scholarly journals X-Ray Crystal Structures of Ti(IV)-4,4′-Methylenebis(antipyrine) Complexes, [Ti(dam)3](ClO4)4. Formation of Eight-Membered Chelate Rings and Aromatic Ring Stacking Responsible for Characteristic Coloration

1991 ◽  
Vol 64 (3) ◽  
pp. 760-765 ◽  
Author(s):  
Akio Yuchi ◽  
Motoo Shiro ◽  
Hiroko Wada ◽  
Genkichi Nakagawa
Keyword(s):  
Crystal Structures ◽  
Aromatic Ring ◽  
X Ray ◽  
Chelate Rings

scholarly journals X-Ray Crystal Structures ofcis- andtrans-Dinitrobis(1,4-butanediamine)cobalt(III) Nitrates. Conformation of Seven-Membered Chelate Rings

1988 ◽  
Vol 61 (10) ◽  
pp. 3491-3496 ◽  
Author(s):  
Mamoru Shimoi ◽  
Yuki Fujinawa ◽  
Hiroshi Ogino ◽  
Kan Kanamori ◽  
Kiyoyasu Kawai
Keyword(s):  
Crystal Structures ◽  
X Ray ◽  
Chelate Rings

scholarly journals Unusual Behaviour During the Route of a Japp-Klingemann Reaction

2010 ◽  
Vol 65 (6) ◽  
pp. 745-S11 ◽  
Author(s):  
Jan Marten ◽  
Wilhelm Seichter ◽  
Jörg Wagler ◽  
Edwin Weber
Keyword(s):  
Solid Solution ◽  
Hydrochloric Acid ◽  
Crystal Structures ◽  
Acid Medium ◽  
Aromatic Ring ◽  
Diazonium Salts ◽  
X Ray ◽  
Unusual Behaviour ◽  
Causal Connections ◽  
Hydrochloric Acid Medium

Performing a standard Japp-Klingemann synthesis that involved diazotation of 2,6-dinitroaniline and reaction with pentane-2,4-dione in aqueous hydrochloric acid medium surprisingly yielded a mixture of the expected 2,6-dinitro- and the unexpected 2-chloro-6-nitro-substituted hydrazones. This mixture was isolated as solid-solution crystals containing the components in an approximate ratio of 1 to 2. Based on both, selected compounds of comparison that show the aromatic ring substituents changed in position and intermediate diazonium salts, potential causal connections of the unusual behaviour during the route of the particular Japp-Klingemann reaction were studied. X-Ray crystal structures of the relevant compounds have been determined to support the discussion.

Color and Conformation of Some Derivatives of Benzil in the Solid-State: Crystal-Structures of 2,2′-Dimethoxy- 4,4′-Dimethoxy- , 4-4′Diethoxy- and 4,4'-Dibenzyloxy-benzil

1989 ◽  
Vol 42 (10) ◽  
pp. 1631 ◽  
Author(s):  
JR Cannon ◽  
VA Patrick ◽  
AH White
Keyword(s):  
Solid State ◽  
Single Crystal ◽  
Least Squares ◽  
Crystal Structures ◽  
Aromatic Ring ◽  
Full Matrix ◽  
X Ray ◽  
Derivatives Of ◽  
Least Squares Techniques

The crystal structures of the colourless 2,2'-dimethoxybenzil (2) and 4,4'-diethoxybenzil (6), the yellow 4,4'-dimethoxybenzi (5), and the yellow polymorph of 4,4'-dibenzyloxybenzil (7) have been determined by single-crystal X-ray studies from diffractometer data at 295 K, and refined by full matrix least-squares techniques to residuals of 0.048 (1281 'observed' reflections), 0.041 (610), 0.052 (662) and 0.043 (2140) respectively. Crystals of 2,2′-dimethoxybenzil (2) are monoclinic, P21/c, a 7.861(4), b 7.991(2), c 21.557(9)�, β90.37(4)�, Z 4. Crystals of 4,4'-dimethoxybenzil (6) are monoclinic C2/c, a 21.912(9), b 4.055(2), c 15.197(5) �,β 102 13(3)� Z 4. Crystals of 4,4′-diethoxybenzil (6) are monoclinic C21/c, a 14.544(7), b 4.781(2), c 22.128(7), β 99.06(3)�, Z 4. Crystals of the yellow modification of 4,4'-dibenzyloxybenzil (7) are monoclinic P21/c, a 19.126(4), b 6.91 1(2), c 16.673(7) � β 99.52(3)�, Z 4. It has been found that there is a correlation between the colour of the crystal and the conformation adopted by the molecule in the solid state with the colourless derivatives of benzil having the aromatic ring planes orthogonal.

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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