STRUCTURAL STUDIES OF COLUMNAR PHASES OF SOME CHIRAL DISK-LIKE MOLECULES

We have performed a structural study of the mesophases of some isomeri c hexa-substituted phenanthrenes. Evidence for a new hexagonal columna r mesophase with three columns per unit cell was found in a chiral iso mer. Moreover, a rectangular columnar phase with four columns per latt ice, similar to the low temperature mesophase of a hexa-substituted ru figallol, ws found in a different material. The relations between the structures and the electro-optical behaviour of the different mesophas es are discussed.