NEW SWITCHABLE COLUMNAR LIQUID-CRYSTALS

Penta- and hexa-substituted phenanthrenes and penta-substituted benzo[ c]-phenanthrenes have been synthesized; these exhibit columnar phases and are electrically switchable when bearing chiral side chains. The l iquid crystalline and electro-optical properties are described. A stro ng tri-state switching behaviour is observed with the phenanthrene der ivatives. A helical phase structure, responsible for this switching be haviour, is proposed and the possible mechanism of the columnar phase switching process is discussed.