Heterocyclic 1,3-Oxazepine Based Liquid Crystals : Synthesis and Mesomorphic Behaviour Oxazepine Compounds Containing Various Substituted Seven Membered Ring

The investigation of LCs containing heterocyclic units has attracted much attention in recent years due to their wide range of structural templates, in the design and synthesis of new mesogenic molecules. The introduction of heterocyclic rings into core structure to generate mesogenic material has been well demonstrated. The presence of heteroatom may have a strong effect on the polarity and polarizability of the molecule. The angle of rotation between its fragments and thereby on the temperatures of the phase transitions. In addition, the heteroatoms may participate in intermolecular interactions and affect the type of mesophase. Finally, by influencing the direction and magnitude of the dipole moment constant of the molecule, the heteroatom may affect the sign and magnitude of the dielectric anisotropy of LC. This information encourages us to build up the 1,3- oxazepine-diones which a seven-membered heterocyclic ring system contain two carbonyl groups. However, the modification of oxazepine core as liquid-crystalline compounds was not well documented.