Non-symmetrical liquid crystal dimers armed with azobenzene and 1,2,3-triazole-cholesterol

作者：Alshargabi Arwa; Yeap Guan Yeow^*; Mahmood Wan Ahmad Kamil; Han Chun Chieh; Lin Hon Cheu; Takeuchi Daisuke

来源：Liquid Crystals, 2015, 42(9): 1337-1349.

DOI：10.1080/02678292.2015.1052998

• non-symmetrical liquid crystals
• azobenzene
• 1,2,3-triazole-cholesterol
• smectic
• chiral nematic

New non-symmetrical dimers which contain respective side units of azobenzene and 1,2,3-triazole-choloesteral have been synthesised from the reaction between 6-azido-[4-(4-acetylphenylazo)phenoxy]alkane and cholesteryl-4-(prop-2-ynyloxy)benzoate. The results show that the derivatives of 6-bromo[4-(4-acetylphenylazo)phenoxy]alkanes which possess the odd alkyl spacers exhibit dimesomorphism of N and SmA phases whilst the members with even numbers are non-mesogenic. However, the 6-azido-[4-(4-acetylphenylazo)phenoxy]-alkanes show N and SmA phases in a wide temperature range. On heating and cooling the target compounds cholesteryl 4-[(1-(6-(4-(4'-acetylphenylazo)phenoxy)alkyl)-1H-1,2,3-triazol-4-yl)methoxy]benzoate show chiral nematic (oily streak and fan-shaped texture) and focal conic texture characteristics of smectic A phases with high thermal stability. Present investigation also reveals the effect of the spacer length upon the phase transition temperature. Intercalated arrangement is favoured by the molecules in the smectic phase. The observation is well established by XRD measurement wherein the actual molecular length is smaller than the theoretical value.

• 出版日期2015-9-2