New Series of Biforked Mesogens Derived from 3,4-Dialkoxycinnamic Acid and 3-(3′4′-Dialkoxyphenyl)Propanoic Acid

Four series of biforked or polycatenar mesogens derived from 3,4-dialkoxycinnamic or 3-(3′,4′-dialkoxyphenyl)propanoic acids are described. These derivatives exhibit an extremely complex polymorphism including lamellar and columnar mesophases as well as nematic and cubic and some unidentified phases. X-Ray measurements have given the first evidence for a thermotropic rhombohedral mesophase. The relationships between the polymorphism and molecular structure are discussed.