Twist-bend nematic liquid crystals based on thioether linkage

We developed twist-bend nematogens based on cyanobiphenyl dimers with thioether or sulfur linkage, as opposed to the commonly used methylene and ether linkages. Based on the smaller bond angle of thioether C-S-C than methylene C-CH2-C and ether C-O-C, we designed two dimer homologous series that are...

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Bibliographic Details
Published inNew journal of chemistry Vol. 43; no. 17; pp. 6786 - 6793
Main Authors Arakawa, Yuki, Komatsu, Kenta, Tsuji, Hideto
Format Journal Article
LanguageEnglish
Published CAMBRIDGE Royal Soc Chemistry 2019
Royal Society of Chemistry
Subjects
Chemistry
Chemistry, Multidisciplinary
Crystals
Dimers
Dipole moments
Homology
Linkages
Liquid crystals
Methylene
Nematic crystals
Physical Sciences
Science & Technology
HAMMETT SUBSTITUENT CONSTANTS
SELECTIVE REFLECTION
ORIENTATIONAL ORDER
ACIDS
PHASE-TRANSITIONS
BIREFRINGENCE
ALKYLTHIO GROUPS
NANOSCALE-PITCH
DIMERS
MOLECULES
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Summary:We developed twist-bend nematogens based on cyanobiphenyl dimers with thioether or sulfur linkage, as opposed to the commonly used methylene and ether linkages. Based on the smaller bond angle of thioether C-S-C than methylene C-CH2-C and ether C-O-C, we designed two dimer homologous series that are more bent, symmetric CBSnSCB with two thioether linkages and asymmetric CBSnOCB with a thioether and an ether linkage, containing odd carbon numbers n = 3, 5, 7, 9, and 11, and also synthesized even-n members n = 6 for each system. Both CBSnSCB with n = 3, 5 and 7 and CBSnOCB with n = 5 and 7 formed a broad range of twist-bend nematic (N-TB) phases that were stable down to room temperature and showed remarkably enhanced glass-forming ability. In addition, CBS9OCB also formed N-TB phase at a fast scan rate. DFT calculations revealed that twist-bend nematogens CBS7SCB and CBS7OCB have smaller bend angles made of the para axes of the two cyanobiphenyl moieties and larger dipole moments than those of the conventional nematogen ether-linked CBO7OCB.
ISSN:1144-0546
1369-9261
DOI:10.1039/c8nj06456c