Novel triphenylene derivatives with acylthiosemicarbazide group: studies the influence of multiple H-bonding on mesomorphic properties

Abstract

Series of triphenylene derivatives with multiple NH groups 3a, 3b, 4a, 4b, 5a and 5b were designed and synthesised by simple procedures in high yields. Their structures were confirmed by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), mass spectrometry (MS) and elemental analysis. Their mesophase behaviours were studied by differential scanning calorimetry, polarising optical microscopy and X-ray diffraction. The triphenylene derivatives 3a and 3b with two NH groups and triphenylene derivatives 4a and 4b with three NH groups possess excellent mesomorphic properties. Compounds 4a and 4b exhibited wider mesophase than compounds 3a and 3b. Triphenylene derivatives 5a and 5b with five NH groups have no mesomorphic properties. These results suggested the units of hydrogen bonds played the crucial roles on mesomorphic properties and acylthiosemicarbazide group with three NH groups was a good functional group for producing excellent mesomorphic properties.