Issue 12, 2007

Intercalated liquid-crystalline phases formed by symmetric dimers with an α,ω-diiminoalkylene spacer

Abstract

Four series of symmetric, dimeric molecules with flexible α,ω-diiminoalkylene spacers have been synthesised and characterised by polarising optical microscopy, differential scanning calorimetry, and X-ray diffraction. The effects on the mesomorphism of the various alkylene spacer (number of methylene units m = 5 to 8) as well as the terminal alkoxy chain length (n = 4 to 14) on the mesomorphic properties have been studied. The compounds with an even-numbered spacer display, in addition to a nematic phase, various smectic phases whose nature depends on the ratio between the length of the terminal chain and the length of the spacer (n/m). A modulated Smà phase was found for the ratio n/m = 1 to 1.6 and a SmC/crystal G polymorphism emerges at n/m > 1.7. In contrast, all liquid-crystalline dimers with odd-numbered spacers display an intercalated B6 phase regardless of the chain length. The preference for intercalated structures is discussed based on dipolar considerations following electronic structure calculations using a model molecule.

Graphical abstract: Intercalated liquid-crystalline phases formed by symmetric dimers with an α,ω-diiminoalkylene spacer

Supplementary files

Article information

Article type
Paper
Submitted
30 Aug 2006
Accepted
11 Dec 2006
First published
09 Jan 2007

J. Mater. Chem., 2007,17, 1154-1165

Intercalated liquid-crystalline phases formed by symmetric dimers with an α,ω-diiminoalkylene spacer

M. Šepelj, A. Lesac, U. Baumeister, S. Diele, H. L. Nguyen and D. W. Bruce, J. Mater. Chem., 2007, 17, 1154 DOI: 10.1039/B612517D

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