Fluorocyclohexene derivatives, and liquid-crystalline medium

Details Fluorocyclohexene derivatives, and liquid-crystalline medium Fluorocyclohexene derivatives, and liquid-crystalline medium

2000-03-31

2002-11-05

Wu, Shean C. (Department: 1756)

Stock material or miscellaneous articles

Structurally defined web or sheet

Including grain, strips, or filamentary elements in...

C252S299610, C252S299630, C570S129000, C570S130000, C570S131000, C570S188000

Reexamination Certificate

active

06475595

ABSTRACT:

The invention relates to novel fluorocyclohexene derivatives of the formula I
R
1
—(A
1
—Z
1
)
n
—A—(Z
2
—A
2
)
m
—Z
3
—B—(Z
4
—A
3
)
p
—R
2
  I
in which
R
1
and R
2
, independently of one another, are H or an alkyl radical having 1-12 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,
A
1
, A
2
and A
3
, independently of one another, including if they occur more than once, are
a) a trans-1,4-cyclohexylene radical, in which, in addition, one or more non-adjacent CH
2
groups may be replaced by —O— and/or —S—,
b) a 1,4-phenylene radical, in which, in addition, one or two CH groups may be replaced by N,
c) a radical from the group consisting of 1,4-bicyclo[2.2.2]octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl and 1,2,3,4-tetrahydronaphthalene-2,6-diyl,
d) 1,4-cyclohexenylene,
 where the radical b) may be monosubstituted or polysubstituted by CN, Cl or F,
B, is a trans-1,4-cyclohexylene radical, in which, in addition, one or more non-adjacent CH
2
groups may be replaced by —O— and/or —S—,
 X
1
and X
2
, independently of one another, are H, F, Cl, CN, CF
3
or CHF
2
,
Z
1
, Z
2
,
Z
3
and
4
are each, independently of one another, —CO—O—, —O—CO—, —CH
2
O—, —O—, —O—CH
2
—, —CH
2
CH
2
—, —CH═CH—, —C≡—C—, —CF
2
CF
2
—, —OCF
2
, —CF
2
O—, —CH═CF—, —CF═CH— or a single bond,
and
n, m and p, independently of one another, are 0, 1, 2 or 3,
where
m+n+p is 0, 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 highly 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 electrically controlled birefringence (ECB) or the effect of dynamic scattering.
DE 4227772 A1 discloses compounds containing fluorocyclohexene rings. However, this document only describes compounds which contain a terminal fluorocyclohexene ring in combination with a perfluoroalkyl radical bonded thereto.
The compounds according to the invention are also covered by a very broad generic claim in DE 4427266 A1, which is directed towards compounds of positive dielectric anisotropy which contain a terminal, optionally fluorinated phenyl radical in combination with a fluorocyclohexene ring. The compounds of the present application are, however, not explicitly mentioned therein.
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 unfavourable elastic and/or dielectric properties.
The invention had the object of finding novel, stable, liquid-crystalline or mesogenic compounds having a broad nematic phase range and negative dielectric anisotropy which are suitable as components of liquid-crystalline media, in particular for TFT and STN displays.
It has now been found that the compounds of the formula I are eminently suitable as components of liquid-crystalline media. They can be used 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 favourable clearing point values.
The provision of compounds of the formula I very generally 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 optimize its threshold voltage and/or its viscosity. The addition of compounds of the formula I to liquid-crystalline dielectrics allows the &Dgr;&egr; values of such media to be significantly reduced.
The meaning of the formula I covers 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 producing 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, p, R
1
, R
2
, A, B, Z
1
, Z
2
, Z
3
, Z
4
, A
1
and A
2
and A
3
are as defined above, unless expressly stated otherwise. If the radical A
1
occurs more than once, it can have the same 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, Dio denotes a 1,3-dioxane-2,5-diyl radical, Phe denotes a 1,4-phenylene radical, Dit denotes a 1,3-dithiane-2,5-diyl radical, and Bi denotes a bicyclo[2.2.2]octylene radical, where Cyc and Phe may be unsubstituted or mono- or polysubstituted by halogen or CN, preferably F or CN.
PheXX below denotes
wherein X
1
and X
2
, independently of one another, are H, F, Cl, CN, CF
3
or CHF
2
, preferably at least one of X
1
and X
2
is F and the other one H or F.
CheF below denotes
The formula I covers the preferred compounds of the sub-formulae Ia1 to Ia2:
R
1
—Chef—PheXX—R
2
  Ia1
R
1
—CheF—CH
2
CH
2
—PheXX—R
2
  Ia2
The formula I covers the preferred compounds of the sub-formulae Ib1 to Ib27, which, in addition to the CheF and PheXX groups, contain a further six-membered ring:
R
1
—CheF—Cyc—PheXX—R
2
  Ib1
R
1
—Cyc—CH
2
CH
2
—CheF—PheXX—R
2
  Ib2
R
1
—Cyc—Chef—PheXX—R
2
  Ib3
R
1
—Dio—Chef—PheXX—R
2
  Ib4
R
1
—CheF—CH
2
CH
2
—Cyc—PheXX—R
2
  Ib5
R
1
—Chef—Phe—PheXX—R
2
  Ib6
R
1
—CheF—CH
2
CH
2
—Phe—PheXX—R
2
  Ib7
R
1
—Dio—CH
2
CH
2
—Dio—Chef—PheXX—R
2
  Ib8
R
1
—Phe—Chef—PheXX—R
2
  Ib9
R
1
—CheF—CH
2
CH
2
—Phe—PheXX—R
2
  Ib10
R
1
—Chef—PheXX—Phe—R
2
  Ib11
R
1
—CheF—CH
2
CH
2
—PheXX—Phe—R
2
  Ib12
R
1
—Chef—PheXX—CH
2
CH
2
—Phe—R
2
  Ib13
R
1
—Chef—PheXX—CH═CH—Phe—R
2
  Ib14
R
1
—Chef—PheXX—C≡C—Phe—R
2
  Ib15
R
1
—CheF—CH
2
CH
2
—PheXX—CH
2
CH
2
—Phe—R
2
  Ib16
R
1
—Chef—PheXX—Cyc—R
2
  Ib17
R
1
—CheF—CH
2
CH
2
—PheXX—Cyc—R
2
  Ib18
R
1
—Chef—PheXX—CH
2
CH
2
—Cyc—R
2
  Ib19
R
1
—CheF—CH
2
CH
2
—PheXX—CH
2
CH
2
—Cyc—R
2
  Ib20
R
1
—Chef—PheXX—Dio—R
2
  Ib21
R
1
—CheF—CH
2
CH
2
—PheXX—Dio—R
2
  Ib22
R
1
—Chef—PheXX—CheF—R
2
  Ib23
 R
1
—CheF—CH
2
CH
2
—PheXX—CheF—R
2
  Ib24
R
1
—CheF—Chef—PheXX—R
2
  Ib25
R
1
—CheF—CH
2
CH
2
—CheF—PheXX—R
2
  Ib26
R
1
—CheF—CheF—CH
2
CH
2
—Ph

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