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New pyrazolium salts as a support for Ionic liquid crystals and Ionic conductors

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Pastor, María Jesús and Sánchez, Ignacio and Campo, José A. and Schmidt, Rainer and Cano, Mercedes (2018) New pyrazolium salts as a support for Ionic liquid crystals and Ionic conductors. Materials, 11 (4). ISSN 1996-1944

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Official URL: http://dx.doi.org/10.3390/ma11040548


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Abstract

Ionic liquid crystals (ILCs) are a class of materials that combine the properties of liquid crystals (LCs) and ionic liquids (ILs). This type of materials is directed towards properties such as conductivity in ordered systems at different temperatures. In this work, we synthesize five new families of ILCs containing symmetrical and unsymmetrical substituted pyrazolium cations, with different alkyl long-chains, and anions such as Cl‾, BF₄‾, ReO₄‾, p-CH₃₋₆H₄SO₃‾(PTS) and CF₃SO₃‾ (OTf). We study their thermal behavior by polarized light optical microscopy (POM) and differential scanning calorimetry (DSC). All of them, except those with OTf as counteranion, show thermotropic mesomorphism. The observations by POM reveal textures of lamellar mesophases. Those agree with the arrangement observed in the X-ray crystal structure of [H₂pzᴿ⁽⁴⁾‚ᴿ⁽⁴⁾][ReO₄]. The nature of the mesophases is also confirmed by variable temperature powder X-ray diffraction. On the other hand, the study of the dielectric properties at variable temperature in mesomorphic (Cl‾‾and BF₄‾) and non-mesomorphic OTf) salts indicates that the supramolecular arrangement of the mesophase favors a greater ionic mobility and therefore ionic conductivity.


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© 2018 by the authors
Mercedes Cano thanks the Spanish Ministerio de Economía y Competitividad (CTQ2015-63858- ) for funding. María Jesús Pastor acknowledges the Ministerio de Economía y Competitividad for her FPI scholarship. Ignacio Sánchez acknowledges the Ministerio de Educación, Cultura y Deporte for his FPU scholarship. Rainer Schmidt wishes to express his gratitude to Alberto Rivera-Calzada, Carlos León and Jacobo Santamaría for allowing the use and assistance with the dielectric spectroscopy facilities

Uncontrolled Keywords:Assemblies; Precursors; Conductivity; Fabrication;Pyridinium; Membranes; Behavior
Subjects:Sciences > Physics > Materials
Sciences > Physics > Solid state physics
ID Code:49109
Deposited On:17 Sep 2018 14:34
Last Modified:17 Sep 2018 15:35

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