Ester type banana-shaped liquid crystalline monomers: Synthesis and physical properties

Katalin Fodor-Csorba, Anikó Vajda, Antal Jákli, Christian Slugov, Gregor Trimmel, Dietrich Demus, Eszter Gács-Baitz, Sándor Holly, Giancarlo Galli

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Abstract

New ester-type banana (bent-shaped) monomers, 1,3-phenylene bis[4′-(alken-1-yloxy)-biphenyl-4-carboxylate]s Ia-Vb, with different substituent(s) on the central phenyl ring (H, CH3, Cl or NO 2) and alkenyl tails in the side arms (decenyl or undecenyl) were prepared. The analogues IIIa-IVb with 4-chloro- or 4,6-dichloro-substituents exhibited a nematic phase, while Va,Vb with 2-nitro-substituent showed a B 7 phase at relatively low temperature. All the compounds were stable, no degradation or polymerization was observed under applied electric fields or heat treatments. Electro-hydrodynamic instabilities were observed in the nematic phase of each sample. In the B7 phase of Vb there was an electro-optical switching in the range 112-114.5 °C with a switching time of about 150 μs at 20 V μm-1 field. At lower temperatures no electro-optical switching occurred, but a ferroelectric-type spontaneous polarization of 22 nC cm-2 could be detected. The bend angle was calculated by the semiempirical CAChe/MOPAC/PM5 method.

Original languageEnglish
Pages (from-to)2499-2506
Number of pages8
JournalJournal of Materials Chemistry
Volume14
Issue number16
DOIs
Publication statusPublished - Aug 21 2004

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ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Chemistry

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