Influence of terminal substituent on non-linear S-shaped oligomers consisting of azobenzene moieties at the peripheral arm: Synthesis, characterisation and phase transition behaviour

Guan Yeow Yeap*, Faridah Osman, Keisuke Ito, Daisuke Takeuchi, Chien Min Lin, Hong-Cheu Lin

*Corresponding author for this work

研究成果: Article同行評審

1 引文 斯高帕斯(Scopus)

摘要

A series of symmetrical S-shaped mesogens based on 4,4′-bis-(6-bromohexyloxy)biphenyl as a central unit containing two 2-{6-[4-(4-substitutedphenylazo)phenoxy]hexyloxy}phenol as side-chain groups has been successfully synthesised. The terminal substituent was varied from halogen (X = F, Cl, Br and I) to non-halogen (X = C2H5 and OC2H5). The oligomers with C2H5 and OC2H5 substituents exhibit predominantly the monotropic nematic (N) phase. The OC2H5-containing derivatives possess long-range stability of N phase than its C2H5-containing analogue in which it has small range of N phase stability. As for halogen-containing analogues, oligomer with F exhibits monotropic N phase whilst oligomers with Cl and Br exhibit monotropic N and smectic A (SmA) phases. In addition, homologue with Br shows additional phase which is smectic B (SmB) phase upon further cooling. However, the oligomers in which F, Cl and Br were substituted by I exhibits purely monotropic SmA and SmB phases. X-ray diffraction measurements reveal that the smectic phase is inclined to the monolayer structure.

原文English
頁(從 - 到)809-821
頁數13
期刊Liquid Crystals
44
發行號5
DOIs
出版狀態Published - 9 四月 2017

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