Glycerol Conformation and the Crystal Structure of Lipids II. A Further Study of Tripalmitin and Conformationally Fixed Analogs by Small-Angle X-Ray Diffraction and Reflection Electron Diffraction

1978 ◽  
Vol 33 (1-2) ◽  
pp. 50-55 ◽  
Author(s):  
Douglas L. Dorset ◽  
Walter A. Pangborn ◽  
Anthony J. Hancock ◽  
Ton C. van Soest ◽  
S. M. Greenwald
Keyword(s):  
Crystal Structure ◽  
Electron Diffraction ◽  
Ab Initio ◽  
Crystal Structure Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cyclopentane Ring ◽  
Structure Determinations ◽  
A Chain ◽  
Reflection Electron Diffraction

Abstract The utility of analogs to glycerol-containing lipids based on the configurational isomers of cyclo-pentane-1,2,3-triol for ab initio crystal structure analysis via electron diffraction is assessed further. Such analogs of tripalmitin are examined with the natural triglyceride via low angle X-ray diffraction. The 1,3/2 (all-trans) and 1,2/3 (cis-trans) analogs give long spacing dimensions some 23 Å greater than found for the β-2 form of the natural compound, consistent with the long spacing observed for a β-3 form. The 1,2,3/0 (all-cis) analog gives a long spacing near that of the a-form of the triglyceride. Reflection electron diffraction measurements on the 1,3/2 and 1,2/3 analogs reveal a chain tilt near 60° for both and untilted chains for 1,2,3/0. A more accurate tilt determination from X-ray long spacings of the homologous series of 1,3/2 pseudotrilaurin to 1,3/2 pseudo-tripalmitin confirm the 67° tilt expected for the β-3 form. Therefore, given the same T,, methylene subcell, the molecular packing is very close to natural triglycerides. The subtle influences of the cyclopentane ring are overcome for 1,3/2 analogs based on stearic and arachidic acids. This emphasizes the utility of these structural analogs for ab initio crystal structure determinations of glycerol containing lipids.

A Morophological and Crystal Structure Analysis of Particulate Rare Earth III Fluorides

1972 ◽  
Vol 30 ◽  
pp. 542-543
Author(s):  
Coy R. Morris
Keyword(s):  
Crystal Structure ◽  
Rare Earth ◽  
Structural Analysis ◽  
Electron Diffraction ◽  
Crystal Structure Analysis ◽  
X Ray Diffraction ◽  
Structural Units ◽  
X Ray ◽  
Lower Chamber ◽  
Rare Earth Trifluorides

Previous work in this area (oftedal-1929, Zalkin and Templeton-1952 ) using X-ray diffraction techniques assigned primitive structural units to the rare earth trifluorides of Lanthanum, Cerium, Praseodymium, Neodymium, Ytterbium and Samarium.The work of greatest interest in this investigation is that of Zalkin and Templeton. In their investigation they found that the 4f trifluorides from La to Nd are hexagonal while those from Sm to Lu are orthorhombic with SmF3 exhibiting a dual structure of both units, depending on the temperature of formation.Continuing the recent work of Barr, the structures of LaF3, NdF3, PrF3, SmF3 and YbF3 were investigated using lower chamber diffraction (LCD) which produced results appearing to conflict with the X-ray work of Zalkin and Templeton. To these authors knowledge there are no known publications dealing with the structural analysis of these five rare earth trifluorides other than the two papers cited. In addition, these works deal with X-ray determinations which, although complementary to electron diffraction, lack the microanalysis and limited innerplanar spacing analysis characteristic to ED.

scholarly journals E. S. Fedorov Promoting the Russian-German Scientific Interrelationship

Minerals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 181 ◽  
Author(s):  
Peter Paufler ◽  
Stanislav K. Filatov
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Structure Analysis ◽  
Crystalline State ◽  
Crystal Structure Analysis ◽  
Present Knowledge ◽  
Personal Contact ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Impact

At the dawn of crystal structure analysis, the close personal contact between researchers in Russia and Germany, well documented in the “Zeitschrift für Krystallographie und Mineralogie”, contributed significantly to the evolution of our present knowledge of the crystalline state. The impact of the Russian crystallographer E. S. Fedorov upon German scientists such as A. Schoenflies and P. Groth and the effect of these contacts for Fedorov are highlighted hundred years after the death of the latter. A creative exchange of ideas paved the way for the analysis of crystal structures with the aid of X-ray diffraction.

Crystal-to-Crystal Diastereoselective Transformation of 2,4,6-Triisopropyl-4'-(S)-phenylalaninocarbonylbenzophenone Methyl Ester

1998 ◽  
Vol 54 (6) ◽  
pp. 907-911 ◽  
Author(s):  
H. Hosomi ◽  
Y. Ito ◽  
S. Ohba
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Methyl Ester ◽  
Absolute Configuration ◽  
Crystal Structure Analysis ◽  
X Ray Diffraction ◽  
Pass Filter ◽  
X Ray ◽  
Ultra High Pressure ◽  
Phenylalanine Methyl Ester

