Issue 36, 2007
From the journal:

Journal of Materials Chemistry

The influence of shape and size of silyl units on the properties of bent-core liquid crystals—from dimers via oligomers and dendrimers to polymers†

Christina Keith,a   Gert Dantlgraber,a   R. Amaranatha Reddy,‡a   Ute Baumeister,b   Marko Prehm,ab   Harald Hahn,c   Heinrich Langc  and  Carsten Tschierske*a  

* Corresponding authors

a Institute of Chemistry, Organic Chemistry, Martin-Luther-University Halle-Wittenberg, Kurt-Mothes-Str. 2, Halle, Germany
E-mail: carsten.tschierske@chemie.uni-halle.de
Fax: +49 345 5527 346
Tel: +49 345 5525 664

b Institute of Chemistry, Physical Chemistry, Martin-Luther-University, Halle-Wittenberg, Mühlpforte 1, Halle, Germany

c Institute of Inorganic Chemistry, Technical University Chemnitz, Faculty of Sciences, Strasse der Nationen 6, Chemnitz, Germany

Abstract

A series of oligomeric and dendritic liquid crystalline materials combining mesogenic bent-core units and silicon-containing linking units (siloxanes and carbosilanes) was synthesized and investigated. The influence of the size and shape of the silyl units upon the mesophase type and the switching behaviour was investigated. Linear oligosiloxane based dimers and dendritic carbosilanes show ferroelectric and non-classical antiferroelectric switching monolayer smectic phases with dark conglomerate textures coexisting with achiral domains, whereas cyclic oligosiloxane and silsesquioxane derivatives have antiferroelectric switching and birefringent smectic phases with double layer structure. It is concluded that ferroelectricity and layer distortion require a certain size of the silyl groups and a monolayer structure where each layer is decoupled by sublayers formed by the silylated units.

Graphical abstract: The influence of shape and size of silyl units on the properties of bent-core liquid crystals—from dimers via oligomers and dendrimers to polymers

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Article information

DOI
https://doi.org/10.1039/B706923E
Article type
Paper
Submitted
08 May 2007
Accepted
25 Jun 2007
First published
11 Jul 2007

J. Mater. Chem., 2007,17, 3796-3805

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The influence of shape and size of silyl units on the properties of bent-core liquid crystals—from dimers via oligomers and dendrimers to polymers

C. Keith, G. Dantlgraber, R. A. Reddy, U. Baumeister, M. Prehm, H. Hahn, H. Lang and C. Tschierske, J. Mater. Chem., 2007, 17, 3796 DOI: 10.1039/B706923E

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