Ethyne derivatives as a component of liquid crystal phases

Details Ethyne derivatives as a component of liquid crystal phases Ethyne derivatives as a component of liquid crystal phases

1988-11-25

1991-11-26

Stoll, Robert L.

Compositions

Liquid crystal compositions

Containing nonsteryl liquid crystalline compound of...

25229901, 544298, 544335, 546 1, C09K 1934, C07D23902

Patent

active

050680536

DESCRIPTION:

BRIEF SUMMARY
The invention relates to ethyne derivatives of the formula I --A.sup.2).sub.n --R.sup.2 I or alkenyl radical having 1 to 15 C. atoms which is unsubstituted, monosubstituted by --CN or at least monosubstituted by halogen, it also being possible for one or more CH.sub.2 groups in these radicals in each case independently of one another to be replaced by --O--, --S--, --CO--, --O--CO--, --O--COO--, --CO--O-- or --C.delta.C-- such that heteroatoms are not linked directly to one another, and one of the radicals R.sup.1 and R.sup.2 can also be H, halogen, --CN or --NCS, replaced by N, CH.sub.2 groups can also be replaced by --O--and/or --S--, 1,4-cyclohexadienylene or 1,4-bicyclo-(2.2.2)-octylene, by halogen, cyano and/or CH.sub.3, --CO--O--, --O--CO--, --CH.sub.2 O--, --OCH.sub.2 --, --CH.sub.2 CH.sub.2 --, --C.tbd.C-- or a single bond, can also be replaced by N, 1,4-cyclohexadienylene and 1,4-bi-cyclo(2.2.2)octylene, than once by halogen, cyano and/or CH.sub.3, is replaced by N and/or at least one of the groups A.sup.3 and A.sup.4 is trans-1,4-cyclohexylene or 1,4-bicyclo(2.2.2)octylene and/or at least one of the groups A.sup.1, A.sup.2, A.sup.3 and A.sup.4 is 1,4-cyclohexenylene or 1,4-cyclohexadienylene, and R.sub.2 are alkyl groups, the alkyl groups in R.sup.1 and R.sub.2 have a different number of C atoms, 15 C atoms, an alkyl or alkenyl radical having 1 to 15 C atoms which is monosubstituted by --CN or at least monosubstituted by halogen, it also being possible for one or two CH.sub.2 groups in these radicals to be replaced by --S-- and/or --C.tbd.C--, or an unsubstituted alkyl radical having 1 to 15 C atoms, wherein at least one CH.sub.2 group is replaced by --S-- or --C.tbd.C--, if m=n=0, A.sup.3 is trans-1,4-cyclohexylene and A.sup.4 is unsubstituted 1,4-phenylene and replaced by N, replaced by N, 1,4-cyclohexadienylene or 1,4-bicyclo-(2.2.2)-octylene, more than once by halogen, cyano and/or CH.sub.3.
For simplicity, in the following text Phe is an unsubstituted 1,4-phenylene group, PheX is a substituted 1,4-phenylene group (wherein X is halogen, CN and/or CH.sub.3), Cyc is a 1,4-cyclohexylene group, Che is a 1,4-cyclohexenylene group, Cha is a 1,4-cyclohexadienylene group, Dio is a 1,3-dioxane-2,5-diyl group, Dit is a 1,3-dithiane-2,5-diyl group, Pyd is a pyridine-2,5-diyl group, Pyr is a pyrimidine-2,5-diyl group, Pyz is a pyrazine-2,5-diyl group, Pyn is a pyridazine-3,6-diyl group, Bco is a 1,4-bicyclo(2.2.2)octylene group and Biphe is a 4,4'-biphenylyl group, wherein one or more CH groups can also be replaced by N.
The compounds of the formula I can be used as components of liquid crystal phases, in particular for displays which are based on the principle of the twisted cell, on the guest-host effect, on the effect of deformation of orientated phases or on the effect of dynamic scattering.
Compounds of the formula I are preferably also suitable for use as components in liquid crystal phases for displays based on the ECB effect.
Similar compounds are known, for example from European Patent 111,695-A, for displays which operate by the two-frequency method.
The invention was based on the object of discovering new stable liquid crystal or mesogenic compounds which are suitable as components of liquid crystal phases. This object was achieved by providing the compounds of the formula I.
It has been found that the compounds of the formula I are outstandingly suitable as components of liquid crystal phases. In particular, stable liquid crystal phases with a relatively high optical anisotropy and negative dielectric anisotropy can be prepared with the aid of these compounds. The substances of the formula I are therefore preferably suitable for use in mixtures for ECB effects.
The ECB effect (electrically controlled birefringence) or also DOP effect (deformation of orientated phases) was described for the first time in 1971 (M.F. Schieckel and K. Fahrenschon, "Deformation of nematic liquid crystals with vertical orientation in electrical fields", Appl. Phys.Lett. 19 (1971), 3912). Works by J.F. Kahn (Appl.Ph

REFERENCES:
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patent: 4707295 (1987-11-01), Pohl et al.
M. Petrzilka, "Polar Acetylenic Liquid Crystals with Broad Mesomorphic Ranges. The Positional Influence of Different C,C-Elements on the Transition Temperatures," Mol. Cryst. Liq. Cryst., 1984, vol. III, pp. 329-346.

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