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.

Synthesis of POSS-functionalized liquid crystalline block copolymers via RAFT polymerization for stabilizing blue phase helical soft superstructures

2018 ◽  
Vol 9 (16) ◽  
pp. 2101-2108 ◽  
Author(s):  
Jianqiu Jin ◽  
Mingjie Tang ◽  
Zhenghe Zhang ◽  
Kang Zhou ◽  
Yun Gao ◽  
...  
Keyword(s):  
Phase Transition ◽  
Liquid Crystals ◽  
Block Copolymers ◽  
Liquid Crystalline ◽  
Raft Polymerization ◽  
Phase Liquid ◽  
Blue Phase

A study of the phase transition behaviors of blue phase liquid crystals containing different amounts of POSS-functionalized LC BCPs.

scholarly journals Synthesis and Characterization of Photoluminescence Liquid Crystals Based on Flexible Chain-Bearing Pentafluorinated Bistolanes

Crystals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 603
Author(s):  
Shigeyuki Yamada ◽  
Masaya Sato ◽  
Tsutomu Konno
Keyword(s):  
Phase Transition ◽  
Liquid Crystals ◽  
Oxygen Atom ◽  
Liquid Crystalline ◽  
Color Change ◽  
Photophysical Properties ◽  
Structure Property ◽  
Flexible Chain ◽  
Structure Property Relationships ◽  
Chiral Nematic

The liquid-crystalline (LC) and photophysical properties of molecules are very sensitive to their electronic and molecular aggregate structures. Herein, to shed light on the structure–property relationships of pentafluorinated bistolane-based photoluminescence (PL) liquid crystals (PLLCs) previously reported by our group, we synthesized pentafluorinated bistolanes with variable flexible chains and evaluated their LC and photophysical properties. The incorporation of an oxygen atom (to afford a 2-methoxyethoxy unit) or an oxygen atom and a methyl group (to afford a 1-methoxyprop-2-oxy unit) into the flexible butoxy chain significantly decreased the temperature of the crystalline-to-LC phase transition, and a chiral nematic phase comprising helical molecular aggregates was observed for the chiral 1-methoxyprop-2-oxy group–bearing bistolane. The synthesized bistolanes exhibited strong blue PL in both solution and crystalline phases; the featuring PL characteristics were maintained in the LC phase (produced by the crystalline-to-LC phase transition) except for a slight PL color change. Thus, it was concluded that the PL behavior of pentafluorinated bistolanes can be modulated by the choice of a suitable flexible chain, and the obtained insights are believed to facilitate the application of PLLCs in thermosensing PL materials.

scholarly journals Chiral Liquid Crystal Lenses Confined in Microchannels

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3761
Author(s):  
Sean M. Hare ◽  
Beatrice Lunsford-Poe ◽  
MinSu Kim ◽  
Francesca Serra
Keyword(s):  
Phase Transition ◽  
Liquid Crystalline ◽  
Focal Length ◽  
Topological Defects ◽  
Experimental Conditions ◽  
Smectic A ◽  
Heating And Cooling ◽  
Chiral Nematic ◽  
Nematic Phases ◽  
Tunable Lenses

It is known that the liquid crystalline smectic-A phase has geometric defects, called focal conic domains, which can be used as gradient-index microlenses. Cholesteric (chiral nematic) phases also have topological defects with a central symmetry and a singularity at their center. We explore a weakly chiral system in which both types of defects can be present in the same material at different temperatures, and with this strategy we create lenses whose focal length is tunable with temperature. We measure the focal length of the tunable lenses, and we investigate the behavior of the defects near the phase transition. We identify the experimental conditions that make the simultaneous presence of the smectic focal conic domains and the circular cholesteric domains possible, such as the concentration of chiral dopant and the rate of heating and cooling. The transformation of focal conic domains into circular cholesteric domains is a new example of memory at the phase transition between smectic-A and nematic liquid crystals.

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 Temperature-Dependent X-Ray Studies of Discotic Hexagonal Columnar Mesophases in Trinuclear Gold(I) Pyrazolate Complex

2021 ◽  
Vol 17 (3) ◽  
pp. 285-294
Author(s):  
Mohamad Azani Abd Khadir Jalani ◽  
Hendrik O. Lintang ◽  
Siew Ling Lee ◽  
Juan Matmin ◽  
Nur Fatiha Ghazalli ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Liquid Crystalline ◽  
Variable Temperature ◽  
Gold Complex ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Heating And Cooling ◽  
Depth Study ◽  
Columnar Mesophases ◽  
Hexagonal Columnar

