scholarly journals Tuning the photonic properties of chiral nematic mesoporous organosilica with hydrogen-bonded liquid-crystalline assemblies

2015 ◽  
Vol 3 (7) ◽  
pp. 1537-1545 ◽  
Author(s):  
Michael Giese ◽  
Tim Krappitz ◽  
Ronald Y. Dong ◽  
Carl A. Michal ◽  
Wadood Y. Hamad ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Optical Microscopy ◽  
Liquid Crystalline ◽  
Cd Spectroscopy ◽  
Polarized Optical Microscopy ◽  
Mesoporous Organosilica ◽  
Chiral Nematic ◽  
Hydrogen Bonded

The thermochromic behaviour of chiral nematic mesoporous organosilica hybrids infiltrated with hydrogen-bonded liquid crystals was investigated by polarized optical microscopy, UV-vis and CD-spectroscopy.

Temperature dependence of the pitch in chiral lyotropic chromonic liquid crystals

Soft Matter ◽  
2019 ◽  
Vol 15 (1) ◽  
pp. 109-115 ◽  
Author(s):  
Timothy Ogolla ◽  
Robert S. Paley ◽  
Peter J. Collings
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Temperature Dependence ◽  
Optical Microscopy ◽  
Helical Axis ◽  
Coexistence Region ◽  
Polarized Optical Microscopy ◽  
Chiral Nematic ◽  
Microscopy Image ◽  
Optical Microscopy Image

Polarized optical microscopy image of a fingerprint texture for a lyotropic chromonic liquid crystal entering the chiral nematic–isotropic coexistence region. The helical axis is in the plane of the image and the perpendicular distance between the stripes is around 50 μm, half the chiral nematic pitch.

scholarly journals New cholesteryl containing bent core liquid crystals

2013 ◽  
Vol 78 (5) ◽  
pp. 669-680 ◽  
Author(s):  
Cosmin-Constantin Huzum ◽  
Irina Carlescu ◽  
Gabriela Lisa ◽  
Dan Scutaru
Keyword(s):  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Optical Microscopy ◽  
Liquid Crystalline ◽  
Benzoic Acids ◽  
Scanning Calorimetry ◽  
Polarized Optical Microscopy ◽  
Acyl Chlorides ◽  
Esterification Reactions

The paper presents the synthesis and mesomorphic behavior of two new series of bent core liquid crystalline compounds based on a 1,3-dihydroxybezene core and containing a cholesteryl 6-oxyhexanoate wing. The two series were obtained by the esterification of the cholesteryl 6-(3-hydroxyphenoxy)hexanoate core with some 4-((4-(n-alkyloxy)phenyl)azo)benzoic acids (n-alkyl = n-hexyl ? n-dodecyl) or 4-(4-(n-alkyloxy)benzoyloxy)benzoic acids (n-alkyl = n-hexyl ? n-decyl). The esterification reactions were performed via the corresponding acyl chlorides or with the DCC / DMAP system. All the synthesized compounds evidenced enantiotropic liquid crystalline properties, with smectic type textures, when investigated by means of differential scanning calorimetry and polarized optical microscopy. Isotropisation and isotropic to liquid crystal transitions were relatively low (between 89 ? 1460C). The compounds containing the azo-aromatic linking group presented the largest range of stability of the mesophases (between 42 and 870C). All the investigated compounds were thermally stable in the existence range of the mesophases.

Experimental and computational (DFT) studies on induced orthogonal smectic A∗ phase in hydrogen-bonded ferroelectric liquid crystals

2018 ◽  
Vol 32 (21) ◽  
pp. 1850223 ◽  
Author(s):  
P. Subhasri ◽  
R. Jayaprakasam ◽  
V. N. Vijayakumar
Keyword(s):  
Liquid Crystals ◽  
Molecular Orbital ◽  
Density Functional ◽  
Liquid Crystalline ◽  
Proton Acceptor ◽  
Dft Studies ◽  
Ferroelectric Liquid Crystals ◽  
Smectic A ◽  
Present Complex ◽  
Hydrogen Bonded

