Chiral compounds and their use as chiral dopants for...

Details Chiral compounds and their use as chiral dopants for... Chiral compounds and their use as chiral dopants for...

2000-03-20

2002-10-22

Wu, Shean C. (Department: 1756)

Compositions

Liquid crystal compositions

Cholesteric liquid crystal composition containing a sterol...

C252S299620, C424S059000, C424S060000, C424S401000, C514S772000, C514S772300, C549S464000, C549S465000, C549S473000

Reexamination Certificate

active

06468444

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to chiral compounds and to the use thereof as chiral dopants for producing cholesteric liquid crystal compositions which can be employed as photostable UV filters in cosmetic and pharmaceutical preparations for protecting the human epidermis or human hair from UV radiation, specifically in the range from 280 to 450 nm.
BACKGROUND OF THE INVENTION
Cholesteric liquid crystals (CLCs) reflect circularly polarized electromagnetic radiation in a wavelength range dependent on the helical structure of the CLC. The central wavelength of the reflection band is determined by the pitch p of the helical structure, and the width of the band by the optical anisotropy of the mesogens. The central wavelength of the reflection band, which is referred to hereinafter as the reflection wavelength, depends on the angle of view. The direction of rotation of the reflected light corresponds to the direction of rotation of the cholesteric helix.
Cholesteric liquid crystal mixtures usually contain one or more optically active components to induce a chiral structure. For example, cholesteric liquid crystal mixtures may consist of a nematic base material and one or more optically active dopants. The latter generate in the nematic either a right or left-handed twist which determines the direction of rotation of the reflected circularly polarized light.
Numerous compounds are known as chiral dopants for liquid crystal phases (e.g. from DE-A 43 42 280, DE-A 195 41 820 and DE-A 196 11 101, and from GB-A-2 314 839 and WO 98/00428).
Frequently suitable for left-helical materials are cholesterol compounds which, apart from the chirality, also introduce sufficient mesogenic properties to generate a stable mesophase. Compounds of this type are described, for example, by H. Finkelmann, H. Ringsdorf et al., in Makromol. Chem. 179, 40 829-832 (1978). However, these compounds have the disadvantage of a complicated synthesis and a high cost of preparation.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide novel chiral compounds which are suitable for producing cholesteric liquid crystal compositions that do not have the abovementioned disadvantages.
We have found that this object is achieved by chiral dopants of the formula I
Z
1
—Y
1
—(A
1
)
m
—Y
2
—M—Y
3
—X—Y
4
—(A
2
)
n
—Y
5
—Z
2
  I
in which the variables have, independently of one another, the following meanings:
A
1
and A
2
a spacer with a chain length of 1 to 30 C atoms;
Y
1
to Y
5
a chemical bond, —O—, —S—, —C(═O)—, —C(═O)—O—, —O—C(═O)—, —CH═CH—C(═O)—O—, —O—C(═O)—O—, —C(═O)—N(R)— or —(R)N—C(═O)—, —CH
2
—O—, —O—CH
2
—, —CH═N—, —N═CH— or —N═N—;
M a mesogenic group;
R hydrogen, C
1
-C
4
-alkyl;
Z
1
and Z
2
hydrogen, C
1
-C
4
-alkyl, a polymerizable group or a radical having a polymerizable group;
X a dianhydrohexitol residue selected from the group consisting of dianhydrosorbitol, dianhydromannitol and dianhydroiditol;
m 0 or 1;
n 0 or 1,
where the radicals Z
1
, Z
2
, Y
1
to Y
5
, A
1
and A
2
can be identical or different, and at least one Z
1
or Z
2
radical is a polymerizable group or a radical comprising a polymerizable group.
Suitable spacers A
1
and A
2
are all groups known for this purpose. The spacers usually contain 1 to 30, preferably 1 to 12, particularly preferably 1 to 6, C atoms and consist of predominantly linear aliphatic groups. They may be interrupted in the chain, for example, by nonadjacent oxygen or sulfur atoms or imino or alkylimino groups such as methylimino groups.
Substituents suitable for the spacer chain are moreover fluorine, chlorine, bromine, cyano, methyl and ethyl.
Examples of representative spacers are:
where r is 1 to 3 and q is 1 to 12.
Preferred spacers are ethylene, propylene, n-butylene, n-pentylene and n-hexylene.
In a preferred embodiment, however, it is also possible to link the dianhydrohexitol residue X without spacer directly to the radical Z
