Chiral 1, 3-dioxane compounds

Details Chiral 1, 3-dioxane compounds Chiral 1, 3-dioxane compounds

2001-03-16

2003-09-09

Wu, Shean C. (Department: 1756)

Stock material or miscellaneous articles

Liquid crystal optical display having layer of specified...

C252S299010, C252S299610, C252S299640, C252S299650, C252S299660, C252S299670, C544S298000, C544S335000, C549S369000, C549S370000

Reexamination Certificate

active

06616990

ABSTRACT:

BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to chiral 1,3-dioxane compounds and diastereomers thereof, and to the use of these compounds as chiral dopants for liquid-crystalline systems.
(2) Description of the Preferred Embodiments
The invention further relates to non-polymerizable or polymerizable liquid-crystalline compositions comprising at least one chiral 1,3-dioxane compound of the invention, the use of these non-polymerizable or polymerizable liquid-crystalline compositions for producing optical components, the use of the polymerizable liquid-crystalline compositions for printing or coating substrates, for preparing dispersions and emulsions, films or pigments and optical components, printed or coated substrates, dispersions and emulsions, films and pigments of this type.
The preparation of cholesteric liquid-crystal mixtures usually involves using a liquid-crystalline (nematic) base material and one or more optically active dopants. This preparation method makes it possible to vary the optical properties of the mixture simply by changing the nematic compound/dopant ratio. However, to minimize possible negative effects of the dopant on the other properties of the nematic host system, such as phase behavior and phase range, there is a particular demand for dopants which, even when added in small amounts, cause large changes in optical properties.
Numerous chiral dopants for liquid-crystalline phases are known from the scientific and patent literature. It is all the more astonishing that chiral 1,3-dioxane compounds were apparently not considered previously as dopants for liquid-crystalline systems.
BRIEF SUMMARY OF THE INVENTION
It is an object of the present invention to provide additional chiral compounds which are suitable for preparing cholesteric liquid-crystalline compositions and have a relatively high twisting power and correspondingly exhibit great effects on the optical properties of the liquid-crystalline host system even in comparatively small amounts.
We have found that this object is achieved by a chiral compound of the general formula I
or a diastereomer thereof,
where
R
1
is [P—Y
1
—(A
1
)
m
—Y
2
—]
q
M—Y
3
—(A
2
)
n
—Y
4
— and
R
2
and R
3
are each, independently of one another and independently of R
1
, [P—Y
1
—(A
1
)
m
—Y
2
—]
q
M—Y
3
—(A
2
)
n
—Y
4′
—,
where
A
1
and A
2
are each a spacer having from one to 30 carbon atoms,
M is a mesogenic group,
Y
1
, Y
2
, Y
3
, Y
4
are each a chemical single bond, —O—, —S—, —CO—, —CO—O—, —O—CO—, —CO—N(R)—, —(R)N—CO—, —O—CO—O—, —O—CO—N(R)—, —(R)N—CO—O— or —(R)N—CO—N(R)—,
Y
4′
is —O—, —O—CO—, —O—CO—O— or —O—CO—N(R)—,
R is hydrogen or C
1
-C
4
-alkyl,
P is hydrogen, C
1
-C
12
-alkyl, a polymerizable group or a group suitable for polymerization or a radical having a polymerizable group or a group suitable for polymerization,
m and n are each 0 or 1, and
q is 1, 2 or 3,
where A
1
, A
2
, Y
1
, Y
2
, Y
3
, Y
4
, Y
4′
, M and P and the indices m, n and q of R
1
to R
3
can be identical or different, and R
2
and R
3
are attached to the 1,3-dioxane skeleton via the oxygen atom of Y
4′
, with the proviso that at least one of the radicals Y, in each case adjacent to A, is a chemical bond if one or both of the indices m and n is/are 0.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Suitable spacers A
1
and A
2
are all groups known for this purpose to a person skilled in the art. The spacers usually contain one to 30, preferably one to 12, particularly preferably one to six, carbon atoms and consist of predominantly linear aliphatic groups. They may be interrupted in the chain, for example by non-adjacent oxygen or sulfur atoms or imino or alkylimino groups, for example methylimino groups. Suitable substituents for the spacer chain are fluorine, chlorine, bromine, cyano, methyl and ethyl.
