Organic compounds -- part of the class 532-570 series – Organic compounds – Nitrogen attached directly or indirectly to the purine ring...
Patent
1987-01-23
1989-04-11
Gron, Teddy S.
Organic compounds -- part of the class 532-570 series
Organic compounds
Nitrogen attached directly or indirectly to the purine ring...
2522995, 25229961, 25229901, 350350R, 350350S, 544179, 544180, 544215, 544219, 544224, 544238, 544239, 544241, 544242, 544295, 544296, 544298, 544315, 544318, 544335, 546275, 546286, 546288, 546298, 546300, 546301, 546302, 546326, 546328, 546320, 546240, 546342, 546339, C09K 1934, C02F 113, C07D23902
Patent
active
048208396
DESCRIPTION:
BRIEF SUMMARY
The invention relates to nitrogen-containing heterocyclic esters of the formula IV --R.sup.2 IV which one or more non-neighbouring CH.sub.2 groups may also be replaced by --O--, --CO--, --O--CO--, --O--COO--, --CO--O-- and/or --CH.dbd.CH--, or one of the radicals R.sup.1 and R.sup.2 is also H, F, Cl, Br or CN, which is unsubstituted or substituted by one or two F and/or Cl and/or Br atoms and/or CH.sub.3 and/or CN groups, which one or more CH groups may also be replaced by N, which is unsubstituted or substituted by one or two F and/or Cl atoms and/or Br atoms and/or CH.sub.3 and/or CN groups, --O--CH--.sub.2 -- or a single bond, and
(1) the compounds contains (sic) at least one laterally substituted 1,4-phenylene group and
(2) in the case of m=0 and ##STR1## A.sup.2 is 1,4-phenylene which is laterally substituted by fluorine or is 1,4-phenylene which is substituted, in the ortho position to R.sup.2, by Cl, Br, CH.sub.3 or CN, and also relates to the preparation of the compounds of the formula IV, liquid-crystalline phases containing compounds of the formula IV, the use thereof as components of liquid-crystalline phases, and also smectic liquid-crystalline phases, particularly chiral tilted smectic phases, containing compounds of the formula IV.
Chiral tilted smectic liquid-crystalline phases having ferroelectric properties can be prepared by adding one or more tilted smectic phases having a suitable chiral doping substance to the basic mixtures (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, which are 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) based on the ferroelectric properties of the chirally tilted phase. In this phase, the elongated molecules are arranged in layers, the molecules having a tilt angle to the layer perpendiculars. When proceeding from layer to layer, the tilt direction changes through a small angle relative to an axis which is perpendicular to the layers, so that a helical structure is formed. In displays which are based on the principle of SSFLC technology, the smectic layers are arranged perpendicular to the plates of the cell. The helical arrangement of the tilt directions of the molecules is suppressed by a very small spacing of 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, two distinct tilt or orientations being produced. Switching to and fro between these two states can be accomplished in the liquid-crystalline phase, which has a spontaneous polarization, by applying a suitable electrical alternating field. This switching process is significantly faster than the conventional twisted cells (TN-LCDs), which are based on nematic liquid crystals.
The low chemical, thermal and light stability of the currently available materials having chirally tilted smectic phases (such as, for example, Sc.sup.*) is a great disadvantage for many applications. A further disadvantageous property of displays based on the currently available chirally tilted smectic mixtures is that the spontaneous polarization has values which are too small, so that the switching time behaviour of the displays is unfavourably influenced and/or the pitch and the tilt of the phases do not correspond to the requirements of display technology. In addition, the temperature range of the ferroelectric phases is usually too small and is mainly at temperatures which are too high.
It has now been found that the use of the compounds of the formula IV as components of chirally tilted smectic mixtures can essentially reduce the disadvantages mentioned. The compounds of the formula IV are thus extremely suitable as components of chirally tilted smectic liquid-crystalline phases. In particular, especially chemically stable chirally tilted smectic liquid-crystal
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Hittich Reinhard
Krause Joachim
Reiffenrath Volker
Scheuble Bernhard
Wachtler Andreas
Gron Teddy S.
Merck Patent Gesellschaft mit beschrankter Haftung
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