Structural studies of a new series of biforked mesogens derived from 3,4 dialkoxy cinnamic acid and 3-(3,4 dialkoxy-phenyl) propanoic acid

Structural studies of selected homologues of some new series of biforked mesogens have been performed by X-ray diffraction methods. These series exhibit a thermotropic mesomorphism which shows some similarities with lyotropics. We have identified three different mesophases with large three dimensional lattice cells (i.e. body centred cubic, hexagonal and rhombohedral). The occurrence of such mesophases is related to the core flexibility; moreover, the chain to core length ratio is one of the main parameters that drive the thermotropic polymorphism, playing a role similar to that of the solvent concentration in a lyotropic system. However the symmetries as well as the lattice constants, in units of molecular size, appear to be different in the two cases owing to differences in their chemical architecture.