About the degree of hydration in potassiumtrisoxalatochromate hydrate

2005 ◽  
Vol 220 (11) ◽  
Author(s):  
Chunhua Hu ◽  
Gernot Heger ◽  
Irmgard Kalf ◽  
Ullrich Englert
Keyword(s):  
Neutron Diffraction ◽  
Water Molecules ◽  
Structure Model ◽  
Hydrogen Atoms ◽  
Neutron Data ◽  
X Ray ◽  
Degree Of Hydration ◽  
Thermogravimetric Data ◽  
Hydration Model ◽  
Good Agreement

AbstractData obtained from single crystal X-ray and neutron diffraction experiments have been combined with results from thermogravimetry in order to derive an improved structure model for potassium tris(oxalato)chromate hydrate. The degree of hydration for this compound has been reinvestigated: Earlier work assumed a trihydrate stoichiometry and had to accept an unusually short K···O distance of 2.3 Å. Our neutron data reveal the position of the hydrogen atoms in the water molecules; they prove that abnormally short separations between a cation and atoms of a water molecule can only occur between sites of mutually exclusive occupancy and hence remain without chemical relevance. Closest K···O distances in our revised hydration model amount to 2.6 Å, in good agreement with expectation. Both diffraction experiments and thermogravimetric data agree with the stoichiometry K

The structure of chromium potassium alum

1958 ◽  
Vol 246 (1244) ◽  
pp. 78-90 ◽  
Keyword(s):  
Hydrogen Bonds ◽  
Neutron Diffraction ◽  
Water Molecule ◽  
Water Molecules ◽  
Hydrogen Atoms ◽  
Potassium Alum ◽  
X Ray ◽  
Single Crystal Study ◽  
Thermal Vibrations ◽  
Oxygen Atoms

A single-crystal study of chromium potassium alum has been made by neutron diffraction, thus completing the structure first indicated by the X-ray investigations of Lipson & Beevers (1935). Hydrogen bonds link the oxygen atoms within the water molecules to other oxygen atoms in the structure. In each case the angle HOH for a water molecule is about 106°, although this sometimes entails appreciable displacement of the hydrogen atoms from the direct O—O line. Large thermal vibrations of the oxygen atoms in the sulphate groups are noteworthy.

scholarly journals Crystallization and preliminary neutron diffraction experiment of human farnesyl pyrophosphate synthase complexed with risedronate

2014 ◽  
Vol 70 (4) ◽  
pp. 470-472 ◽  
Author(s):  
Takeshi Yokoyama ◽  
Andreas Ostermann ◽  
Mineyuki Mizuguchi ◽  
Nobuo Niimura ◽  
Tobias E. Schrader ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Structural Characteristics ◽  
Water Molecules ◽  
Farnesyl Pyrophosphate ◽  
Neutron Diffraction Experiment ◽  
Neutron Data ◽  
Farnesyl Pyrophosphate Synthase ◽  
X Ray ◽  
Complex Crystals ◽  
Clinical Drug

Nitrogen-containing bisphosphonates (N-BPs), such as risedronate and zoledronate, are currently used as a clinical drug for bone-resorption diseases and are potent inhibitors of farnesyl pyrophosphate synthase (FPPS). X-ray crystallographic analyses of FPPS with N-BPs have revealed that N-BPs bind to FPPS with three magnesium ions and several water molecules. To understand the structural characteristics of N-BPs bound to FPPS, including H atoms and hydration by water, neutron diffraction studies were initiated using BIODIFF at the Heinz Maier-Leibnitz Zentrum (MLZ). FPPS–risedronate complex crystals of approximate dimensions 2.8 × 2.5 × 1.5 mm (∼3.5 mm3) were obtained by repeated macro-seeding. Monochromatic neutron diffraction data were collected to 2.4 Å resolution with 98.4% overall completeness. Here, the first successful neutron data collection from FPPS in complex with N-BPs is reported.

The water molecules in CuSO 4 .5H 2 O

1962 ◽  
Vol 266 (1324) ◽  
pp. 95-108 ◽  
Keyword(s):  
Hydrogen Bonds ◽  
Neutron Diffraction ◽  
Single Crystals ◽  
Water Molecules ◽  
X Ray Diffraction ◽  
Neutron Data ◽  
X Ray ◽  
Atomic Nuclei ◽  
Different Temperatures ◽  
Molecular Rotations

