TETRAHEDRALLY SUBSTITUTED TRIBENZOSILATRANES - MESOMORPHIC PROPERTIESAND STRUCTURES

The tribenzosilatrane moiety has been substituted with four long paraf finic chains. The physicochemical properties (optical microscopy, diff erential scanning calorimetry) of the condensed phases have been deter mined as a function of the chain length. Several crystalline or mesomo rphic phases have been characterized by X-ray diffraction. In some cas es, original layered structures have been found with a hexagonal order within the lamellae. However, none of the mesophases can be attribute d to the class of plastic crystals. A globularity criterion has been d efined which relates the shape of the molecular unit with the type of arrangement in the mesophases.