A set of novel 1,2,3-triazolium based ionic liquid crystals was synthesized and their mesomorphic behaviour studied by DSC (differential scanning calorimetry), POM (polarizing optical microscopy) and SAXS (small angle X-ray scattering). Beside the variation of the chain length (C 10 , C 12 and C 14 ) at the 1,2,3-triazolium cation also the anion has been varied (Br À , I À , I 3 À , BF 4 À , SbF 6 À , N(CN) 2 À , Tf 2 N À ) to study the influence of ion size, symmetry and H-bonding capability on the mesophase formation. Interestingly, for the 1,3didodecyl-1,2,3-triazolium cation two totally different conformations were found in the crystal structure of the bromide (U-shaped) and the triiodide (rod shaped).
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 -, I 3 -, PF 6 -, and Tf 2 N -[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. Disciplines Ceramic Materials | Complex Fluids | Other Chemical Engineering | Other Materials Science and Engineering CommentsReprinted with permission from Cryst. Growth Des., 2015, 15 (2) 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 −
A systematic study on the microwave-assisted thermolysis of the single source precursor (EtSb)Te (1) in different asymmetric 1-alkyl-3-methylimidazolium- and symmetric 1,3-dialkylimidazolium-based ionic liquids (ILs) reveals the distinctive role of both the anion and the cation in tuning the morphology and microstructure of the resulting SbTe nanoparticles as evidenced by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and X-ray photoelectron spectroscopy (XPS). A comparison of the electrical and thermal conductivities as well as the Seebeck coefficient of the SbTe nanoparticles obtained from different ILs reveals the strong influence of the specific IL, from which CmimI was identified as the best solvent, on the thermoelectric properties of as-prepared nanosized SbTe. This work provides design guidelines for ILs, which allow the synthesis of nanostructured thermoelectrics with improved performances.
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