Hydrogen-bonded ferroelectric liquid crystals (HBFLC) are designed and synthesized from nonmesogenic chiral proton donor compound of (R)-([Formula: see text])-Methylsuccinic acid (MSA) and mesogenic proton acceptor compound of 4-undecyloxybenzoic acid (11OBA) in a different mole ratio. Intermolecular hydrogen bonds (H-bond) between the nonmesogenic and mesogenic compounds have been confirmed through experimental Fourier transform infrared spectroscopy (FTIR) and density functional theory (DFT) computational studies. The steric hindrance and inductive effects of the present complex and its influence on the structure are discussed. A rich phase polymorphism in the liquid crystalline complex has been studied using polarizing optical microscope (POM) and differential scanning calorimetry (DSC). The chiral phases observed in the present complex are due to the presence of lone pair (n) to anti-bonding ([Formula: see text]) transition symmetry which is validated by DFT studies. A noteworthy observation of induced smectic A[Formula: see text](Sm A[Formula: see text]) by quenching of traditional phase (nematic) has been identified and the reason for the same has been discussed by DFT studies. The unusual phase order of Sm A[Formula: see text], smectic C[Formula: see text](Sm C[Formula: see text]) and smectic G[Formula: see text][Formula: see text](Sm G[Formula: see text]) mesogenic phases are observed. The other liquid crystalline parameters are evaluated by experimental and theoretical calculations and the same has been compared. Increased tilt angle in liquid crystal (LC) molecules has been theoretically analyzed by natural bond orbital (NBO) studies. Stability of the HBFLC phases and its origination mechanism have been discussed with the help of highest occupied molecular orbital and lowest unoccupied molecular orbital (HOMO–LUMO) energies.

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.

Synthesis and Mesomorphic Properties of a Series of Cholesteric Liquid Crystals

2010 ◽  
Vol 663-665 ◽  
pp. 759-762 ◽  
Author(s):  
Qing Lan Ma ◽  
Yuan Ming Huang
Keyword(s):  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Optical Microscopy ◽  
Scanning Calorimetry ◽  
Polarized Optical Microscopy ◽  
Phase Transition Temperatures ◽  
Second Category ◽  
Mesomorphic Properties

A series of cholesterol liquid crystal compounds was synthesized. Phase-transition temperatures and mesomorphic textures of these synthesized compounds were characterized with differential scanning calorimetry and polarized optical microscopy, respectively. In these molecules the terminal ester chains CnH2n-1COO-, where n was the number of carbon atoms in the terminal ester chains, were linked to the cholesterol core. All of the synthesized cholesterol compounds exhibited mesophases for the first heating. However, as temperature decreased from their clearing points, their micrographs can also be divided into two categories, the first category exhibits branch-like mesophase textures for n in the range of 1-10 while the second category exhibits branch-like crystal textures for n in the range of 11-18.

Synthesis and Properties of a Novel Liquid Crystalline Monomer Containing Chalcone Moiety

2011 ◽  
Vol 380 ◽  
pp. 326-330 ◽  
Author(s):  
Ji Lei Li ◽  
Wei Min Zhang ◽  
Yu Lei Zhao ◽  
Jia Ling Pu
Keyword(s):  
Thermal Properties ◽  
Liquid Crystal ◽  
Optical Microscopy ◽  
1H Nmr ◽  
Nematic Phase ◽  
Nmr Spectra ◽  
Liquid Crystalline ◽  
Crystal Temperature ◽  
Polarized Optical Microscopy ◽  
Ft Ir

A kind of novel liquid crystalline monomer containing double photosensitive groups which were azo and chalcone groups was synthesized. The structures of the intermediates and the final monomer were confirmed by FT-IR and 1H NMR spectra. The thermal properties of monomer were measured by DSC and the liquid crystalline texture was measured by polarized optical microscopy. And the results indicated that the monomer showed nematic phase and liquid crystal temperature range was 150.8-186.5oC.

Smectogenic liquid crystals and nanoparticles: an approach for potential application in photovoltaics

2015 ◽  
Vol 3 (33) ◽  
pp. 8566-8573 ◽  
Author(s):  
A. Meneses-Franco ◽  
A. E. Fierro-Armijo ◽  
P. Romero-Hasler ◽  
L. G. Salamanca-Riba ◽  
L. J. Martínez-Miranda ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Optical Microscopy ◽  
Potential Application ◽  
Planar Geometry ◽  
Wide Angle ◽  
X Ray Diffraction ◽  
Polarized Optical Microscopy ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

We synthesized monomeric liquid crystals, M6R8 and I6R8, and nanoparticles of TiO2, to form a nanocomposite, which was characterized by polarized optical microscopy (POM), DSC and structurally with both wide angle X-ray diffraction and by X-ray scattering using the planar geometry.

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.

Thermal Switching of the Reflection in Chiral Nematic Mesoporous Organosilica Films Infiltrated with Liquid Crystals

2013 ◽  
Vol 5 (15) ◽  
pp. 6854-6859 ◽  
Author(s):  
Michael Giese ◽  
Joanna C. De Witt ◽  
Kevin E. Shopsowitz ◽  
Alan P. Manning ◽  
Ronald Y. Dong ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Mesoporous Organosilica ◽  
Chiral Nematic ◽  
Thermal Switching
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