scholarly journals The Role of Substitution in the Apex Position of the Bent-Core on Mesomorphic Properties of New Series of Liquid Crystalline Materials

Crystals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 735 ◽  
Author(s):  
Helena Skopalová ◽  
Petr Špaček ◽  
Václav Kozmík ◽  
Jiří Svoboda ◽  
Vladimíra Novotná ◽  
...  
Keyword(s):  
Liquid Crystalline ◽  
Structural Parameters ◽  
Phase Identification ◽  
Crystalline Materials ◽  
X Ray ◽  
Alkyl Chains ◽  
Calorimetric Measurements ◽  
Liquid Crystalline Materials ◽  
Mesomorphic Properties

We present the synthesis and mesomorphic properties of the new series of bent-core liquid crystals based on 3-hydroxybenzoic acid bearing a lateral substituent in the apex position. Four different substituents of various sizes and electronic properties have been used. We have found that only compounds substituted with fluorine are mesogenic and exhibit one mesophase, whose type differs when prolonging the terminal alkyl chain. For homologues with shorter alkyl chains (octyl, decyl), a columnar B1-type of a mesophase was observed, while materials with longer terminal chains (dodecyl, tetradecyl) exhibited a switchable lamellar SmCAPA phase. Calorimetric measurements, texture observations under a polarizing microscope were performed and electro-optical properties studied. Additionally, dielectric measurements were realized to characterize the molecular dynamics in the SmCAPA phase. All mesogenic compounds were further studied by X-ray measurements to confirm phase identification and obtain more information about their structural parameters.

scholarly journals Mesomorphism behaviour and photoluminescent properties of new asymmetrical 1,2-di(4-alkoxybenzylidene)hydrazines

2019 ◽  
Vol 43 (1-2) ◽  
pp. 67-77 ◽  
Author(s):  
Adil A Awad ◽  
Al-Ameen Bariz OmarAli ◽  
Ahmed Jasim M Al-Karawi ◽  
Zyad Hussein J Al-Qaisi ◽  
Samer Ghanim Majeed
Keyword(s):  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
Liquid Crystalline ◽  
Polarized Light ◽  
Luminescent Properties ◽  
Scanning Calorimetry ◽  
Crystalline Materials ◽  
X Ray ◽  
Step Procedure ◽  
Liquid Crystalline Materials

{1-[4-( n-Alkoxy)]-2-(4’-decyloxy)benzylidene}hydrazines ( n-alkoxy = O(CH2) nH, n = 1–9, 12, 16 or 18), an asymmetrical series of 1,2-disubstituted hydrazines, were prepared in a simple two-step procedure as a part of our continuing work in evaluating hydrophobic azine compounds as photoluminescent liquid crystalline materials. The compounds were characterized spectroscopically and their liquid crystalline behaviour and luminescent properties were evaluated using polarized light optical microscopy, differential scanning calorimetry and X-ray powder diffraction techniques. The studies revealed that all of these compounds are liquid crystalline materials exhibiting photoluminescent properties in the crystalline and liquid crystal states.

Lamellar Liquid Crystalline Materials Modulated by 1-Ethyl-3-Methylimidazolium Hexafluorophosphate

2014 ◽  
Vol 1025-1026 ◽  
pp. 760-764
Author(s):  
Guo Dong Zhang ◽  
Wen Chang Zhuang ◽  
Jing Tian ◽  
Chang Cheng Zhang ◽  
Long Li Zhang ◽  
...  
Keyword(s):  
Liquid Crystalline ◽  
Lamellar Phase ◽  
Tetraethylene Glycol ◽  
Imidazolium Salt ◽  
Polarized Optical Microscopy ◽  
Crystalline Materials ◽  
X Ray ◽  
X Ray Scattering ◽  
Lauryl Ether ◽  
Liquid Crystalline Materials

Liquid crystal was formed in a ternary system of tetraethylene glycol lauryl ether, water and 1-ethyl-3-methylimidazolium hexafluorophosphate. Its structure was identified by polarized optical microscopy and small-angle X-ray scattering techniques. Compared to that in the binary system, lamellar phase was retained with the addition of a small amount of imidazolium salt. Molecules of 1-ethyl-3-methylimidazolium hexafluorophosphate were considered to be solubilized in the polar domain of the ordered assemblies. Results on their influence on the lamellar phase enlighten the use of imidazolium salts to modulate liquid crystalline materials and other assemblies.

scholarly journals Thermotropic and lyotropic behaviour of new liquid-crystalline materials with different hydrophilic groups: synthesis and mesomorphic properties

2013 ◽  
Vol 9 ◽  
pp. 425-436 ◽  
Author(s):  
Alexej Bubnov ◽  
Miroslav Kašpar ◽  
Věra Hamplová ◽  
Ute Dawin ◽  
Frank Giesselmann
Keyword(s):  
Liquid Crystalline ◽  
Molecular Structures ◽  
Scanning Calorimetry ◽  
Crystalline Materials ◽  
Smectic Phases ◽  
Chiral Nematic ◽  
Nematic Phases ◽  
Liquid Crystalline Materials ◽  
Hydroxy Groups ◽  
Mesomorphic Properties

