Document Type

Article

Publication Date

11-7-2017

Publication Title

Liquid Crystals

Volume

45

Issue

6

First page number:

872

Last page number:

885

Abstract

A series of extended, symmetric viologen triflimides were synthesised by the metathesis reaction of lithium triflimide with the respective viologen tosyalates in methanol. Their chemical structures were characterised by Fourier Transform Infrared, 1H and 13C Nuclear Magnetic Resonance spectroscopy and elemental analysis. Their thermotropic liquid-crystalline (LC) properties were examined by a number of experimental techniques including differential scanning calorimetry, thermogravimetric analysis, polarising optical microscopy and variable temperature X-ray diffraction. The viologen salts containing alkyl chain of two carbon and three carbon atoms were relatively low melting salts. Those of alkyl chains of four carbon and five carbon atoms formed ionic liquids at 88 and 42°C, respectively. Those of alkyl chain of 9, 10 and 11 carbon atoms were high melting salts, as high as 166°C. Those of higher alkyl chains of 16, 18 and 20 carbon atoms showed thermotropic LC phases forming SmC, SmA and an unidentified smectic (SmX) phases, and showed SmA to isotropic transitions at high temperatures. As expected, all the viologen triflimides had excellent stabilities in the temperature range of 338–365°C.

Keywords

Ionic liquid crystals; Symmetric viologens; Differential scanning calorimetry; Polarising optical microscope; Thermotropic; X-ray diffraction; Smectic A phase; Smectic C phase

Disciplines

Chemistry

File Format

application/pdf

File Size

4,168 kb

Language

English

Permissions

This is an Accepted Manuscript of an article published by Taylor & Francis in Liquid Crystals on 07 Nov 2017, available online: http://www.tandfonline.com/10.1080/02678292.2017.1397213.

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