Substituted tetrabenzocyclophanes as mesogenic units of new polycondensates exhibiting columnar mesophases

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Abstract
Recently a new family of flexible mesogens has been described namely hexa-alkylated derivatives of cyclotetraveratrylene. We have functionalized these compounds, obtaining monofunctionalized and bifunctionalized derivatives with heptyloxy side groups. A model dimer and polycondensates were synthesized. Calorimetric data as well as optical data prove that they exhibit columnar meso-phases. At this point it is not clear whether the conformation of the mesogenic units in the mesophase is tetragonal pyramidic with all of the mesogens being extended in one direction or discotic because of the high internal flexibility of the mesogenic core. The synthesis of the model dimer and the polycondensates as well as the calorimetric and optical data are the subject of this article.