Dialkyne compounds

Details Dialkyne compounds Dialkyne compounds

2001-07-19

2003-10-14

Wu, Shean C. (Department: 1756)

Stock material or miscellaneous articles

Liquid crystal optical display having layer of specified...

C252S299610, C252S299630, C549S369000, C549S373000, C549S374000, C570S131000, C570S188000, C585S534000

Reexamination Certificate

active

06632484

ABSTRACT:

The invention relates to dialkyne compounds of the formula I
in which
R
1
and R
2
, independently of one another, are H, F, or an alkyl radical having 1-15 carbon atoms which is unsubstituted or at least monosubstituted by halogen or CN and in which, in addition, one or more CH
2
groups may each, independently of one another, be replaced by —O—, —S—, —CO—,
—CO—O—, —O—CO—, —O—CO—O— or —CH═CH— in such a way that heteroatoms are not connected directly,
X
1
, X
2
, X
3
and X
4
are each, independently of one another, H or —C≡C—C≡C—R
3
, where at least one of the groups X
1
, X
2
, X
3
and X
4
is —C≡C—C≡C—R
3
,
R
3
is H, Cl, CN, SF
5
, CF
3
, or an alkyl radical having 1-15 carbon atoms which is unsubstituted or at least monosubstituted by halogen and in which, in addition, one or more CH
2
groups may be replaced, in each case independently of one another, by —CH═CH— or —O— in such a way that —O— atoms are not connected directly,
Q is —CH
2
— or —O—, and
Y
1
and Y
2
, independently of one another, are C or Si,
A
1
and A
2
, independently of one another, are a trans-1,4-cyclohexylene radical which is unsubstituted or substituted by F or CN and in which, in addition, one or more non-adjacent CH
2
groups may be replaced by —O— and/or —S—, or are
Z
1
and Z
2
are each, independently of one another, —CO—O—, —O—CO—, —CH
2
O—, —O—, —OCH
2
—, —CF
2
O—, —OCF
2
—, —CF
2
CF
2
—, —CF═CF—, —CH
2
CH
2
—, —CH═CH— or a single bond, and
n and m, independently of one another, are 0, 1, 2 or 3, where
m+n is 1, 2 or 3.
The invention also relates to the use of the compounds of the formula I as components of liquid-crystalline media, and to liquid-crystal and electro-optical display elements which contain the liquid-crystalline media according to the invention.
The compounds of the formula I frequently have a low positive or negative value of the dielectric anisotropy and can be used as components of liquid-crystalline media, in particular for displays based on the principle of the twisted cell, the guest-host effect, the effect of deformation of aligned phases DAP or ECB (electrically controlled birefringence) or the effect of dynamic scattering.
The substances employed hitherto for this purpose all have certain disadvantages, for example inadequate stability to the action of heat, light or electric fields, or unfavorable elastic and/or dielectric properties.
The invention has an object of finding novel stable liquid-crystalline or mesogenic compounds having particularly low optical anisotropy (&Dgr;n) and negative or positive dielectric anisotropy (&Dgr;&egr;) which are suitable as components of liquid-crystalline media, in particular for TFT and STN displays.
Upon further study of the specification and appended claims, further objects and advantages of this invention will become apparent to those skilled in the art.
It has now been found that the compounds of the formula I are eminently suitable as components of liquid-crystalline media. With their aid, it is possible to obtain stable liquid-crystalline media, in particular suitable for TFT or STN displays. The novel compounds are distinguished, in particular, by high thermal stability, which is advantageous for a high holding ratio, and exhibit favorable clearing point values. At a reduced temperature of 0.9 and a wavelength of 589 nm, the compounds of the formula I have an optical anisotropy value &Dgr;n of <0.03, preferably <0.02, which is attributable to a particularly large value of n
1
. The reduced temperature here is defined as follows:
measurement
⁢
 
