The heterogeneous thermal transformation of the orange diethyl NN′-diphenyl-2,5-diaminoterephthalate benzene complex to the red solvent-free compound. X-Ray crystal structures of the two forms

1981 ◽  
pp. 1583-1590 ◽  
Author(s):  
Barbara J. Mann ◽  
Iain C. Paul ◽  
David Y. Curtin
Keyword(s):  
Crystal Structures ◽  
Thermal Transformation ◽  
Solvent Free ◽  
X Ray

The crystal structures of solvent-free alkali-metal squarates from powder diffraction data

2005 ◽  
Vol 220 (11) ◽  
Author(s):  
Robert E. Dinnebier ◽  
Hanne Nuss ◽  
Martin Jansen
Keyword(s):  
High Resolution ◽  
Alkali Metal ◽  
Crystal Structures ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Room Temperature ◽  
Solvent Free ◽  
Crystallographic Data ◽  
Powder Diffraction Data ◽  
X Ray

AbstractThe crystal structures of solvent-free lithium, sodium, rubidium, and cesium squarates have been determined from high resolution synchrotron and X-ray laboratory powder patterns. Crystallographic data at room temperature of Li

Solvent–guest control of two extremely similar tetrahydrofuran inclusion structures

2014 ◽  
Vol 70 (1) ◽  
pp. 126-131 ◽  
Author(s):  
Jiabin Gao ◽  
Mohan M. Bhadbhade ◽  
Roger Bishop
Keyword(s):  
Crystal Structures ◽  
Inclusion Compounds ◽  
Crystal Form ◽  
Solvent Free ◽  
Guest Molecules ◽  
Crystal Forms ◽  
X Ray

Racemic 2,4,6,8-tetracarbomethoxybicyclo[3.3.0]octa-2,6-diene-3,7-diol, C16H18O10(1), was known previously to yield two solvent-free polymorphs and also a clathrate inclusion crystal form. Crystallization of (1) yields two inclusion compounds containing tetrahydrofuran (THF): (1)4·THF is obtained from a mixture of THF and methanol, whereas (1)2·THF is obtained from pure THF. The X-ray crystal structures reveal that the two compounds are extremely similar and that their host arrangements are essentially identical. They differ, however, in the proportion, orientation and host–guest interaction of the included THF molecules. The disordered guest molecules in (1)4·THF are oriented along the guest channel direction, whereas in (1)2·THF they lie across the channel. This unusual solvent–guest control of inclusion structures has implications relating to the formation of polymorphic structures and other competing crystal forms.

Conflicting Behavior of a Versatile Host Compound: X-ray Crystal Structures Arising from Solvent-free and Solvent-Containing Crystal Formation†

2010 ◽  
Vol 10 (2) ◽  
pp. 862-869 ◽  
Author(s):  
Konstantinos Skobridis ◽  
Vassiliki Theodorou ◽  
Wilhelm Seichter ◽  
Edwin Weber
Keyword(s):  
Crystal Structures ◽  
Solvent Free ◽  
Crystal Formation ◽  
X Ray ◽  
Host Compound

The first report of the crystal structure of non-solvated μ-oxo boron subphthalocyanine and the crystal structures of two solvated forms

2012 ◽  
Vol 68 (6) ◽  
pp. 636-645 ◽  
Author(s):  
Mabel V. Fulford ◽  
Alan John Lough ◽  
Timothy P. Bender
Keyword(s):  
Crystal Structure ◽  
Chemical Synthesis ◽  
Single Crystal ◽  
Single Crystals ◽  
Crystal Structures ◽  
Solvent Free ◽  
X Ray ◽  
Hydrated Crystal ◽  
Boron Subphthalocyanine ◽  
Work Up

The first instance of the solvent-free X-ray determined single-crystal structure of the oxygen-bridged boron subphthalocyanine dimer [μ-oxo-(BsubPc)2, C48H24B2N12O] is reported. Single crystals obtained by train sublimation were found to have μ-oxo-(BsubPc)2 organized into a C2/c space group. The crystal structure obtained by sublimation is of particular interest as it is highly symmetric and also of notably high density when compared with other BsubPc crystals. The acquisition of this crystal structure came about from the direct chemical synthesis of μ-oxo-(BsubPc)2 followed by a work-up which culminated in obtaining the single crystals by sublimation. Several methods for the direct chemical synthesis of μ-oxo-(BsubPc)2 were also investigated each using dichlorobenzene as the solvent. On standing, these reaction mixtures produced a crystal of the dichlorobenzene (DCB) solvate of μ-oxo-(BsubPc)2 [μ-oxo-(BsubPc)2·2DCB]. It is also reported that the conversion of bromo-boron subphthalocyanine (Br-BsubPc) to μ-oxo-(BsubPc)2 happens on train sublimation which resulted in the acquisition of a partially hydrated crystal [μ-oxo-(BsubPc)2·0.25H2O].