Examples of representative spacers are:
—(CH
2
)
u
—, —(CH
2
CH
2
O)
v
CH
2
CH
2
—, —CH
2
CH
2
SCH
2
CH
2
——CH
2
CH
2
NHCH
2
CH
2
—,
where u is 1 to 30, preferably 1 to 12, v is 1 to 14, preferably 1 to 5, and w is 1 to 9, preferably 1 to 3.
Preferred spacers are ethylene, propylene, n-butylene, n-pentylene and n-hexylene.
Particularly suitable mesogenic groups are those of the formula Ia
where
T at each occurrence is a divalent, saturated or unsaturated carbocyclic or heterocyclic radical,
Y
5
at each occurrence is a chemical single bond, —O—, —S—, —CO—, —CO—O—, —O—CO—, —CO—N(R)—, —(R)N—CO—, —O—CO—O—, —O—CO—N(R)—, —(R)N—CO—O— or —(R)N—CO—N(R)—, and
r is 0, 1, 2 or 3, where, if r<0, T in each instance it occurs is identical or different and Y
5
in each instance it occurs is identical or different.
Note: The definition of the radical T as being divalent requires further explanation. It will be understood that this divalency only applies to the attachment of a radical T in question to the adjacent radical(s) T, one of the q moieties P—Y
1
—(A
1
)
m
—Y
2
— and/or —Y
3
—(A
2
)
n
—Y
4
— or —Y
3
—(A
2
)
n
—Y
4′
—, respectively.
For example, when two or three moieties P—Y
1
—(A
1
)
m
—Y
2
— (q equals two or three) are attached to the mesogenic group M, which as such has a valency of (q+1) according to its definition in formula I, the valency of at least one radical T in question obviously increases to three or possibly even four.
This may be illustrated by way of example for q equals 3 and r equals 3 for two of the possible isomers, i.e.
In the former case, the radical T in question (marked with
x
) is divalent in terms of attachment of one moiety P—Y
1
—(A
1
)
m
—Y
2
— and an adjacent radical T, but has a total valency of four, since it has two additional moieties P—Y
1
—(A
1
)
m
—Y
2
— attached to it. In the latter case, the two radicals T in question are divalent in terms of attachment of one moiety P—Y
1
—(A
1
)
m
—Y
2
— and one adjacent radical T or two adjacent radicals T, but the attachment of, in each case, one additional moiety P—Y
1
—(A
1
)
m
—Y
2
— results in a valency of three for the two radicals T in question.
Furthermore, here and throughout this application, at least one of the q moieties P—Y
1
—(A
1
)
m
—Y
2
— is attached terminally to the mesogenic group M as defined in the formulae I or Ia.
The radicals T may be ring systems which are substituted by fluorine, chlorine, bromine, cyano, hydroxyl, formyl, nitro, 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 or C
1
-C
20
-alkylcarbonylamino. Preferred radicals T are:
Examples of mesogenic groups M for R
1
, R
2
and R
3
are:
Further possible mesogenic groups M correspond to the following formulae:
In accordance with the above examples for possible radicals T, the (unsubstituted) mesogenic groups shown above may of course be substituted by fluorine, chlorine, bromine, cyano, hydroxyl, formyl, nitro, 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 or C
1
-C
20
-alkylcarbonylamino. Preferred substituents are in particular 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.
Preferred 1,3-dioxane compounds are those in which, in the mesogenic group of the formula Ia, the index r is 0 for R
1
and the index r, independently at each occurrence, is 0 or 1 for R
2
and R
3
. As mesogenic groups, mention may be made in particular of
for R
1
, and
for R
2
and R
3
:
Furthermore, these mesogenic groups may be substituted, as mentioned above.
It is furthermore also possible to attach one or more of the mesogenic radicals M directly to the corresponding groups P without a spacer A
1
. In these cases, the indices m or n are 0, and Y
1
/Y
2
together are a chemical single bond.
C
1
-C
12
-Alkyl radicals for P are branched or unbranched C
1
-C
12
-alkyl chains, f

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