Hydrogen-Bond Nature Studied by X-ray and Neutron Structure Analyses of MeHPLN at Room Temperature

2003 ◽  
Vol 72 (11) ◽  
pp. 2816-2821 ◽  
Author(s):  
R. Kiyanagi ◽  
A. Kojima ◽  
T. Hayashide ◽  
H. Kimura ◽  
M. Watanabe ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Room Temperature ◽  
X Ray ◽  
Neutron Structure

scholarly journals The caesium phosphates Cs3(H1.5PO4)2(H2O)2, Cs3(H1.5PO4)2, Cs4P2O7(H2O)4, and CsPO3

2020 ◽  
Vol 151 (9) ◽  
pp. 1317-1328
Author(s):  
Matthias Weil ◽  
Berthold Stöger
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Single Crystal ◽  
Diffraction Data ◽  
Room Temperature ◽  
Structure Type ◽  
Solid State Reactions ◽  
X Ray Diffraction ◽  
Hydrogen Phosphate ◽  
X Ray

Abstract The caesium phosphates Cs3(H1.5PO4)2(H2O)2 and Cs3(H1.5PO4)2 were obtained from aqueous solutions, and Cs4P2O7(H2O)4 and CsPO3 from solid state reactions, respectively. Cs3(H1.5PO4)2, Cs4P2O7(H2O)4, and CsPO3 were fully structurally characterized for the first time on basis of single-crystal X-ray diffraction data recorded at − 173 °C. Monoclinic Cs3(H1.5PO4)2 (Z = 2, C2/m) represents a new structure type and comprises hydrogen phosphate groups involved in the formation of a strong non-symmetrical hydrogen bond (accompanied by a disordered H atom over a twofold rotation axis) and a very strong symmetric hydrogen bond (with the H atom situated on an inversion centre) with symmetry-related neighbouring anions. Triclinic Cs4P2O7(H2O)4 (Z = 2, P$$\bar{1}$$ 1 ¯ ) crystallizes also in a new structure type and is represented by a diphosphate group with a P–O–P bridging angle of 128.5°. Although H atoms of the water molecules were not modelled, O···O distances point to hydrogen bonds of medium strengths in the crystal structure. CsPO3 is monoclinic (Z = 4, P21/n) and belongs to the family of catena-polyphosphates (MPO3)n with a repetition period of 2. It is isotypic with the room-temperature modification of RbPO3. The crystal structure of Cs3(H1.5PO4)2(H2O)2 was re-evaluated on the basis of single-crystal X-ray diffraction data at − 173 °C, revealing that two adjacent hydrogen phosphate anions are connected by a very strong and non-symmetrical hydrogen bond, in contrast to the previously described symmetrical bonding situation derived from room temperature X-ray diffraction data. In the four title crystal structures, coordination numbers of the caesium cations range from 7 to 12. Graphic abstract

scholarly journals New Insights Into the Structure of Hydroxylated and Alkylated Glycols: A Comparative X-ray Diffraction, Raman and Molecular Dynamics Study of Ethane-1,2-Diol, 2-Methoxyethan-1-ol and 1,2-Dimethoxy Ethane

2020 ◽  
Author(s):  
Lorenzo Gontrani ◽  
Pietro Tagliatesta ◽  
Antonio Agresti ◽  
Sara Pescetelli ◽  
Marilena Carbone
Keyword(s):  
Molecular Dynamics ◽  
Hydrogen Bond ◽  
Room Temperature ◽  
Intermolecular Hydrogen Bond ◽  
Hydroxyl Groups ◽  
Gauche Conformation ◽  
X Ray ◽  
Hydrogen Bond Interactions ◽  
Diffraction Patterns ◽  
Intramolecular Hydrogen

In this study, we report a detailed experimental and theoretical investigation of three glycols, namely ethane-1,2-diol, 2-methoxyethan-1-ol and 1,2-dimethoxy ethane. For the first time, the X-Ray spectra of the latter two liquids was measured at room temperature, and they were compared with the newly measured spectrum of ethane-1,2-diol. The experimental diffraction patterns were interpreted very satisfactorily with molecular dynamics calculations, and suggest that in liquid ethane-1,2-diol most molecules are found in gauche conformation, with intramolecular hydrogen bond between the two hydroxyl groups. Intramolecular H-bonds are established in the mono-alkylated diol, but the interaction is weaker. The EDXD study also evidences strong intermolecular hydrogen-bond interactions, with short O···O correlations in both systems, while longer methyl-methyl interactions are found in 1,2-dimethoxy ethane. X-Ray studies are complemented by micro Raman investigations at room temperature and at 80°C, that confirm the conformational analysis predicted by X-Ray experiments and simulations.

