Heterocyclic pyridine-based liquid crystals: synthesis and mesomorphic properties

Lay Khoon Ong, Sie Tiong Ha*, Guan Yeow Yeap, Hong-Cheu Lin

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

A series of new calamitic liquid crystals, 4-{[(pyridin-4-yl)methylidene]amino}phenyl 4-alkoxybenzoates comprising a heterocyclic (pyridine) and two phenyl rings core system, terminal alkoxy chain, imine and ester linkers were synthesised and characterised. This series consists of nine members wherein the members differ by the length of alkoxy chain (CnH2n+1O–, where n = 2, 4, 6, 8, 10, 12, 14, 16, 18). Spectral analysis results were in accordance with the expected structure. Their thermotropic behaviours were studied by using differential scanning calorimetry, optical polarising microscopy and powder X-ray diffraction techniques. A single mesophase (nematic) was observed for the first three members of the series (n = 2, 4 and 6). As the alkoxy chain increased to n = 8 and n = 10, the nematic phase appeared together with an additional smectic A (SmA) phase. When moving from n = 12 until the highest members (n = 18), the nematic phase disappeared and these compounds only exhibited a single mesophase (SmA).

Original languageEnglish
Pages (from-to)1574-1584
Number of pages11
JournalLiquid Crystals
Volume45
Issue number11
DOIs
StatePublished - 2 Sep 2018

Keywords

  • Pyridine
  • enantiotropic
  • nematic
  • smectic A

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