Sulfur-linked cyanobiphenyl-based liquid crystal dimers and the twist-bend nematic phase

Ewan Cruickshank, Mirosław Salamończyk, Damian Pociecha, Grant J. Strachan, John M.D. Storey, Cheng Wang, Jun Feng, Chenhui Zhu, Ewa Gorecka, Corrie T. Imrie* (Corresponding Author)

*Corresponding author for this work

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

The synthesis and characterisation of two series of cyanobiphenyl-based liquid crystal dimers containing sulfur links between the spacer and mesogenic units, the 4ʹ-[1,ω-alkanediylbis(thio)]bis-[1,1ʹ-biphenyl]-4-carbonitriles (CBSnSCB), and 4ʹ-({ω-[(4ʹ-cyano[1,1ʹ-biphenyl]-4-yl)oxy]alkyl}thio)[1,1ʹ-biphenyl]-4-carbonitriles (CBSnOCB) are described. The odd members of both series show twist-bend nematic and nematic phases, whereas the even members exhibit only the nematic phase. An analogous cyanoterphenyl-based dimer, 34-{6-[(4ʹ-cyano[1,1ʹ-biphenyl]-4-yl)thio]-hexyl}[11,21:24,31-terphenyl]-14-carbonitrile (CT6SCB), is also reported and shows enantiotropic NTB and N phases. The transitional properties of these dimers are discussed in terms of molecular curvature, flexibility and biaxiality. The same molecular factors also influence the birefringence of nematic phases. Resonant X-ray scattering studies of the twist-bend nematic phase at both the carbon and sulfur absorption edges were performed, which allowed for the determination of critical behaviour of the helical pitch at the transition to the nematic phase, the behaviour was found to be independent of molecular structure. It was also observed that despite the different molecular bending angle and flexibility, in all compounds the helical pitch length far from the N-NTB transition corresponds to 4 longitudinal molecular distances.

Original languageEnglish
Pages (from-to)1595-1609
Number of pages15
JournalLiquid Crystals
Volume46
Issue number10
Early online date1 Aug 2019
DOIs
Publication statusPublished - 9 Aug 2019

Fingerprint

Liquid Crystals
Sulfur
Dimers
Liquid crystals
sulfur
liquid crystals
dimers
flexibility
terphenyls
Birefringence
X ray scattering
spacers
Molecular structure
birefringence
molecular structure
curvature
Carbon
carbon
synthesis
scattering

Keywords

  • birefringence
  • cyanobiphenyl
  • liquid crystal dimers
  • resonant X-ray scattering
  • sulfur linked
  • Twist-bend nematic phase
  • TRANSITIONAL PROPERTIES
  • ETHER
  • BIREFRINGENCE
  • MESOGENIC LINKING UNIT
  • OLIGOMERS
  • MOLECULES

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Chemistry(all)
  • Materials Science(all)

Cite this

Sulfur-linked cyanobiphenyl-based liquid crystal dimers and the twist-bend nematic phase. / Cruickshank, Ewan; Salamończyk, Mirosław; Pociecha, Damian; Strachan, Grant J.; Storey, John M.D.; Wang, Cheng; Feng, Jun; Zhu, Chenhui; Gorecka, Ewa; Imrie, Corrie T. (Corresponding Author).

In: Liquid Crystals, Vol. 46, No. 10, 09.08.2019, p. 1595-1609.

Research output: Contribution to journalArticle

Cruickshank, E, Salamończyk, M, Pociecha, D, Strachan, GJ, Storey, JMD, Wang, C, Feng, J, Zhu, C, Gorecka, E & Imrie, CT 2019, 'Sulfur-linked cyanobiphenyl-based liquid crystal dimers and the twist-bend nematic phase', Liquid Crystals, vol. 46, no. 10, pp. 1595-1609. https://doi.org/10.1080/02678292.2019.1641638
Cruickshank, Ewan ; Salamończyk, Mirosław ; Pociecha, Damian ; Strachan, Grant J. ; Storey, John M.D. ; Wang, Cheng ; Feng, Jun ; Zhu, Chenhui ; Gorecka, Ewa ; Imrie, Corrie T. / Sulfur-linked cyanobiphenyl-based liquid crystal dimers and the twist-bend nematic phase. In: Liquid Crystals. 2019 ; Vol. 46, No. 10. pp. 1595-1609.
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title = "Sulfur-linked cyanobiphenyl-based liquid crystal dimers and the twist-bend nematic phase",
abstract = "The synthesis and characterisation of two series of cyanobiphenyl-based liquid crystal dimers containing sulfur links between the spacer and mesogenic units, the 4ʹ-[1,ω-alkanediylbis(thio)]bis-[1,1ʹ-biphenyl]-4-carbonitriles (CBSnSCB), and 4ʹ-({ω-[(4ʹ-cyano[1,1ʹ-biphenyl]-4-yl)oxy]alkyl}thio)[1,1ʹ-biphenyl]-4-carbonitriles (CBSnOCB) are described. The odd members of both series show twist-bend nematic and nematic phases, whereas the even members exhibit only the nematic phase. An analogous cyanoterphenyl-based dimer, 34-{6-[(4ʹ-cyano[1,1ʹ-biphenyl]-4-yl)thio]-hexyl}[11,21:24,31-terphenyl]-14-carbonitrile (CT6SCB), is also reported and shows enantiotropic NTB and N phases. The transitional properties of these dimers are discussed in terms of molecular curvature, flexibility and biaxiality. The same molecular factors also influence the birefringence of nematic phases. Resonant X-ray scattering studies of the twist-bend nematic phase at both the carbon and sulfur absorption edges were performed, which allowed for the determination of critical behaviour of the helical pitch at the transition to the nematic phase, the behaviour was found to be independent of molecular structure. It was also observed that despite the different molecular bending angle and flexibility, in all compounds the helical pitch length far from the N-NTB transition corresponds to 4 longitudinal molecular distances.",
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T1 - Sulfur-linked cyanobiphenyl-based liquid crystal dimers and the twist-bend nematic phase

