Quantitative Electron-Density Contour Delineation in the Electronic Fourier Synthesizer for Crystal Structure Analysis

Nature ◽  
1948 ◽  
Vol 162 (4105) ◽  
pp. 22-23 ◽  
Author(s):  
R. PEPINSKY ◽  
D. SAYRE
Keyword(s):  
Crystal Structure ◽  
Electron Density ◽  
Structure Analysis ◽  
Crystal Structure Analysis ◽  
Density Contour

Performance of a new furnace for high-resolution synchrotron powder diffraction up to 1900 K: application to determine electron density distribution of the cubic CaTiO3perovskite at 1674 K

2004 ◽  
Vol 37 (5) ◽  
pp. 786-790 ◽  
Author(s):  
Masatomo Yashima ◽  
Masahiko Tanaka
Keyword(s):  
Crystal Structure ◽  
High Resolution ◽  
Density Distribution ◽  
Electron Density ◽  
Structure Analysis ◽  
High Temperatures ◽  
Powder Diffraction ◽  
Electron Density Distribution ◽  
Crystal Structure Analysis ◽  
Synchrotron Powder Diffraction

Accurate crystal structure analysis at high temperatures is an important challenge in science and technology. A new electric furnace for the measurement of high-resolution (δd/d= 0.03%) synchrotron radiation powder diffraction profiles from materials at high temperatures (up to 1900 K in air) has been designed and fabricated. This furnace consists of a ceramic refractory with MoSi2heaters, an aluminium body cooled by flowing water, and a sample stage with a spinner and a controller for sample-height adjustment.In situsynchrotron powder diffraction measurement for a calcium titanate perovskite specimen at 1674 K has been performed using the furnace at beamline 3A of the Photon Factory. The electron density distribution of the cubic perovskite at 1674 K was successfully obtained using a combination of Rietveld refinement, the maximum-entropy method (MEM) and MEM-based pattern-fitting techniques. The Ti atoms exhibit covalent bonding with the O atoms in the cubic CaTiO3perovskite at this temperature, while the Ca atoms are ionic. These results indicate that the new furnace yields high-quality data for accurate crystal structure analysis.

Crystal structure analysis of 4-R-phenyl-2,6-dimethyl-3,5-N-(dimethylcarbamoyl)-1,4-dihydropyridines [R=2-nitro (1), 4-methoxy (2) and 3,4-dichloro (3)]

1998 ◽  
Vol 213 (3) ◽  
Author(s):  
M. Bidya Sagar ◽  
K. Ravikumar ◽  
Y. S. Sadanandam
Keyword(s):  
Crystal Structure ◽  
Calcium Channel ◽  
Structure Analysis ◽  
Crystal Structure Analysis ◽  
Calcium Channel Antagonists

AbstractThe crystallographic characterization of the following three calcium channel antagonists is reported here: 2,6-dimethyl-3,5-dicarbamoyl-4-[2-nitro]-1,4-dihydropyridine (

scholarly journals Combined Use of Structure Analysis, Studies of Molecular Association in Solution, and Molecular Modelling to Understand the Different Propensities of Dihydroxybenzoic Acids to Form Solid Phases

Pharmaceutics ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 734
Author(s):  
Aija Trimdale ◽  
Anatoly Mishnev ◽  
Agris Bērziņš
Keyword(s):  
Crystal Structure ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Structure Analysis ◽  
Crystal Structure Analysis ◽  
Molecular Association ◽  
Hydroxyl Groups ◽  
Solid Phases ◽  
Solvent Molecules ◽  
Dynamics Simulations

The arrangement of hydroxyl groups in the benzene ring has a significant effect on the propensity of dihydroxybenzoic acids (diOHBAs) to form different solid phases when crystallized from solution. All six diOHBAs were categorized into distinctive groups according to the solid phases obtained when crystallized from selected solvents. A combined study using crystal structure and molecule electrostatic potential surface analysis, as well as an exploration of molecular association in solution using spectroscopic methods and molecular dynamics simulations were used to determine the possible mechanism of how the location of the phenolic hydroxyl groups affect the diversity of solid phases formed by the diOHBAs. The crystal structure analysis showed that classical carboxylic acid homodimers and ring-like hydrogen bond motifs consisting of six diOHBA molecules are prominently present in almost all analyzed crystal structures. Both experimental spectroscopic investigations and molecular dynamics simulations indicated that the extent of intramolecular bonding between carboxyl and hydroxyl groups in solution has the most significant impact on the solid phases formed by the diOHBAs. Additionally, the extent of hydrogen bonding with solvent molecules and the mean lifetime of solute–solvent associates formed by diOHBAs and 2-propanol were also investigated.

scholarly journals Preparative-scale HPLC Resolution of Metallacyclic η3-Allyltricarbonyliron Complexes and Determination of the Absolute Configuration by X-Ray Crystal Structure Analysis

1999 ◽  
Vol 23 (9) ◽  
pp. 578-579
Author(s):  
Rainer Schobert ◽  
Hermann Pfab ◽  
Jutta Böhmer ◽  
Frank Hampel ◽  
Andreas Werner
Keyword(s):  
Crystal Structure ◽  
Silica Gel ◽  
Structure Analysis ◽  
Absolute Configuration ◽  
Crystal Structure Analysis ◽  
Preparative Scale ◽  
X Ray ◽  
The Absolute

Racemates of (η3-allyl)tricarbonyliron lactone complex Fe(CO)3{η1:η3-C(O)XCH2CHCMeCH2} 1a (X = O) and (η3-allyl)tricarbonyliron lactam complex 2a (X = NMe) are resolved on a preparative scale by HPLC on cellulose tris(3,5-dimethylphenyl)carbamate/silica gel RP-8 and the absolute configuration of (-)-2a is determined by X-ray crystal structure analysis.

Second-Generation Inhibitors for the Metalloprotease Neprilysin Based on Bicyclic Heteroaromatic Scaffolds: Synthesis, Biological Activity, and X-Ray Crystal-Structure Analysis

2005 ◽  
Vol 88 (4) ◽  
pp. 731-750 ◽  
Author(s):  
Stefan Sahli ◽  
Brian Frank ◽  
W. Bernd Schweizer ◽  
François Diederich ◽  
Denise Blum-Kaelin ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Biological Activity ◽  
Structure Analysis ◽  
Second Generation ◽  
Crystal Structure Analysis ◽  
X Ray
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