Single crystals of fully hydrated copper sulphate have been studied by neutron diffraction and the measurements have been used to construct projections of the neutron-scattering density, due to the atomic nuclei, on the three crystallographic axial planes. These provide full details of the shape and environment of the water molecules and of the hydrogen bonds which link together the atoms in the structure, which was originally proposed by Beevers & Lipson as a result of X -ray diffraction work. It is found that the H—O—H angles for all the water molecules are within a degree or two of the tetrahedral value and the hydrogen bonds have to be bent by up to 26° in order to accommodate them. Corresponding measurements have been made at a series of five different temperatures between 20 and 90°C in order to test a suggestion that molecular rotations of the water molecules occurred before the onset of dehydration: the neutron data refute this suggestion.

scholarly journals Neutron crystal structure of human FPPS complexed with risedronate

2014 ◽  
Vol 70 (a1) ◽  
pp. C1220-C1220
Author(s):  
Takeshi Yokoyama ◽  
Andreas Ostermann ◽  
Mineyuki Mizuguchi ◽  
Nobuo Niimura ◽  
Tobias Schrader ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Neutron Diffraction ◽  
Antitumor Agents ◽  
Structural Characteristics ◽  
Water Soluble ◽  
Water Molecules ◽  
Protonation State ◽  
Hydrogen Atoms ◽  
X Ray ◽  
Hydrogen Bond Networks

Nitrogen-containing bisphosphonates (N-BPs), such as risedronate and zoledronate, are currently used as clinical drug for bone-resorption diseases and are potent inhibitor of farnesyl pyrophosphate synthase (FPPS). The potential of N-BPs as antitumor agents has also been suggested by the several in vitro and in vivo preclinical studies. However, BP drugs limit their therapeutic use to bone-related diseases, because BPs are highly charged and water soluble molecules. X-ray crystallographic analyses of FPPS with N-BPs have revealed that N-BPs bind to FPPS with three magnesium ions and several water molecules. In order to develop a novel FPPS inhibitor, the hydrogen-bond networks formed by FPPS, BPs and water molecules are necessary to be elucidated. To understand the structural characteristics of N-BPs bound to FPPS, including hydrogen atoms and hydration by water, neutron diffraction studies were initiated using BIODIFF at the Heinz Maier-Leibnitz Zentrum (MLZ). FPPS-risedronate complex crystals of approximate dimensions 2.8 × 2.5 × 1.5 mm (~ 3.5 mm3) were obtained by repeated macro-seeding. Monochromatic neutron diffraction data were collected to 2.4 Å resolution with 98.4% overall completeness and 10.7% Rmerge. As a result of X-ray/neutron joint refinment, R and Rfree values for the neutron data were 19.6 and 23.3%, respectively. This neutron structure clearly reveals the protonation state of risedronate, hydration in the inhibitor-binding region. Furthermore, the amide H/D exchange analysis showed that there is a highly rigid region which regulate the structural change upon the binding of the ligands. Here we will discuss the detailed hydrogen-bond network and the protonation state of FPPS and risedronate.

Investigation of Residual Strains of the Second Kind in Plastically Deformed Metallic Materials

1994 ◽  
Vol 376 ◽  
Author(s):  
M. Vrána ◽  
P. Klimanek ◽  
T. Kschidock ◽  
P. Lukáš ◽  
P. Mikula
Keyword(s):  
High Resolution ◽  
Neutron Diffraction ◽  
Stacking Faults ◽  
Metallic Materials ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
X Ray ◽  
Neutron Diffractometer ◽  
Residual Strains ◽  
Good Agreement

ABSTRACTInvestigation of strongly distorted crystal structures caused by dislocations, stacking-faults etc. in both plastically deformed f.c.c. and b.c.c. metallic materials was performed by the analysis of the neutron diffraction line broadening. Measurements were realized by means of the high resolution triple-axis neutron diffractometer equipped by bent Si perfect crystals as monochromator and analyzer at the NPI Řež. The substructure parameters obtained in this manner are in good agreement with the results of X-ray diffraction analysis.

scholarly journals Lower resolution Laue neutron data yield correct nanocluster formulations

2014 ◽  
Vol 70 (a1) ◽  
pp. C187-C187
Author(s):  
Alison Edwards
Keyword(s):  
Neutron Diffraction ◽  
Single Crystal ◽  
Diffraction Pattern ◽  
Precise Determination ◽  
Data Sets ◽  
X Rays ◽  
Low Resolution ◽  
Neutron Data ◽  
X Ray ◽  
Product Formulation

