X-ray Diffraction and NMR Studies on a Series of Binap-Based Ru(II) Hydroxyphosphine π-Arene Complexes

2004 ◽  
Vol 43 (6) ◽  
pp. 1920-1928 ◽  
Author(s):  
Tilmann J. Geldbach ◽  
Frank Breher ◽  
Volker Gramlich ◽  
P. G. Anil Kumar ◽  
Paul S. Pregosin
Keyword(s):  
Arene Complexes ◽  
X Ray Diffraction ◽  
Nmr Studies ◽  
X Ray

New Copper Compounds with Antiplatelet Aggregation Activity

2019 ◽  
Vol 15 (8) ◽  
pp. 850-862
Author(s):  
Mirthala Flores-García ◽  
Juan Manuel Fernández-G. ◽  
Cristina Busqueta-Griera ◽  
Elizabeth Gómez ◽  
Simón Hernández-Ortega ◽  
...  
Keyword(s):  
Schiff Base ◽  
Solid State ◽  
Thrombotic Event ◽  
X Ray Diffraction ◽  
Nmr Studies ◽  
Schiff Base Ligands ◽  
X Ray ◽  
Antiplatelet Aggregation ◽  
Aggregation Activity ◽  
L1 And L2

Background: Ischemic heart disease, cerebrovascular accident, and venous thromboembolism have the presence of a thrombotic event in common and represent the most common causes of death within the population. Objective: Since Schiff base copper(II) complexes are able to interact with polyphosphates (PolyP), a procoagulant and potentially prothrombotic platelet agent, we investigated the antiplatelet aggregating properties of two novel tridentate Schiff base ligands and their corresponding copper( II) complexes. Methods: The Schiff base ligands (L1) and (L2), as well as their corresponding copper(II) complexes (C1) and (C2), were synthesized and characterized by chemical analysis, X-ray diffraction, mass spectrometry, and UV-Visible, IR and far IR spectroscopy. In addition, EPR studies were carried out for (C1) and (C2), while (L1) and (L2) were further analyzed by 1H and 13C NMR. Tests for antiplatelet aggregation activities of all of the four compounds were conducted. Results: X-ray diffraction studies show that (L1) and (L2) exist in the enol-imine tautomeric form with a strong intramolecular hydrogen bond. NMR studies show that both ligands are found as enol-imine tautomers in CDCl3 solution. In the solid state, the geometry around the copper(II) ion in both (C1) and (C2) is square planar. EPR spectra suggest that the geometry of the complexes is similar to that observed in the solid state by X-ray crystallography. Compound (C2) exhibited the strongest antiplatelet aggregation activity. Conclusion: Schiff base copper(II) complexes, which are attracting increasing interest, could represent a new approach to treat thrombosis by blocking the activity of PolyP with a potential anticoagulant activity and, most importantly, demonstrating no adverse bleeding events.

Comparison of the orientational order parameters determined from X-ray diffraction and13C NMR studies of a hockey stick-shaped compound

2009 ◽  
Vol 82 (6) ◽  
pp. 433-443 ◽  
Author(s):  
Gautam Sarkar ◽  
Malay Kumar Das ◽  
Ranjit Paul ◽  
Banani Das ◽  
Wolfgang Weissflog
Keyword(s):  
Orientational Order ◽  
Order Parameters ◽  
X Ray Diffraction ◽  
Nmr Studies ◽  
Hockey Stick ◽  
X Ray

Zirconolite transformation under reducing conditions

1998 ◽  
Vol 13 (11) ◽  
pp. 3181-3190 ◽  
Author(s):  
B. D. Begg ◽  
E. R. Vance ◽  
B. A. Hunter ◽  
J. V. Hanna
Keyword(s):  
Perovskite Phase ◽  
Charge Compensation ◽  
Fluorite Structure ◽  
Second Phase ◽  
X Ray Diffraction ◽  
Nmr Studies ◽  
Paramagnetic Resonance ◽  
X Ray ◽  
Reducing Conditions ◽  
Quadrupole Resonance

