrous DMSO and admixed with 0.02 mol (1.8 g) of CS ₂ under ice-cooling and nitrogen as protective gas. To this mixture adds 0.04 mol (1.04 g) NaH in portions and then stirred for 5 hours at room temperature. Thereafter, with stirring and ice cooling, 0.02 mol (6.3 g) of 2-octyl-1,3-dibromopropane is slowly added dropwise, stirred for 24 hours at room temperature (to complete the reaction) and finally the reaction mixture poured into ice water. The precipitated crystals are filtered off, dried in air and then recrystallized from methanol.

Yield: about 25% of theory

Claims (1)

Crystalline liquid substances for optoelectronic components, characterized in that new 5-subst.-2- (4-subst.-benzoylmethylene) -1,3-dithiane of the general formula ₍ C-CH = /> -C ^H 2n + 1 where R ¹ = -C _n H _{2n +} , - OC _n H _{2n +} ,, - SC _n H _2n .
0OC-C _n H _{2n +} !, - CN, -halogen,