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

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-...

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Bibliographic Details
Published in:Liquid crystals 2015-09, Vol.42 (9), p.1337-1349
Main Authors: Alshargabi, Arwa, Yeap, Guan-Yeow, Mahmood, Wan Ahmad Kamil, Han, Chun-Chieh, Lin, Hon-Cheu, Takeuchi, Daisuke
Format: Article
Language:English
Subjects:
1,2,3-triazole-cholesterol
azobenzene
Chemical compounds
Chemical reactions
Chemical synthesis
chiral nematic
Derivatives
Dimers
Liquid crystal polymers
Liquid crystals
Molecules
non-symmetrical liquid crystals
Phase transitions
Phases
Shape memory alloys
smectic
Spacers
Surface layer
Temperature effects
Texture
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Summary: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-(4ʹ-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.
ISSN:0267-8292
1366-5855
DOI:10.1080/02678292.2015.1052998