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

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(OCnH2n+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 (Colh) mesophase in fairly wide temperature ranges.