DD261802A1 - FERROELECTRIC FLUID CRYSTALS - Google Patents

Abstract

The invention relates to ferroelectric liquid crystals for optoelectronic devices that switch quickly, have memory properties and behave stably over time. According to the invention, new ferroelectric crystalline 2,5-disubstituted thiadiazoles of the general formula are used in mixtures with one another and with other crystalline-liquid or non-crystalline liquids. formula

Description

R = C _n H _2n + 1, -OC _n _ 1 H _2n -1

with η = 2 to 16 a, b = 0.1 c = O to 6 A = R ² -E-

R 2 / -> LJ f-lp I! QP LJ

- ^ _m rl2m + 1 / ^u "m ⁿ 2m + 1 / ~ ^ol Tti ⁿ 2m + 1

m = 1 to 16

d, e, f = 0.1

d + e + f = 0,1,2

X, Y = H, Cl, F, Br, CH _3, CN.

If b = 0, then E can be added

with Z = -00 C, -COO-, -

) -, -OCH ₀ -, -SC-, -CS OO

- ^sei0 »

with g = 1, 2, where g can also be 0 if a and b = 0 with U = -COO-, -OOC-, -CH ₂ O-, -OCH ₂ -

wherein the total number of ring systems is 2 to 4, used in mixtures with each other and with other crystalline liquid or non-crystalline liquid substances.

Field of application of the invention

The invention relates to crystalline liquid ferroelectric substances for use in optoelectronic components for modulation of the incident or transmitted light, for the representation of numbers, characters and images as well as for the storage of information. Optoelectronic components of this type can, for. B. can be used as displays in electronic clocks, computers and devices and in TV terminals.

Characteristic of the known technical solutions

It has already been proposed to use ferroelectric liquid crystals for producing fast switching displays with memory properties (N.A. Clark, S. T. Lagerwall, Appl. Phys. Lett., 36, 988 [1980]).

In recent years, a larger number of ferroelectric liquid crystals have been produced, but there are still no substances with even approximately optimal properties (ST Lagerwall, J.Wahl, NAClark, Proceed SID Symposium October 1985 San Diego, USA, JW Goodby, Science 231, 350 [1986]; F. Dahl, ST Lagerwall, Ferroelectrics 58, 215 [1984]; D. Demus, H. Zaschke, Liquid Crystals in Tables II, Leipzig 1984).

Various ferroelectric liquid crystals are thermally and chemically unstable, others are too high

Melting temperatures or only a small polarization, some are difficult to orient on the substrates. -

Therefore, new ferroelectric liquid crystals are constantly being searched for in order to have enough components available for the preparation of suitable mixtures.

Object of the invention "

The aim of the invention are optoelectronic components that switch quickly, have memory properties and behave stably for a long time.

Explanation of the essence of the invention

The object of the invention are ferroelectric crystalline liquid substances with smectic C phases and favorable properties in terms of melting and clearing temperatures, width of the smectic C range, stability to thermal stress and electric fields, especially against racemization. Erfindun.gsgemäß are new ferroelectric crystalline liquid 2,5-disubstituted thiadiazoles of the general formula

". -, τ r \ CH-,

R = C _{n n} H 2n + 1, OC H2 _ ι _n _ 1

with η = 2 to 16 a, b = 0.1 c = 0 to 6

A = R ² -E- '

R = C _m H2m + I / "OCmH ₂ Ri ₊ i, -SC _m H2

m = 1 to 16

E =

d + e + f = 0,1,2

X, Y = H, Cl, F, Br, CH ₃ , CN,

if b = 0, E may be additional

with Z = -O-C, -COO-, -CH ₂ O-, -OCH ₂ -, -SC-, -CS-,

B =

with g = 1.2, where g can also be 0 if a and b = 0,

and U = -COO-, -O-C-Y-CH ₂ O-, -OCH ₂ -,

wherein the total number of ring systems is 2 to 4 in mixtures with each other and with other crystalline liquid or non-crystalline substances suitable for use in fast switching optoelectronic devices with memory properties.

The 2,5-disubstituted thiadiazoles according to the invention have broad chiral S _c -existence regions with low melting temperatures and in particular high clearing temperatures.

The new substances are stable against heat, irradiation with visible and ultraviolet light and electrical DC and alternating fields. In contrast to the previously known derivatives of 2,5-disubstituted thiadiazole (liquid crystals in Tables II, pp.359-361) they have broad smectic C * phase regions.

