Separation of nematic and smectic-A potential effects on solute ordering in a series of binary 6OCB–8OCB mixtures

2011 ◽  
Vol 89 (7) ◽  
pp. 900-908 ◽  
Author(s):  
E. Elliott Burnell ◽  
Ronald Y. Dong ◽  
Adrian C.J. Weber ◽  
Xuan Yang ◽  
Anand Yethiraj
Keyword(s):  
Phase Diagram ◽  
Binary Mixture ◽  
Optical Microscopy ◽  
Absolute Magnitude ◽  
Order Parameters ◽  
The Novel ◽  
Temperature Range ◽  
H Nmr ◽  
Smectic A ◽  
Phase Sequence

1H NMR and optical microscopy have been used to study four solutes dissolved in samples of a binary mixture of 4-n-hexyloxy-4′-cyanobiphenyl (6OCB) and 4-n-octyloxy-4′-cyanobiphenyl (8OCB) that are close to the region of the phase diagram where the smectic-A (SmA) and re-entrant nematic (RN) phases exist. Optical microscopy clearly indicates that one of the four studied samples shows the phase sequence of isotropic–nematic–SmA–RN. The derived solute order parameters were interpreted by means of two Maier–Saupe mechanisms in conjunction with the Kobayashi–McMillan theory in the case of the SmA phase. The novel feature of this study is that the nematic potential is extrapolated from the nematic to the SmA phase based on concentrations of the 6OCB–8OCB mixtures. The derived smectic order parameters for each of the studied solutes clearly show a maximum absolute magnitude near the centre of the SmA temperature range. The different partitioning of these solutes in the binary mixture is also discussed.

scholarly journals Induced smectic phase in binary mixtures of twist-bend nematogens

2018 ◽  
Vol 9 ◽  
pp. 1297-1307 ◽  
Author(s):  
Anamarija Knežević ◽  
Irena Dokli ◽  
Marin Sapunar ◽  
Suzana Šegota ◽  
Ute Baumeister ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Binary Mixtures ◽  
Wide Temperature Range ◽  
Nematic Phase ◽  
Smectic Phase ◽  
Phase Behaviour ◽  
Scanning Calorimetry ◽  
Temperature Range ◽  
Phase Sequence ◽  
Pure Compounds

The investigation of liquid crystal (LC) mixtures is of great interest in tailoring material properties for specific applications. The recent discovery of the twist-bend nematic phase (NTB) has sparked great interest in the scientific community, not only from a fundamental viewpoint, but also due to its potential for innovative applications. Here we report on the unexpected phase behaviour of a binary mixture of twist-bend nematogens. A binary phase diagram for mixtures of imino-linked cyanobiphenyl (CBI) dimer and imino-linked benzoyloxy-benzylidene (BB) dimer shows two distinct domains. While mixtures containing less than 35 mol % of BB possess a wide temperature range twist-bend nematic phase, the mixtures containing 55–80 mol % of BB exhibit a smectic phase despite that both pure compounds display a Iso–N–NTB–Cr phase sequence. The phase diagram shows that the addition of BB of up to 30 mol % significantly extends the temperature range of the NTB phase, maintaining the temperature range of the nematic phase. The periodicity, obtained by atomic force microscopy (AFM) imaging, is in the range of 6–7 nm. The induction of the smectic phase in the mixtures containing 55–80 mol % of BB was confirmed using polarising optical microscopy (POM), differential scanning calorimetry (DSC) and X-ray diffraction. The origin of the intercalated smectic phase was unravelled by combined spectroscopic and computational methods and can be traced to conformational disorder of the terminal chains. These results show the importance of understanding the phase behaviour of binary mixtures, not only in targeting a wide temperature range but also in controlling the self-organizing processes.

scholarly journals Density Measurements of an Air-Like Binary Mixture over the Temperature Range from 100 K to 298.15 K at Pressures up to 8.0 MPa