Several new calamitic liquid-crystalline (LC) materials with flexible hydrophilic chains, namely either hydroxy groups or ethylene glycol units, or both types together, have been synthesized in order to look for new functional LC materials exhibiting both, thermotropic and lyotropic behaviour. Such materials are of high potential interest for challenging issues such as the self-organization of carbon nanotubes or various nanoparticles. Thermotropic mesomorphic properties have been studied by using polarizing optical microscopy, differential scanning calorimetry and X-ray scattering. Four of these nonchiral and chiral materials exhibit nematic and chiral nematic phases, respectively. For some molecular structures, smectic phases have also been detected. A contact sample of one of the prepared compounds with diethylene glycol clearly shows the lyotropic behaviour; namely a lamellar phase was observed. The relationship between the molecular structure and mesomorphic properties of these new LCs with hydrophilic chains is discussed.

scholarly journals Introduction to Colloidal and Microfluidic Nematic Microstructures

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 956
Author(s):  
Simon Čopar ◽  
Miha Ravnik ◽  
Slobodan Žumer
Keyword(s):  
Soft Matter ◽  
Liquid Crystalline ◽  
Colloidal Particles ◽  
Topological Defects ◽  
Crystalline Materials ◽  
Inherent Anisotropy ◽  
Metastable Structures ◽  
Liquid Crystalline Materials ◽  
Mesoscopic Theory

In this brief review, we give an introduction to selected colloidal and microfluidic nematic microstructures, as enabled by the inherent anisotropy and microscopic orientational ordering in complex liquid crystalline materials. We give a brief overview of the mesoscopic theory, for equilibrium and dynamics, of nematic fluids, that provides the framework for understanding, characterization, and even prediction of such microstructures, with particular comment also on the role of topology and topological defects. Three types of nematic microstructures are highlighted: stable or metastable structures in nematic colloids based on spherical colloidal particles, stationary nematic microfluidic structures, and ferromagnetic liquid crystal structures based on magnetic colloidal particles. Finally, this paper is in honor of Noel A. Clark, as one of the world pioneers that helped to shape this field of complex and functional soft matter, contributing at different levels to works of various groups worldwide, including ours.

scholarly journals Perhydroazulene-based liquid-crystalline materials with smectic phases

2012 ◽  
Vol 8 ◽  
pp. 403-410 ◽  
Author(s):  
Zakir Hussain ◽  
Henning Hopf ◽  
S Holger Eichhorn
Keyword(s):  
Liquid Crystalline ◽  
X Ray Diffraction ◽  
Core System ◽  
Crystalline Materials ◽  
Smectic Phases ◽  
Differential Scanning Colorimetry ◽  
Temperature Ranges ◽  
Nematic Phases ◽  
Liquid Crystalline Materials ◽  
Mesomorphic Properties

New liquid-crystalline materials with a perhydroazulene core were synthesized and the stereochemistry of these compounds was investigated. The mesomorphic properties of the new LC compounds were investigated by differential scanning colorimetry, polarizing optical microscopy and X-ray diffraction. We report here on the LC properties of nonchiral materials, which predominantly exhibit smectic phases and display nematic phases only within narrow temperature ranges. The dependence of the mesogenic behavior of the new materials on the stereochemistry of the core system was also investigated. All newly synthesized compounds were fully characterized by the usual spectroscopic and analytical methods.

Thermal analysis and X-ray studies of chiral ferroelectric liquid crystalline materials and their binary mixtures

2005 ◽  
Vol 82 (2) ◽  
pp. 519-523 ◽  
Author(s):  
Dusanka Ž. Obadović ◽  
Anikó Vajda ◽  
Maya Garić ◽  
A. Bubnov ◽  
Vera Hamplová ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Binary Mixtures ◽  
Liquid Crystalline ◽  
Crystalline Materials ◽  
X Ray ◽  
Liquid Crystalline Materials

scholarly journals Chiral Photoresponsive Liquid Crystalline Materials Derived from Cyanoazobenzene Central Core: Effect of UV Light Illumination on Mesomorphic Behavior

Crystals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1161
Author(s):  
Anna Poryvai ◽  
Alexej Bubnov ◽  
Michal Kohout
Keyword(s):  
Liquid Crystalline ◽  
Uv Light ◽  
Structural Type ◽  
Optical Microscope ◽  
Light Illumination ◽  
Aromatic System ◽  
Scanning Calorimetry ◽  
Crystalline Materials ◽  
Liquid Crystalline Materials ◽  
Mesomorphic Properties

One of the most frequently utilized liquid crystalline (LC) materials is a rod-like (calamitic) compound 4-cyano-4′-pentylbiphenyl (5-CB). The main objective of this work is to enhance its functionality by introducing a photoresponsive diazenyl spacer in the aromatic core and replace the non-chiral pentyl chain with various chiral alkyl carboxylate units. The mesomorphic properties of the prepared materials have been studied using polarizing optical microscopy and differential scanning calorimetry. It has been found that materials with an extended aromatic system possess the liquid crystalline behavior. The studied LC materials have shown mesophases at lower temperatures than previously reported analogous substances. Furthermore, one of them exhibits a chiral orthogonal frustrated twist grain boundary smectic phase, which has not been previously observed for this structural type of materials. We also investigated photoresponse of the mesophases under illumination with UV-light (365 nm) using a polarizing optical microscope. A non-conventional photoresponse of the prepared materials in a crystalline phase is presented and discussed.

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