New insights into the liquid crystal behaviour of hydrogen-bonded mixtures provided by temperature-dependent FTIR spectroscopy

Daniel A. Paterson, Alfonso Martinez-Felipe, Suzanne M. Jansze, Antonius T. M. Marcelis, John M. D. Storey, Corrie T. Imrie*

*Corresponding author for this work

Research output: Contribution to journalArticle

40 Citations (Scopus)

Abstract

The phase behaviour of equimolar mixtures of 6-(4'-cyanobiphenyl-4-yl)hexyloxybenzoic acid (CB6OBA) with either 1-(4-butylazobenzene-4'-oxy)-5-(4-oxypyridine)pentane (BuABO5OPyr) or 1-(4-butylazobenzene-4'-oxy)-6-(4-oxypyridine)hexane (BuABO6OPyr) is reported. CB6OBA shows a monotropic twist-bend nematic phase and an enantiotropic nematic phase whereas the two pyridyl-based components do not exhibit liquid crystallinity. Both equimolar mixtures (CB6OBA/BuABOnOPyr) show enantiotropic nematic phases. The nematic-isotropic transition temperature and associated entropy change are higher for the CB6OBA/BuABO6OPyr mixture than for the CB6OBA/BuABO5OPyr mixture. This may be accounted for in terms of the average shapes of the hydrogen-bonded 1:1 complexes formed between the two differing components in the mixtures. However, Fourier transform infrared spectroscopy reveals that this complex is not formed quantitatively, 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.

Original languageEnglish
Pages (from-to)928-939
Number of pages12
JournalLiquid Crystals
Volume42
Issue number5-6
Early online date25 Jun 2015
DOIs
Publication statusPublished - 2015

Keywords

  • liquid crystal dimers
  • variable temperature FTIR
  • hydrogen bonding
  • twist-bend nematic
  • low molar-mass
  • side-chain
  • carboxylic-acids
  • benzoic acids
  • amorphous polymers
  • pyridyl moieties
  • IR-spectra
  • dimers
  • phase
  • complexes

Cite this

New insights into the liquid crystal behaviour of hydrogen-bonded mixtures provided by temperature-dependent FTIR spectroscopy. / Paterson, Daniel A.; Martinez-Felipe, Alfonso; Jansze, Suzanne M.; Marcelis, Antonius T. M.; Storey, John M. D.; Imrie, Corrie T.

In: Liquid Crystals, Vol. 42, No. 5-6, 2015, p. 928-939.

Research output: Contribution to journalArticle

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abstract = "The phase behaviour of equimolar mixtures of 6-(4'-cyanobiphenyl-4-yl)hexyloxybenzoic acid (CB6OBA) with either 1-(4-butylazobenzene-4'-oxy)-5-(4-oxypyridine)pentane (BuABO5OPyr) or 1-(4-butylazobenzene-4'-oxy)-6-(4-oxypyridine)hexane (BuABO6OPyr) is reported. CB6OBA shows a monotropic twist-bend nematic phase and an enantiotropic nematic phase whereas the two pyridyl-based components do not exhibit liquid crystallinity. Both equimolar mixtures (CB6OBA/BuABOnOPyr) show enantiotropic nematic phases. The nematic-isotropic transition temperature and associated entropy change are higher for the CB6OBA/BuABO6OPyr mixture than for the CB6OBA/BuABO5OPyr mixture. This may be accounted for in terms of the average shapes of the hydrogen-bonded 1:1 complexes formed between the two differing components in the mixtures. However, Fourier transform infrared spectroscopy reveals that this complex is not formed quantitatively, 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.",
keywords = "liquid crystal dimers, variable temperature FTIR, hydrogen bonding, twist-bend nematic, low molar-mass, side-chain, carboxylic-acids, benzoic acids, amorphous polymers, pyridyl moieties, IR-spectra, dimers, phase, complexes",
author = "Paterson, {Daniel A.} and Alfonso Martinez-Felipe and Jansze, {Suzanne M.} and Marcelis, {Antonius T. M.} and Storey, {John M. D.} and Imrie, {Corrie T.}",
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T1 - New insights into the liquid crystal behaviour of hydrogen-bonded mixtures provided by temperature-dependent FTIR spectroscopy

AU - Paterson, Daniel A.

AU - Martinez-Felipe, Alfonso

AU - Jansze, Suzanne M.

AU - Marcelis, Antonius T. M.

AU - Storey, John M. D.

AU - Imrie, Corrie T.

N1 - Disclosure statement No potential conflict of interest was reported by the authors.

PY - 2015

Y1 - 2015

N2 - The phase behaviour of equimolar mixtures of 6-(4'-cyanobiphenyl-4-yl)hexyloxybenzoic acid (CB6OBA) with either 1-(4-butylazobenzene-4'-oxy)-5-(4-oxypyridine)pentane (BuABO5OPyr) or 1-(4-butylazobenzene-4'-oxy)-6-(4-oxypyridine)hexane (BuABO6OPyr) is reported. CB6OBA shows a monotropic twist-bend nematic phase and an enantiotropic nematic phase whereas the two pyridyl-based components do not exhibit liquid crystallinity. Both equimolar mixtures (CB6OBA/BuABOnOPyr) show enantiotropic nematic phases. The nematic-isotropic transition temperature and associated entropy change are higher for the CB6OBA/BuABO6OPyr mixture than for the CB6OBA/BuABO5OPyr mixture. This may be accounted for in terms of the average shapes of the hydrogen-bonded 1:1 complexes formed between the two differing components in the mixtures. However, Fourier transform infrared spectroscopy reveals that this complex is not formed quantitatively, 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.

AB - The phase behaviour of equimolar mixtures of 6-(4'-cyanobiphenyl-4-yl)hexyloxybenzoic acid (CB6OBA) with either 1-(4-butylazobenzene-4'-oxy)-5-(4-oxypyridine)pentane (BuABO5OPyr) or 1-(4-butylazobenzene-4'-oxy)-6-(4-oxypyridine)hexane (BuABO6OPyr) is reported. CB6OBA shows a monotropic twist-bend nematic phase and an enantiotropic nematic phase whereas the two pyridyl-based components do not exhibit liquid crystallinity. Both equimolar mixtures (CB6OBA/BuABOnOPyr) show enantiotropic nematic phases. The nematic-isotropic transition temperature and associated entropy change are higher for the CB6OBA/BuABO6OPyr mixture than for the CB6OBA/BuABO5OPyr mixture. This may be accounted for in terms of the average shapes of the hydrogen-bonded 1:1 complexes formed between the two differing components in the mixtures. However, Fourier transform infrared spectroscopy reveals that this complex is not formed quantitatively, 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.

KW - liquid crystal dimers

KW - variable temperature FTIR

KW - hydrogen bonding

KW - twist-bend nematic

KW - low molar-mass

KW - side-chain

KW - carboxylic-acids

KW - benzoic acids

KW - amorphous polymers

KW - pyridyl moieties

KW - IR-spectra

KW - dimers

KW - phase

KW - complexes

U2 - 10.1080/02678292.2015.1037122

DO - 10.1080/02678292.2015.1037122

M3 - Article

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SP - 928

EP - 939

JO - Liquid Crystals

JF - Liquid Crystals

SN - 0267-8292

IS - 5-6

ER -