High-pressure DTA Studies of the Phase Behaviors of 4-n -butyl-thiocyanobiphenyl (4TCB) and 4-w-pentyl-4’-n-phenyl-cyanocyclohexane (5HCP)

1999 ◽  
Vol 54 (12) ◽  
pp. 675-678 ◽  
Author(s):  
M. Massalska-Arodź ◽  
A. Würflinger ◽  
D. Büsinga
Keyword(s):  
High Pressure ◽  
Liquid Crystal ◽  
Transition Temperature ◽  
Pressure Dependence ◽  
Nematic Phase ◽  
Liquid Crystalline ◽  
Melting Curve ◽  
Liquid Crystal Phase ◽  
Dta Studies ◽  
Phase Behaviors

Abstract DTA measurements of 4-n-butyl-thiocyanobiphenyl (4TCB) and ρ-cyano-ρ’-pentylphenyl-cyclohex-ane (5HCP) have been performed in the temperature range 220 K-390 K and pressures up to 400 MPa. For 4TCP a transition from a crystalline to a liquid crystal phase (probably smectic E) could be detect-ed at higher pressures > 90 MPa. The pressure dependence of the transition temperature has been estab-lished. At pressures lower than 88.7 MPa no transition of SmE into a crystal or into a glass has been found. For 5HCP only the melting curve was observed, in contrast to 5PCH, which displays a liquid crystalline nematic phase.

scholarly journals Synthesis and Diagnosis New Metallotropic LCs from Organotin (IV) Complex

2021 ◽  
Vol 26 (1) ◽  
pp. 1-9
Author(s):  
Mohammed Hussein ◽  
Alaa Adnan Rashad ◽  
Hamsa Thamer ◽  
Alaa Mohammed ◽  
Ali H. Jawad ◽  
...  
Keyword(s):  
Phase Transition ◽  
Liquid Crystal ◽  
Transition Temperature ◽  
Nematic Phase ◽  
Liquid Crystalline ◽  
Chloride Salt ◽  
New Class ◽  
Tin Chloride ◽  
Elemental Analyses ◽  
Optical Textures

Organotin (IV) complex is part of the organometallic chemistry and in recently decades have a variety of interesting and application used it. A new class of metallomesogens LC (A) Ph3Sn(VAL), (B) Bu3Sn(VAL), (C) Ph2Sn(VAL)2 and (D) Bu2Sn(VAL)2 was synthesis through the reaction of valsartan ligand with (di- or tri- butyl tin chloride salt) and (di- or tri- phenyl tin chloride salt) in methanol solvent. 1H NMR,119 Sn NMR, FTIR and CHN elemental analyses were measure and the liquid crystalline properties were study by POM.  The mesophase in all organotin (IV) carboxylate complexes are thermotropic nematic phase. In complexes (A, C) the optical textures of A show a typical droplet texture and thread shape LC phase transition between (400-440⁰C) higher than mesophase textures in C between (230 -250⁰C). In complexes (B, D) the optical textures of B appearance a thread shape and the LC phase transition temperature between (200 -400⁰C) and in D thread shape and the transition temperature beginning up to 280⁰C. From a temperature of phase transition show that the complexes (C, D) are start liquid crystal mesophase in lower than complex (A, C) because effect of  R-group and types which due to an asymmetric arrangement of the molecule and a geometry was calamitic in which the length of the molecule is major in compare with its diameter.

scholarly journals A fibre forming smectic twist–bent liquid crystalline phase

RSC Advances ◽  
2015 ◽  
Vol 5 (15) ◽  
pp. 11207-11211 ◽  
Author(s):  
M. G. Tamba ◽  
S. M. Salili ◽  
C. Zhang ◽  
A. Jákli ◽  
G. H. Mehl ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Crystalline Phase ◽  
Nematic Phase ◽  
Liquid Crystalline ◽  
Liquid Crystalline Phase ◽  
Crystal Phase ◽  
Liquid Crystal Phase ◽  
Filament Formation

We demonstrate the nanostructure and filament formation of a novel liquid crystal phase of a dimeric mesogen below the twist–bend nematic phase.

High Pressure Studies of Liquid Crystalline Transitions

1983 ◽  
Vol 22 ◽  
Author(s):  
R. Shashidhar
Keyword(s):  
High Pressure ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Nematic Phase ◽  
Liquid Crystalline ◽  
Maximum Pressure ◽  
Multicritical Point ◽  
Smectic A ◽  
High Pressure Studies ◽  
Molecular Ordering

ABSTRACTSome of the important results emerging from our recent investigations on liquid crystals at high pressure are presented. In particular the following topics will be discussed: i) The relation between Pm, the maximum pressure of smectic stability, and the temperature range of the nematic phase in reentrant nematogenic compounds. ii) Piezothermal studies in the vicinity of the smectic A-nematic transition in 8 OCB. iii) The effect of molecular ordering on the pressure behaviour of the nematic-isotropic transition in reentrant nematic mixtures. iv) The first observation of a multicritical point in a single component liquid crystal.

