Tetrahedrally substituted tribenzosilatranes: Mesomorphic properties and structures

The tribenzosilatrane moiety has been substituted with four long paraffinic chains. The physicochemical properties (optical microscopy, differential scanning calorimetry) of the condensed phases have been determined as a function of the chain length. Several crystalline or mesomorphic phases have been characterized by X-ray diffraction. In some cases, original layered structures have been found with a hexagonal order within the lamellae. However, none of the mesophases can be attributed to the class of plastic crystals. A globularity criterion has been defined which relates the shape of the molecular unit with the type of arrangement in the mesophases.