⁢
temperature
⁢
 
⁢
in
⁢
 
⁢
K
clearing
⁢
 
⁢
point
⁢
 
⁢
temperature
⁢
 
⁢
in
⁢
 
⁢
K
=
reduced
⁢
 
⁢
temperature
Liquid-crystalline media having very low optical anisotropy values are of particular importance for reflective and transflective applications, i.e. applications in which the respective LCD experiences no or only supporting background illumination. Low values of An are achieved by the use of substituents X
1
, X
2
, X
3
and/or X
4
having the highest possible polarizability. Owing to the small volume of the groups X
1
, X
2
, X
3
and X
4
, the other LC properties, such as clearing point and viscosity, of liquid-crystalline mixtures to which the compounds according to the invention have been added are only impaired to a relatively small extent.
Very generally, the provision of compounds of the formula I considerably broadens the range of liquid-crystalline substances which are suitable, from various applicational points of view, for the preparation of liquid-crystalline mixtures.
The compounds of the formula I have a broad range of applications. Depending on the choice of substituents, these compounds can serve as base materials of which liquid-crystalline media are predominantly composed; however, it is also possible to add compounds of the formula I to liquid-crystalline base materials from other classes of compound in order, for example, to modify the dielectric and/or optical anisotropy of a dielectric of this type and/or to optimise its threshold voltage and/or its viscosity. Addition of compounds of the formula I to liquid-crystalline dielectrics enables &Dgr;n values of such media to be significantly reduced.
The meaning of the formula I includes all isotopes of the chemical elements bound in the compounds of the formula I. In enantiomerically pure or enriched form, the compounds of the formula I are also suitable as chiral dopants and in general for achieving chiral mesophases.
In the pure state, the compounds of the formula I are colorless and form liquid-crystalline mesophases in a temperature range which is favorably located for electro-optical use. They are stable chemically, thermally and to light.
The invention thus relates to the compounds of the formula I and to the use of these compounds as components of liquid-crystalline media. The invention furthermore relates to liquid-crystalline media comprising at least one compound of the formula I and to liquid-crystal display elements, in particular electro-optical display elements, which contain media of this type.
Above and below, n, m, R
1
, R
2
, R
3
, X
1
, X
2
, X
3
, X
4
, Z
1
, Z
2
, A
1
, A
2
, Q, Y
1
and Y
2
are as defined above, unless expressly stated otherwise. If the radical X
1
occurs more than once, it may adopt identical or different meanings. The same applies to all other groups which occur more than once.
For reasons of simplicity, Cyc below denotes a cyclohexane-1,4-diyl radical or a 1- or 4-silacyclohexane-1,4-diyl radical, Dio denotes a 1,3-dioxane-2,5-diyl radical, Dit denotes a 1,3-dithiane-2,5-diyl radical, and Boc denotes a bicyclo[2,2,2]octylene radical, where Cyc may be unsubstituted or monosubstituted or polysubstituted by F or CN.
W denotes the following structural unit:
in which X
1
, X
2
, X
3
, X
4
, Q, Y
1
, Y
2
and Z
2
are as defined above, and p is 0, 1, 2 or 3.
Preferred meanings of the group W are represented by the sub-formulae W1 to W7:
in which Z
2
and R
3
are as defined above.
Formula I covers the preferred compounds of the sub-formulae Ia1 to Ia12, which, besides the group W, contain a six-membered ring:
R
1
-W-Cyc-R
2
Ia1
R
1
-W-CH
2
CH
2
-Cyc-R
2
Ia2
R
1
-W-COO-Cyc-R
2
Ia3
R
1
-W-Dio-R
2
Ia4
R
1
-W-CH
2
CH
2
-Dio-R
2
Ia5
R
1
-W-COO-Dio-R
2
Ia6
R
1
-Cyc-W-R
2
Ia7
R
1
-Dio-W-R
2
Ia8
R
1
-Cyc-CH
2
CH
2
-W-R
2
Ia9
R
1
-Dio-CH
2
CH
2
-W-R
2
Ia10
R
1
-Cyc-COO-W-R
2
Ia11
R
1
-Dio-COO-W-R
2
Ia12
furthermore the likewise preferred compounds of the sub-formulae Ib1 to 1b72, which, in addition to the group W, contain two six-membered rings:
R
1
-Cyc-Cyc-W-R
2
Ib1
R
1
-Dio-Cyc-W-R
2
Ib2
R
1
-Cyc-CH
2
CH
2
-Cyc-W-R
2
Ib3
R
1
-Dio-CH
2
CH
2
-Cyc-W-R
2
Ib4
R
1
-Cyc-COO-Cyc-W-R
2
Ib5
R
1
-Dio-COO-Cyc-W-R
2
Ib6
R
1
-Cyc-Dio-W-R
2
Ib7
R
1
-Dio-Dio-W-R
2
Ib8
R
1
-Cyc-CH
2
CH
2
-W-R
2
Ib9
R
1
-Dio-CH
2
CH
2
-W-R
2
Ib10
R
1
-Cyc-COO-Dio-W-R
2
Ib11
R
1
-Dio-COO-Dio-W-R
2
Ib12
R
1
-Cyc-Cyc-CH
2
CH
2
-W-R
2
Ib13
R
1
-Dio-Cyc-CH

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