Molecular topology of three ring nematogens from 13C–1H dipolar couplings

RSC Advances ◽  
2014 ◽  
Vol 4 (63) ◽  
pp. 33383-33390 ◽  
Author(s):  
Nitin P. Lobo ◽  
Bibhuti B. Das ◽  
T. Narasimhaswamy ◽  
K. V. Ramanathan
Keyword(s):  
Molecular Orientation ◽  
Order Parameter ◽  
Dipolar Couplings ◽  
Molecular Topology

A facile way of estimating the order parameter and the molecular orientation from 13C–1H dipolar couplings for three ring based nematogens with a terminal C–H vector.

NMR and molecular structure of partially oriented mono and para methyl- and chlorobenzenes dissolved in nematic liquid crystals

1999 ◽  
Vol 77 (11) ◽  
pp. 1761-1774 ◽  
Author(s):  
Raymond T Syvitski ◽  
E Elliott Burnell
Keyword(s):  
Molecular Structure ◽  
Nuclear Magnetic Resonance ◽  
Liquid Crystal ◽  
High Resolution ◽  
Order Parameter ◽  
Structural Parameters ◽  
Dipolar Couplings ◽  
Methyl Groups ◽  
Multiple Quantum ◽  
Spectral Parameters

Spectral parameters, order parameters, and structural parameters, including the vibrationally corrected ralpha structure of the partially oriented solutes p-xylene, p-chlorotoluene, p-dichlorobenzene, toluene, and chlorobenzene dissolved in three liquid crystal mixtures, are reported. For samples containing the three solutes p-xylene, p-dichlorobenzene, and 1,3,5-trichlorobenzene, multiple quantum (MQ) nuclear magnetic resonance was used to aid in the analysis of the complex high-resolution spectra of the p-xylene. The high-resolution spectra of 1,3,5-trichlorobenzene and p-dichlorobenzene were easily identified and analyzed once the calculated p-xylene spectrum was subtracted from the experimental one. The methyl groups of p-xylene, p-chlorotoluene, and toluene have similar geometries when the structure is determined from dipolar couplings corrected for harmonic vibrations.Key words: nematic liquid crystal, NMR, molecular structure, order parameter.

scholarly journals Drug orientations within statin-loaded lipoprotein nanoparticles by 19F solid-state NMR

2019 ◽  
Vol 55 (88) ◽  
pp. 13287-13290
Author(s):  
Sophie Lau ◽  
Naomi Stanhope ◽  
John Griffin ◽  
Eleri Hughes ◽  
David A. Middleton
Keyword(s):  
Drug Delivery ◽  
Solid State ◽  
Chemical Shift ◽  
Drug Delivery System ◽  
Delivery System ◽  
Solid State Nmr ◽  
Molecular Orientation ◽  
Chemical Shift Anisotropy ◽  
Dipolar Couplings ◽  
Statin Drugs

NMR measurements of 19F chemical shift anisotropy and 1H–19F dipolar couplings provide novel information on the molecular orientation of fluorine-containing statin drugs in rHDL lipoprotein nanoparticles, a drug delivery system under investigation.

Molecular Orientation in Uniaxial Liquid Crystal Phases as Studied by Electron Paramagnetic Resonance

1999 ◽  
Vol 54 (5) ◽  
pp. 299-304 ◽  
Author(s):  
Hanka Moryson ◽  
Danuta Bauman ◽  
Wojciech Hilczer ◽  
Stanislaw Hoffmann
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Liquid Crystal ◽  
Molecular Orientation ◽  
Order Parameter ◽  
Paramagnetic Resonance ◽  
Optical Birefringence ◽  
Dichroic Dye ◽  
Crystal Phases ◽  
Electron Paramagnetic ◽  
Uniaxial Liquid Crystal

Abstract The electron paramagnetic resonance spectra of 3/ß-doxyl-5α-cholestane dissolved in five liquid crystals have been recorded as a function of temperature in the isotropic and mesogenic phases. From these spectra the order parameter (P2) has been determined. The results have been com-pared with the data obtained from the optical birefringence measurements and from the polarized absorption spectra of the dichroic dye dissolved in liquid crystal host.