2021 ◽  
Vol 42 (9) ◽  
Author(s):  
Nils von Preetzmann ◽  
Reiner Kleinrahm ◽  
Philipp Eckmann ◽  
Giuseppe Cavuoto ◽  
Markus Richter
Keyword(s):  
Binary Mixture ◽  
Saturated Vapor ◽  
Saturation Pressure ◽  
Transmission Error ◽  
Magnetic Suspension ◽  
Mixture Component ◽  
Liquid Region ◽  
Force Transmission ◽  
Temperature Range ◽  
Combined Uncertainty

AbstractDensities of an air-like binary mixture (0.2094 oxygen + 0.7906 nitrogen, mole fractions) were measured along six isotherms over the temperature range from 100 K to 298.15 K at pressures up to 8.0 MPa, using a low-temperature single-sinker magnetic suspension densimeter. The measurements were carried out at T = (100, 115, and 130) K in the homogeneous gas and liquid region, and at T = (145, 220, and 298.15) K in the supercritical region (critical temperature TC = 132.35 K); in total, we present results for 52 (T, p) state points. The relative expanded combined uncertainty (k = 2) of the experimental densities was estimated to be between 0.03 % and 0.13 %, except for four values near the critical point. The largest error is caused by the magnetic suspension coupling in combination with the mixture component oxygen, which is strongly paramagnetic; the resulting force transmission error is up to 1.1 %. However, this error can be corrected with a proven correction model to an uncertainty contribution in density of less than 0.044 %. Due to a supercritical liquefaction procedure and the integration of a special VLE-cell, it was possible to measure densities in the homogeneous liquid phase without changing the composition of the liquefied mixture. Moreover, saturated liquid and saturated vapor densities were determined at T = (100, 115, and 130) K by extrapolation of the experimental single-phase densities to the saturation pressure. The new experimental results were compared with the mixture model of Lemmon et al. for the system (nitrogen + argon + oxygen) and the GERG-2008 equation of state.

Studies of critical behaviour at the nematic to smectic A phase transition in C6 and C7 binary mixture system

2008 ◽  
Vol 41 (6) ◽  
pp. 062002 ◽  
Author(s):  
SeungYeon Jeong ◽  
DongWoo Kim ◽  
KungWon Rhie ◽  
MunPyo Hong ◽  
Satyendra Kumar ◽  
...  
Keyword(s):  
Phase Transition ◽  
Binary Mixture ◽  
Critical Behaviour ◽  
Smectic A ◽  
Smectic A Phase ◽  
Mixture System

Excitations, order parameters, and phase diagram of solid deuterium at megabar pressures

1995 ◽  
Vol 51 (21) ◽  
pp. 14987-14997 ◽  
Author(s):  
Lijing Cui ◽  
Nancy H. Chen ◽  
Isaac F. Silvera
Keyword(s):  
Phase Diagram ◽  
Order Parameters ◽  
Solid Deuterium

Organometallic oxides: preparation of the cluster [(η-C5Me5)Mo]4O7 by reduction of [(η-C5Me5)MoCl(O)]2(μ-O) or (η-C5Me5)MoCl2(O)

2000 ◽  
Vol 78 (3) ◽  
pp. 383-394
Author(s):  
Frank Bottomley ◽  
Victor Sanchez ◽  
Robert C Thompson ◽  
Olusola O Womiloju ◽  
Zhiqiang Xu
Keyword(s):  
Nmr Spectra ◽  
Chloroform Solution ◽  
X Ray Diffraction ◽  
Broad Resonance ◽  
Nmr Spectrum ◽  
X Ray ◽  
Temperature Range ◽  
H Nmr ◽  
Tributyltin Hydride ◽  
Effective Moment

