Synthesis and mesomorphism of ether-ester mixed tail C_3-symmetrical truxene discotic liquid crystals

摘要

Truxene discotic liquid crystals are interesting for their polymesomorphism and as organic semiconductor candidates. We developed an efficient synthetic method for C_3-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[OOCC_6H_2(OC_nH_2n+1)_3]_3 were prepared. The truxene discogens HTn (n=4-8, 10, 12) were characterised by using ~1H and ~(13)C 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.