The synthesis and mesomorphic properties of liquid crystals with bulky terminal groups designed for bookshelf geometry ferroelectric mixtures

Radini, Ibrahim A.; Hird, Michael

Abstract

The synthesis and mesomorphic properties of a systematic range of ortho difluoroterphenyls with a bulky terminal chain are detailed. The bulky terminal chain consists of either a tertiarybutyl group or a trimethylsilyl unit, each separated from the core by a short (dimethylene) chain, with the other terminal chain being either octyloxy or heptyl. The synthesis of the materials was affected efficiently using a combination of low temperature lithiations and palladium-catalysed cross-coupling reactions. Unusually for liquid crystals with bulky terminal chains, the smectic phase stability (particularly smectic C) is upheld by more than the nematic phase stability, and in most cases the smectic C phase stability is actually higher than comparable analogues with conventional unbranched terminal chains. It is postulated that the surprisingly high smectic C phase stability results from a phase separation effect due to the incompatibility of the spherical bulky group and the conventional unbranched terminal chain, hence implying that the smectic 'layers' are well defined, and such definition of the layers bodes well for bookshelf geometry in ferroelectric mixtures.

Citation

Radini, I. A., & Hird, M. (2009). The synthesis and mesomorphic properties of liquid crystals with bulky terminal groups designed for bookshelf geometry ferroelectric mixtures. Liquid crystals, 36(12), 1417-1430. https://doi.org/10.1080/02678290903268328

• Journal Article Type: Article
• Acceptance Date: Aug 18, 2009
• Online Publication Date: Dec 14, 2009
• Publication Date: 2009-12
• Journal: LIQUID CRYSTALS
• Print ISSN: 0267-8292
• Publisher: Taylor and Francis
• Peer Reviewed: Peer Reviewed
• Volume: 36
• Issue: 12
• Article Number: PII 917778275
• Pages: 1417-1430
• DOI: https://doi.org/10.1080/02678290903268328
• Keywords: Tertiary butyl; Trimethylsilyl; Smectic C; Phase separation
• Public URL: https://hull-repository.worktribe.com/output/395909
• Publisher URL: https://www.tandfonline.com/doi/abs/10.1080/02678290903268328