Synthesis and mesogenic properties of novel board-like liquid crystals

The syntheses of novel octa- and tetra-substituted systems based on tetrabe nz[a, c, h, j] anthracene are reported. The disc-shaped octa- substituted m aterial exhibits a columnar mesophase, whereas the tetra- substituted mater ial exhibits a lamellar phase. Binary mixtures of the two materials were ex amined in order to explore the change over from discotic to calamitic behav iour as a function of concentration. At the crossover point, the possibilit y of the formation of a biaxial phase was investigated.