Alkene and Alkyne Reactivity Toward a Bisruthenium(II) μ2-Dinitrogen Complex Containing the “Pincer” Ligand 2,6-Bis[(dimethylamino)methyl]pyridine (NN‘N). The X-ray Crystal Structures of [Ru(CCHPh)Cl2(NN‘N)] and [Ru(CCHPh)(OTf)(NN‘N)(PPh3)][OTf] (OTf = Trifluoromethane Sulfonate)

1999 ◽  
Vol 18 (6) ◽  
pp. 1097-1105 ◽  
Author(s):  
Ignacio del Río ◽  
Robert A. Gossage ◽  
Milja S. Hannu ◽  
Martin Lutz ◽  
Anthony L. Spek ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Pincer Ligand ◽  
X Ray ◽  
Dinitrogen Complex ◽  
Methyl Pyridine

New Multidentate Pyrazolyl - Pyridine Ligands—Synthesis and Structures

2003 ◽  
Vol 56 (7) ◽  
pp. 665 ◽  
Author(s):  
Zöe R. Bell ◽  
Jon A. McCleverty ◽  
Michael D. Ward
Keyword(s):  
Crystal Structures ◽  
Multidentate Ligands ◽  
Pyridyl Group ◽  
X Ray ◽  
Pyridine Ligands ◽  
Nitrogen Donor ◽  
Methyl Naphthalene ◽  
Methyl Benzene ◽  
Additional Nitrogen ◽  
Methyl Pyridine

Five new multidentate ligands have been prepared containing N,N-bidentate pyrazolyl–pyridine units linked to a central aromatic spacer unit. The ligands 3,3′-bis(3-{pyridin-2-yl}-pyrazol-1-yl-methyl)-p-terphenyl (1), 4,4′-bis(3-{pyridin-2-yl}-pyrazol-1-yl)biphenyl (2), and 1,8-bis(3-{pyridin-2-yl}-pyrazol-1-yl-methyl)naphthalene (3) have two bidentate arms and are therefore potentially tetradentate; 2,6-bis(3-{pyridin-2-yl}-pyrazol-1-yl-methyl)pyridine (4) has two bidentate arms with an additional nitrogen-donor in the aromatic spacer unit (a pyridyl group) and is therefore potentially pentadentate; and 1,3,5-trimethyl-2,4,6-tris(3-{pyridin-2-yl}-pyrazol-1-yl-methyl)benzene (5) has three bidentate arms and is therefore potentially hexadentate. The X-ray crystal structures of all of these ligands have been determined.

The X-Ray Crystal Structures of Two Derivatives of 2,6-Bis{[2-(dimethoxymethyl)phenoxy]methyl}pyridine

1997 ◽  
pp. 188-189 ◽  
Author(s):  
Harry Adams ◽  
David E. Fenton ◽  
Yuh-Shan Ho ◽  
Blanca A. Najera ◽  
Cecilia O. Rodriguez de Barbarin
Keyword(s):  
Crystal Structures ◽  
X Ray ◽  
Derivatives Of ◽  
Methyl Pyridine

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>

Effect of Hydrated Metal Salts on the Coordination Product of Cobalt(II) halide and PNP Type Ligand, 2,6-bis(di-tertbutylphosphinomethyl) pyridine

2018 ◽  
Author(s):  
Tasneem Siddiquee ◽  
Abdul Goni
Keyword(s):  
Metal Salts ◽  
Molar Ratio ◽  
Pincer Complexes ◽  
Asymmetric Unit ◽  
X Ray Diffraction ◽  
Pincer Ligand ◽  
Tetrahedral Geometry ◽  
X Ray ◽  
Distorted Tetrahedral Geometry ◽  
Cobalt Center

Chemical treatment of CoX<sub>2</sub><b><sup>. </sup></b>6H<sub>2</sub>O (X = Cl, Br, I) with the potentially tridentate PNP pincer ligand 2,6-bis(di-<i>tert</i>-butylphosphinomethyl)pyridine in 1:1 molar ratio results in cobalt(II) halide-PNP pincer complexes. The effect of the hydrated metal source on molecular structure and geometry of the complexes was studied by single crystal X-ray diffraction analysis. The complexes are neutral and the cobalt center adopts a penta-coordinate system with potential atropisomerization. Within the unit cell there are two distinct molecules per asymmetric unit. One of the two phosphorus atoms in the PNP ligand was observed to be partially oxidized to phosphinoxide. Disorder in the structure reflects a mixture of square pyramidal and distorted tetrahedral geometry.

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