Structural aspects of optical resolutions. Optical resolution of (R,S)-mandelic acid. DSC and X-ray studies of the diastereoisomeric salts

1992 ◽  
pp. 2011 ◽  
Author(s):  
M�ria Acs ◽  
Elisabeth Novotny-Bregger ◽  
K�lm�n Simon ◽  
Gyula Argay
Keyword(s):  
Mandelic Acid ◽  
Optical Resolution ◽  
X Ray ◽  
Structural Aspects

scholarly journals Simple Methylcadmium Alkoxides

2007 ◽  
Vol 62 (10) ◽  
pp. 1339-1342 ◽  
Author(s):  
Surajit Jana ◽  
Tania Pape ◽  
Norbert W. Mitzel
Keyword(s):  
Mass Spectrometry ◽  
Solid State ◽  
Molecular Formula ◽  
Equimolar Ratio ◽  
X Ray ◽  
X Ray Crystallography ◽  
Elemental Analyses ◽  
Solid State Structures ◽  
Structural Aspects ◽  
C Nmr

The reaction of dimethylcadmium with alcohols R-OH in equimolar ratio leads to the formation of tetrameric methylcadmium alkoxides with molecular formula [(MeCd)4 (OR)4] [R = Me (1), Et (2) and iPr (3)]. These compounds have been characterised by 1H, 13C NMR and IR spectroscopy, by mass spectrometry, elemental analyses and by X-ray crystallography (for 2 and 3). The solid state structures show distorted cubane-type aggregates with Cd4O4 cores. The structural aspects and the spectroscopic characterisations of these compounds are discussed.

Structural aspects of the hisingerite-neotocite series

Clay Minerals ◽  
1983 ◽  
Vol 18 (1) ◽  
pp. 21-31 ◽  
Author(s):  
R. A. Eggleton ◽  
J. H. Pennington ◽  
R. S. Freeman ◽  
I. M. Threadgold
Keyword(s):  
Function Analysis ◽  
Pore Space ◽  
Hollow Spheres ◽  
X Ray ◽  
Broken Hill ◽  
Transmission Electron ◽  
X Ray Absorption ◽  
Interconnected Pore ◽  
Intermediate Member ◽  
Structural Aspects

AbstractTransmission electron microscopy, X-ray radial distribution function analysis, chemical analysis, X-ray absorption edge spectroscopy, and Mössbauer spectroscopy combine to confirm an amorphous or gel structure for minerals of the hisingerite-neotocite series: (Fe,Mn)0.8SiO3.1.2H2O. A framework of (Fe,Mn)O6 octahedra and [SiO4] tetrahedra form hollow spheres, 50–100 Å in diameter, cross-bonded into a physically isotropic solid with as much as 10% interconnected pore space. The outer 10–20 Å of the spheres has a rudimentary structure, possibly marking the onset of segregation into Si-rich and (Fe,Mn)-rich layers. The Broken Hill mineral ‘sturtite’ is an intermediate member of the hisingerite-neotocite series.

Structural Aspects of Fe–Mg Artificial Superstructure Films Studied by X-Ray Diffraction

1986 ◽  
Vol 55 (1) ◽  
pp. 251-262 ◽  
Author(s):  
Yasuhiko Fujii ◽  
Teruhito Ohnishi ◽  
Tomoyuki Ishihara ◽  
Yasusada Yamada ◽  
Kenji Kawaguchi ◽  
...  
Keyword(s):  
X Ray Diffraction ◽  
X Ray ◽  
Structural Aspects

scholarly journals Microwave-Assisted Synthesis of(±)-Mandelic Acid-d5, Optical Resolution, and Absolute Configuration Determination

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Claudio Bruno ◽  
Giovanni Lentini ◽  
Angelo Lovece ◽  
Maria Maddalena Cavalluzzi ◽  
Alessia Carocci ◽  
...  
Keyword(s):  
Capillary Electrophoresis ◽  
Mandelic Acid ◽  
Optical Resolution ◽  
Racemic Mixture ◽  
Microwave Assisted Synthesis ◽  
Salt Formation ◽  
Microwave Assisted ◽  
Diastereomeric Salts ◽  
Chiral Capillary Electrophoresis ◽  
Resolving Agents

An efficient microwave-assisted synthesis of(±)-mandelic acid-d5was developed. The racemic mixture was resolved by diastereomeric salt formation using 1-phenylethylamine enantiomers as resolving agents. At each step, the resolution process was checked by determining mandelic acid-d5enantiomer ee values directly on fractional crystallized diastereomeric salts by chiral capillary electrophoresis analysis. Highly enriched (−)- and (+)-mandelic acid-d5(95% and 90% ee, resp.) were obtained and their absolute configurations—RandS, respectively—were determined by correlation of the (−)-mandelic acid-d5circular dichroism spectrum to the (R)-mandelic acid one.

