Neutron Structure Analysis of CsH3(SeO3)2at Room Temperature

Heterocyclic cage compounds of type I (compounds 8-10) have been prepared by condensation reactions of 1,2,2-trifunctional disilanes Me(R)XSiSiMeX2 (R = Me, Ph, OEt; X = NMe2, OEt) with triethanolamine using the “Dilution Principle”. The starting compounds are obtained by Si-Me cleavage of Si2Me6 with acetylchloride/AlCl3 followed by either aminolysis with HNMe2 or alcoholysis with EtOH. 1H NMR spectra indicate N→Si(1) intraction with the more acidic Si atom in 8 and 9. This result is proved by the X-ray structure analysis of 8 (monoclinic, P21/c; a = 7,088(2), b = 15,070(4), c = 12,701(4) Å, β = 104,96(2) at -130 °C, Z = 4); the Si(1)···N distance is found to be 2,768 Å , connected with a significant angular distortion of the tetrahedral coordination around Si(1) towards a trigonal bipyramid. In compound 10, too, N→Si(1) coordination is observed at room temperature in spite of almost equal acidity for both Si atoms. This can be explained by the preference of 5- over 6-membered chelating ring systems. At higher temperatures the 1H NMR spectra show a fluctuation of the N-donor between the two Si centres.

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Facile Synthesis of 4,5-Dihydro-1,3,4-Thiadiazoles by 1,3-Dipolar Cycloaddition of Thioisomünchnones

Australian Journal of Chemistry ◽

10.1071/ch08412 ◽

2009 ◽

Vol 62 (4) ◽

pp. 356 ◽

Cited By ~ 3

Author(s):

Bárbara Sánchez ◽

José Luis Bravo ◽

María Josí Arívalo ◽

Ignacio López ◽

Mark E. Light ◽

...

Keyword(s):

Structure Analysis ◽

Structure Elucidation ◽

Room Temperature ◽

Dipolar Cycloaddition ◽

Two Dimensional ◽

Facile Synthesis ◽

X Ray ◽

Mild Conditions ◽

Nmr Techniques

The present paper summarizes a straightforward synthesis of 4,5-dihydro-1,3,4-thiadiazoles by the 1,3-dipolar cycloaddition of thioisomünchnones. These reactions have been carried out in dichloromethane and are essentially complete within 60 min at room temperature. Under such mild conditions the asymmetric version has been explored as well. Unequivocal structure elucidation has been accomplished by means of one- and two-dimensional NMR techniques as well as X-ray structure analysis.

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Ambient pressure synthesis and neutron structure analysis of YBa2Cu4O8

Physica C Superconductivity ◽

10.1016/0921-4534(91)90458-b ◽

1991 ◽

Vol 182 (1-3) ◽

pp. 67-72 ◽

Cited By ~ 15

Author(s):

I.K. Gopalakrishnan ◽

J.V. Yakhmi ◽

H. Rajagopal ◽

A. Sequeira ◽

R.M. Iyer

Keyword(s):

Structure Analysis ◽

Ambient Pressure ◽

Neutron Structure ◽

Pressure Synthesis

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The recombinant dihydropyridine receptor II–III loop and partly structured ‘C’ region peptides modify cardiac ryanodine receptor activity

Biochemical Journal ◽

10.1042/bj20041152 ◽

2005 ◽

Vol 385 (3) ◽

pp. 803-813 ◽

Cited By ~ 15

Author(s):

Angela F. DULHUNTY ◽

Yamuna KARUNASEKARA ◽

Suzanne M. CURTIS ◽

Peta J. HARVEY ◽

Philip G. BOARD ◽

...

Keyword(s):

