Synthesis, liquid crystalline properties and fluorescence of polycatenar 1,3,4‐oxadiazole derivatives

Abstract

A series of hexacatenar liquid crystals containing the 1,3,4‐oxadiazole group as rigid core, i.e. 1,4‐bis[(3,4,5‐trialkoxyphenyl)‐1,3,4‐oxadiazolyl]‐ benzene (P‐P‐oxd‐n), were designed and synthesised. Based on a detailed study of their thermotropic phase behaviour and mesophase structures, it was revealed that columnar phases are generated in these materials. Furthermore, combination of experimental and calculated results enabled a proposal for the molecular packing in the mesophase. The photoluminescent properties of these materials were examined using P‐P‐oxd‐8 as an example. A strong blue light emission (λ_max = 456 nm) was observed in P‐P‐oxd‐8 and a higher quantum yield was obtained in dilute chloroform solution.

Keywords:

• polycatenar liquid crystals
• columnar mesophase
• fluorescence
• 1,3,4‐oxadiazole derivatives

Acknowledgement

Haitao Wang would like to thank Dr. Renfan Shao and Arthur Klittnick for helpful discussions. This work was supported by Program for New Century Excellent Talents in Universities of China Ministry of Education, Special Foundation for PhD Program in Universities of China (MOE, Project No. 20050183057), Project 985‐Automotive Engineering of Jilin University, and the State Scholarship Fund from the China Scholarship Council.