scholarly journals Synthesis and mesomorphic properties of nonsymmetric liquid crystalline dimers containing azobenzene groups

2009 ◽  
Vol 82 (3) ◽  
pp. 228-239 ◽  
Author(s):  
Md Lutfor Rahman ◽  
Jahimin Asik ◽  
Sandeep Kumar ◽  
Sidik Silong ◽  
Mohd Zaki Ab Rahman
Keyword(s):  
Liquid Crystalline ◽  
Mesomorphic Properties ◽  
Azobenzene Groups

Synthesis and Characterization of a Novel Liquid Crystalline Polymer Bearing Azobenzene

2011 ◽  
Vol 181-182 ◽  
pp. 47-50
Author(s):  
Xin De Tang ◽  
Ye Chen ◽  
Xin Wang ◽  
Fa Qi Yu ◽  
Mei Shan Pei
Keyword(s):  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Gel Permeation Chromatography ◽  
Crystalline Polymer ◽  
Side Chain ◽  
Scanning Calorimetry ◽  
Polymer Bearing ◽  
Mesomorphic Properties ◽  
Azobenzene Groups

A novel liquid crystalline polymer bearing azobenzene groups in both main chain and side chain has been successfully synthesized by atom transfer radical polymerization (ATRP). Dual bromide-terminated azobenzene was used as the initiator for the ATRP of azobenzene-containing monomer (M6C). The structure of the resulting polymer was confirmed by nuclear magnetic resonance (NMR), and the molecular weight and its dispersity was characterized by gel permeation chromatography (GPC). The mesomorphic properties of this novel polymer were characterized by means of polarized optical microscopy (POM) and differential scanning calorimetry (DSC). The results demonstrated that this polymer can form mesophases.

2000 Macromolecular Science and Engineering Award LectureThe versatility of azobenzene polymers

2001 ◽  
Vol 79 (7) ◽  
pp. 1093-1100 ◽  
Author(s):  
Almeria Natansohn ◽  
Paul Rochon
Keyword(s):  
Liquid Crystalline ◽  
Surface Deformation ◽  
Polymer Structure ◽  
Light Polarization ◽  
Polymer Materials ◽  
Science And Engineering ◽  
Crystalline Polymers ◽  
The Third ◽  
Macroscopic Motion ◽  
Azobenzene Groups

The well-known trans–cis–trans photoisomerization of azobenzenes produces at least three different kinds of motion in the polymer materials to which the azobenzenes are bound. The first is a photoinduced motion of the azobenzene groups only, and they can align in a selected position with respect to the light polarization. The second is a macroscopic motion of huge amounts of polymeric material, producing surface deformation, and the third is a reorganization of smectic domains in liquid crystalline polymers. These motions and their consequences are briefly discussed in relation to the polymer structure and some possible photonic applications are mentioned.Key words: photoinduced orientation, azobenzene polymers, surface gratings, photonics, thermochromism, photochromism, photorefractivity, photoinduced chirality and switching.

Photophysical, electrochemical, and mesomorphic properties of a liquid-crystalline [60]fullerene–peralkylated ferrocene dyad

2008 ◽  
Vol 18 (13) ◽  
pp. 1504 ◽  
Author(s):  
Stéphane Campidelli ◽  
Marjorie Séverac ◽  
David Scanu ◽  
Robert Deschenaux ◽  
Ester Vázquez ◽  
...  
Keyword(s):  
Liquid Crystalline ◽  
Mesomorphic Properties

Liquid Crystalline Properties of 4,4and#39;-methylenebis(N-(4-Alkanoxybenzylidene)aniline): Synthesis, Characterization, and Theoretical study

2019 ◽  
Vol 41 (6) ◽  
pp. 1107-1107
Author(s):  
Mohammed Taha Yaseen and Abdullah Hussein Kshash Mohammed Taha Yaseen and Abdullah Hussein Kshash
Keyword(s):  
Liquid Crystalline ◽  
Theoretical Study ◽  
Basis Set ◽  
Spectroscopic Techniques ◽  
Benzene Nucleus ◽  
Crystal Properties ◽  
Ft Ir ◽  
Alkoxy Groups ◽  
Gaussian Program ◽  
Mesomorphic Properties

The paper presents six homologues series of Schiff bases ether compounds distinguished by the length of terminal alkoxy groups which substituted on a side benzene nucleus. The above structures were demonstrated through the use of spectroscopic techniques, like FT- IR and 1H-NMR. Polarized hot stage optical microscopy was used to study both mesomorphic properties and phase transitions. The results showed that out of the six compounds only three (B2, B3 and B4) were pure (marble) nematic mesophase, while no liquid crystal properties for (B5, B6 and B7) compounds. The theoretical study for the electronic structures was intended to study the effects of alkyl chain length on the electronic structure by using Gaussian program, DFT and 6-31G as basis set. The theoretical results indicate that there is no effect to the terminal substituted alkoxy groups on the HOMO energies but there is an effect on LUMO energies through decreasing energy for the prepared compounds.

