Synthesis, mesomorphic behaviour and photo-luminescent property of new mesogens containing 1,3,4-oxadiazole fluorophore

Abstract

A series of 1,3,4-oxadiazole derivatives, namely cholesteryl 4-(4-(5-(4-(alkoxy)phenyl)-1,3,4-oxadiazol-2-yl)phenylethynyl)benzoate (Ch-OXD- n , n = 6, 8, 10) and methyl 4-(4-(5-(4-(alkoxy)phenyl)-1,3,4-oxadiazol-2-yl)phenylethynyl)benzoate (Me-OXD- n , n = 6, 8, 10) were synthesised and characterised by means of ¹H NMR, ¹³C NMR, MS and HRMS. The phase behaviours of these two series of compounds have been investigated by polarising microscopic and calorimetric studies. All compounds Ch-OXD- n exhibited a cholesteric mesophase with wide mesomorphic temperature range, while the compounds Me-OXD- n displayed nematic and/or smectic A mesophases with relatively narrow temperature ranges. Both Ch-OXD- 8 and Me-OXD- 8 in chloroform individually exhibited an intense absorption band (λ_max = 330 nm) and a strong blue fluorescence emission (λ_max = 404 nm) with good photoluminescence quantum yields.

Keywords:

• heterocyclic liquid crystal
• spectroscopic property
• cholesteric mesophase
• synthesis

Acknowledgements

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