The structural behavior of zirconolite (CaZrTi2O7) under reducing conditions at high temperature has been studied, mainly by scanning electron microscopy (SEM) and x-ray diffraction (XRD), but also with x-ray absorption spectroscopy, thermogravimetry, and electron paramagnetic resonance. The partial reduction of Ti4+ to Ti3+, associated with a reducing atmosphere heat treatment, led to the initial formation of perovskite (CaTiO3) as a second phase. As the concentration of Ti3+ in the zirconolite increased, so did the amount of perovskite until the zirconolite was totally transformed into a fluorite structured phase. Analysis of the reduced zirconolites showed them to be consistently deficient in Ca and enriched in Zr, in proportion to the concentration of Ti3+. To determine how electroneutrality was preserved in these reduced zirconolites, a series of zirconolites were prepared in air using In3+ and Ga3+ as models for Ti3+. These samples were then investigated by neutron and x-ray diffraction, SEM, solid state nuclear magnetic resonance (NMR), and nuclear quadrupole resonance (NQR). 71Ga MAS NMR studies of the Ga substituted zirconolite exhibited a narrow resonance at ˜13 ppm which was attributed to six-coordinate Ga incorporated in a trace perovskite phase. Broadline 71Ga NMR and 69/71Ga NQR were required to characterize the Ga incorporated in the zirconolite. The resultant quadrupolar parameters of CQ = 30.0 ± 0.05 MHz and η = 1.0 ± 0.03 indicate that the Ga site is in a highly distorted environment which would suggest that it is located on the five-coordinate Ti site within the zirconolite lattice. These results were complemented by Rietveld refinement of the neutron diffraction data from the In-doped zirconolite sample, which was optimal when all the In was located on the five-coordinate Ti site with the excess Zr located on the Ca site. It would therefore appear that charge compensation for the presence of Ti3+ in zirconolite is effected via the substitution of an appropriate amount of Zr on the Ca site. The Ti3+-stabilized fluorite structure was readily oxidized back to a single phase zirconolite upon heating in air.

Crystalline Li3ThF7 : X-Ray Diffraction and NMR Studies

1989 ◽  
Vol 42 (1) ◽  
pp. 41-50 ◽  
Author(s):  
Sandra Helena Pulcinelli ◽  
Regina Helena de Almeida Santos ◽  
Jean Senegas
Keyword(s):  
X Ray Diffraction ◽  
Nmr Studies ◽  
X Ray

Synthesis and Structural Characterization of a Series of Group 11 2,2-Dialkyl-1,3-dicyclohexylguanidinate Complexes

2014 ◽  
Vol 67 (7) ◽  
pp. 1021 ◽  
Author(s):  
Sonya K. Adas ◽  
Jesus A. Ocana ◽  
Scott D. Bunge
Keyword(s):  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
X Ray Diffraction ◽  
Nmr Studies ◽  
X Ray ◽  
7Li Nmr ◽  
Elemental Analyses ◽  
Lithium Diethylamide ◽  
Structural Aspects

The addition of either lithium dimethylamide or lithium diethylamide to a tetrahydrofuran (THF) solution of 1,3-dicyclohexylcarbodiimide yielded THF adducts of lithium 2,2-dimethyl-1,3-dicyclohexylguandidinate (1) and lithium 2,2-diethyl-1,3-dicyclohexylguandidinate (2), respectively. One equivalent of either 1 or 2 was subsequently reacted with one equivalent of Group 11 halide (CuCl, AgBr, and AuCl) to generate oligonuclear complexes with the general formula {M[CyNC(NR2)NCy]}n where M, R, and n are respectively Cu, CH3, 2 (3); Cu, CH2CH3, 2 (4); Ag, CH3, 3 (5); Ag, CH2CH3, 3 (6); Au, CH3, 2 (7); and Au, CH2CH3, 2 (8). Compounds 1–8 were characterized by single-crystal X-ray diffraction. The bulk powders for all complexes were found to be in agreement with the crystal structures based on elemental analyses, Fourier transform infrared spectroscopy, and 1H, 13C, and 7Li NMR studies. The unique structural aspects of this family of Group 11 complexes are highlighted.