The substances can be used particularly advantageously in mixtures with one another and with other ferroelectric crystalline liquid substances, for the induction of ferroelectric properties in non-chiral compounds with smectic mesophases and for the induction of smectic C phases.

The substances are accessible according to known regulations by reaction of carboxylic acid hydrazides with carbonyl chlorides, in particular chiral 4-alkyloxy-benzoylchloriden or achiral 4-acyloxy-benzoylchloriden, and subsequent sulfurization with P4S10 in organic "solvents, especially in pyridine, or in the absence thereof :

-R-C-NH-NH

Cl-C-R '

1)

pyridine

2 λ,

The reaction of achiral 4-acyloxy-benzoyl chlorides with carboxylic hydrazides leads to achiral 2-substituted-4- (4-AcyxloxyphenyO-thiadiazoles, according to the following reaction scheme first saponified to the corresponding phenols and then again with chiral carboxylic acids directly or via their acid chloride be esterified.

-OCR '

¹ ^ KOH

<3Η, 0Η / Η. 2) η ³ Θ '

-OH

1)

Cl

H-B

Vr *

The chiral carboxylic acids are z. B.

By oxidation of chiral alcohols (such as (S) isoamyl alcohol)

By asymmetric synthesis, e.g. Example by means of chiral oxazolones or chiral imides

By etherification of 4-hydroxybenzoic acid with chiral alkyl halides or tosylates

- By esterification of 4-hydroxybenzaldehyde with chiral carboxylic acids and subsequent oxidation or by "direct esterification of 4-hydroxybenzoic acid

- prepared by alkylation of chiral (! -Hydroxycarboxylic acids (e.g., lactic acid) and derivatives thereof.

embodiment example 1

(S) -2- (4-n-octyloxyphenyl) -5- [4- (2-methylbutanoyloxy) phenyl] thiadiazol

A solution of 2,64g (0,01 mol) 4-n-octyloxybenzoic acid hydrazide in 30 ml absolute pyridine was stirred at 0-5 ⁰ C under stirring with 2.4 g (0.01 mol) of (S) -4- (2 -Methylbutanoyl-oxy) benzoic acid chloride added dropwise. Thereafter, the reaction mixture is stirred at O ⁰ C, 45min at 20 ° C and 3 h at 8O ⁰ C 45min.

After cooling to room temperature, 3g P ₄ Si ₀ added, and after the exothermic reaction was for 1 hour at 80 ° C and stirred at 100 ⁰ C for 12 h.

After cooling to room temperature _t was added 10 ml of ethanol and the reaction mixture into 200 ml of ice water

cast. ,

The solution was neutralized with aqueous NaOH and the reaction product was filtered off, washed with H ₂ O and recrystallized from ethanol.

Yield: 2.8 g = 60% of theory

In accordance with this provision, further compounds were synthesized (see Table 1, 3).

Example 2

(S) -2- (2-Methylpropyl) -5- (4-n-octyloxyphenyl) thiadiazole (Comp. 1/2)

In accordance with the procedure of Example 1, 2.64 g (0.01 mol) of 4-n-octyloxybenzoic acid hydrazide were reacted with 1.20 g (0.01 mol) of (S) -2-methylbutyl chloride

 Yield: 2.7 g 74% of theory.

= 0.0074 mol

Example 3

2- (4-n-Pentyloxyphenyl) -5- (4-hydroxyphenyl) thiadiazole 4.0 g (0.01 mol) of 2- (4-n-pentyloxyphenyl) -5- (4-acetoxy-phenyl) thiadiazole were dissolved in 40 ml Suspended methanol and treated with a solution of 2.0 g KOH in 90 ml of methanol. The mixture was refluxed for 2 hours.

The solvent was then distilled off on a rotary evaporator and the residue was dissolved in 50 ml of H ₂ O. The solution was acidified with 5% HCl, and the resulting precipitate was filtered off with suction and recrystallized from ethanol.

Yield: 3.2 g 94% of theory.