Characterization of some mesogenic alkyl 1-thioglycosides

2002 ◽  
Vol 80 (8) ◽  
pp. 1162-1165 ◽  
Author(s):  
B Henrissat ◽  
G K Hamer ◽  
M G Taylor ◽  
R H Marchessault
Keyword(s):  
Phase Transition ◽  
Liquid Crystal ◽  
Solid State ◽  
Solid State Nmr ◽  
Liquid Crystalline ◽  
Liquid Crystal Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Liquid Crystalline Phases

A series of dodecyl 1-thio-β-D-glycosides has been synthesized and characterized (DSC, NMR, CP MAS, X-ray diffraction) as possible new marking materials with liquid-crystalline properties. These compounds undergo solid to liquid crystal phase transitions at various temperatures, which depend on the nature of the carbohydrate part of the structure. Their liquid-crystalline phases show extreme shear thinning behaviour.Key words: liquid crystal, powder X-ray diffraction, phase transition, thioglycoside, solid-state NMR, marking material

Synthesis and Characterization of Terthiophene-Based Rod-Like Liquid Crystals

2012 ◽  
Vol 532-533 ◽  
pp. 61-65
Author(s):  
Xiao Hui Liu ◽  
Zhong Xiao Li ◽  
Song Ya Zhang ◽  
Jia Ling Pu
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystalline ◽  
Crystal Phase ◽  
Liquid Crystal Phase ◽  
Schiff’S Base ◽  
Thermally Induced ◽  
H Nmr ◽  
Clearing Point ◽  
Temperature Ranges

With 2,2',5',2''-Terthiophene as starting material, two liquid crystalline compounds containing Schiff’s base unit were synthesized in this paper. The structure of the compounds was confirmed by FTIR and 1H NMR. The thermally induced phase transition behaviors were investigated by POM and DSC, and the temperature ranges of liquid crystal phase of the two compounds were compared. Results showed that the symmetric compound exhibited a lower clearing point temperature and broader temperature range of liquid crystal phase.

scholarly journals High temperature superconductivity in sulfur hydride under ultrahigh pressure: A complex superconducting phase beyond conventional BCS

2016 ◽  
Vol 2 (1) ◽  
Author(s):  
Annette Bussmann-Holder ◽  
Jürgen Köhler ◽  
M.-H. Whangbo ◽  
Antonio Bianconi ◽  
Arndt Simon
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Transition Temperature ◽  
Hydrogen Bonds ◽  
Pressure Dependence ◽  
High Temperature Superconductivity ◽  
Superconducting Phase ◽  
Ultrahigh Pressure ◽  
Phonon Modes ◽  
Interband Coupling

AbstractThe recent report of superconductivity under high pressure at the record transition temperature of Tc =203 K in pressurized H2S has been identified as conventional in view of the observation of an isotope effect upon deuteration. Here it is demonstrated that conventional theories of superconductivity in the sense of BCS or Eliashberg formalisms cannot account for the pressure dependence of the isotope coefficient. The only way out of the dilemma is a multi-band approach of superconductivity where already small interband coupling suffices to achieve the high values of Tc together with the anomalous pressure dependent isotope coefficient. In addition, it is shown that anharmonicity of the hydrogen bonds vanishes under pressure whereas anharmonic phonon modes related to sulfur are still active.

Antiferroelectric Liquid Crystals from Achiral Molecules And A Liquid Conglomerate

1999 ◽  
Vol 559 ◽  
Author(s):  
David M. Walba ◽  
Eva Körblova ◽  
Renfan Shao ◽  
Joseph E. Maclennan ◽  
Darren R. Link ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Liquid Crystalline ◽  
Crystal Phase ◽  
Liquid Crystal Phase ◽  
Crystalline Structures ◽  
Chiral Liquid Crystal ◽  
Antiferroelectric Liquid Crystals ◽  
Liquid Crystal Structure

ABSTRACTUntil recently, it was an empirical fact that creation of a chiral liquid crystal phase required enantiomerically enriched molecules. In addition, to date known ferroelectric and antiferroelectric smectics have also been composed of enantiomerically enriched molecules. Herein are described the first examples of the formation of chiral and antiferroelectric supermolecular liquid crystalline structures from achiral molecules. In one case (apparently metastable) the liquid crystal structure is macroscopically chiral, with samples composed of heterochiral macroscopic domains: a liquid conglomerate.

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.

scholarly journals Revealing the polar nature of a ferroelectric nematic by means of circular alignment

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Per Rudquist
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Experimental Verification ◽  
Nematic Phase ◽  
Direct Method ◽  
Experimental Demonstration ◽  
Liquid Crystal Phase ◽  
Sample Cell ◽  
Points Of View ◽  
A Direct Method

AbstractThe recent discovery of spontaneously polar nematic liquid crystals—so-called ferroelectric nematics—more than a century after the first discussions about their possible existence—has attracted large interest, both from fundamental scientific and applicational points of view. However, the experimental demonstration of such a phase has, so-far, been non-trivial. Here I present a direct method for the experimental verification of a ferroelectric nematic liquid crystal phase. The method utilizes a single sample cell where the two substrates are linearly and circularly rubbed, respectively, and the ferroelectric nematic phase (NF) is revealed by the orientation of the resulting disclination lines in the cell.

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