Dichroic dye liquid crystal composition containing the dye, and liquid-crystal element

A liquid-crystal composition comprising a liquid-crystal compound and a dichroic azo dye represented by general formula (I):

• ##STR42## wherein D.sup.1 and D.sup.2 each represents an optionally substituted phenyl group or an aromatic heterocyclic group;
• W represents a connecting group comprising a linear polycyclic aromatic group selected from 4,4'-biphenylene, 2,6-naphthylene, 2,6-anthracylene, 2,7-phenanthrylene or 4,4"-p-terphenylene which each may have one or more substituents;
• X represents a group selected from the group consisting of--OCH.sub.2 --, --CH.sub.2 O--, --OOC--, --COO--, --CH.sub.2 NR--and--NRCH.sub.2 --, where R represents a hydrogen atom or a methyl group;
• Z.sup.1 to Z.sup.12 each represents a hydrogen atom, a halogen atom, a methyl group or a methoxy group, or Z.sup.2 and Z.sup.3, Z.sup.5 and Z.sup.6, Z.sup.8 and Z.sup.9 and Z.sup.11 and Z.sup.12 are bonded to each other to form an aliphatic ring or an aromatic ring;
• and m and n each represents a number of 0 to 2.

A liquid-crystal element which comprises a liquid-crystal composition sandwiched between two substrates each having an electrode, at least one of said electrode-possessing substrates being transparent, the liquid-crystal composition comprising a liquid-crystal compound and a dichroic azo dye represented by general formula (I):

• ##STR43## wherein D.sup.1 and D.sup.2 each represents an optionally substituted phenyl group or an aromatic heterocyclic group;
• W represents a connecting group comprising a linear polycyclic aromatic group selected from 4,4'-biphenylene, 2,6-naphthylene, 2,6-anthracylene, 2,7-phenanthrylene or 4,4"-p-terphenylene which each may have one or more substituents;
• X represents a group selected from the group consisting of--OCH.sub.2 --, --CH.sub.2 O--, --OOC--, --COO--, --CH.sub.2 NR--and--NRCH.sub.2 --, where R represents a hydrogen atom or a methyl group;
• Z.sup.1 to Z.sup.12 each represents a hydrogen atom, a halogen atom, a methyl group or a methoxy group, or Z.sup.2 and Z.sup.3, Z.sup.5 and Z.sup.6, Z.sup.8 and Z.sup.9 and Z.sup.11 and Z.sup.12 are bonded to each other to form an aliphatic ring or an aromatic ring;
• and m and n each represents a number of 0 to 2.