Reduction of [(η-C5Me5)MoCl(O)]2(μ-O) or (η-C5Me5)MoCl2(O) with sodium or magnesium amalgam, magnesium turnings, or tributyltin hydride produced [(η-C5Me5)Mo]4O7, with [(η-C5Me5)Mo(O)(μ-O)]2 as a co-product. [(η-C5Me5)Mo]4O7 was characterized by X-ray diffraction, mass spectrometry, 1H NMR and IR spectroscopies, and magnetism. Crystals of [(η-C5Me5)Mo]4O7 contained a tetrahedral [(η-C5Me5)Mo]4 unit (Mo-Mo = 2.909 (3) Å) with the Mo4O7 core having the structure Mo4(μ2-O(b))3(µ2-O(c))3(µ3-O(a)) (3). Microcrystalline samples of [(η-C5Me5)Mo]4O7 were paramagnetic over the temperature range 2-300 K, with an effective moment of 1.26 μB at 300 K. [(η-C5Me5)Mo]4O7 was also paramagnetic in chloroform solution, over the temperature range 223-298 K, with an effective moment of 1.43 µB at 298 K. The 1H NMR spectrum showed a broad resonance at 16.3 ppm (Δν 1/2 = 113 Hz) and two narrow resonances at 1.89 ppm and 1.69 ppm (Δν 1/2 = 5 Hz). The magnetism and NMR spectra showed that [(η-C5Me5)Mo]4O7 existed in two forms which were in equilibrium in solution. One form was paramagnetic (S = 1), with the Mo4O7 core having the geometry 3, and the other was diamagnetic (S = 0), with the Mo4O7 core having the geometry 4.Key words: cluster, cyclopentadienyl, molybdenum, oxide, paramagnetism.

Phase Diagram and Component Order Parameters in a Nematic Mixture: A Combined Deuterium and Proton NMR Study

1986 ◽  
Vol 139 (3-4) ◽  
pp. 217-239 ◽  
Author(s):  
P. Esnault ◽  
F. Volino ◽  
M. M. Gauthier ◽  
A. M. Giroud-godquin
Keyword(s):  
Phase Diagram ◽  
Proton Nmr ◽  
Order Parameters ◽  
Nmr Study ◽  
Component Order

scholarly journals Synthesis of Novel Compounds as New Potent Tyrosinase Inhibitors

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Hooshang Hamidian
Keyword(s):  
Kojic Acid ◽  
Azo Compounds ◽  
The Novel ◽  
Mushroom Tyrosinase ◽  
Reference Standard ◽  
Tyrosinase Inhibition ◽  
H Nmr ◽  
Ft Ir ◽  
Tyrosinase Inhibitors ◽  
C Nmr

In the present paper, we report the synthesis and pharmacological evaluation of a new series of azo compounds with different groups (1-naphthol, 2-naphthol, andN,N-dimethylaniline) and trifluoromethoxy and fluoro substituents in the scaffold. All synthesized compounds (5a–5f) showed the most potent mushroom tyrosinase inhibition (IC50values in the range of 4.39 ± 0.76–1.71 ± 0.49 µM), comparable to the kojic acid, as reference standard inhibitor. All the novel compounds were characterized by FT-IR,1H NMR,13C NMR, and elemental analysis.

scholarly journals Optical Microscopy Observations and Construction of Dupin Cyclides at the Isotropic/Smectic A Phase Transition

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4539
Author(s):  
Mikhael Halaby Macary ◽  
Gauthier Damême ◽  
Antoine Gibek ◽  
Valentin Dubuffet ◽  
Benoît Dupuy ◽  
...  
Keyword(s):  
Phase Transition ◽  
Numerical Simulation ◽  
Liquid Crystal ◽  
Optical Microscopy ◽  
Smectic A ◽  
Polarized Microscopy ◽  
Smectic A Phase ◽  
Dupin Cyclides

In this work, we are interested in the nucleation of bâtonnets at the Isotropic/Smectic A phase transition of 10CB liquid crystal. Very often, these bâtonnets are decorated with a large number of focal conics. We present here an example of a bâtonnet obtained by optical crossed polarized microscopy in a frequently observed particular area of the sample. This bâtonnet presents bulges and one of them consists of a tessellation of ellipses. These ellipses are two by two tangent, one to each other, and their confocal hyperbolas merge at the apex of the bâtonnet. We propose a numerical simulation with Python software to reproduce this tiling of ellipses as well as the shape of the smectic layers taking the well-known shape of Dupin cyclides within this particular bâtonnet area.

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