Gold(I) pyrazolate complex ([Au3Pz3]C10TEG) has been widely studied due to its interesting liquid crystalline properties by exhibiting the discotic hexagonal columnar arrangement. Generally, the liquid crystalline properties of the gold complex were confirmed based on their differential scanning calorimetry thermogram and polarized optical microscopy (POM) images. However, there is still no in-depth study on the phase transition in liquid crystals of [Au3Pz3]C10TEG especially on its structural change at variable temperature. In this study, the resulting liquid crystalline properties of [Au3Pz3]C10TEG upon being heated and cooled was extensively demonstrated via variable-temperature POM (VT-POM) and small angle X-ray scattering (VT-SAXS). Based on the VT-POM images, it was indicated that [Au3Pz3]C10TEG displayed a fan-shaped texture for typical arrangements of discotic hexagonal columnar of liquid crystals. Moreover, VT-SAXS results was in good agreement with the VT-POM images as it showed that [Au3Pz3]C10TEG might consist of two types of stacking system, which are ordered and disordered hexagonal discotic arrangements. Likewise, VT-SAXS analysis also demonstrated that hexagonal columnar mesophase of [Au3Pz3]C10TEG could be recovered even after the heating and cooling for two cycles.

scholarly journals Order Parameters, Orientational Distribution Functions and Heliconical Tilt Angles of Oligomeric Liquid Crystals

2019 ◽  
Author(s):  
Richard Mandle ◽  
John W. Goodby
Keyword(s):  
Phase Transition ◽  
Liquid Crystals ◽  
Tilt Angle ◽  
Order Parameter ◽  
Nematic Phase ◽  
Liquid Crystalline ◽  
Thermal Evolution ◽  
Order Parameters ◽  
Distribution Functions ◽  
Orientational Distribution

We compare the order parameters, orientational distribution functions (ODF) and heliconical tilt angles of the TB phase exhibited by a liquid-crystalline dimer (CB7CB) to a tetramer (O47) and hexamer (O67) by SAXS/WAXS. Following the N-TB phase transition we find that all order parameters decrease, and while 〈P2 〉 remains positive 〈P4 〉 becomes negative. For all three materials the order parameter 〈P6 〉 is near zero in both phases. The ODF is sugarloaf-like in the nematic phase and volcano-like in the TB phase, allowing us to estimate the heliconical tilt angle of each material and its thermal evolution. The heliconical tilt angle appears to be largely independent of the material studied despite the differing number of mesogenic units.

Development of light-emitting liquid-crystalline polymers with a pentafluorinated bistolane-based luminophore

2020 ◽  
Vol 44 (15) ◽  
pp. 5684-5691 ◽  
Author(s):  
Shigeyuki Yamada ◽  
Akira Mitsuda ◽  
Kaoru Adachi ◽  
Mitsuo Hara ◽  
Tsutomu Konno
Keyword(s):  
Phase Transition ◽  
Solid State ◽  
Liquid Crystalline ◽  
Dynamic Change ◽  
Liquid Crystalline Polymers ◽  
Light Emitting ◽  
Light Blue ◽  
Crystalline Polymers ◽  
Thermal Phase Transition ◽  
Thermal Phase

Light-emitting liquid-crystalline polymers showing PL in the pristine solid state can control their PL color from blue to light-blue via a thermal phase transition to LC phases, which originates from a dynamic change of aggregated structures.

Fluorine-containing bistolanes as light-emitting liquid crystalline molecules

2017 ◽  
Vol 15 (28) ◽  
pp. 5949-5958 ◽  
Author(s):  
Shigeyuki Yamada ◽  
Kazuya Miyano ◽  
Tsutomu Konno ◽  
Tomohiro Agou ◽  
Toshio Kubota ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Liquid Crystalline ◽  
Light Emitting

Fluorine-containing dissymmetric bistolanes were found to be promising light-emitting liquid crystals, which could switch luminescence depending on molecular aggregations.

scholarly journals Critical point for the blue-phase-III–isotropic phase transition in chiral liquid crystals

1996 ◽  
Vol 53 (5) ◽  
pp. 4955-4963 ◽  
Author(s):  
Zdravko Kutnjak ◽  
Carl W. Garland ◽  
Colin G. Schatz ◽  
Peter J. Collings ◽  
Christopher J. Booth ◽  
...  
Keyword(s):  
Phase Transition ◽  
Liquid Crystals ◽  
Critical Point ◽  
Phase Iii ◽  
Isotropic Phase ◽  
Blue Phase ◽  
Chiral Liquid Crystals

Self-assembled blue-light emitting materials for their liquid crystalline and OLED applications: from a simple molecular design to supramolecular materials

2020 ◽  
Vol 5 (10) ◽  
pp. 1691-1705
Author(s):  
Vinay S. Sharma ◽  
Anuj S. Sharma ◽  
Nikhil K. Agarwal ◽  
Priyanka A. Shah ◽  
Pranav S. Shrivastav
Keyword(s):  
Liquid Crystals ◽  
Blue Light ◽  
Self Assembly ◽  
Liquid Crystalline ◽  
Molecular Design ◽  
Supramolecular Materials ◽  
Light Emitting ◽  
New Family ◽  
Self Assembled

A new family of blue-light-emitting supramolecular bowl-shaped columnar hexagonal liquid crystals based on p-tert-butylcalix[4]arene and functionalized via chalconyl–ester-linked biphenyl amine derivatives form a self-assembly and their applications.

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