A new polymorph of ammonium succinate – serendipity in action

2019 ◽  
Vol 75 (2) ◽  
pp. 208-212
Author(s):  
Eynav Kats ◽  
Joel Bernstein ◽  
Andreas Lemmerer
Keyword(s):  
Crystal Structure ◽  
Succinic Acid ◽  
19Th Century ◽  
Structure Determination ◽  
Crystal Structure Determination ◽  
Ammonium Ion ◽  
Ionic Compound ◽  
Ammonium Succinate ◽  
Molecular Salt

Succinic acid has been known since 1546 and was first chemically identified in the mid-19th century. In an attempt to prepare a molecular salt of succinic acid with (S)-(−)-α-methylbenzylamine, we have obtained the second polymorph of the monoammonium salt of succinic acid, NH4 +·C4H5O4 −. The crystal structure determination proves the structure of the ionic compound and the intimate role of the ammonium ion in the structure, which is compared to the earlier described 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).

scholarly journals Automated Crystal Structure Determination has its Pitfalls: Correction to the Crystal Structures of Iodine Azide

2021 ◽  
Author(s):  
Ulrich Müller ◽  
Sergei Ivlev ◽  
Stephan Schulz ◽  
Christoph Wölper
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Structure Determination ◽  
Crystal Structure Determination
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