Organic compounds -- part of the class 532-570 series – Organic compounds – Chalcogen in the nitrogen containing substituent
Reexamination Certificate
1999-05-28
2001-04-10
Raymond, Richard L. (Department: 1624)
Organic compounds -- part of the class 532-570 series
Organic compounds
Chalcogen in the nitrogen containing substituent
C544S099000
Reexamination Certificate
active
06214990
ABSTRACT:
FIELD OF ART
The present invention relates to a novel triphenodioxazine compound that can be used as a dichroic dye useful in the art of liquid crystal display elements, a method for preparing the compound, use of the compound as a dichroic dye, and a liquid crystal composition.
BACKGROUND ART
Compositions containing a liquid-crystalline material and a small amount of a dichroic dye are used for production of liquid crystal display elements of a guest-host type (abbreviated as GH hereinbelow). The GH type element is an important type of a liquid crystal display element, and has been attracting attention particularly as means for improving the efficiency of light utilization in color liquid crystal display elements. A variety of GH liquid crystal display elements have been drawing interests, such as those consisting of a laminate of Heilmeier type GH cells, those consisting of DGH (double layer GH) cells, and those consisting of two or three laminated layers of PCGH (cholesteric-nematic phase change type GH) cells. Recently, reflection type liquid crystal display elements are of particular interest in view of energy conservation or securance of battery life in portable devices. The reflection type liquid crystal display elements lack auxiliary light sources such as back lights, so that use of such GH liquid crystal display elements in the reflection type elements is believed to be advantageous due to their high efficiency of light utilization.
As dichroic dyes for the GH liquid crystal displays, excellent materials with high dichroic ratios have been developed, such as azo dyes, anthraquinone dyes, and quinophthalone dyes. Such materials exhibit high dichroic ratios in many liquid-crystalline materials (Alexander V. Ivashchenko,
Dichroic Dyes for Liquid Crystal Displays,
p165-337, (CRC Press), 1994).
In general, the absorption spectra of dichroic dyes have considerable influence on colored display of GH liquid crystal displays. Thus, in order to broaden the range of the displayable color tones and to ensure color rendering properties, it is necessary to control each of the primaries independently and to combine dyes which overlap little in absorbable wavelength.
The overlap of absorbable wavelengths prevents the independent control of the primaries to narrow the range of the displayable colors, and accompanies additional light absorption to lower the efficiency of light utilization. For avoiding the overlap of absorbable wavelengths, selection of the peak absorption wavelength for each color is important. However, mere selection of the peak absorption wavelength still allows some overlap of absorbable wavelengths since absorption spectra of dyes are generally broad. Thus, it is particularly desired for dichroic dyes to have as narrow light absorption bands as possible in order to reduce the overlap.
Triphenodioxazine was originally developed as a kind of pigments, and it is now generally known to have a narrow light absorption band and to exhibit vivid color tones.
However, the dichroic ratios of conventional dichroic dyes having a triphenodioxazine skeleton are relatively low in liquid crystal, i.e. about 6 to 7 at the best, compared to those of azo dyes and anthraquinone dyes (Alexander V. Ivashchenko,
Dichroic Dyes for Liquid Crystal Displays,
p173, (CRC Press), 1994). Consequently, development of triphenodioxazine dyes with higher dichroic ratios is desired.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide a novel triphenodioxazine compound having a high dichroic ratio and a narrow light absorption band, a method for preparing such a compound, use of such a compound as a dichroic dye, and a liquid crystal composition.
The present inventors have made intensive studies for achieving the above object to find out that a novel compound having a triphenodioxazine skeleton with particular substituents incorporated thereto has a high dichroic ratio in liquid crystal, thereby completing the present invention.
According to the present invention, there is provided a triphenodioxazine compound represented by the formula (1)
wherein each of Y
1
to Y
4
stands for a group represented by the formula (2) or (3) with at least one of Y
1
to Y
4
being a group represented by the formula (2); X stands for a hydrogen atom, a halogen atom, a cyano group, an alkyl group, an aryl group, an alkoxy group, an acylamino group, or a carboxylate group:
wherein h is an integer of 1 to 2, i is an integer of 1 to 2, and j is an integer of 0 to 2; A stands for a group selected from group (I) consisting of:
wherein k is an integer of 1 to 6; one or more of hydrogen atoms in a phenylene group may be substituted by an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, a perfluoroalkyl group having 1 to 6 carbon atoms, or a halogen atom; end (a) binds to E and end (b) binds to the ester group in the formula (2);
each of E, J, and M stands for a group selected from group (II) consisting of:
wherein m is an integer of 1 to 12, and each of q and r is an integer of 1 to 8; one or more of hydrogen atoms in a phenylene group may be substituted by an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a perfluoroalkyl group having 1 to 6 carbon atoms, or a halogen atom; when E in the formula (2) is a group having ends (a) and (b) selected from group (II), end (a) binds to G or E and end (b) binds to A or E; when J in the formula (3) is a group having ends (a) and (b) selected from group (II), end (a) binds to M, J, or Q in the formula (3) and end (b) binds to J or the triphenodioxazine skeleton; when M in the formula (3) is a group having ends (a) and (b) selected from group (II), end (a) binds to M or Q and end (b) binds to M or J;
G and Q each stands for a group selected from group (III) consisting of:
wherein n is an integer of 1 to 12, and each of q, r, and s is an integer of 1 to 8.
According to the present invention, there is also provided use of the triphenodioxazine compound represented by the formula (1) as a dichroic dye.
According to the present invention, there is also provided a method for preparing the triphenodioxazine compound represented by the formula (1) comprising reacting a dianilide compound represented by the formula (4) with an acid chloride represented by the formula (5) to have said dianilide compound undergo ring closure and to esterify at least one hydroxyl or methoxy group of the dianilide compound with said acid chloride:
wherein each of Z
1
to Z
4
stands for a hydroxyl group, a methoxy group, or a group represented by the formula (3) with at least one of Z
1
to Z
4
being a hydroxyl or a methoxy group; X is the same as X in the formula (1)
wherein h is an integer of 1 to 2; each of A, E, and G is the same as A, E, and G in the formula (2), respectively.
According to the present invention, there is also provided a liquid crystal composition comprising at least one triphenodioxazine compound represented by the formula (1) and a liquid-crystalline material.
REFERENCES:
patent: 52-140683 (1977-11-01), None
Ivashchenko, Alexander;Dichroic Dyes for Liquid Crystal Displays;pp. 165-337; Jan. 16, 1997.
Ashida Toru
Tanaka Toshihiko
Birch Stewart Kolasch & Birch
Patel Sudhaker B.
Raymond Richard L.
Sumitomo Chemical Company Limited
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