According to this regulation, the following compounds were synthesized:

Mp / ° C /

-OH

194

193

7 ^a i5 <

100-101

152-153

Example 4

(S) -2- [4- (2-Hexyloxypropanoyloxy) -phenyl] -5- (4-n-pentyloxyphenyl) thiadiazole 0.36 g (1 mmol) of 2- (4-n-pentyloxyphenyl) -5- (4 hydroxyphenyl) -thiadiazol; 2.6 g (1.5 mmol) of (S) -xyxypropanoic acid, 0.4 g (1.3 mmol) of EDC.methiodide and 10 mg of DMAP are suspended in 5 ml of CH ₂ Cl ₂ and stirred at room temperature for 20 h. The resulting solution is diluted with 100 mL CH ₂ Cl _2, washed twice with 100 ml H ₂ O and once with 100 ml 5% NaHCO ₃ solution, the solvent distilled off on a rotary evaporator and the residue recrystallized from ethanol.

Yield: 0.35 g = 70% of theory.

In accordance with this provision, further compounds were synthesized (see Table 1, 2, 3).

Table 1:

Vr

No. R

1.1

CH.

1/2 C ₈ H ₁₇ O-

"9 ^Λ 19

-CH-C ₂ H ₅ CH "

1/3 C ₂ H ₅ -CH-COO-CH ₃

is

52 (.19) *

53.5 -

1.4

CH ₃

55 -

1/5 C ₆ H ₁₃ O-CH-COO- O-C ₂ ^H 5 ^{β 75 (} * ⁶¹⁾ *

CH ₃

K = crystalline-solid

S _A , Sc = smectic A ^ C phase

CH = cholesteric phase

is = isotropic-liquid

Table 2:

° ^H 2n + 1

.-00C

-00C-CH-C CH3

2.1

η 7

S _n p. CH

ο 115 - -.

2.2

Table 3:

* 2

-OOC-CH-R ^ ι

CH "

.R

CH

3/2 C ₁₀ H ₂₁ - -OCH ₃

1Ο ^Η 21 "

3/4 C ₅ H ₁₁ O-3/5 C ₅ H ₁₁ O-

5 / D ν Γ-Ι1 j ^ U · * 3/7 C ₅ H ₁₁ O-

3.8

3 / 1.0 3/11

OCH.

-OC _{1 (}

OCH,

»108 .139 , 5 .139,5. »110 .121 , 5 .155 οΐ6ΐ ο163 _ο 96 .155 , 5 .165 93 ο138 ο 92 .133 - · - · _o , 89 .163 mm mm _a , 85 .143 mm m * _# "80 .134 ο101 ο163 .166 ο 78 ο 144

3/12 C ₉ H ₁₉ O- OC ₆ H ₁₃

Example 5

By mixing several substances according to the invention, the melting points of the ferroelectric crystalline liquid material are lowered and the area of existence substantially expanded. This is shown by the following two mixtures: Mi 1

, 3.9

No ₀ 3/10

Mi 2 No. 3/9

ο 3/5

-O-O-CH-CH ^OG 6 ^H 13

'-00G-GH-CH ₃ °° 10 ^H 21

K 60 - 65 S ₀ * 133-134 Is

.-DOC-CH-CH-

^OG 6 ^H 13

-OOG-GH-GH, OCH "

50 mol% 50 mol%

50 mol%

50 mol%

K 7OS ₀ Jf 146-47 .N * 156-57 Is

These two mixtures can be used in optoelectronic displays.

Example 6

The properties of the substances according to the invention are substantially modified by mixing with other substances, preferably those which themselves have ferroelectric smectic C * phases or nonchiral C phases. This should prove the following three mixtures:

* ^ CH ₀

COO

CO

Cl

-OOC-CH-GH

Cl

3 _r / ^CH 3

CH.

.-00G-CH-CH. \

^OC 6 ^H ₁₃ K 37 S ₀ * 60 S _A 84 N * 90 Is

mol%

35

37.5

27.5

COO

COO ^

-00C-CH-CH

Cl

OOC-ch-ch:

Cl ^GH 3

Mole% 45

35

ITr. 3.9

-OOC-CK-CH,

20

K 33 S ₀ * 46 S _A 78 IT 81 _o 5 Is

-coo-Zfyvooc-CH-ca ei

CH.

3.9

-OOC-CH-CH.

S-COO

COO-Zr ^ -GOO

^{QC 6H} 13

K 25 S ₀ * 47 S _A 70 H * 79 Is mol% 44

14

These mixtures are also well suited for use in displays.

Claims (1)

Invention claim: Ferroelectric liquid crystals for optoelectronic components, characterized in that new crystalline liquid 2,5-disubstituted thiadiazoles of the general formula Ή-Ή CH,
ι J -ι "Σ-R ¹ 't