Fluorinated biphenyldiole derivatives

Details Fluorinated biphenyldiole derivatives Fluorinated biphenyldiole derivatives

1989-07-14

1993-01-26

Stoll, Robert L.

Compositions

Liquid crystal compositions

Containing nonsteryl liquid crystalline compound of...

25229901, 25229963, 25229961, C09K 1912, C09K 1930, C09K

Patent

active

051820471

DESCRIPTION:

BRIEF SUMMARY
The invention relates to fluorinated biphenyldiole derivatives of the formula I ##STR3## wherein R.sup.1 and R.sup.2 wherein one CH2-group can also be replaced by --O--, --O--CO--, --CO--O-- and/or --HC.dbd.CH-- with the proviso that two O atoms are not directly linked, formula II may also be replaced by --O--, --OCO--, --CO--O-- and/or --HC.dbd.CH--, CH.sub.2 groups may be replaced by --O-- and/or --S--, a 1,4-bicyclooctylene group, or a 1,4-phenylene group, wherein one or two CH groups are replaced by N, and of the formula III ##STR4## wherein R.sup.4 denotes an alkyl, alkoxy, alkanoyl-oxy or alkoxycarbonyl residue with 1 to 15 C atoms, one CH.sub.2 group which is not linked to Z.sup.2 can also be replaced by --O--, --O--CO--, --CO--O-- or --CH.dbd.CH--, residues R.sup.4, X and Y are different from each other, ##STR5## denotes a 1,4-phenylene group optionally substituted by up to four F atoms, and
Chiral tilted smectic liquid crystal phases with ferroelectric properties can be prepared by adding a suitable chiral doping substance to base mixtures with one or more tilted smectic phases (L.A. Beresnev et al., Mol. Cryst. Liq. Cryst. 89, 327 (1982); H.R. Brand et al., J. Physique 44 (lett.), L-771 (1983)). Such phases can be used as dielectrics for rapidly switching displays based on the principle of SSFLC technology described by Clark and Lagerwall (N. A. Clark and S. T. Lagerwall, Appl. Phys. Lett. 36, 899 (1980); U.S. Pat. No. 4,367,924) on the basis of ferroelectric properties of the chiral tilted phase. In this phase, the longitudinally stretched molecules are arranged in layers, the molecules having a tilt angle relative to the normal of the layers. On advancing from layer to layer, the tilt direction changes by a small angle in respect of an axis vertical to the layers, so that a helix structure is formed. In displays based on the principle of SSFLC technology, the smectic layers are arranged vertical to the plates of the cell. The helical arrangement of the tilt direction of the molecules is suppressed by a very small distance between the plates (about 1-2 .mu.m). The longitudinal axes of the molecules are thereby forced to align themselves in a plane parallel to the plates of the cell, which means that two distinct tilt orientations result. By applying a suitable alternating electrical field, a system can be switched back and forth between these two states in the liquid crystal phase which exhibits spontaneous polarization. This switching process is considerably more rapid than in conventional twisted cells (TN-LCDs) based on nematic liquid crystals.
The chiral compounds of the formula I which have three rings are partially covered by a broad formula of the European Patent Applications 01 53 826 and 02 43 209 wherein compounds of the formula ##STR6## are claimed. But no compound according to this invention is disclosed there. Only compounds wherein X or Y denotes bromine or a cyano group are described. One skilled in the art, therefore, could neither infer how to synthesize these fluorinated compounds nor recognize that they show favourable mesophase ranges and an extraordinarily low viscosity.
Similar compounds e.g. are described in the European Patent Application 01 32 377 and the European Patent Application 02 36 215. But the compounds disclosed there are derivatives of 4,4'-disubstituted-2,2'-difluorobiphenyl.
A great disadvantage for many applications of the materials currently available with chiral tilted smectic phases (such as, for example, Sc*) is their low chemical, heat and light stability. Another adverse property of displays based on the chiral tilted smectic mixtures currently available is that high order smectic phases such as, for example, S.sub.I, occur at low temperatures, so that the switch time properties of the displays are adversely influenced and/or the pitch and/or the tilt and/or the viscosity of the phases do not meet the requirements of display technology. Moreover, the temperature range of the ferroelectric phases is usually too small and is predominantly at temperatures

REFERENCES:
patent: 4368135 (1983-01-01), Osman et al.
patent: 4405488 (1983-09-01), Sugimori et al.
patent: 4490305 (1984-12-01), Eidenschink et al.
patent: 4551264 (1985-11-01), Eidenschunk et al.
patent: 4732699 (1988-03-01), Higuchi et al.
patent: 4855076 (1989-08-01), Goto et al.
patent: 4886621 (1989-12-01), Sage et al.
patent: 4911863 (1990-03-01), Sage et al.

Affiliated with

Also associated with

Rating

Fluorinated biphenyldiole derivatives does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Fluorinated biphenyldiole derivatives, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fluorinated biphenyldiole derivatives will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1411296