Further NMR studies of fluoride ion motion in doped β‐PbF2

1976 ◽  
Vol 65 (3) ◽  
pp. 912-916 ◽  
Author(s):  
T. Y. Hwang ◽  
I. J. Lowe ◽  
K. F. Lau ◽  
R. W. Vaughan
Keyword(s):  
Fluoride Ion ◽  
Nmr Studies ◽  
Ion Motion

Failure of the Frenkel Defect Model to Explain the Trend in Anionic Conductivity in the MF2 Fluorite Structure and Related MSnF4 Materials

1994 ◽  
Vol 369 ◽  
Author(s):  
Georges Denes
Keyword(s):  
Fluorite Structure ◽  
Fluoride Ion ◽  
Defect Model ◽  
Fluoride Ions ◽  
Frenkel Defect ◽  
Ion Motion ◽  
Frenkel Defects ◽  
Fluorite Type ◽  
High Fluoride ◽  
Anionic Conductivity

AbstractThe high fluoride ion conductivity of fluorite type MF2 has been attributed tothe fact that half of the F8 cubes present in this structure are empty and therefore, are potential vacant sites for interstitial fluoride ions in the formation of Frenkel defects. However, the model of long range ion motion through Frenkel defects by use of empty F8 cubes is in contradiction with: (i) the little difference between the conductivities of CaF2 and BaF2, (ii) the conductivity of β-PbF2 being much larger than that of BaF2, and (iii) the much higher performance of MSnF4 even though there is no empty cube to form Frenkel defects in the MSnF4 structures.

NMR Studies of F Ion Motion in Doped β-PbF2

1976 ◽  
pp. 413-414
Author(s):  
T. Y. Hwang ◽  
I. J. Lowe ◽  
K. F. Lau ◽  
R. W. Vaughan
Keyword(s):  
Nmr Studies ◽  
Ion Motion

Study of Fluoride Ion Motions in PbSnF4 and BaSnF4 Compounds With Molecular Dynamics Simulation and Solid State NMR Techniques

2000 ◽  
Vol 658 ◽  
Author(s):  
Santanu Chaudhuri ◽  
Michael Castiglione ◽  
Francis Wang ◽  
Mark Wilson ◽  
Paul A. Madden ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Solid State ◽  
Solid State Nmr ◽  
Md Simulations ◽  
Dynamics Simulation ◽  
Double Layers ◽  
Fluoride Ion ◽  
Fluoride Ions ◽  
Ion Motion ◽  
Fluorine Ions

ABSTRACTA combined approach, using solid state NMR and Molecular Dynamics (MD) simulations, has been employed in this work to investigate fluoride-ion motion in the PbSnF4 family of anionic conductors, materials that contain double layers of Sn2+ and M2+ cations. 19F MAS NMR spectra of PbSnF4 and BaSnF4 show that the fluoride ions are mobile on the NMR timescale (10−4 s), even at room temperature. In the case of BaSnF4, two different groups of fluoride ions were observed, one group corresponding to fluorine atoms between the layers of Ba2+ cations, and the other set, corresponding to mobile fluoride ions undergoing exchange between sites in the Ba-Sn and Sn-Sn layers. The 119Sn NMR suggests a highly distorted Sn environment in these compounds, consistent with the presence of stereoactive Sn lone pairs. MD simulations, using the Polarizable Ion Model, have been carried out to probe the conduction mechanism. These simulations are able to reproduce elements of the structure such as the reduction in the occupancy of the fluorine ions between the Sn-Sn layers. Anisotropic conductivity, involving primarily motion in the M-Sn layers, is predicted, consistent with the NMR results. In the case of BaSnF4, no motion involving the fluoride ions in the Ba-Ba layers is observed on the simulation timescale (10−12 s) and a cyclic mechanism of fluoride-ion motion involving two types of fluoride ions in the Ba-Sn layers is proposed.

NMR studies of the R2 repeat and related peptide fragments of the DNA binding domain of c-Myb. New light on the structure and folding of R2.

1999 ◽  
Vol 96 (9/10) ◽  
pp. 1580-1584 ◽  
Author(s):  
I. Ségalas ◽  
S. Desjardins ◽  
H. Oulyadi ◽  
Y. Prigent ◽  
S. Tribouillard ◽  
...  
Keyword(s):  
Dna Binding ◽  
Binding Domain ◽  
Dna Binding Domain ◽  
Peptide Fragments ◽  
Nmr Studies ◽  
Related Peptide

2D NMR studies on muscle and cerebral metabolism in vivo

1994 ◽  
Vol 91 ◽  
pp. 697-703 ◽  
Author(s):  
B Gillet ◽  
BT Doan ◽  
C Verre-Sebrie ◽  
O Fedeli ◽  
JC Beloeil ◽  
...  
Keyword(s):  
Cerebral Metabolism ◽  
2D Nmr ◽  
Nmr Studies

NMR STUDIES OF CONCENTRATED LITHIUM-AMMONIA SOLUTIONS

1980 ◽  
Vol 41 (C8) ◽  
pp. C8-32-C8-35
Author(s):  
Y. Nakamura ◽  
M. Niibe ◽  
M. Shimoji
Keyword(s):  
Nmr Studies

NMR STUDIES OF Co-BASED NITRIDE AMORPHOUS FILMS

1988 ◽  
Vol 49 (C8) ◽  
pp. C8-1713-C8-1714
Author(s):  
K. Le Dang ◽  
P. Veillet ◽  
H. Sakakima ◽  
R. Krishnan
Keyword(s):  
Amorphous Films ◽  
Nmr Studies

Physico-Chemical Properties of Recombinant Desulphatohirudin

1990 ◽  
Vol 63 (03) ◽  
pp. 499-504 ◽  
Author(s):  
A Electricwala ◽  
L Irons ◽  
R Wait ◽  
R J G Carr ◽  
R J Ling ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Gel Filtration ◽  
Chemical Properties ◽  
Alpha Helix ◽  
Apparent Molecular Weight ◽  
Correlation Spectroscopy ◽  
Nmr Studies ◽  
Recombinant Hirudin ◽  
Physico Chemical ◽  
Recombinant Molecule

SummaryPhysico-chemical properties of recombinant desulphatohirudin expressed in yeast (CIBA GEIGY code No. CGP 39393) were reinvestigated. As previously reported for natural hirudin, the recombinant molecule exhibited abnormal behaviour by gel filtration with an apparent molecular weight greater than that based on the primary structure. However, molecular weight estimation by SDS gel electrophoresis, FAB-mass spectrometry and Photon Correlation Spectroscopy were in agreement with the theoretical molecular weight, with little suggestion of dimer or aggregate formation. Circular dichroism studies of the recombinant molecule show similar spectra at different pH values but are markedly different from that reported by Konno et al. (13) for a natural hirudin-variant. Our CD studies indicate the presence of about 60% beta sheet and the absence of alpha helix in the secondary structure of recombinant hirudin, in agreement with the conformation determined by NMR studies (17)

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