Non-symmetric liquid crystal dimers based on 1,3,4-oxadiazole derivatives: synthesis, photoluminescence and liquid crystal behaviour

Abstract

A series of non-symmetric liquid crystal compounds consisting of two different semi-rigid anisometric cores, namely 1,3,4-oxidiazole and biphenyl units, and two short terminal groups, have been synthesised in good yield. It has been shown by polarising optical microscopy and differential scanning calorimetry that all these compounds display liquid crystalline behaviour, with nematic and/or smectic A mesophases. The nature of the mesophases is dependent on the electronic properties of the terminal groups. In methylene chloride solution all the compounds displayed a room temperature emission with λ_max at 358–396 nm and quantum yields of 0.29–0.56. The effect of the terminal groups on the mesomorphic and photoluminescent properties is briefly discussed in the context of their electronic characteristics.

Keywords:

• liquid crystal dimer
• photoluminescence
• 1,3,4-oxadiazole
• synthesis

Acknowledgements

This study was financially supported by grants from the Open Project of the State Key Laboratory of Supramolecular Structure and Materials (SKLSSM200908) and from the National Natural Science Foundation of China (No. 20772064).