Effects of 1,3,4-oxadiazoles with different rigid cores on the thermal and electro-optical performances of liquid crystalline blue phases

Abstract

A series of symmetrically 2,5-disubstituted 1,3,4-oxadiazoles with different rigid cores were synthesised under the microwave irradiation based on green chemistry and atom economy. The induced blue phase (BP) behaviours of these bent-shaped compounds were investigated after blending them with a high twisted power chiral dopant or doping them into the chiral nematic liquid crystal (N*LC). It was found that the BP ranges varied greatly with the difference in the rigid cores of 2,5-disubstituted 1,3,4-oxadiazoles, and the bent-shaped molecules with higher miscibility and twisted molecular conformation significantly contribute to the stabilisation of BPs. In addition, the electro-optical performances of pure BPs and polymer-stabilised BPs in the systems containing 1,3,4-oxadiazoles with different rigid cores were also explored, which shows that the Kerr constant decreases after being polymerised and varies with the doping of the compounds possessing different rigid cores in the polymerised mixtures.

Keywords:

• 1,3,4-oxadiazoles
• blue phase
• temperature range
• electro-optical performances

Acknowledgements

We thank AU Optronics Corporation for providing the cells and performing electro-optic performance testing. This work was supported by the China Postdoctoral Science Foundation (Grant No. 20100470205), Fundamental Research Funds for the Central Universities of China (Grant No. 06103024), the National Natural Science Foundation Youth Fund of China (Grant No. 61007016), the National Natural Science Fund for Distinguished Young Scholar (Grant No. 51025313) and the National Natural Science Foundation (Grant Nos. 50973010 and 51173003).