scholarly journals NMR Spectroscopic Study of Orientational Order in Imidazolium-Based Ionic Liquid Crystals

Crystals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 495 ◽  
Author(s):  
Jing Dai ◽  
Debashis Majhi ◽  
Boris B. Kharkov ◽  
Sergey V. Dvinskikh
Keyword(s):  
Ionic Liquid ◽  
Liquid Crystals ◽  
Structural Model ◽  
Orientational Order ◽  
Smectic Layer ◽  
Charge Delocalization ◽  
Smectic A ◽  
Counter Ions ◽  
Bonding Properties ◽  
Ionic Liquid Crystals

We report on molecular and local orientational order of a series of imidazolium-based ionic liquid crystals exhibiting layered smectic A mesophase. Materials constituting of 1-dodecyl-3-methylimidazolium cation, and different counter-ions, were investigated. We apply two-dimensional 13C-1H dipolar NMR spectroscopy to quantify orientational order of C-H bonds of the organic cation. The experimental data supported the structural model of the interdigitated chains aligned with the smectic layer normal. Molecular order parameter S was found to increase in the anion sequence BF4− < I− < Br− < Cl−. This trend correlates well with ionic radius, negative charge delocalization, and hydrogen-bonding properties of the anions.

scholarly journals Ion conformation and orientational order in a dicationic ionic liquid crystal studied by solid-state nuclear magnetic resonance spectroscopy

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Debashis Majhi ◽  
Sergey V. Dvinskikh
Keyword(s):  
Ionic Liquid ◽  
Ionic Liquids ◽  
Liquid Crystals ◽  
Bond Order ◽  
Van Der Waals ◽  
Orientational Order ◽  
Smectic Phase ◽  
Side Chains ◽  
Dicationic Ionic Liquid ◽  
Ionic Liquid Crystals

AbstractIonic liquids crystals belong to a special class of ionic liquids that exhibit thermotropic liquid-crystalline behavior. Recently, dicationic ionic liquid crystals have been reported with a cation containing two single-charged ions covalently linked by a spacer. In ionic liquid crystals, electrostatic and hydrogen bonding interactions in ionic sublayer and van der Waals interaction in hydrophobic domains are the main forces contributing to the mesophase stabilization and determining the molecular orientational order and conformation. How these properties in dicationic materials are compared to those in conventional monocationic analogs? We address this question using a combination of advanced NMR methods and DFT analysis. Dicationic salt 3,3′-(1,6-hexanediyl)bis(1-dodecylimidazolium)dibromide was studied. Local bond order parameters of flexible alkyl side chains, linker chain, and alignment of rigid polar groups were analyzed. The dynamic spacer effectively “decouples” the motion of two ionic moieties. Hence, local order and alignment in dicationic mesophase were similar to those in analogous single-chain monocationic salts. Bond order parameters in the side chains in the dicationic smectic phase were found consistently lower compared to double-chain monocationic analogs, suggesting decreasing contribution of van der Waals forces. Overall dication reorientation in the smectic phase was characterized by low values of orientational order parameter S. With increased interaction energy in the polar domain the layered structure is stabilized despite less ordered dications. The results emphasized the trends in the orientational order in ionic liquid crystals and contributed to a better understanding of interparticle interactions driving smectic assembly in this and analogous ionic mesogens.

Effect of counter ions on the mesogenic ionic N-phenylpyridiniums

CrystEngComm ◽  
2018 ◽  
Vol 20 (18) ◽  
pp. 2593-2607 ◽  
Author(s):  
Ren-Tzong Wang ◽  
Gene-Hsiang Lee ◽  
Chung K. Lai
Keyword(s):  
Ionic Liquid ◽  
Liquid Crystals ◽  
Counter Ions ◽  
Ionic Liquid Crystals ◽  
Mesomorphic Properties

Two series of ionic liquid crystals (ILCs) derived from N-phenylpyridinium 1–2 were prepared and their mesomorphic properties were investigated.

scholarly journals NMR Spectroscopic Studies of Cation Dynamics in Symmetrically-Substituted Imidazolium-Based Ionic Liquid Crystals

2020 ◽  
Vol 21 (14) ◽  
pp. 5024
Author(s):  
Debashis Majhi ◽  
Andrei V. Komolkin ◽  
Sergey V. Dvinskikh
Keyword(s):  
Ionic Liquid ◽  
Liquid Crystals ◽  
Liquid Crystalline ◽  
Orientational Order ◽  
Soft Materials ◽  
Spectroscopic Studies ◽  
Single Chain ◽  
Self Assembling ◽  
Ionic Liquid Crystals ◽  
Cation Size

