The role of hydrogen bonding in the phase behaviour of supramolecular liquid crystal dimers

Alfonso Martinez-Felipe*, Corrie T. Imrie

*Corresponding author for this work

Research output: Contribution to journalArticle

60 Citations (Scopus)

Abstract

The phase behaviour of equimolar mixtures of 4-octyloxybenzoic acid, OOBA, and either 1-(4-butylazobenzene-4'-oxy)-6-(4-oxypyridine)pentane, BuABO5OPyr, or 1-(4-butylazobenzene-4'-oxy)-6-(4-oxypyridine)hexane, BuABO6OPyr, is reported. OOBA exhibits enantiotropic smectic C and nematic phases, whereas BuABO5OPyr and BuABO6OPyr are not liquid crystalline. Both the OOBA/BuABO5OPyr and OOBA/BuABO6OPyr equimolar mixtures show an enantiotropic smectic A phase identified using Xray diffraction and polarised light microscopy. The liquid crystallinty of the mixtures is attributed, in part, to the formation of a 1:1 hydrogen-bonded complex between OOBA and either BuABO5OPyr or BuA-BO60Pyr. Differences in the transitional properties of the mixtures are accounted for in terms of the average shapes of these 1:1 complexes. Temperature dependent FTIR spectroscopy shows, however, that the formation of the complex is not quantitative in the mixtures but instead a complex mixture exists over the complete temperature range studied, involving the 1:1 complex, both cyclic and open acid dimers, free acid and hence, free BuABOnOPyr molecules. (C) 2015 Elsevier B.V. All rights reserved.

Original languageEnglish
Pages (from-to)429-437
Number of pages9
JournalJournal of Molecular Structure
Volume1100
Early online date1 Aug 2015
DOIs
Publication statusPublished - 15 Nov 2015

Keywords

  • Liquid crystal dimers
  • Hydrogen bonding
  • Temperature variable FTIR
  • Supramolecular liquid crystals
  • Low molar-mass
  • Side-chain
  • Pyridyl moieties
  • Carboxylic-acid
  • Molecular-orientation
  • Amorphous polymers
  • FTIR spectroscopy
  • IR-spectra
  • Oligomers
  • Mixtures

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