Synthesis and mesomorphism of ether–ester mixed tail C₃-symmetrical truxene discotic liquid crystals

Abstract

Truxene discotic liquid crystals are interesting for their polymesomorphism and as organic semiconductor candidates. We developed an efficient synthetic method for C₃-symmetrical truxene derivative 2,7,12-trihydroxy-3,8,13-trimethoxytruxene 5, and further a series of ether–ester mixed tail truxene discogens HTn, TR(OMe)₃[OOCC₆H₂(OC_nH_2n+1)₃]₃ were prepared. The truxene discogens HTn (n = 4–8, 10, 12) were characterised by using ¹H and ¹³C nuclear magnetic resonance, and high-resolution mass spectrometry. Their thermal stability was studied with thermal gravimetric analysis and their liquid crystal properties were investigated by using polarising optical microscopy, differential scanning calorimetry and X-ray diffraction. They exhibit a hexagonal columnar (Col_h) mesophase in fairly wide temperature ranges.

Keywords:

• truxene
• discotic liquid crystal
• columnar mesophase
• mixed tail discogen

Acknowledgement

This research was supported by the National Nature Science Foundation of China (contract numbers 50811140156, 20872104, 50973076).