Document Type

Article

Publication Version

Published Version

Publication Date

2015

Journal or Book Title

Crystal Growth & Design

Volume

15

Issue

2

First Page

752

Last Page

758

DOI

10.1021/cg501564j

Abstract

The influence of the counteranion on the ability of the mesogenic cation 1-methyl-3-dodecyl-triazolium to form mesophases is explored. To that avail, salts of the cation with anions of different size, shape, and hydrogen bonding capability such as Cl, Br, I, I3, PF6, and Tf2N [bis(trifluorosulfonyl)amide] were synthesized and characterized. The crystal structures of the bromide, the iodide, and the triiodide reveal that the cations form bilayers with cations oriented in opposite directions featuring interdigitated alkyl tails. Within the layers, the cations are separated by anions. The rod-shaped triiodide anion forces the triazolium cation to align with it in this crystal structure but due to its space requirement reduces the alkyl chain interdigitation which prevents the formation of a mesophase. Rather the compound transforms directly from a crystalline solid to an (ionic) liquid like the analogous bis(trifluorosulfonyl)amide. In contrast, the simple halides and the hexafluorophosphate form liquid crystalline phases. Their clearing points shift with increasing anion radius to lower temperatures.

Comments

Reprinted with permission from Cryst. Growth Des., 2015, 15 (2), pp 752–758. Copyright 2014 American Chemical Society.

Copyright Owner

American Chemical Society

Language

en

File Format

application/pdf

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