100 Years of X-ray Crystallography

2017 ◽  
Vol 100 (1) ◽  
pp. 25-44 ◽  
Author(s):  
Terence J. Kemp ◽  
Nathaniel W. Alcock
Keyword(s):  
Data Analysis ◽  
Synchrotron Radiation ◽  
Binary Systems ◽  
Molecular Structures ◽  
X Ray ◽  
X Ray Crystallography ◽  
Bonding Theory ◽  
Enzyme Substrate ◽  
Radiation Sources ◽  
Disciplinary Field

The developments in crystallography, since it was first covered in Science Progress in 1917, following the formulation of the Bragg equation, are described. The advances in instrumentation and data analysis, coupled with the application of computational methods to data analysis, have enabled the solution of molecular structures from the simplest binary systems to the most complex of biological structures. These developments are shown to have had major impacts in the development of chemical bonding theory and in offering an increasing understanding of enzyme–substrate interactions. The advent of synchrotron radiation sources has opened a new chapter in this multi-disciplinary field of science.

EXELFS revisited: An improved data analysis technique

1993 ◽  
Vol 51 ◽  
pp. 584-585
Author(s):  
Maoxu Qian ◽  
Mehmet Sarikaya ◽  
Edward A. Stern
Keyword(s):  
Fine Structure ◽  
Data Analysis ◽  
Synchrotron Radiation ◽  
High Spatial Resolution ◽  
Detection System ◽  
X Ray ◽  
Statistical Fluctuations ◽  
Analysis Technique ◽  
Radiation Sources ◽  
Acquisition Technique

EXELFS (extended energy loss fine structure) spectroscopy contains unique information of local atomic structure, same as XAFS (X-ray fine structure), but has several advantages overXAFS, such as having high spatial resolution (nanoscale versus bulk), better low Z element sensitivity, parallel detectability, and no dependability on synchrotron-radiation-sources. Due to poor statistical total counts, however, EELS data quality is inferior and, therefore, EXELFS technique has not been well developed to its full advantages. The main limitations in EELS acquisition are channel-to-channel gain variations (CCGV) in the parallel detection system and low S/N ratio due to the instability of instrument that prevents long acquisition times. Techniques that circumvent CCGV, such as first or second difference, do not allow the retrieval of EXELFS signal from the spectra. Recently we have improved the EELS data acquisition technique so that CCGV could effectively be corrected and statistical fluctuations could reach a level much lower man that in the fine structure.

Synthesis, structural characterization and catalytic activity of chlororuthenium(II) complexes with substituted Schiff base/phosphine ancillary ligands

2020 ◽  
Vol 75 (9-10) ◽  
pp. 851-857
Author(s):  
Chong Chen ◽  
Fule Wu ◽  
Jiao Ji ◽  
Ai-Quan Jia ◽  
Qian-Feng Zhang
Keyword(s):  
Schiff Base ◽  
Catalytic Activity ◽  
Structural Characterization ◽  
Room Temperature ◽  
Molecular Structures ◽  
Cationic Complex ◽  
Neutral Complex ◽  
Ancillary Ligands ◽  
X Ray ◽  
X Ray Crystallography

AbstractTreatment of [(η6-p-cymene)RuCl2]2 with one equivalent of chlorodiphenylphosphine in tetrahydrofuran at reflux afforded a neutral complex [(η6-p-cymene)RuCl2(κ1-P-PPh2OH)] (1). Similarly, the reaction of [Ru(bpy)2Cl2·2H2O] (bpy = 2,2′-bipyridine) and chlorodiphenylphosphine in methanol gave a cationic complex [Ru(bpy)2Cl(κ1-P-PPh2OCH3)](PF6) (2), while treatment of [RuCl2(PPh3)3] with [2-(C5H4N)CH=N(CH2)2N(CH3)2] (L1) in tetrahydrofuran at room temperature afforded a ruthenium(II) complex [Ru(PPh3)Cl2(κ3-N,N,N-L1)] (3). Interaction of the chloro-bridged complex [Ru(CO)2Cl2]n with one equivalent of [Ph2P(o-C6H4)CH=N(CH2)2N(CH3)2] (L2) led to the isolation of [Ru(CO)Cl2(κ3-P,N,N-L2)] (4). The molecular structures of the ruthenium(II) complexes 1–4 have been determined by single-crystal X-ray crystallography. The properties of the ruthenium(II) complex 4 as a hydrogenation catalyst for acetophenone were also tested.

scholarly journals X‐ray monochromator system for use with synchrotron radiation sources

1981 ◽  
Vol 52 (4) ◽  
pp. 509-516 ◽  
Author(s):  
J. A. Golovchenko ◽  
R. A. Levesque ◽  
P. L. Cowan
Keyword(s):  
Synchrotron Radiation ◽  
X Ray ◽  
Radiation Sources

Machine Learning Powered by Principal Component Descriptors as the Key for Sorted Structural Fit of XANES

2021 ◽  
Author(s):  
Andrea Martini ◽  
Alexander A. Guda ◽  
Sergey A. Guda ◽  
Aram L. Bugaev ◽  
Olga V. Safonova ◽  
...  
Keyword(s):  
Machine Learning ◽  
Structural Analysis ◽  
Synchrotron Radiation ◽  
Free Electron Laser ◽  
Principal Component ◽  
Analytical Tool ◽  
X Ray ◽  
Radiation Sources ◽  
X Ray Absorption

Modern synchrotron radiation sources and free electron laser made X-ray absorption spectroscopy (XAS) an analytical tool for the structural analysis of materials under in situ or operando conditions. Fourier approach...

scholarly journals Silylated gallium and indium chalcogenide ring systems as potential precursors to ME (E=O, S) materials

2013 ◽  
Vol 11 (7) ◽  
pp. 1225-1238
Author(s):  
Iliana Medina-Ramírez ◽  
Cynthia Floyd ◽  
Joel Mague ◽  
Mark Fink
Keyword(s):  
Thermal Decomposition ◽  
Room Temperature ◽  
Membered Ring ◽  
Molecular Structures ◽  
Nmr Studies ◽  
X Ray ◽  
X Ray Crystallography ◽  
High Yields ◽  
Vt Nmr ◽  
State 1

AbstractThe reaction of R3M (M=Ga, In) with HESiR′3 (E=O, S; R′3=Ph3, iPr3, Et3, tBuMe2) leads to the formation of (Me2GaOSiPh3)2(1); (Me2GaOSitBuMe2)2(2); (Me2GaOSiEt3)2(3); (Me2InOSiPh3)2(4); (Me2InOSitBuMe2)2(5); (Me2InOSiEt3)2(6); (Me2GaSSiPh3)2(7); (Et2GaSSiPh3)2(8); (Me2GaSSiiPr3)2(9); (Et2GaSSiiPr3)2(10); (Me2InSSiPh3)3(11); (Me2InSSiiPr3)n(12), in high yields at room temperature. The compounds have been characterized by multinuclear NMR and in most cases by X-ray crystallography. The molecular structures of (1), (4), (7) and (8) have been determined. Compounds (3), (6) and (10) are liquids at room temperature. In the solid state, (1), (4), (7) and (9) are dimers with central core of the dimer being composed of a M2E2 four-membered ring. VT-NMR studies of (7) show facile redistribution between four- and six-membered rings in solution. The thermal decomposition of (1)–(12) was examined by TGA and range from 200 to 350°C. Bulk pyrolysis of (1) and (2) led to the formation of Ga2O3; (4) and (5) In metal; (7)–(10) GaS and (11)–(12) InS powders, respectively.

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