Photoresponsive Liquid Crystalline Polymeric Materials

2012 ◽  
Vol 77 ◽  
pp. 325-332 ◽  
Author(s):  
Dan Qing Liu ◽  
Casper Van Oosten ◽  
Cees W.M. Bastiaansen ◽  
Dirk J. Broer
Keyword(s):  
Molecular Orientation ◽  
Order Parameter ◽  
Liquid Crystalline ◽  
Polymer Networks ◽  
Polymeric Materials ◽  
Molecular Organization ◽  
Surface Topology ◽  
Network Configuration ◽  
Lithographic Patterning

In-situ photopolymerization of liquid crystalline (LC) monomers has proven to be a valuable technique for the formation of well-ordered polymer networks. Their anisotropic properties led to a variety of applications in optics, electronics and mechanics. The use of light to initiate polymerization enables lithographic patterning. In addition the LC behavior enables formation of complex morphologies on molecular level. Controlling the director profile of an LC network film in transversal direction gives geometrical morphing upon minor changes in order parameter. Examples of suited profiles of molecular orientation are twisted or splayed director configurations tied up in the network configuration. Reversible order parameter changes can be induced by light using the photo-activated trans-cis isomerization of a copolymerized azobenzene monomer. This is demonstrated in photoresponsive cilia inkjet printed on a substrate. The cilia possess a splayed molecular organization and show well-controlled bending when addressed by light. We demonstrate a patterned film with alternating helicoidal and perpendicular-uniaxial molecular orientation. When applied as coating on glass, photo-activation in this case leads to a dynamically switching surface topology

Polarized microbeam FT-IR analysis of single fibers

1996 ◽  
Vol 54 ◽  
pp. 206-207
Author(s):  
Liling Cho ◽  
David L. Wetzel
Keyword(s):  
Molecular Orientation ◽  
Transition Point ◽  
Polymer Fibers ◽  
Single Fiber ◽  
Wire Grid ◽  
Polyester Fibers ◽  
Ft Ir ◽  
Ir Analysis ◽  
The Relationship ◽  
Wire Grid Polarizer

Polarized infrared microscopy has been used for forensic purposes to differentiate among polymer fibers. Dichroism can be used to compare and discriminate between different polyester fibers, including those composed of polyethylene terephthalate that are frequently encountered during criminal casework. In the fiber manufacturering process, fibers are drawn to develop molecular orientation and crystallinity. Macromolecular chains are oriented with respect to the long axis of the fiber. It is desirable to determine the relationship between the molecular orientation and stretching properties. This is particularly useful on a single fiber basis. Polarized spectroscopic differences observed from a single fiber are proposed to reveal the extent of molecular orientation within that single fiber. In the work presented, we compared the dichroic ratio between unstretched and stretched polyester fibers, and the transition point between the two forms of the same fiber. These techniques were applied to different polyester fibers. A fiber stretching device was fabricated for use on the instrument (IRμs, Spectra-Tech) stage. Tension was applied with a micrometer screw until a “neck” was produced in the stretched fiber. Spectra were obtained from an area of 24×48 μm. A wire-grid polarizer was used between the source and the sample.

Observing the relaxation of molecular orientation in sheared liquid crystalline polymer solutions

1990 ◽  
Vol 48 (4) ◽  
pp. 1092-1093
Author(s):  
Wendy Putnam ◽  
Christopher Viney
Keyword(s):  
Molecular Orientation ◽  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Crystalline Polymer ◽  
Polymer Processing ◽  
Molecular Alignment ◽  
Global Alignment ◽  
Shear Direction ◽  
Axial Strength ◽  
Strength And Stiffness

Liquid crystalline polymers (solutions or melts) can be spun into fibers and films that have a higher axial strength and stiffness than conventionally processed polymers. These superior properties are due to the spontaneous molecular extension and alignment that is characteristic of liquid crystalline phases. Much of the effort in processing conventional polymers goes into extending and aligning the chains, while, in liquid crystalline polymer processing, the primary microstructural rearrangement involves converting local molecular alignment into global molecular alignment. Unfortunately, the global alignment introduced by processing relaxes quickly upon cessation of shear, and the molecular orientation develops a periodic misalignment relative to the shear direction. The axial strength and stiffness are reduced by this relaxation.Clearly there is a need to solidify the liquid crystalline state (i.e. remove heat or solvent) before significant relaxation occurs. Several researchers have observed this relaxation, mainly in solutions of hydroxypropyl cellulose (HPC) because they are lyotropic under ambient conditions.

EFFECT OF ORDER PARAMETER RELAXATION ON JOSEPHSON JUNCTION TRANSIENTS

1978 ◽  
Vol 39 (C6) ◽  
pp. C6-550-C6-551
Author(s):  
H. Suhl ◽  
J. Hurell ◽  
A. H. Silver ◽  
Y. Song
Keyword(s):  
Josephson Junction ◽  
Order Parameter
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