X-ray Diffraction and13C Solid-State NMR Studies of the Dimethylformamide Solvate of Tetra(C-undecyl)calix[4]resorcinarene

2000 ◽  
Vol 104 (9) ◽  
pp. 1921-1926 ◽  
Author(s):  
Marek Pietraszkiewicz ◽  
Oksana Pietraszkiewicz ◽  
Waclaw Kolodziejski ◽  
Krzysztof Wozniak ◽  
Neil Feeder ◽  
...  
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
X Ray Diffraction ◽  
Nmr Studies ◽  
X Ray

Beryllium Coordination to Bio-Ligands: Isolation from Aqueous Solution and Crystal Structure of a Hexanuclear Complex of Be2+ with Glycolic Acid, Na4[Be6(OCH2CO2)8]

1992 ◽  
Vol 47 (12) ◽  
pp. 1717-1720 ◽  
Author(s):  
O. Kumberger ◽  
J. Riede ◽  
H. Schmidbaur
Keyword(s):  
Aqueous Solutions ◽  
Glycolic Acid ◽  
Complexing Agents ◽  
Hydroxyl Groups ◽  
X Ray Diffraction ◽  
Nmr Studies ◽  
X Ray ◽  
Biological Substrates ◽  
Complex Features ◽  
Hexanuclear Complex

Beryllium and its compounds are highly toxic to most living cells, but the mechanisms of the interference with the biological substrates on the molecular level is not understood. From observations in (attempted) chemotherapy of beryllium poisoning using a variety of complexing agents it has been concluded that Be2+ is interacting predominantly with carboxyl as well as hydroxyl functions of protein bio-polymers, with complete deprotonation of the alkoxy or phenoxy functions involved. As a first support for this hypothesis, an analytically well-defined beryllium complex of glycolic acid has now been isolated from aqueous solutions under nearphysiological conditions, crystallized and its structure determined by X-ray diffraction. The hexanuclear complex features beryllium in two different environments, mono- and bis-chelated by glycolate ligands with deprotonated hydroxyl groups. In 9Be-NMR studies of aqueous solutions of the complex (pH 6) the persistence of complexation in two different environments of Be2+ could also be confirmed. The new structure may serve as a model for beryllium complexation with larger bio-ligands.

Article

1999 ◽  
Vol 77 (5-6) ◽  
pp. 1057-1065
Author(s):  
John T Edward ◽  
Francis L Chubb ◽  
Denis FR Gilson ◽  
Rosemary C Hynes ◽  
Françoise Sauriol ◽  
...  
Keyword(s):  
Nmr Spectra ◽  
Acidic Solution ◽  
Variable Temperature ◽  
X Ray Diffraction ◽  
Nmr Studies ◽  
Cage Compounds ◽  
Amine Nitrogen ◽  
X Ray ◽  
Bridgehead Nitrogen ◽  
C Nmr

Three new cage peroxides, 1,6-diaza-3,4,8,9-tetraoxabicyclo[4.4.2]dodecane (3a),1,6-diaza-3,4,8,9-tetraoxa-11-methylbicyclo[4.4.2]dodecane (3b), and 1,6-diaza-3,4,8,9-tetraoxatricyclo[4.4.2.411,12]hexadecane (4), have been prepared by reaction of 1,2-diaminoethane, 1,2-diaminopropane, and trans-1,2-diaminocyclohexane, respectively, with formaldehyde and hydrogen peroxide in aqueous acidic solution. Their structures have been established by X-ray diffraction, and show the bridgehead nitrogen atoms to be predominantly sp2 hybridized. The structures accord with 1H and 13C NMR spectra. Variable temperature NMR studies show that the diperoxide 3a begins to undergo rapid inversion (on the NMR time scale) at about 303 K; up to 370 K the diperoxides 3b and 4 show no conformational change.Key words: cage compounds, formaldehyde, peroxides, amine nitrogen, hybridization.

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