AU - Cruickshank, Ewan

AU - Salamończyk, Mirosław

AU - Pociecha, Damian

AU - Strachan, Grant J.

AU - Storey, John M.D.

AU - Wang, Cheng

AU - Feng, Jun

AU - Zhu, Chenhui

AU - Gorecka, Ewa

AU - Imrie, Corrie T.

N1 - Acknowledgements EG and DP acknowledge the support of the National Science Centre (Poland): (Grant Number 2016/22/A/ST5/00319). We acknowledge the use of Beamline 5.3.1 and 11.0.1.2 of the Advanced Light Source supported by the Director of the Office of Science, Office of Basic Energy Science, of The U.S. Department of Energy under contract no. DE-AC02-05CH11231. We thank Alex Liebman-Pelaez for designing the heating stage used for TReXS measurement.

PY - 2019/8/9

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N2 - The synthesis and characterisation of two series of cyanobiphenyl-based liquid crystal dimers containing sulfur links between the spacer and mesogenic units, the 4ʹ-[1,ω-alkanediylbis(thio)]bis-[1,1ʹ-biphenyl]-4-carbonitriles (CBSnSCB), and 4ʹ-({ω-[(4ʹ-cyano[1,1ʹ-biphenyl]-4-yl)oxy]alkyl}thio)[1,1ʹ-biphenyl]-4-carbonitriles (CBSnOCB) are described. The odd members of both series show twist-bend nematic and nematic phases, whereas the even members exhibit only the nematic phase. An analogous cyanoterphenyl-based dimer, 34-{6-[(4ʹ-cyano[1,1ʹ-biphenyl]-4-yl)thio]-hexyl}[11,21:24,31-terphenyl]-14-carbonitrile (CT6SCB), is also reported and shows enantiotropic NTB and N phases. The transitional properties of these dimers are discussed in terms of molecular curvature, flexibility and biaxiality. The same molecular factors also influence the birefringence of nematic phases. Resonant X-ray scattering studies of the twist-bend nematic phase at both the carbon and sulfur absorption edges were performed, which allowed for the determination of critical behaviour of the helical pitch at the transition to the nematic phase, the behaviour was found to be independent of molecular structure. It was also observed that despite the different molecular bending angle and flexibility, in all compounds the helical pitch length far from the N-NTB transition corresponds to 4 longitudinal molecular distances.

AB - The synthesis and characterisation of two series of cyanobiphenyl-based liquid crystal dimers containing sulfur links between the spacer and mesogenic units, the 4ʹ-[1,ω-alkanediylbis(thio)]bis-[1,1ʹ-biphenyl]-4-carbonitriles (CBSnSCB), and 4ʹ-({ω-[(4ʹ-cyano[1,1ʹ-biphenyl]-4-yl)oxy]alkyl}thio)[1,1ʹ-biphenyl]-4-carbonitriles (CBSnOCB) are described. The odd members of both series show twist-bend nematic and nematic phases, whereas the even members exhibit only the nematic phase. An analogous cyanoterphenyl-based dimer, 34-{6-[(4ʹ-cyano[1,1ʹ-biphenyl]-4-yl)thio]-hexyl}[11,21:24,31-terphenyl]-14-carbonitrile (CT6SCB), is also reported and shows enantiotropic NTB and N phases. The transitional properties of these dimers are discussed in terms of molecular curvature, flexibility and biaxiality. The same molecular factors also influence the birefringence of nematic phases. Resonant X-ray scattering studies of the twist-bend nematic phase at both the carbon and sulfur absorption edges were performed, which allowed for the determination of critical behaviour of the helical pitch at the transition to the nematic phase, the behaviour was found to be independent of molecular structure. It was also observed that despite the different molecular bending angle and flexibility, in all compounds the helical pitch length far from the N-NTB transition corresponds to 4 longitudinal molecular distances.

KW - birefringence

KW - cyanobiphenyl

KW - liquid crystal dimers

KW - resonant X-ray scattering

KW - sulfur linked

KW - Twist-bend nematic phase

KW - TRANSITIONAL PROPERTIES

KW - ETHER

KW - BIREFRINGENCE

KW - MESOGENIC LINKING UNIT

KW - OLIGOMERS

KW - MOLECULES

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U2 - 10.1080/02678292.2019.1641638

DO - 10.1080/02678292.2019.1641638

M3 - Article

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JO - Liquid Crystals

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SN - 0267-8292

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