"The renaissance in Laue studies - at neutron sources - provides us with access to single crystal neutron diffraction data for synthetic compounds without requiring synthesis of prohibitively large amounts of compound or improbably large crystals. Such neutron diffraction studies provide vital data where proof of the presence or absence of hydrogen in particular locations is required and which cannot validly be proved by X-ray studies. Since the commissioning of KOALA at OPAL in 2009[1] we have obtained numerous data sets which demonstrate the vital importance of measuring data even where the extent of the diffraction pattern is at relatively low resolution - especially when compared to that obtainable for the same compound with X-rays. In the Laue experiment performed with a fixed radius detector, data reduction is only feasible for crystals in the ""goldilocks"" zone – where the unit cell is relatively large for the detector, a correspondingly low resolution diffraction pattern in which adjacent spots are less affected by overlap will yield more data against which a structure can be refined than a pattern of higher resolution – one where neighbouring spots overlap rendering both unusable (in our current methodology). Analogous application of powder neutron diffraction in such determinations is also considered. Single crystal neutron diffraction studies of several important compounds (up to 5KDa see figure below)[2] in which precise determination of hydride content by neutron diffraction was pivotal to the final formulation will be presented. The neutron data sets typically possess 20% or fewer unique data at substantially "lower resolution" than the corresponding X-ray data sets. Careful refinement clearly reveals chemical detail which is typically unexplored in related X-ray diffraction studies reporting high profile chemistry despite the synthetic route being one which hydride ought to be considered/excluded in product formulation."

scholarly journals Molecular Dynamics Modellization and Simulation of Water Diffusion through Plant Cutin

1999 ◽  
Vol 54 (11) ◽  
pp. 896-902 ◽  
Author(s):  
Antonio Matas ◽  
Antonio Heredia
Keyword(s):  
Experimental Data ◽  
Molecular Dynamics ◽  
Structural Information ◽  
Md Simulations ◽  
Water Molecules ◽  
Plant Cuticle ◽  
X Ray Diffraction ◽  
Cross Link ◽  
X Ray ◽  
Good Agreement

Abstract A theoretical molecular modelling study has been conducted for cutin, the biopolyester that forms the main structural component of the plant cuticle. Molecular dynamics (MD) simulations, extended over several ten picoseconds, suggests that cutin is a moderately flexible netting with motional constraints mainly located at the cross-link sites of functional ester groups. This study also gives structural information essentially in accordance with previously reported experimental data, obtained from X -ray diffraction and nuclear magnetic resonance experiments. MD calculations were also performed to simulate the diffusion of water mole­cules through the cutin biopolymer. The theoretical analysis gives evidence that water perme­ation proceedes by a “hopping mechanism”. Coefficients for the diffusion of the water molecules in cutin were obtained from their mean-square displacements yielding values in good agreement with experimental data.

scholarly journals Dynamics of Water in Crystal Hydrates

1967 ◽  
Vol 22 (9) ◽  
pp. 1440-1451 ◽  
Author(s):  
Ingo Berthold ◽  
Alarich Weiss
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Dynamical Behaviour ◽  
Water Molecules ◽  
Intensity Data ◽  
Two Dimensional ◽  
Fourier Synthesis ◽  
Hydrogen Atoms ◽  
X Ray ◽  
H Nmr

The crystal structure of Na2S2O6·2 H2O has been refined by means of single crystal X-ray intensity data. The structure of the isotypic Li2S2O6·2 H20 was also determined by single crystal studies. Two dimensional differential FOURIER synthesis revealed the approximate positions of the hydrogen atoms. From 1H-NMR investigations, the crystal structure, and information gained by IR spectroscopy the complete atomic arrangement in these two substances was obtained. The influence of the dynamical behaviour of the water molecules is taken into account in determining the hydrogen positions.

The crystal and molecular structure of guanine hydrochloride dehydrate

1965 ◽  
Vol 288 (1414) ◽  
pp. 418-439 ◽  
Keyword(s):  
Hydrogen Bonds ◽  
Least Squares Method ◽  
Three Dimensional ◽  
Water Molecules ◽  
Hydrogen Atoms ◽  
X Ray ◽  
Anisotropic Temperature ◽  
Chlorine Ions ◽  
Atomic Coordinates ◽  
Single Crystal Analysis

The structure of guanine hydrochloride monohydrate has been determined by X-ray single crystal analysis and the parameters (including anisotropic temperature vibrations) have been refined by the three-dimensional least squares method. The unit cell is monoclinic with a = 14.69 ± 0.01, b = 13.40 ± 0.01, c = 4.840 ± 0.005 Å; β = 93.8°± 0.1°; space group P 2 1 / a . For 1600 independent reflexions the final value of the agreement index R was 0.07 and the standard deviations of atomic coordinates are in the region of 0.0035 Å. Two guanine molecules are linked together by hydrogen bonds to form a centrosymmetrical dimer. The dimer is linked by hydrogen bonds to four water molecules which are then hydrogen bonded to two chlorine ions. It is shown that the guanine molecule has associated with it six centres of electron density corresponding to hydrogen atoms and it is therefore in the form (H guanine) + with protonation at the N 7 position.

Sign in / Sign up

Export Citation Format

Share Document