Measurements of Soft and Ultrasoft X-Rays with Total Reflection Monochromator

1986 ◽  
Vol 30 ◽  
pp. 213-223
Author(s):  
Tomoya Arai
Keyword(s):  
Gas Flow ◽  
Bragg Reflection ◽  
Optical Resolution ◽  
Fluorescence Analysis ◽  
Total Reflection ◽  
X Rays ◽  
Light Elements ◽  
Lower Intensity ◽  
Measured Intensity ◽  
X Ray

The development of X-ray spectrographic analysis of light elements, which are O, C and B, has bee n performed for many applications using an end-window type X-ray tube with Rh-target and thin Be-window, wavelength dispersing devices, which are synthetic multilayers or total reflection mirror (with a specific filter) and a gas flow proportional counter with a thin film window. In Fig. 1 factors related to the intensity measurements in X-ray fluorescence analysis are shown. The excitation efficiency in the soft and ultrasoft X-ray region is very low because of the lower intensity of primary X-rays and low fluorescence yield of light elements. Instead of the wavelength dispersive method of Bragg reflection, having high resolution and low reflectivity, monochromatization combining total reflection by a selected mirror and an appropriate filter offered an alternate approach in order to increase measured intensity with reasonable optical resolution. Synthetic multilayers which have higher resolution and lower intensity compared with the performance of the mirror method have become popular for the detection of soft and ultrasoft X-ray region.

Insights into the Structural Aspects of the mGlu Receptor Orthosteric Binding Site

2019 ◽  
Vol 19 (26) ◽  
pp. 2421-2446 ◽  
Author(s):  
Junliang Hao ◽  
Qi Chen
Keyword(s):  
Binding Pocket ◽  
Receptor Subtypes ◽  
X Ray ◽  
Mglu Receptor ◽  
Metabotropic Glutamate ◽  
Amino Terminal ◽  
Subtype Selectivity ◽  
Agonist And Antagonist ◽  
Amino Terminal Domain ◽  
Structural Aspects

The amino terminal domain (ATD) of the metabotropic glutamate (mGlu) receptors contains the orthosteric glutamate recognition site, which is highly conserved across the eight mGlu receptor subtypes. In total, 29 X-ray crystal structures of the mGlu ATD proteins have been reported to date. These structures span across 3 subgroups and 6 subtypes, and include apo, agonist- and antagonist-bound structures. We will discuss the insights gained from the analysis of these structures with the focus on the interactions contributing to the observed group and subtype selectivity for select agonists. Furthermore, we will define the full expanded orthosteric ligand binding pocket (LBP) of the mGlu receptors, and discuss the macroscopic features of the mGlu ATD proteins.

Selten-Erd-Mandelate. Synthese und Kristallstrukturen von Pr(Man)3(ManH) und Er(Man)3(H2O)2 / Synthesis and Crystal Structures of Pr(Man)3(ManH) and Er(Man)3(H2O)2

2005 ◽  
Vol 60 (7) ◽  
pp. 753-757 ◽  
Author(s):  
Claudia Bromant ◽  
Wassiliki Nika ◽  
Ingo Pantenburg ◽  
Gerd Meyer
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Mandelic Acid ◽  
Hydroxyl Group ◽  
Water Molecules ◽  
X Ray ◽  
Carboxylate Oxygen ◽  
Rare Earth Salts ◽  
Alcoholic Hydroxyl ◽  
Oxygen Atoms

Pr(Man)3(ManH) and Er(Man)3(H2O)2 (ManH = mandelic acid) have been synthesized by slow evaporation of aqueous solutions of rare-earth salts (Pr(OH)3, ErCl3 · 6H2O) with mandelic acid (α-hydroxy-phenyl acetic acid, C8H8O3) and their crystal structures were determined on the basis of X-ray data. In the crystal structure of Pr(Man)3(ManH) (1) (monoclinic, P21, a = 574.8(1), b = 3042.5(4), c = 908.4(1) pm, β = 92.09(2)°, Z = 2) the Pr(III) ions are surrounded by eight oxygen atoms in a distorted square antiprismatic fashion with distances Pr-O in the range 241 to 254 pm. These polyhedra are connected by coordinative bonds to chains paralleling the crystallographic [100] direction. In Er(Man)3(H2O)2 (2) (orthorhombic, P212121, a = 577.7(3), b = 1816.3(13), c = 2329.4(13) pm, Z = 4) the crystal structure contains isolated complexes with octa-coordinated erbium atoms chelated by three mandelate anions through one of their carboxylate oxygen atoms and the alcoholic hydroxyl group. Two water molecules complete the distorted square antiprismatic coordination sphere.

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