Thioether-linked benzylideneaniline-based twist-bend nematic liquid crystal dimers: Insights into spacer lengths, mesogenic arm structures, and linkage types

The first examples of thioether-linked benzylideneaniline-based liquid crystal dimer homologues, namely symmetric N-(4-cyanobenzylidene)aniline-based homologues [i.e., (CN)BASnSBA(CN)] and unsymmetric N-(4-cyanobenzylidene)aniline- and 4-cyanobiphenyl-based homologues [i.e., (CN)BASnSCB] possessing different alkylene spacers (CnH2n, n = 3, 5, 6, 7, 9, and 11) were synthesized and characterized. The odd-n (CN)BASnSBA(CN) and (CN)BASnSCB homologues formed twist-bend nematic (N-TB) phases below the temperatures of conventional nematic (N) phases upon cooling. Remarkably, the N-TB phases of the unsymmetric (CN)BASnSCB (n = 3, 5, 7, and 9) homologues were supercooled below room temperature and vitrified as the N-TB glass phases. The impacts of the N-(4-cyanobenzylidene)aniline structure on the LC phase-transition behavior were revealed in terms of the spacer lengths, mesogenic arm structures (or symmetry), and linkage types. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This study synthesized and characterized thioether-linked benzylideneaniline-based liquid crystal dimer homologues, revealing a new twist-bend nematic phase and the impact of the N-(4-cyanobenzylidene)aniline structure on the liquid crystal phase-transition behavior.