Columnar self-assembly of star-shaped luminescent oxadiazole and thiadiazole derivatives

A new class of blue light emitting liquid crystalline star-shaped molecules based on 1,3,4-thiadiazoles have been designed and synthesized. These compounds were investigated using polarizing optical microscopy, differential scanning calorimetry, X-ray diffraction, cyclic voltammetry and photophysical studies. In comparison to their 1,3,4-oxadiazole counterparts, these thiadiazole-based molecules are promising as they stabilize the hexagonal columnar phases over a broad thermal range. The thermal behavior and photophysical properties of these new star-shaped molecules are extremely dependent on the number and types of peripheral tails in the molecular structure. 1,3,4-Thiadiazole derivatives exhibit sky-blue emission in solution, unlike the deep blue emission of 1,3,4-oxadiazole derivatives. They also exhibit a lower band gap as compared to their oxadiazole counterparts and offer great potential in organic light emitting diode applications.