scholarly journals Tuning the Liquid Crystallinity of Cholesteryl-o-Carborane Dyads: Synthesis, Structure, Photoluminescence, and Mesomorphic Properties

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 133
Author(s):  
Albert Ferrer-Ugalde ◽  
Arántzazu González-Campo ◽  
José Giner Planas ◽  
Clara Viñas ◽  
Francesc Teixidor ◽  
...  
Keyword(s):  
Liquid Crystalline ◽  
Type I ◽  
Chiral Phase ◽  
Liquid Crystallinity ◽  
Cross Metathesis ◽  
Chiral Nematic ◽  
Covalently Bonded ◽  
Blue Phase ◽  
Terminal Olefins ◽  
Mesomorphic Properties

A set of mesomorphic materials in which the o-carborane cluster is covalently bonded to a cholesteryl benzoate moiety (mesogen group) through a suitably designed linker is described. The olefin cross-metathesis between appropriately functionalized styrenyl-o-carborane derivatives and a terminal alkenyl cholesteryl benzoate mesogen (all type I terminal olefins) leads to the desired trans-regioisomer, which is the best-suited configuration to obtain mesomorphic properties in the final materials. The introduction of different substituents (R = H (M2), Me (M3), or Ph (M4)) to one of the carbon atoms of the o-carborane cluster (Ccluster) enables the tailoring of liquid crystalline properties. Compounds M2 and M3 show the chiral nematic (N*) phase, whereas M4 do not show liquid crystal behavior. Weaker intermolecular interactions in the solid M3 with respect to those in M2 may allow the liquid crystallinity in M3 to be expressed as enantiotropic behavior, whereas breaking the stronger intermolecular interaction in the solid state of M2 leads directly to the isotropic state, resulting in monotropic behavior. Remarkably, M3 also displays the blue phase, which was observed neither in the chiral nematic precursor nor in the styrenyl-cholesterol model (M5) without an o-carborane cluster, which suggests that the presence of the cluster plays a role in stabilizing this highly twisted chiral phase. In the carborane-containing mesogens (M2 and M3), the o-carborane cluster can be incorporated without destroying the helical organization of the mesophase.

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 2-Chloroalkoxy-Substituted Pentafluorinated Bistolanes as Novel Light-Emitting Liquid Crystals

Crystals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 195 ◽  
Author(s):  
Shigeyuki Yamada ◽  
Kazuya Miyano ◽  
Tomohiro Agou ◽  
Toshio Kubota ◽  
Tsutomu Konno
Keyword(s):  
Phase Transition ◽  
Liquid Crystals ◽  
Liquid Crystalline ◽  
Valuable Insight ◽  
The Novel ◽  
Light Emitting ◽  
Heating And Cooling ◽  
Chiral Nematic ◽  
Blue Phase ◽  
Insight Into

In this study, we designed and synthesized novel pentafluorinated bistolane derivatives with 2-chloropentyl or 2-chlorohexyl flexible units as novel light-emitting liquid crystals (LELCs). By measuring the phase-transition behaviors, all derivatives were found to display liquid-crystalline (LC) phases during both heating and cooling processes. Among the novel bistolanes, the S- and R-configured derivatives exhibited a chiral nematic (N*) phase with a typical Grandjean optical texture. Interestingly, the chiral derivatives also exhibited a blue phase with a typical platelet texture in a narrow temperature range (2–4 °C). Photophysical measurements revealed that the 2-chloroalkoxy-substituted pentafluorinated bistolanes exhibited intense photoluminescence (PL) both in solution and in crystalline phases. The PL characteristics, especially the maximum PL wavelength, were found to switch sensitively during the heating and cooling cycles depending on the molecular aggregates through the crystal (Cr) ⇄ N* phase transition. The 2-chloroalkoxy flexible units induced dynamic changes in the LC and PL properties, providing valuable insight into the potential of various LELCs as PL sensing materials.

