Dichroic dyes from attaching two mono-, dis- or tris-azo dyes to a linear polycyclic aromatic linker and liquid-crystal compositions amp; elements therefrom

摘要

A dichroic azo dye of general formula [I]: [wherein D 1 and D 2 each represents an optionally substituted phenyl group or an aromatic heterocyclic group; W represents a connecting group comprising a linear polycyclic aromatic group; X represents a group selected from the group consisting of -OCH 2 -, -CH 2 O-, -OOC-, -COO-, -CH 2 NR-, and -NRCH 2 -, where R represents a hydrogen atom or a methyl group; Z 1 to Z 12 each represents a hydrogen atom, a halogen atom, a methyl group, or a methoxy group, or Z 2 and Z 3 , Z 5 and Z 6 , Z 8 and Z 9 , and Z 11 and Z 12 are bonded to each other to form an aliphatic ring, an aromatic ring, or a nitrogen-containing aromatic ring; and m and n each represents a number of 0 to 2] as well as a liquid-crystal composition containing the above dye and a liquid-crystal element employing the composition are disclosed. This invention has application in liquid crystal displays, such as in automotive display panels. W is preferably an optionally substituted 4,4'-biphenylene, 2,6-naphthylene, 2,6-anthracylene, 2,7-phenanthrylene, or 4,4''-p-terphenylene group.