Paramagnetic iron-containing ionic liquid crystals

Wang X, Valldor M, Spielberg ET, Heinemann FW, Meyer K, Mudring AV (2020)

Publication Type: Journal article

Publication year: 2020

Journal

Journal of Molecular Liquids Elsevier

Book Volume: 304

Article Number: 112583

DOI: 10.1016/j.molliq.2020.112583

Abstract

Iron-containing ionic liquid crystals of N,N′-dialkylimidazolium salts ([(CnH2n+1)2IM]3[Fe(CN)6], with n = 12 (1), 14 (2), 16 (3), 18 (4), IM = imidazolium) were prepared and their structures and properties were characterized. Differential scanning calorimetry (DSC), polarizing optical microscopy (POM) as well as powder X-ray diffraction (PXRD) analysis reveal for all compounds thermotropic liquid crystalline behavior. The observed textures point to smectic A and smectic X phases. The crystal structure of the solvate [C12C12IM]3[Fe(CN)6]·2 DMSO (DMSO = dimethylsulfoxide) was examined by single crystal X-ray diffraction analysis which reveals two crystallographically independent [C12C12IM]+ cations with different conformation, U-shape and rod-shape, together with a nearly ideal octahedral [Fe(CN)6]3− anion and two DMSO solvent molecules. The crystal packing is characterized by alternating bilayers of almost linearly arranged imidazolium cations with the U-shaped cations being arranged in a head-to-head fashion and the cations' hydrophobic dodecyl chains being interdigitated. Magnetic measurements for compounds 1–4 show paramagnetic moments, μeff, of ~1.7 μB, which are close to the theoretically expected value for a d5 low-spin Fe3+ spin-only S = 1/2 system (μeff s.o. = 1.73 μB). It was possible to obtain an Fe3+ containing ILC material that combines liquid crystalline behavior over a large mesophase window (from 33 °C to 170 °C) with high magnetic susceptibility by mixing compound 3 with [C16C16IM][FeCl4] (5), which contains the d5 high-spin Fe3+ ion (S = 5/2). All compounds are highly hydrophobic and stable in the atmosphere indicating a great potential of applications as functional materials.

Authors with CRIS profile

Frank Wilhelm Heinemann Lehrstuhl für Anorganische und Allgemeine Chemie Karsten Meyer Lehrstuhl für Anorganische und Allgemeine Chemie

Involved external institutions

Northeastern University / 东北大学 CN China (CN) Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden e.V. (IFW) / Leibniz Institute for Solid State and Materials Research Dresden DE Germany (DE) Ruhr-Universität Bochum (RUB) DE Germany (DE)

How to cite

APA:

Wang, X., Valldor, M., Spielberg, E.T., Heinemann, F.W., Meyer, K., & Mudring, A.V. (2020). Paramagnetic iron-containing ionic liquid crystals. Journal of Molecular Liquids, 304. https://dx.doi.org/10.1016/j.molliq.2020.112583

MLA:

Wang, Xinjiao, et al. "Paramagnetic iron-containing ionic liquid crystals." Journal of Molecular Liquids 304 (2020).

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