First crystal-structure determination of natural lansfordite, MgCO3·5H2O

2017 ◽  
Vol 81 (5) ◽  
pp. 1063-1071 ◽  
Author(s):  
Fabrizio Nestola ◽  
Anatoly V. Kasatkin ◽  
Sergey S. Potapov ◽  
Olga YA. Chervyatsova ◽  
Arianna Lanza
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Single Crystal ◽  
Structure Determination ◽  
Room Temperature ◽  
Crystal Structure Determination ◽  
Hydrogen Atoms ◽  
Synthetic Analogues ◽  
X Ray

AbstractThis study presents the first crystal-structure determination of natural MgCO3·5H2O, mineral lansfordite, in comparison with previous structural works performed on synthetic analogues. A new prototype single-crystal X-ray diffractometer allowed us to measure an extremely small crystal (i.e. 0.020 mm × 0.010 mm × 0.005 mm) and refine anisotropically all non-hydrogen atoms in the structure and provide a robust hydrogen-bond arrangement. Our new data confirm that natural lansfordite can be stable for several months at room temperature, in contrast with previous works, which reported that such a mineral could be stable only below 10°C.

The correlation between O—H stretching frequencies and hydrogen bond distances in a crystalline sugar monohydrate

1979 ◽  
Vol 57 (19) ◽  
pp. 2640-2645 ◽  
Author(s):  
J. Umemura ◽  
G. I. Birnbaum ◽  
D. R. Bundle ◽  
W. F. Murphy ◽  
H. J. Bernstein ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Infrared Spectra ◽  
Room Temperature ◽  
Isotopic Dilution ◽  
X Ray

The Raman and infrared spectra of crystalline methyl 3,6-dideoxy-β-D-ribo-hexopyranoside monohydrate in the O—H stretching region have been studied at room temperature and lower temperatures. Four bands have been identified and correlated with the corresponding O … O distances of the four distinct hydrogen bonds obtained from X-ray data. The assignments were substantiated by a deuterium isotopic dilution study.

Neuartige zwitterionische λ5-Spirosilicate: Synthese und Kristallstruktur von Bis[l,2-benzoldiolato(2 – )][2-(dimethylammonio)phenyl]silicat sowie Synthese von Bis[2,3-naphthalindiolato(2 – )][2-(dimethylammonio)phenyl]silicat-Hemiacetonitril-Solvat / Novel Zwitterionic λ5-Spirosilicates: Synthesis and Crystal Structure of Bis[1,2-benzenediolato(2–)][2-(dimethylammonio)phenyl]silicate and Synthesis of Bis[2,3-naphthalenediolato(2–)][2-(dimethylammonio)phenyl]silicate Hemiacetonitrile Solvate

1992 ◽  
Vol 47 (10) ◽  
pp. 1370-1376 ◽  
Author(s):  
Reinhold Tacke ◽  
Frank Wiesenberger ◽  
Angel Lopez-Mras ◽  
Jörg Sperlich ◽  
Günter Mattern
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Carbon Atom ◽  
Coordination Polyhedron ◽  
Room Temperature ◽  
Trigonal Bipyramid ◽  
X Ray Diffraction ◽  
Apical Position ◽  
Synthesis And Crystal Structure ◽  
X Ray

