3,5-Dialkoxy Substituted Triphenyl-tristriazolotriazines: Fluorescent Discotic Liquid Crystals

Abstract

Tristriazolotriazines with a threefold 3,5-dialkoxyphenyl substitution were prepared from the corresponding phenyltetrazoles and cyanuric chloride. These star-shaped compounds are discotic liquid crystals that form broad and stable thermotropic mesophases. The thermal behaviour was studied by DSC and polarizing optical microscopy. An increasing length of the side chains reduces the phase transition temperatures, this effect is more pronounced for the crystalline to mesophase transition than for the clearing temperature. XRD on an oriented sample revealed a hexagonal columnar structure for the mesophase. All TTTs emit a strong fluorescence in the UV-violet region.

Keywords:

• star-shaped compounds
• discotic liquid crystals
• X-ray diffraction
• differential scanning calorimetry
• polarizing optical microscopy
• fluorescence