2
. In this case, n is 0 and Y
4
or Y
5
is a chemical bond.
It is also possible to link the mesogenic radical M without spacer directly to the radical Z
1
. In this case, m is 0 and Y
1
or Y
2
is a chemical bond.
All known mesogenic groups can be used as M radicals.
Particularly suitable mesogenic groups are those of the formula
(—T—Y
10
)
s
—T—
in which the variables have the following meanings:
T identical or different divalent saturated or unsaturated iso- or heterocyclic radicals,
Y
10
groups of the definition for Y
1
to Y
5
,
s 0, 1, 2 or 3,
where in the case where s>0, both the T radicals and the Y
10
groups can each be identical to or different from one another.
It is preferred for s to be 1 or 2.
The T radicals may also be ring systems substituted by fluorine, chlorine, bromine, cyano, hydroxyl or nitro. Preferred T radicals are:
Examples of preferred mesogenic groups M are:
Particularly preferred mesogenic groups M are those of the following formulae
where each aromatic ring may have up to three identical or different substituents from the following group:
hydrogen, C
1
-C
20
-alkyl, C
1
-C
20
-alkoxy, C
1
-C
20
-alkoxycarbonyl, C
1
-C
20
-monoalkylaminocarbonyl, C
1
-C
20
-alkylcarbonyl, C
1
-C
20
-alkylcarbonyloxy, C
1
-C
20
-alkylcarbonylamino, formyl, halogen, cyano, hydroxyl or nitro.
Preferred substituents for the aromatic rings are, besides fluorine, chlorine, bromine, cyano, formyl and hydroxyl, especially short-chain aliphatic radicals such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, tert-butyl, and alkoxy, alkoxycarbonyl, alkylcarbonyl, alkylcarbonyloxy, alkylcarbonylamino and monoalkylaminocarbonyl radicals which contain these alkyl groups.
The outer benzene rings of the particularly preferred M groups preferably have the following substitution patterns:
or they are substituted analogously with F, Br, CH
3
, OCH
3
, CHO, COCH
3
, OCOCH
3
or CN in place of Cl, it also being possible for mixed substituents to be present. Mention should also be made of the structures
in which w is 2 to 20, preferably 8 to 15.
The preferred substitution patterns of the middle benzene ring of the particularly preferred M groups are
Alkyl radicals which may be mentioned for R and for Z
1
and Z
2
are branched or unbranched C
1
-C
4
-alkyl chains, preferably methyl, ethyl, n-propyl, 1-methylethyl, n-butyl, 1-methylpropyl-, 2-methylpropyl or 1,1-dimethylethyl.
Preferred Z
1
and Z
2
radicals are:
 —N═C═O, —N═C═S, —O—C≡N, —COOH, —OH or NH
2
where the R
2
radicals may be identical or different and are hydrogen or C
1
-C
4
-alkyl such as methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl or tert-butyl. Of the reactive polymerizable groups, the cyanates are capable of spontaneous trimerization to cyanurates and are therefore preferred. The other groups mentioned require other compounds with complementary reactive groups for the polymerization. Thus, for example, isocyanates can polymerize with alcohols to form urethanes and with amines to form urea derivatives. Analogous statements apply to thuiranes and aziridines. Carboxyl groups can be condensed to form polyesters and polyamides. The maleimido group is particularly suitable for free-radical copolymerization with olefinic compounds such as styrene. The complementary reactive groups may moreover either be present in a second compound according to the invention, which is mixed with the first, or be incorporated into the polymeric network by auxiliary compounds containing 2 or more of these complementary groups.
Particularly preferred Z
1
—Y
1
and Y
5
—Z
2
groups are acrylate and methacrylate.
Y
1
—Y
5
may have the abovementioned meanings, with a chemical bond being intended to mean a single covalent bond.
Suitable dianhydrohexitol residues are selected from the group consisting of dianhydrosorbitol, dianhydromannitol and dianhydroiditol. Dianhydrosorbitol and dianhydromannitol residues are preferred, and dianhydromannitol is particularly preferred.
Particularly preferred chiral dopants are those cont

Affiliated with

Also associated with

Rating

Chiral compounds and their use as chiral dopants for... does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Chiral compounds and their use as chiral dopants for..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Chiral compounds and their use as chiral dopants for... will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2973595