DD265155A1 - NEMATIC LIQUID CRYSTALS WITH GLASS PHASES - Google Patents

Abstract

The invention relates to nematic liquid crystals with glass phases as solid, optically anisotropic media for the production of optical components, eg. As compensators, prisms, plates with optical rotation, polarizers and for thermo-electro-optical memory displays. According to the invention, novel, glass-phase-forming 1,4-bis- and 2,3,4-substituted benzoyloxybenzenes of the general formula I are present in mixtures with one another or with other liquid-crystalline or non-liquid-crystalline substances for the production of solid, optically anisotropic media optical components or thermo-electro-optical memory displays suitable. Formula I

Description

C (OH,), O (OH-)

R ¹ , R ² - -OC _n H _{2n + 1} , -O _n H _{2n + 1} , -OH, -O (CH ₁ ,).,, -NO ₂

R ³ , R ⁴ »R ⁵ , R ⁶ - -

, -01, -Br, -I, -H, -OH, -0 _k H _{2k + 1,} -01, -Br, -I, -H, -OH,

-000 (0Η ₂ ) _χ

" ⁰⁰ IH _{21 + 1} ,

-OH

, -ON, -NOg, -

with k, I, m, η, χ = 1 to 10, which are used in mixtures with each other or with other crystalline liquid or non-crystalline liquid substances.

Field of application of the invention

The invention relates to nematic liquid crystals with glass phases as solid, optically anisotropic media for the production of optical components, eg. As capacitors, prisms, plates with optical rotation, polarizers and for thermo-electro-optical memory displays.

Characteristic of the known technical solutions

Glassy liquid-crystalline phases have been known for some time (H.Kecker, R. Hatz, Handbook of Liquid Crystals, Verlag Chemie Weinhöim 1980, N.Kirov, MP Fontana, N.Afanassieva, Mol.Cryst.Llq.Cryst.89, 193 (1982). ).

In the substances that have been known for some time, the glass transition regions are at too low temperatures, which precludes a practical use of this phase behavior. So z. B. the (p-butyl-p'-methoxy) azoxybenzene (Grebovicz N., B. Wunderlich, Mol.Cry: t.Liq.Cryst.76, 287 [1981]) a glass transition range at about -66 ⁰ C.

It has been patented a class of compounds with liquid crystalline and non-liquid crystalline Homoligen having glass transition temperatures above or at room temperature (DD WP 242626). The substances all have glass transition temperatures which are below the melting temperatures, so that the glass state of the idine substances is in the thermodynamically metastable range. Therefore, many of these substances tend to crystallize once heated above the glass transition temperature. In order to prevent crystallization, suitable mixing partners are required

themselves form nematic glass phases.

Object of the invention

The aim of the invention are solid, anisotropic optical media for the production of optical components and for thermo-electro-optical memory displays with good mechanical stability, low temperature dependence of the optical properties and good phase stability at room temperature.

-2- 265165

Explanation of the essence of the invention

Object of the invention are suitable for the formation of glass phases nematic liquid crystals. In accordance with the invention, novel, glass-forming 1,4-biu [2,3,4-substituted benzoyloxybenzenes of the general formula

where X. "

"013) 3

(0H ₃ ) ₃

, r2. -OC _n H _{2n + 1} ,

, -ON, -C (CH ₃ ).,, -NO

, R

- ^OO m ^H 2m ₊ 1. -Van-H · ~ ^ö1 · ^. *. "*. -"

R ⁵ ,

-00 _k H _{2k + 1,}

-000 (CH ₀ ),

C Λ

, -01, -Br, -I, -H, -OH,

/ Γ

, -ON, «N0 _g , -0 (0H ₃ > ₃ , [; | l

-OH

'.' KV

rait k, 1, m, η, χ «1 are 10,

in mixtures with each other or with other liquid-crystalline or non-liquid-crystalline substances for the production of solid ,. optically anisotropic media for optical devices (capacitors, prisms, optical rotation plates, polarizers) or; Thermo-electro-optical memory displays suitable. <'

The substances mentioned can be oriented by the action of external fields so that use as optical Kompeneatoren and prisms, and after the addition of dichroic dyes as polarizers, is possible. In twisted orientation, optical rotation disks, as well as the use of appropriate cells, can be used to fabricate thermo-electro-optical memory displays.

The substances are colorless, can be produced in good purity and are chemically and thermally stable. They also result in non-crystalline liquid glass-forming substances in mixtures with other crystalline liquid or non-crystalline liquid or non-organic compounds.

glass-forming substances glassy solidifying nematic phases. The percentage of nematelchen glass-forming j; I

In any case, the mixture components must be higher than 60 mol%. Under these conditions, a lowering of the '' j melting points possible, the clearing points are sufficiently high, the Haltbarkelt the glass phase is significantly increased, and \ "the tendency to crystallize, both in the glass phase and when heating above the 'glass transitions range hlnau'i , ''

suppressed. .