Sarcoplasmic Reticulum ◽

Secondary Structure ◽

Cardiac Muscle ◽

Ryanodine Receptor ◽

Structure Analysis ◽

Room Temperature ◽

Random Coil ◽

Cardiac Sarcoplasmic Reticulum ◽

Excitation Contraction Coupling ◽

Contraction Coupling

A physical association between the II–III loop of the DHPR (dihydropryidine receptor) and the RyR (ryanodine receptor) is essential for excitation–contraction coupling in skeletal, but not cardiac, muscle. However, peptides corresponding to a part of the II–III loop interact with the cardiac RyR2 suggesting the possibility of a physical coupling between the proteins. Whether the full II–III loop and its functionally important ‘C’ region (cardiac DHPR residues 855–891 or skeletal 724–760) interact with cardiac RyR2 is not known and is examined in the present study. Both the cardiac DHPR II–III loop (CDCL) and cardiac peptide (Cc) activated RyR2 channels at concentrations >10 nM. The skeletal DHPR II–III loop (SDCL) activated channels at ≤100 nM and weakly inhibited at ≥1 μM. In contrast, skeletal peptide (Cs) inhibited channels at all concentrations when added alone, or was ineffective if added in the presence of Cc. Ca2+-induced Ca2+ release from cardiac sarcoplasmic reticulum was enhanced by CDCL, SDCL and the C peptides. The results indicate that the interaction between the II–III loop and RyR2 depends critically on the ‘A’ region (skeletal DHPR residues 671–690 or cardiac 793–812) and also involves the C region. Structure analysis indicated that (i) both Cs and Cc are random coil at room temperature, but, at 5 °C, have partial helical regions in their N-terminal and central parts, and (ii) secondary-structure profiles for CDCL and SDCL are similar. The data provide novel evidence that the DHPR II–III loop and its C region interact with cardiac RyR2, and that the ability to interact is not isoform-specific.

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Supersilylverbindungen Der Borgruppenelemente, IV [1]. Supersilylelementhalogenide tBu3SIEX2 Und (tBu3Si)2Ex Mit E = Al, Ga, In: Synthesen, Eigenschaften, Strukturen [2] / Supersilylated Compounds of the Thirteenth Group, IV [I]. Supersilylelement Halides tBu3SIEX2 And (tBu3Si)2Ex with E = Al, Ga, In: Syntheses, Properties, Structures [2]

Zeitschrift für Naturforschung B ◽

10.1515/znb-1998-0312 ◽

1998 ◽

Vol 53 (3) ◽

pp. 333-348 ◽

Cited By ~ 16

Author(s):

Nils Wiberg ◽

Kerstin Amelunxen ◽

Hans-Wolfram Lemer ◽

Heinrich Nöth ◽

Jörg Knizek ◽

...

Keyword(s):

Thermal Decomposition ◽

Gas Phase ◽

Structure Analysis ◽

Room Temperature ◽

Group Iv ◽

Lewis Acidity ◽

X Ray ◽

Oxygen Sensitive

Abstract Water and oxygen sensitive compounds (tBu3SiEX2)2, tBu3SiEX2 Do and (tBu3Si)2EX (E = AI, Ga, In; X = (F), Cl, Br; Do = OR2, NR3) have been synthezised by reaction of EX3 with tBu3SiNa in the absence or presence of donors. In addition, (tBu3Si)AlBr2, (tBu3Si)2InF and tBu3SiInBr2 were prepared by reaction of AlBr3 with (tBu3Sij2Zn or of (tBu3Si)2In- In(Si/Bu3)2 with AgF2 and HBr, respectively. The adduct [tBu3SiAlBr2 · AlBr3 ·1/2MgBr2]2 is formed from AlBr3 and (tBu3Si)2Mg(THF)2. Thermal decomposition of the compounds in solution or in the gas phase leads to the formation of tBu3SiEX2 (from the dimers or the donor adducts) and of tBu3SiX. The Lewis acidity of tBu3SiEX2 against donors increases in the direction Do = Et2O < THF < NEtMe2. Dehalogenation of (tBu3Si)2ECl with tBu3SiNa(THF)2 in pentane at room temperature leads to clusters (tBu3Si)4Al2, (tBu3Si)3Ga2•, (tBu3Si)4In2 and (tBu3Si)3Ga2Na(THF)3, reduction of tBu3SiGaCl2 with Na or K in heptane at 100°C to the tetrahedran (tBu3Si)4Ga4. The structures of (tBu3SiGaCl2)2, (tBu3Si)2GaCl, and [tBu3SiAlBr2 AlBr3 ·1/2MgBr2]2 have been determined by X-ray structure analysis.

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Tetra-n-butylammonium orotate monohydrate: knowledge-based comparison of the results of accurate and lower-resolution analyses and a non-routine disorder refinement

Acta Crystallographica Section E Crystallographic Communications ◽

10.1107/s2056989019013380 ◽

2019 ◽

Vol 75 (11) ◽

pp. 1632-1637

Author(s):

Irene Ara ◽

Zeineb Basdouri ◽

Larry R. Falvello ◽

Mohsen Graia ◽

Pablo Guerra ◽

...