Transmission electron microscope studies in special ceramics

1978 ◽  
Vol 36 (1) ◽  
pp. 268-269
Author(s):  
A. Zangvil ◽  
L.J. Gauckler ◽  
G. Schneider ◽  
M. Rühle
Keyword(s):  
Phase Diagrams ◽  
Crystal Structures ◽  
Thin Foil ◽  
Limited Extent ◽  
Complex Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
Lattice Resolution

The use of high temperature special ceramics which are usually complex materials based on oxides, nitrides, carbides and borides of silicon and aluminum, is critically dependent on their thermomechanical and other physical properties. The investigations of the phase diagrams, crystal structures and microstructural features are essential for better understanding of the macro-properties. Phase diagrams and crystal structures have been studied mainly by X-ray diffraction (XRD). Transmission electron microscopy (TEM) has contributed to this field to a very limited extent; it has been used more extensively in the study of microstructure, phase transformations and lattice defects. Often only TEM can give solutions to numerous problems in the above fields, since the various phases exist in extremely fine grains and subgrain structures; single crystals of appreciable size are often not available. Examples with some of our experimental results from two multicomponent systems are presented here. The standard ion thinning technique was used for the preparation of thin foil samples, which were then investigated with JEOL 200A and Siemens ELMISKOP 102 (for the lattice resolution work) electron microscopes.

Crystal Structures of Fragments D and Double-D from Fibrinogen and Fibrin

1999 ◽  
Vol 82 (08) ◽  
pp. 271-276 ◽  
Author(s):  
Glen Spraggon ◽  
Stephen Everse ◽  
Russell Doolittle
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Crystal Structures ◽  
Structure And Function ◽  
X Ray ◽  
Long Period ◽  
And Function

IntroductionAfter a long period of anticipation,1 the last two years have witnessed the first high-resolution x-ray structures of fragments from fibrinogen and fibrin.2-7 The results confirmed many aspects of fibrinogen structure and function that had previously been inferred from electron microscopy and biochemistry and revealed some unexpected features. Several matters have remained stubbornly unsettled, however, and much more work remains to be done. Here, we review several of the most significant findings that have accompanied the new x-ray structures and discuss some of the problems of the fibrinogen-fibrin conversion that remain unresolved. * Abbreviations: GPR—Gly-Pro-Arg-derivatives; GPRPam—Gly-Pro-Arg-Pro-amide; GHRPam—Gly-His-Arg-Pro-amide

Synthesis of Sulfoquinovose and Sulfoquinovosyl Diacylglycerides, and a Fluorogenic Substrate for Sulfoquinovosidases

2019 ◽  
Author(s):  
Yunyang Zhang ◽  
Janice Mui ◽  
Thimali Arumaperuma ◽  
James P. Lingford ◽  
ETHAN GODDARD-BORGER ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Fluorogenic Substrate ◽  
Potassium Salts ◽  
X Ray ◽  
Sulfoquinovosyl Diacylglycerol ◽  
Sodium And Potassium

<p>The sulfolipid sulfoquinovosyl diacylglycerol (SQDG) and its headgroup, the sulfosugar sulfoquinovose (SQ), are estimated to harbour up to half of all organosulfur in the biosphere. SQ is liberated from SQDG and related glycosides by the action of sulfoquinovosidases (SQases). We report a 10-step synthesis of SQDG that we apply to the preparation of saturated and unsaturated lipoforms. We also report an expeditious synthesis of SQ and (<sup>13</sup>C<sub>6</sub>)SQ, and X-ray crystal structures of sodium and potassium salts of SQ. Finally, we report the synthesis of a fluorogenic SQase substrate, methylumbelliferyl a-D-sulfoquinovoside, and examination of its cleavage kinetics by two recombinant SQases.</p>

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