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Substituted Azolium Disposition: Examining the Effects of Alkyl Placement on Thermal Properties

Center for Multidimensional Carbon Materials (CMCM), Institute for Basic Science (IBS), Ulsan 44919, Korea
Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 40, 48149 Münster, Germany
UNIST Central Research Facilities (UCRF) and School of Natural Science, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Korea
Department of Chemistry, UNIST, Ulsan 44919, Korea
Department of Energy Engineering, UNIST, Ulsan 44919, Korea
Authors to whom correspondence should be addressed.
These authors contributed equally to this work.
Crystals 2019, 9(1), 34;
Received: 23 December 2018 / Revised: 4 January 2019 / Accepted: 6 January 2019 / Published: 11 January 2019
(This article belongs to the Special Issue Ionic Liquid Crystals)
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We describe the thermal phase characteristics of a series of 4,5-bis(n-alkyl)azolium salts that were studied using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), polarized-light optical microscopy (POM), and synchrotron-based small- to wide-angle X-ray scattering (SWAXS) measurements. Key results were obtained for 1,3-dimethyl-4,5-bis(n-undecyl)imidazolium iodide (1-11), 1,3-dimethyl-4,5-bis(n-pentadecyl)imidazolium iodide (1-15), and 1,2,3-trimethyl-4,5-bis(n-pentadecyl)imidazolium iodide (2), which were found to adopt enantiotropic smectic A mesophases. Liquid-crystalline mesophases were not observed for 1,3-dimethyl-4,5-bis(n-heptyl)imidazolium iodide (1-7), 3-methyl-4,5-bis(n-pentadecyl)thiazolium iodide (3), and 2-amino-4,5-bis(n-pentadecyl)imidazolium chloride (4). Installing substituents in the 4- and 5-positions of the imidazolium salts appears to increase melting points while lowering clearing points when compared to data reported for 1,3-disubstituted analogues. View Full-Text
Keywords: liquid crystals; ionic liquid crystals; ionic liquids; imidazolium; thiazolium; mesophases liquid crystals; ionic liquid crystals; ionic liquids; imidazolium; thiazolium; mesophases

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Goossens, K.; Rakers, L.; Shin, T.J.; Honeker, R.; Bielawski, C.W.; Glorius, F. Substituted Azolium Disposition: Examining the Effects of Alkyl Placement on Thermal Properties. Crystals 2019, 9, 34.

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