Keyword(s):

Low Temperature ◽

Structure Analysis ◽

Room Temperature ◽

Accurate Determination ◽

Temperature Structure ◽

Knowledge Based ◽

Using Data ◽

Comparison Of The Results ◽

A Minor ◽

Molecular Salt

The title hydrated molecular salt (systematic name: tetra-n-butylammonium 2,6-dioxo-1,2,3,6-tetrahydropyrimidine-4-carboxylate monohydrate), C16H36N+·C5H3N2O4 −·H2O, crystallizes with N—H...O and O—H...O hydrogen-bonded double-stranded antiparallel ribbons consisting of the hydrophilic orotate monoanions and water molecules, separated by the bulky hydrophobic cations. The hydrophobic and hydrophilic regions of the structure are joined by weaker non-classical C—H...O hydrogen bonds. An accurate structure analysis conducted at T = 100 K is compared to a lower-resolution less accurate determination using data measured at T = 295 K. The results of both analyses are evaluated using a knowledge-based approach, and it is found that the less accurate room-temperature structure analysis provides geometric data that are similar to those derived from the accurate low-temperature analysis, with both sets of results consistent with previously analyzed structures. A minor disorder of one methyl group in the cation at low temperature was found to be slightly more complex at room temperature; while still involving a minor fraction of the structure, the disorder at room temperature was found to require a non-routine treatment, which is described in detail.

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X-ray structure analysis of symmetrically substituted 1,1′-diformylruthenocene

Acta Crystallographica Section E Crystallographic Communications ◽

10.1107/s2056989018010642 ◽

2018 ◽

Vol 74 (9) ◽

pp. 1186-1189

Author(s):

Bertin Anzaldo ◽

Pankaj Sharma ◽

Francisco Lara Ochoa ◽

Claudia P. Villamizar C. ◽

René Gutiérrez Pérez

Keyword(s):

Structure Analysis ◽

Room Temperature ◽

Dimensional Structure ◽

Two Dimensional ◽

Asymmetric Unit ◽

Orthorhombic System ◽

Space Group ◽

X Ray ◽

Π Interactions ◽

Independent Molecules

1,1′-Diformylruthenocene, [Ru(C6H5O)2], crystallizes in the orthorhombic system in the P212121 space group at room temperature. There are two crystallographically independent molecules in the asymmetric unit. The cyclopentadienyl rings have eclipsed configuration. The molecules self-assemble in a two-dimensional structure by C—H...O and C—H...π interactions with cisoid relative orientations of the two formyl groups. The crystal studied was refined as an inversion twin.

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A microscopic system for high-resolution electron crystallography

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100136726 ◽

1995 ◽

Vol 53 ◽

pp. 70-71

Author(s):

Y. Fujiyoshi ◽

K. Murata ◽

K. Mitsuoka ◽

T. Hirai ◽

A. Miyazawa ◽

...

Keyword(s):

High Resolution ◽

Structure Analysis ◽

Room Temperature ◽

Point Of View ◽

Irradiation Damage ◽

High Resolution Data ◽

Light Harvesting Complex ◽

Resolution Electron ◽

Structural Point ◽

Resolution Data

High-resolution electron cryo-microscopy is one of good candidate for structure analysis of membrane-protein, and also actually analyzed the structure of membrane-proteins such as bacteriorhodopsin (bR) and plant light-harvesting complex (LHC). By developing an expeditious method for structure analysis up to atomic or near atomic resolution, we would like to interpret a function of protein from the structural point of view. However, there are some difficulties in electron microscopy for structure analysis of protein. Especially, the most serious problems are the specimen damage caused by electron irradiation, the denaturation of biomolecules caused by dehydration and missing high-resolution data on electron micrographs at high-tilted angle.The irradiation damage at 8K has been found to be reduced to 1/20 compared with that at room temperature. We have, therefore, developed a high-resolution electron cryo-microscope and improved it by which images can be recorded with higher resolution than 3 Å at a specimen-stage temperature of 4.2 K, even when the specimen is highly tilted. The highly tilted data are essential for reduction of the missing corn effect.

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