Embodiment * ^: The invention will be explained in more detail with reference to the following examples and the data in the tables.

Example 1 'μ

0.01 mol of 2,3-sub 8-t-hydroquinone (X) in 20 ml of dry pyridine is added at room temperature to 0.02 mol with stirring. of ;' ,,,,, $

correspondingly substituted benzoylchlorides are added dropwise to 30 ml of dry yridine. One lets one day stand, warmed ^ WA

then one hour with stirring to about 70 ⁰ C and the reaction solution is poured after cooling in a mixture of '± ^: H

Ice and concentrated sulfuric acid. The precipitate is filtered off, washed with dilute sulfuric acid and Wastfer _v ,: | ^{; i} , W and stirred for one hour with 300 ml of a £% lgon NaHCO ₃ solution. After filtering off and washing several times with H ₂ O.

is recrystallized. _l4

All solvents are alcohol or alcohol / Dloxan-Gemlsche suitable. The acyllerton 2,3-8ubst. Hydrbchlnbrie fall in '' yields of 66 to 85% of theory. '

Example 2 It becomes a eutectic mixture of the substance given in Table 1

000

with the substance

prepared (hereinafter referred to as mixture I). The physico-chemical parameters of substance (b) are as follows:

Τα »Tf

(A)

= 35 ⁰ C = 188.1 ⁰ C = 32.2 kJ / mol.

The corresponding physical-chemical parameters of the mixture I are given in Table 2.

The result is a homogeneous mixture of red color with a melting temperature of 160 ° C without liquid crystalline phase. The glass age of the mixture is above room temperature. The glass phase thus obtained is stable for months.

Table 1: Thermodynamic data of selected compounds according to formula I.

-OC

fr -H -H -fV

51 215.0 241.6

-OC ₂ H ₅ -OC ₂ H ₅

-Br -H

-OC ₂ H ₅ -OC ₂ H ₅ -H -H

-OC ₃ H ₇ -OC ₃ H ₇

-H -H

.OCH ₃ -OCH ₃ -H -H

59 195.0

23 160.6 172.8

42 172.2 21 7.0

27,19.5 111.8

(CH).!

-OC ₂ H ₅ -OC ₂ H ₅ -H -H

₂ H ₅ -OC ₂ H ₅ -Br -:

C (CH) ₃

(CH),

22 143.0 137.6

55 218.0

4-665165

Toi ,, ... lower limit of the glass transition interval Tf ... melting point of the most stable crystal modification

T _c i ... transformation temperature nematic-isotropic

Table 2: Physico-chemical data of the mixture I

pure components component α r-H / kJ mo! ~ '

mixture

Tci / ° C

41.7 32.2

0.33 0.67

32

160.0

A _F H ... enthalpy of fusion of the most stable crystal modification p. · · · Component oil break In the mixture

Example 3

It is a eutectic mixture of the substances in the Toblle 1 angegobenen

(A)

(O

prepared (hereinafter referred to as mixture II).

Table 3: Physico-chemical data of the mixture Il

pure components mixture

Component ifH / kJmol " ¹ Xcomp. Toi _a , /" C

41.7 39.1

0.21 0.79

32

176.6

The result is counter in contrast to Example 2, a colorless, homogeneous mixture having a melt temperature of 128 "C and a class" ¹ temperature of 176.6 ⁰ C.

The GInst imperatur of the mixture is above room temperature. The mixture may be oriented in a molten state by wallwilds, electric and magnetic fields, and then frozen in the glassy state by rapid cooling to temperatures around ⁰ ° C. The orientation is maintained by heating to temperatures above the melting point The orientation obtained is stable for several months.

Example 4

A series of mixtures of different concentrations is prepared from the two following substances listed in Table 1:

(D)

(Θ)

br

(hereinafter referred to as mixtures IHA, IHB, IHC and IHD).

The physico-chemical parameters of the mixtures are given in Table 4.

-5- 265165

Table 4: Physico-chemical parameters of the mixtures III A-IIID

No. of Mixture x (d) T _O | "/ ° CT _F / ° CT _C , / ^U C

INA HIB HIC HID x (d) ... mole fraction of component (d)

This results in colorless, homogeneous mixtures with a nematic phase, although a mixture partner of these binary mixtures is not a precursor of liquid-crystalline properties. The glass transition temperatures of the mixtures are at or below the room temperature and can be varied by varying the mixture composition and / or the glass transition temperatures of the two mixing parameters. The characteristics for the practical use of these mixtures are the same as those given in Example 3.

0.19 25.0 139.0 133.0 0.40 36.0 130.0 122.5 0.60 43.0 173.0 108.0 0.80 50.0 192.0 92.0

Claims (1)

Claim: Nematic liquid crystals with glass phases as anisotropic media for the production of solid, optically anisotropic media for optical components and for thermo-electro-optical information storage, characterized by new, crystalline liquid 1,4-bis [2,3,4-substituted benzoyloxy] benzene of general formula (D