The zwitterionic λ5-spirosilicates bis[1,2-benzenediolato(2–)][2-(dimethylammonio)-phenyl]silicate (4) and bis [2,3-naphthalenediolato(2–)][2-(dimethylammonio)phenyl]silicate (5; isolated as 5 · ½CH3CN) were synthesized and the crystal structure of 4 was studied by X-ray diffraction. 4 was prepared by reaction of [2-(dimethylamino)phenyl]trimethoxysilane (7) or bis[2-(dimethylamino)phenyl]dimethoxysilane (8) with 1,2-dihydroxybenzene in acetonitrile at room temperature. 5 was synthesized analogously by reaction of 7 or 8 with 2,3-dihydroxynaphthalene. The silanes 7 and 8 were obtained by reaction of tetramethoxysilane (6) with [2-(dimethylamino)phenyl]lithium. The reactions 8 → 4 and 8 → 5 involve a remarkable Si–C cleavage leading to the formation of (dimethylamino)benzene. The pentacoordinate silicon atoms of 4 and 5 are surrounded by four oxygen atoms and one sp2 hybridized carbon atom. The coordination polyhedron of 4 can be described as a distorted square pyramid, the carbon atom being in the apical position (the structure is distorted by 69,1 % from the trigonal bipyramid towards the square pyramid). In the crystal, 4 forms an intramolecular N-H···O hydrogen bond.

Synthese, Kristallstruktur und Eigenschaften von 1,1,3,3,3-Pentaaminol- 1-thio-1 λ5,3λ5-diphosphaz-2-en (NH2)2P(S)N=P(NH2)3 / Synthesis, Crystal Structure, and Properties of 1,1,3,3,3-Pentaam 1-thio-1 λ5,3λ5-diphosphaz-2-en (NH2)2P(S)N=P(NH2)3

1997 ◽  
Vol 52 (4) ◽  
pp. 490-495 ◽  
Author(s):  
Stefan Horstmann ◽  
Wolfgang Schnick
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Hydrogen Atom ◽  
Room Temperature ◽  
Acetonitrile Solution ◽  
Structure And Properties ◽  
X Ray ◽  
Hydrogen Bonding Interactions ◽  
Ray Methods

Abstract (NH2)2P(S)N=P(NH2)3 has been prepared by a two step synthesis. Suitable single crystals were obtained from an acetonitrile solution in a temperature gradient between 60 °C and room temperature. The crystal structure of (NH2)2P(S)N=P(NH2)3 has been determined by single crystal X-ray methods (P21/c, a = 998.27(9) b = 762.78(8), c = 1007.70(15) pm, β = 107.340(7)°, Z = 4). In the crystal structure each hydrogen atom is subject to a hydrogen bond. Four N-H -N hydrogen bonding interactions per molecule build up a framework connecting two molecules in eight-membered rings. Each sulfur atom shows six distances N-H···S in the range of weak hydrogen bonding interactions.

scholarly journals Neutron structure of human carbonic anhydrase II in complex with methazolamide: mapping the solvent and hydrogen-bonding patterns of an effective clinical drug

IUCrJ ◽  
2016 ◽  
Vol 3 (5) ◽  
pp. 319-325 ◽  
Author(s):  
Mayank Aggarwal ◽  
Andrey Y. Kovalevsky ◽  
Hector Velazquez ◽  
S. Zoë Fisher ◽  
Jeremy C. Smith ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Active Site ◽  
Room Temperature ◽  
Carbonic Anhydrases ◽  
Structural Comparison ◽  
Methyl Derivative ◽  
X Ray ◽  
Solvent Displacement ◽  
Neutron Structure ◽  
Clinical Drug

Carbonic anhydrases (CAs; EC 4.2.1.1) catalyze the interconversion of CO2and HCO3−, and their inhibitors have long been used as diuretics and as a therapeutic treatment for many disorders such as glaucoma and epilepsy. Acetazolamide (AZM) and methazolamide (MZM, a methyl derivative of AZM) are two of the classical CA inhibitory drugs that have been used clinically for decades. The jointly refined X-ray/neutron structure of MZM in complex with human CA isoform II (hCA II) has been determined to a resolution of 2.2 Å with anRcrystof ∼16.0%. Presented in this article, along with only the second neutron structure of a clinical drug-bound hCA, is an in-depth structural comparison and analyses of differences in hydrogen-bonding network, water-molecule orientation and solvent displacement that take place upon the binding of AZM and MZM in the active site of hCA II. Even though MZM is slightly more hydrophobic and displaces more waters than AZM, the overall binding affinity (Ki) for both of the drugs against hCA II is similar (∼10 nM). The plausible reasons behind this finding have also been discussed using molecular dynamics and X-ray crystal structures of hCA II–MZM determined at cryotemperature and room temperature. This study not only allows a direct comparison of the hydrogen bonding, protonation states and solvent orientation/displacement of AZM and MZM, but also shows the significant effect that the methyl derivative has on the solvent organization in the hCA II active site.

