Orientational order in liquid normal alkanes: An investigation using gas-chromatographic data

1978 ◽  
Vol 7 (7) ◽  
pp. 485-495 ◽  
Author(s):  
H. Klunder ◽  
W. E. Hammers ◽  
C. L. de Ligny
Keyword(s):  
Orientational Order ◽  
Normal Alkanes ◽  
Chromatographic Data

Bond-orientational order in liquid aluminium80-transition metal20 alloys

1993 ◽  
Vol 3 (8) ◽  
pp. 1873-1888 ◽  
Author(s):  
M. Maret ◽  
F. Lançon ◽  
L. Billard
Keyword(s):  
Orientational Order ◽  
Bond Orientational Order

Cellular fatty acids derived from normal alkanes byCandida rugosa

1980 ◽  
Vol 20 (7) ◽  
pp. 449-457 ◽  
Author(s):  
M. Iida ◽  
H. Kobayashi ◽  
H. Iizuka
Keyword(s):  
Fatty Acids ◽  
Normal Alkanes ◽  
Cellular Fatty Acids

scholarly journals Ion conformation and orientational order in a dicationic ionic liquid crystal studied by solid-state nuclear magnetic resonance spectroscopy

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Debashis Majhi ◽  
Sergey V. Dvinskikh
Keyword(s):  
Ionic Liquid ◽  
Ionic Liquids ◽  
Liquid Crystals ◽  
Bond Order ◽  
Van Der Waals ◽  
Orientational Order ◽  
Smectic Phase ◽  
Side Chains ◽  
Dicationic Ionic Liquid ◽  
Ionic Liquid Crystals

AbstractIonic liquids crystals belong to a special class of ionic liquids that exhibit thermotropic liquid-crystalline behavior. Recently, dicationic ionic liquid crystals have been reported with a cation containing two single-charged ions covalently linked by a spacer. In ionic liquid crystals, electrostatic and hydrogen bonding interactions in ionic sublayer and van der Waals interaction in hydrophobic domains are the main forces contributing to the mesophase stabilization and determining the molecular orientational order and conformation. How these properties in dicationic materials are compared to those in conventional monocationic analogs? We address this question using a combination of advanced NMR methods and DFT analysis. Dicationic salt 3,3′-(1,6-hexanediyl)bis(1-dodecylimidazolium)dibromide was studied. Local bond order parameters of flexible alkyl side chains, linker chain, and alignment of rigid polar groups were analyzed. The dynamic spacer effectively “decouples” the motion of two ionic moieties. Hence, local order and alignment in dicationic mesophase were similar to those in analogous single-chain monocationic salts. Bond order parameters in the side chains in the dicationic smectic phase were found consistently lower compared to double-chain monocationic analogs, suggesting decreasing contribution of van der Waals forces. Overall dication reorientation in the smectic phase was characterized by low values of orientational order parameter S. With increased interaction energy in the polar domain the layered structure is stabilized despite less ordered dications. The results emphasized the trends in the orientational order in ionic liquid crystals and contributed to a better understanding of interparticle interactions driving smectic assembly in this and analogous ionic mesogens.

Quality evaluation of fingerprints of herbal medicine with chromatographic data

2004 ◽  
Vol 514 (1) ◽  
pp. 69-77 ◽  
Author(s):  
Bo-Yan Li ◽  
Yun Hu ◽  
Yi-Zeng Liang ◽  
Pei-Shan Xie ◽  
Yi-Ping Du
Keyword(s):  
Herbal Medicine ◽  
Quality Evaluation ◽  
Chromatographic Data

Fatty acyl chain structure, orientational order, and the lipid phase transition in Acholeplasma laidlawii B membranes. A review of recent 19F nuclear magnetic resonance studies

1984 ◽  
Vol 62 (11) ◽  
pp. 1134-1150 ◽  
Author(s):  
P. M. Macdonald ◽  
B. D. Sykes ◽  
R. N. McElhaney
Keyword(s):  
Phase Transition ◽  
Fatty Acids ◽  
Nuclear Magnetic Resonance ◽  
Acyl Chain ◽  
Orientational Order ◽  
Membrane Lipid ◽  
Fatty Acyl ◽  
Fatty Acyl Chain ◽  
Lipid Phase ◽  
Lipid Phase Transition

The orientational order parameters of monofluoropalmitic acids biosynthetically incorporated into membranes of Acholeplasma laidlawii B in the presence of a large excess of a variety of structurally diverse fatty acids have been determined via 19F nuclear magnetic resonance (19F NMR) spectroscopy. It is demonstrated that these monofluoropalmitic acids are relatively nonperturbing membrane probes based upon physical (differential scanning calorimetry), biochemical (membrane lipid analysis), and biological (growth studies) criteria. 19F NMR is shown to convey the same qualitative and quantitative picture of membrane lipid order provided by 2H-NMR techniques and to be sensitive to the structural characteristics of the membrane fatty acyl chains, as well as to the lipid phase transition. Representatives of each naturally occurring class of fatty acyl chain structures, including straight-chain saturated, methyl-branched, monounsaturated, and alicyclic-ring-substituted fatty acids, were studied and the 19F-NMR order parameters were correlated with the lipid phase transitions (determined calorimetrically). The lipid phase transition was the prime determinant of overall orientational order regardless of fatty acid structure. Effects upon orientational order attributable to specific structural substituents were discernible, but were secondary to the effects of the lipid phase transition. In the gel state, relative overall order was directly proportional to the temperature of the particular lipid phase transition. Not only the overall order, but also the order profile across the membrane was sensitive to the presence of particular structural substituents. In particular, in the gel state specific fatty acyl structures demonstrated a characteristic disordering effect in the membrane order profile. These various observations can be merged to provide a unified picture of the manner in which fatty acyl chain chemistry modulates the physical state of membrane lipids.

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