Liquid crystallinity-embodied imidazolium-based ionic liquids and their chiral mesophases induced by axially chiral tetra-substituted binaphthyl derivatives

2015 ◽  
Vol 3 (16) ◽  
pp. 3960-3970 ◽  
Author(s):  
Sangbum Ahn ◽  
Shohei Yamakawa ◽  
Kazuo Akagi
Keyword(s):  
Ionic Liquids ◽  
Liquid Crystalline ◽  
The Novel ◽  
Liquid Crystallinity ◽  
Chiral Nematic ◽  
Axially Chiral ◽  
Chiral Dopants

The novel liquid crystalline ionic liquids (LCILs) were synthesised by introducing LC chains into both sides of imidazolium derivatives. The LCILs exhibited chiral nematic (N*) phases when the chiral dopants were added to the LCILs.

scholarly journals Dielectric properties and molecular motions of liquid crystal molecules in 4-(2-methylbytyl)phenyl 4-(4-octylphenyl)benzoate liquid crystal having blue phase (CE8)

2015 ◽  
Vol 33 (2) ◽  
pp. 418-429
Author(s):  
W. Otowski ◽  
G. Lewińska
Keyword(s):  
Molecular Dynamics ◽  
Liquid Crystal ◽  
Liquid Crystalline ◽  
Liquid Crystal Display ◽  
Phase System ◽  
Component System ◽  
Chiral Nematic ◽  
Phase Liquid ◽  
Blue Phase ◽  
Multi Component System

AbstractBlue phase liquid crystals exhibit unique properties which are used in the new type of display. A blue-phase liquid crystal display was first presented commercially by Samsung in 2007. The blue-phase-three-color pixel display eliminates the need for color filters. This type of display uses blue-phase multi-component liquid crystal. Considering the one-component systems, it turns out that they are stable only in a very narrow range of temperatures between the isotropic and the chiral nematic phase (about 1 K). In 2005, a wide temperature range BP multi-component system was reported by researchers from the University of Cambridge. There are still several unsolved problems left. One of them is chemical stability and reliability. Therefore, the knowledge of molecular dynamics of blue phase liquid crystal is a prerequisite for understanding of blue-phase multi-component system. Understanding the molecular dynamics of a single component liquid-crystalline blue phase system can facilitate the solution of these problems. We present the molecular dynamics investigation of 4-(2-methylbytyl)phenyl 4-(4-octylphenyl)benzoate (CE8), which may be a good candidate to form materials suitable for blue-phase liquid crystal displays.

scholarly journals Concentric chiral nematic polymeric fibers from cellulose nanocrystals

2021 ◽  
Author(s):  
Arash Momeni ◽  
Christopher M. Walters ◽  
Yi-Tao Xu ◽  
Wadood Y. Hamad ◽  
Mark J. MacLachlan
Keyword(s):  
Cellulose Nanocrystals ◽  
Liquid Crystalline ◽  
Capillary Tube ◽  
Single Domain ◽  
Cellulose Nanocrystal ◽  
Polymeric Fibers ◽  
Chiral Nematic ◽  
Chiral Nematic Structure ◽  
Crystalline Suspension

A cellulose nanocrystal liquid crystalline suspension was mixed with monomers and confined to a capillary tube. After photopolymerization, a fiber with a single-domain concentric chiral nematic structure throughout the length of the fiber was obtained.

Effect of the grain size on hysteresis of liquid-crystalline Blue Phase I

2012 ◽  
Vol 20 (6) ◽  
pp. 318 ◽  
Author(s):  
Prasenjit Nayek ◽  
Heon Jeong ◽  
Shin-Woong Kang ◽  
Seung Hee Lee ◽  
Heung-Shik Park ◽  
...  
Keyword(s):  
Grain Size ◽  
Phase I ◽  
Liquid Crystalline ◽  
Blue Phase

Thermal phase transition behaviours of the blue phase of bent-core nematogen and chiral dopant mixtures under different boundary conditions

Soft Matter ◽  
2014 ◽  
Vol 10 (41) ◽  
pp. 8224-8228 ◽  
Author(s):  
Min-Jun Gim ◽  
Gohyun Han ◽  
Suk-Won Choi ◽  
Dong Ki Yoon
Keyword(s):  
Phase Transition ◽  
Boundary Conditions ◽  
Liquid Crystalline ◽  
Isotropic Phase ◽  
Different Boundary Conditions ◽  
Various Boundary Conditions ◽  
Thermal Phase Transition ◽  
Thermal Phase ◽  
Blue Phase ◽  
Chiral Dopants

We have investigated dramatic changes in the thermal phase transition of a liquid-crystalline (LC) blue phase (BP) consisting of bent-core nematogen and chiral dopants under various boundary conditions during cooling from the isotropic phase.

scholarly journals Liquid-crystalline blue phase III and structures of broken icosahedral symmetry

1993 ◽  
Vol 48 (3) ◽  
pp. 2296-2299 ◽  
Author(s):  
Lech Longa ◽  
Werner Fink ◽  
Hans-Rainer Trebin
Keyword(s):  
Liquid Crystalline ◽  
Phase Iii ◽  
Icosahedral Symmetry ◽  
Blue Phase
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