Electron Microscopy of Human Gallstones

1971 ◽  
Vol 29 ◽  
pp. 296-297
Author(s):  
C. Wolpers ◽  
R. Blaschke
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Bile Pigment ◽  
X Ray Diffraction ◽  
Triclinic Crystal System ◽  
X Ray ◽  
Follow Up Study ◽  
Infra Red ◽  
Main Components

Scanning microscopy was used to study the surface of human gallstones and the surface of fractures. The specimens were obtained by operation, washed with water, dried at room temperature and shadowcasted with carbon and aluminum. Most of the specimens belong to patients from a series of X-ray follow-up study, examined during the last twenty years. So it was possible to evaluate approximately the age of these gallstones and to get information on the intensity of growing and solving.Cholesterol, a group of bile pigment substances and different salts of calcium, are the main components of human gallstones. By X-ray diffraction technique, infra-red spectroscopy and by chemical analysis it was demonstrated that all three components can be found in any gallstone. In the presence of water cholesterol crystallizes in pane-like plates of the triclinic crystal system.

Opening images of synaptic vesicles and calcium localization by means of microwave fixation method

1990 ◽  
Vol 48 (2) ◽  
pp. 182-183
Author(s):  
Vinci Mizuhira ◽  
Hiroshi Hasegawa
Keyword(s):  
Synaptic Vesicles ◽  
Room Temperature ◽  
Osmium Tetroxide ◽  
Sampling Procedure ◽  
Fixation Method ◽  
Potassium Oxalate ◽  
X Ray ◽  
Cacodylate Buffer ◽  
Ultrathin Sections ◽  
Microwave Fixation

Microwave irradiation (MWI) was applied to 0.3 to 1 cm3 blocks of rat central nervous system at 2.45 GHz/500W for about 20 sec in a fixative, at room temperature. Fixative composed of 2% paraformaldehyde, 0.5% glutaraldehyde in 0.1 M cacodylate buffer at pH 7.4, also contained 2 mM of CaCl2 , 1 mM of MgCl2, and 0.1% of tannic acid for conventional observation; and fuether 30-90 mM of potassium oxalate containing fixative was applied for the detection of calcium ion localization in cells. Tissue blocks were left in the same fixative for 30 to 180 min after MWI at room temperature, then proceeded to the sampling procedure, after postfixed with osmium tetroxide, embedded in Epon. Ultrathin sections were double stained with an useal manner. Oxalate treated sections were devided in two, stained and unstained one. The later oxalate treated unstained sections were analyzed with electron probe X-ray microanalyzer, the EDAX-PU-9800, at 40 KV accelerating voltage for 100 to 200 sec with point or selected area analyzing methods.

Evidence for ordered Fe3Ni

1987 ◽  
Vol 45 ◽  
pp. 216-217
Author(s):  
K.B. Reuter ◽  
D.B. Williams ◽  
J.I. Goldstein
Keyword(s):  
Experimental Data ◽  
Martensitic Transformation ◽  
Electron Diffraction ◽  
Room Temperature ◽  
Direct Evidence ◽  
Transformation Product ◽  
Iron Meteorites ◽  
X Ray ◽  
Ni Content ◽  
Temperature Transformation

In the Fe-Ni system, although ordered FeNi and ordered Ni3Fe are experimentally well established, direct evidence for ordered Fe3Ni is unconvincing. Little experimental data for Fe3Ni exists because diffusion is sluggish at temperatures below 400°C and because alloys containing less than 29 wt% Ni undergo a martensitic transformation at room temperature. Fe-Ni phases in iron meteorites were examined in this study because iron meteorites have cooled at slow rates of about 10°C/106 years, allowing phase transformations below 400°C to occur. One low temperature transformation product, called clear taenite 2 (CT2), was of particular interest because it contains less than 30 wtZ Ni and is not martensitic. Because CT2 is only a few microns in size, the structure and Ni content were determined through electron diffraction and x-ray microanalysis. A Philips EM400T operated at 120 kV, equipped with a Tracor Northern 2000 multichannel analyzer, was used.

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