Dissymmetry of the photoproduct was induced by using a chiral substituent, (S)-methylphenylalanine, in the title compound {N-4-(2,4,6-triisopropylbenzoyl)benzoyl]-(S)-phenylalanine methyl ester (I)}. On irradiation with light from a 250 W ultra-high-pressure Hg lamp for 7 h through a long-pass filter, the photoreaction in a crystal was 100% complete without the loss of crystallinity. The crystal structures (I), before, and (II) {N-[4-(7-hydroxy-3,5-diisopropyl-8,8-dimethylbicyclo[4.2.0]octa-1,3,5-trien-7-yl)benzoyl]-(S)-phenylalanine methyl ester}, after photocyclization, have been determined by X-ray diffraction. For comparison, a crystal structure analysis has also been carried out for the photoproduct (III) of the 3′-COOMe derivative after recrystallization {methyl 3-(7-hydroxy-3,5-diisopropyl-8,8-dimethylbicyclo[4.2.0]octa-1,3,5-trien-7-yl)benzoate}. The dihedral angle between the central carbonyl plane and the triisopropylphenyl ring deviates from 90° by 10 (1)° in (I), which makes an imbalance in the intramolecular O(carbonyl)...H(methine) distances of the isopropyl groups at positions 2 and 6. The crystal structure of (II) indicates that the nearer methine H was predominantly abstracted by the carbonyl O atom in the reaction. The absolute configuration around the asymmetric C atom in the cyclobutenol ring of the product is S.

A fourfold interpenetrating diamond-like three-dimensional zinc(II) coordination polymer: synthesis, crystal structure and physical properties

2019 ◽  
Vol 75 (5) ◽  
pp. 504-507 ◽  
Author(s):  
Hui-Ru Chen
Keyword(s):  
Crystal Structure ◽  
Room Temperature ◽  
Three Dimensional ◽  
Fluorescence Emission ◽  
Crystal Structure Analysis ◽  
The Novel ◽  
X Ray Diffraction ◽  
Metal Compounds ◽  
X Ray ◽  
Coordination Framework

Excellent fluorescence properties are exhibited by d 10 metal compounds. The novel three-dimensional ZnII coordination framework, poly[[{μ2-bis[4-(2-methyl-1H-imidazol-1-yl)phenyl] ether-κ2 N 3:N 3′}(μ2-furan-2,5-dicarboxylato-κ2 O 2:O 5)zinc(II)] 1.76-hydrate], {[Zn(C6H2O5)(C20H18N4O)]·1.76H2O} n , has been prepared and characterized using IR spectroscopy, elemental analysis and single-crystal X-ray diffraction. The crystal structure analysis revealed that the compound exhibits a novel fourfold interpenetrating diamond-like network. This polymer also displays a strong fluorescence emission in the solid state at room temperature.

scholarly journals A Salt Metathesis Route To Ruthenium Carbene Complex Isomers With Pyridine Dicarboxamide-Derived Chelate Pincer Ligands

2007 ◽  
Vol 62 (6) ◽  
pp. 783-790 ◽  
Author(s):  
Carolin Wallenhorst ◽  
Kirill V. Axenov ◽  
Joseph S. M. Samec ◽  
Roland Fröhlich ◽  
Gerhard Erker
Keyword(s):  
Crystal Structure ◽  
Single Crystals ◽  
Structure Analysis ◽  
Crystal Structure Analysis ◽  
Pincer Ligands ◽  
X Ray Diffraction ◽  
X Ray ◽  
Carbene Complex ◽  
Related Complex

Reaction of the doubly deprotonated pyridine 2,6-dicarboxamido ligand (1) with (PCy3)2Cl2 Ru=CHPh (3a) in THF gave a mixture of (lig)(PCy3)Ru=CHPh isomers (4). The pentane soluble N,N,O-4 isomer was isolated by extraction and characterized by X-ray diffraction. The O,N, O-4 isomer was identified in the residue. Single crystals of the closely related complex (lig)(NHC) Ru=CHPh, O,N,O-5, were obtained from the reaction of 1 with (NHC)(PCy3)Cl2Ru=CHPh (3b) and used for the X-ray crystal structure analysis of the system

Lewis-Base Adducts of Group 11 Metal(I) Compounds. LIX. Crystal Structure Determinations of Tetrakis(trimethylphosphine)copper(I) Halides and Tetrakis(triphenylphosphine)-copper(I) and -silver(I) Hexafluorophosphates

1990 ◽  
Vol 43 (10) ◽  
pp. 1697 ◽  
Author(s):  
GA Bowmaker ◽  
PC Healy ◽  
LM Engelhardt ◽  
JD Kildea ◽  
BW Skelton ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Crystal Structures ◽  
Lewis Base ◽  
X Ray Diffraction ◽  
Coordination Environment ◽  
X Ray ◽  
Bond Lengths ◽  
Cu Complex ◽  
Structure Determinations

The crystal structures of [Cu(Pme3)4]X (X = Cl , Br, I) and of [M(PPh3)4] [PF6] (M = Cu, Ag) have been determined by single-crystal X-ray diffraction methods at 295 K. The former compounds contain nearly tetrahedral [Cu(PMe3)4]+ ions on sites of m symmetry with mean Cu-P bond lengths of 2.270, 2.271 and 2.278 Ǻ for X = Cl , Br and I respectively. The latter compounds contain [M(PPh3)4]+ ions on sites of 3 symmetry. In the M =Ag complex the coordination environment is close to tetrahedral, but in the M =Cu complex the length of the axial Cu-P bond [2.465(2)Ǻ] is significantly shorter than that of the off-axis bonds [2.566(2)Ǻ]. Possible reasons for this are discussed.

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