scholarly journals Mesomorphic properties of liquid crystalline compounds with chalconyl central linkage in two phenyl rings

2017 ◽  
Vol 26 (3) ◽  
pp. 46-54 ◽  
Author(s):  
Vinay S. Sharma ◽  
Rajesh H. Vekariya ◽  
Anuj S. Sharma ◽  
R. B. Patel
Keyword(s):  
Liquid Crystalline ◽  
Phenyl Rings ◽  
Mesomorphic Properties

scholarly journals Synthesis and mesomorphic properties of calamitic malonates and cyanoacetates tethered to 4-cyanobiphenyls

2012 ◽  
Vol 8 ◽  
pp. 371-378 ◽  
Author(s):  
Katharina C Kress ◽  
Martin Kaller ◽  
Kirill V Axenov ◽  
Stefan Tussetschläger ◽  
Sabine Laschat
Keyword(s):  
Differential Scanning Calorimetry ◽  
Ambient Temperature ◽  
Liquid Crystalline ◽  
X Ray Diffraction ◽  
Cyanoacetic Acid ◽  
Scanning Calorimetry ◽  
Isotropic Liquid ◽  
X Ray ◽  
Nematic Phases ◽  
Mesomorphic Properties

4-Cyano-1,1'-biphenyl derivatives bearing ω-hydroxyalkyl substituents were reacted with methyl 3-chloro-3-oxopropionate or cyanoacetic acid, giving liquid-crystalline linear malonates and cyanoacetates. These compounds formed monotropic nematic phases at 62 °C down to ambient temperature upon cooling from the isotropic liquid. The mesomorphic properties were investigated by differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction (WAXS).

scholarly journals Discotic Liquid Crystals Based on Cu(I) Complexes with Benzoylthiourea Derivatives Containing a Perfluoroalkyl Chain

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Monica Iliş ◽  
Viorel Cîrcu
Keyword(s):  
Liquid Crystalline ◽  
Large Temperature ◽  
Discotic Liquid Crystals ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Polarized Optical Microscopy ◽  
X Ray ◽  
Ir And Nmr Spectroscopy ◽  
Hexagonal Columnar ◽  
Mesomorphic Properties

Mesomorphic three-coordinate copper(I) complexes ([Cu(BTU)2X], where X = Cl or Br) based on a new N-benzoylthiourea (BTU) ligand with two decyloxy and one perfluorooctyl groups at its periphery were designed and prepared. The BTU ligand coordinates via the S atom in a neutral monodentate fashion as confirmed by IR and NMR spectroscopy data. The liquid crystalline behavior of these copper(I) complexes was investigated by a combination of polarized optical microscopy (POM), differential scanning calorimetry (DSC), and X-ray diffraction analysis (XRD), while their thermal stability was studied by thermogravimetric analysis (TGA). These new copper(I) complexes have mesomorphic properties and exhibit a hexagonal columnar mesophase over a large temperature range, more than 100°C.

scholarly journals Chiral liquid-crystalline polyacrylates from (S)-(-)-2-methyl-1-butanol. Synthesis, mesomorphic properties and light scattering

2001 ◽  
Vol 12 (2) ◽  
pp. 184-191 ◽  
Author(s):  
Aloir A. Merlo ◽  
Olga M. S. Ritter ◽  
Fabiano V. Pereira ◽  
Carolina H. Vieira ◽  
Nádya P. da Silveira
Keyword(s):  
Light Scattering ◽  
Liquid Crystalline ◽  
Mesomorphic Properties

scholarly journals Synthesis and Mesomorphic Properties of Novel Bent-shaped Naphthyl Diketones

2019 ◽  
Vol 92 (2) ◽  
pp. 173-179 ◽  
Author(s):  
Anđela Buljan ◽  
Anamarija Knežević ◽  
Irena Dokli ◽  
Andreja Lesac
Keyword(s):  
Thermal Behaviour ◽  
Nematic Phase ◽  
Liquid Crystalline ◽  
Molecular Packing ◽  
Broad Temperature Range ◽  
Structural Modifications ◽  
Temperature Range ◽  
Mesomorphic Properties

The synthesis and liquid-crystalline properties are reported for novel naphthyl-based diketones incorporating variant terminal chains and lateral fluoro- substitution. Newly prepared materials exhibit a broad temperature range of the nematic phase. The study demonstrates how subtle structural modifications can be exploited to alter the efficiency of molecular packing and consequently the thermal behaviour.

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.

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