PHASMID AND BIFORKED MESOGENS WITH THIOBENZOATE END-GROUPS

One phasmid and fourteen biforked mesogens with thiobenzoate end groups have been synthesized and studied. The phasmid displays a hexagonal columnar phase with a lattice parameter a = 45.5 angstrom at 70-degrees-C. This phase is not observed for the biforked mesogens which exhibit only a nematic phase, a smectic C phase for short chains and an unknown phase for long chains. The tilt angle of the molecules in the smectic C phase is about 50-degrees (the layer thickness is 38.2 angstrom for a molecular length l = 61 angstrom in the case of IA (n = 12). The crystal structure of compound IB (n = 12) is monoclinic and the molecules adopt a zigzag form.