Ionic liquid crystals (ILCs) present a new class of non-molecular soft materials with a unique combination of high ionic conductivity and anisotropy of physicochemical properties. Symmetrically-substituted long-chain imidazolium-based mesogenic ionic liquids exhibiting a smectic liquid crystalline phase were investigated by solid state NMR spectroscopy and computational methods. The aim of the study was to reveal the correlation between cation size and structure, local dynamics, and orientational order in the layered mesophase. The obtained experimental data are consistent with the model of a rod-shaped cation with the two chains aligned in opposite directions outward from the imidazolium core. The alignment of the core plane to the phase director and the restricted conformations of the chain segments were determined and compared to those in single-chain counterparts. The orientational order parameter S~0.5–0.6 of double-chain ionic liquid crystals is higher than that of corresponding single-chain analogues. This is compatible with the enhanced contribution of van der Waals forces to the stabilization of smectic layers. Increased orientational order for the material with Br− counterions, which exhibit a smaller ionic radius and higher ability to form hydrogen bonds as compared to that of BF4−, also indicated a non-negligible influence of electrostatic and hydrogen bonding interactions. The enhanced rod-shape character and higher orientational order of symmetrically-substituted ILCs can offer additional opportunities in the design of self-assembling non-molecular materials.

First Examples of de Vries-like Smectic A to Smectic C Phase Transitions in Ionic Liquid Crystals

ChemPhysChem ◽  
2016 ◽  
Vol 17 (24) ◽  
pp. 4116-4123 ◽  
Author(s):  
Nadia Kapernaum ◽  
Carsten Müller ◽  
Svenja Moors ◽  
M. Christian Schlick ◽  
Eugen Wuckert ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Phase Transitions ◽  
Liquid Crystals ◽  
Smectic A ◽  
Smectic C ◽  
De Vries ◽  
Ionic Liquid Crystals

Viologen-based ionic liquid crystals: induction of a smectic A phase by dimerisation

2014 ◽  
Vol 16 (11) ◽  
pp. 5048-5051 ◽  
Author(s):  
Girolamo Casella ◽  
Valerio Causin ◽  
Federico Rastrelli ◽  
Giacomo Saielli
Keyword(s):  
Ionic Liquid ◽  
High Temperature ◽  
Liquid Crystals ◽  
Smectic A ◽  
Smectic A Phase ◽  
Ionic Liquid Crystals

Not just a tale of tails. Viologen dimer salts of bistriflimide exhibit rich mesomorphism, including a high temperature SmA phase which is not observed for the corresponding monomers.

Cyanobiphenyl versus Alkoxybiphenyl: Which Mesogenic Unit Governs the Mesomorphic Properties of Guanidinium Ionic Liquid Crystals?

2014 ◽  
Vol 67 (7) ◽  
pp. 1088 ◽  
Author(s):  
Johannes Christian Haenle ◽  
Manuel M. Neidhardt ◽  
Stuart Beardsworth ◽  
Jochen Kirres ◽  
Angelika Baro ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Liquid Crystals ◽  
Head Group ◽  
Substitution Pattern ◽  
Smectic A ◽  
Mesophase Formation ◽  
Mesogenic Unit ◽  
Ionic Liquid Crystals ◽  
Mesomorphic Properties ◽  
Thermal Stability Of

A series of phenylguanidinium salts 3·X, which are linked via an alkoxy spacer either to a 4-decyloxy- or 4-cyano-substituted biphenyl mesogen, was prepared and the mesomorphism studied. A decyloxybiphenyl core and a spacer of at least C6 chain length were required for mesophase formation. Replacement of the chloride counterion by other anions like bromide or tetrafluoroborate improved the thermal stability of the mesophase. A comparison of substitution pattern (meta v. para) on the phenyl ring revealed decreased melting and clearing points for the bent cationic head group. All guanidinium ionic liquid crystals 3 displayed only smectic A (SmA) phases. A packing model is assumed where the molecules in a bilayer stack over each other in opposite direction with interdigitated terminal decyloxy groups and spacers.

Tyrosine-Based Ionic Liquid Crystals: Switching from a Smectic A to a Columnar Mesophase by Exchange of the Spherical Counterion

2016 ◽  
Vol 22 (46) ◽  
pp. 16494-16504 ◽  
Author(s):  
Manuel M. Neidhardt ◽  
Manpreet Wolfrum ◽  
Stuart Beardsworth ◽  
Tobias Wöhrle ◽  
Wolfgang Frey ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Liquid Crystals ◽  
Smectic A ◽  
Ionic Liquid Crystals

Molecular dynamics and electrical conductivity of Guanidinium based ionic liquid crystals: Influence of cation headgroup configuration

2021 ◽  
Vol 330 ◽  
pp. 115666
Author(s):  
Mohamed A. Kolmangadi ◽  
Arda Yildirim ◽  
Kathrin Sentker ◽  
Martin Butschies ◽  
Andrea Bühlmeyer ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Electrical Conductivity ◽  
Ionic Liquid ◽  
Liquid Crystals ◽  
Ionic Liquid Crystals

Liquid-crystalline behaviour and electrorheological effect of phthalocyanine-based ionic liquid crystals

2020 ◽  
pp. 1-10
Author(s):  
Aikebaier Reheman ◽  
Shuangying Hu ◽  
Lianjun Cao ◽  
Danhua Xie ◽  
Guiyang Yan ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Liquid Crystals ◽  
Liquid Crystalline ◽  
Electrorheological Effect ◽  
Ionic Liquid Crystals
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