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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 4'-[1,ω-alkanediylbis(thio)]bis-[1,1'-biphenyl]-4-carbonitriles (CBS nSCB), and 4'-({ω-[(4'-cyano[1,1'-biphenyl]-4-yl)oxy]alkyl}thio)[1,1'-biphenyl]-4-carbonitriles (CBS nOCB) 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, 3 4-{6-[(4'-cyano[1,1'-biphenyl]-4-yl)thio]-hexyl}[1 1,2 1:2 4,3 1-terphenyl]-1 4-carbonitrile (CT6SCB), is also reported and shows enantiotropic N TB 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-N TB transition corresponds to 4 longitudinal molecular distances.

Authors:
 [1];  [2]; ORCiD logo [3]; ORCiD logo [1];  [1];  [4];  [4];  [4];  [3]; ORCiD logo [1]
  1. Univ of Aberdeen, Scotland (United Kingdom). Dept. of Chemistry, School of Natural and Computing Sciences
  2. Univ. of Warsaw (Poland). Faculty of Chemistry; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)
  3. Univ. of Warsaw (Poland). Faculty of Chemistry
  4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1561902
Grant/Contract Number:  
AC02-05CH11231
Resource Type:
Accepted Manuscript
Journal Name:
Liquid Crystals
Additional Journal Information:
Journal Volume: 46; Journal Issue: 10; Journal ID: ISSN 0267-8292
Publisher:
Taylor & Francis
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Cruickshank, Ewan, Salamończyk, Mirosław, Pociecha, Damian, Strachan, Grant J., Storey, John M. D., Wang, Cheng, Feng, Jun, Zhu, Chenhui, Gorecka, Ewa, and Imrie, Corrie T. Sulfur-linked cyanobiphenyl-based liquid crystal dimers and the twist-bend nematic phase. United States: N. p., 2019. Web. doi: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. United States. doi: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, and Imrie, Corrie T. Thu . "Sulfur-linked cyanobiphenyl-based liquid crystal dimers and the twist-bend nematic phase". United States. doi:10.1080/02678292.2019.1641638.
@article{osti_1561902,
title = {Sulfur-linked cyanobiphenyl-based liquid crystal dimers and the twist-bend nematic phase},
author = {Cruickshank, Ewan and Salamończyk, Mirosław and Pociecha, Damian and Strachan, Grant J. and Storey, John M. D. and Wang, Cheng and Feng, Jun and Zhu, Chenhui and Gorecka, Ewa and Imrie, Corrie T.},
abstractNote = {The synthesis and characterisation of two series of cyanobiphenyl-based liquid crystal dimers containing sulfur links between the spacer and mesogenic units, the 4'-[1,ω-alkanediylbis(thio)]bis-[1,1'-biphenyl]-4-carbonitriles (CBSnSCB), and 4'-({ω-[(4'-cyano[1,1'-biphenyl]-4-yl)oxy]alkyl}thio)[1,1'-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-[(4'-cyano[1,1'-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.},
doi = {10.1080/02678292.2019.1641638},
journal = {Liquid Crystals},
number = 10,
volume = 46,
place = {United States},
year = {2019},
month = {6}
}

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Works referenced in this record:

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