Molecular and crystal structure of a high-temperature polymorph of chitosan from electron diffraction data

1994 ◽  
Vol 27 (26) ◽  
pp. 7606-7612 ◽  
Author(s):  
Karim Mazeau ◽  
William T. Winter ◽  
Henri Chanzy
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Electron Diffraction ◽  
Diffraction Data ◽  
Molecular And Crystal Structure ◽  
Electron Diffraction Data ◽  
High Temperature Polymorph

Crystal Structure Determination of Glycerol-Containing Lipids from Electron Diffraction Data. Use of Analog Compounds Based upon Configurational Isomers of Cyclopentane-1, 2, 3-TRIOL

1977 ◽  
Vol 35 ◽  
pp. 24-25
Author(s):  
Douglas L. Dorset ◽  
Anthony J. Hancock
Keyword(s):  
Crystal Structure ◽  
Electron Diffraction ◽  
Diffraction Data ◽  
Structure Determination ◽  
Crystal Surface ◽  
Coherent Scattering ◽  
Crystal Structure Determination ◽  
Electron Diffraction Data ◽  
Polar Group ◽  
Axis Orientation

Lipids containing long polymethylene chains were among the first compounds subjected to electron diffraction structure analysis. It was only recently realized, however, that various distortions of thin lipid microcrystal plates, e.g. bends, polar group and methyl end plane disorders, etc. (1-3), restrict coherent scattering to the methylene subcell alone, particularly if undistorted molecular layers have well-defined end planes. Thus, ab initio crystal structure determination on a given single uncharacterized natural lipid using electron diffraction data can only hope to identify the subcell packing and the chain axis orientation with respect to the crystal surface. In lipids based on glycerol, for example, conformations of long chains and polar groups about the C-C bonds of this moiety still would remain unknown.One possible means of surmounting this difficulty is to investigate structural analogs of the material of interest in conjunction with the natural compound itself. Suitable analogs to the glycerol lipids are compounds based on the three configurational isomers of cyclopentane-1,2,3-triol shown in Fig. 1, in which three rotameric forms of the natural glycerol derivatives are fixed by the ring structure (4-7).

Crystal structure redetermination of ε-Ni3Si2 from a single nanowire by dynamical refinement of precession electron diffraction data

2016 ◽  
Vol 672 ◽  
pp. 505-509 ◽  
Author(s):  
Cinthia Antunes Corrêa ◽  
Mariana Klementová ◽  
Vladislav Dřínek ◽  
Jaromír Kopeček ◽  
Lukáš Palatinus
Keyword(s):  
Crystal Structure ◽  
Electron Diffraction ◽  
Diffraction Data ◽  
Electron Diffraction Data ◽  
Single Nanowire ◽  
Precession Electron Diffraction

The use of Direct Phasing Methods for Single Crystal Electron Diffraction Data. I. Methylene Subcells

1976 ◽  
Vol 34 ◽  
pp. 544-545
Author(s):  
D. L. Dorset ◽  
H. A. Hauptman
Keyword(s):  
Crystal Structure ◽  
Electron Diffraction ◽  
Diffraction Data ◽  
Crystal Structure Analysis ◽  
Electron Diffraction Data ◽  
Trial And Error ◽  
Mosaic Crystals ◽  
Crystal Electron ◽  
Kinematical Theory

The significant impediment to the use of electron diffraction data for crystal structure analysis is, of course, the perturbation of n-beam dynamical effects. In more severe cases this dynamical perturbation gives an intensity distribution in the diffraction pattern which is not directly related to the underlying crystal structure, thus making the determination of complex structures nearly impossible by this technique.However, as was experimentally established in Vainshtein's laboratory and is theoretically predicted, the diffraction of electrons from thin mosaic crystals composed of light atoms is in accord with kinematical theory to a good first approximation and, furthermore, ab initiocrystal structure analyses are tractable viastandard crystallographic phase determination. To date the few electronographic determinations of unknown organic structures have used either trial and error or Patterson techniques.

scholarly journals Ab-initio crystal structure analysis and refinement approaches of oligo p-benzamides based on electron diffraction data

2012 ◽  
Vol 68 (2) ◽  
pp. 171-181 ◽  
Author(s):  
Tatiana E. Gorelik ◽  
Jacco van de Streek ◽  
Andreas F. M. Kilbinger ◽  
Gunther Brunklaus ◽  
Ute Kolb
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Electron Diffraction ◽  
Ab Initio ◽  
Structure Analysis ◽  
Diffraction Data ◽  
Crystal Structure Analysis ◽  
Electron Diffraction Data ◽  
Perfect Agreement ◽  
Bonding Scheme

Ab-initio crystal structure analysis of organic materials from electron diffraction data is presented. The data were collected using the automated electron diffraction tomography (ADT) technique. The structure solution and refinement route is first validated on the basis of the known crystal structure of tri-p-benzamide. The same procedure is then applied to solve the previously unknown crystal structure of tetra-p-benzamide. In the crystal structure of tetra-p-benzamide, an unusual hydrogen-bonding scheme is realised; the hydrogen-bonding scheme is, however, in perfect agreement with solid-state NMR data.

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