Journal ArticleDOI
Phase annealing in SHELX-90: direct methods for larger structures
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In this article, a phase annealing method, related to the simulated-annealing approach in other optimization problems, is proposed and it is shown that it can result in an improvement of up to an order of magnitude in the chances of solving large structures at atomic resolution.Abstract:
A number of extensions to the multisolution approach to the crystallographic phase problem are discussed in which the negative quartet relations play an important role. A phase annealing method, related to the simulated annealing approach in other optimization problems, is proposed and it is shown that it can result in an improvement of up to an order of magnitude in the chances of solving large structures at atomic resolution. The ideas presented here are incorporated in the program system SHELX-90; the philosophical and mathematical background to the direct-methods part (SHELXS) of this system is described.read more
Citations
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Journal ArticleDOI
Selective substitution of corroles: nitration, hydroformylation, and chlorosulfonation.
TL;DR: This work demonstrates the feasibility and power of electrophilic substitution on the peripheral carbon atoms of triarylcorroles as a synthetic tool to new derivatives by a combination of X-ray crystallography of the various products and detailed analysis of their NMR spectra.
Journal ArticleDOI
Industrial Synthesis of the Key Precursor in the Synthesis of the Anti-Influenza Drug Oseltamivir Phosphate (Ro 64-0796/002, GS-4104-02): Ethyl (3R,4S,5S)-4,5-epoxy-3-(1-ethyl-propoxy)-cyclohex-1-ene-1-carboxylate
Muriel Cordon Federspiel,Rolf Fischer,Michael Hennig,Hans-Jürgen Mair, ,‖,Thomas Oberhauser,Gösta Rimmler,Thomas Albiez,Jürg Bruhin,Heinrich Estermann,Carsten Gandert,Volker Göckel,Stephan Götzö,Ursula Hoffmann,Gabriel Huber,Günter Janatsch,Stephan Lauper,Odette Röckel-Stäbler,and Rene Trussardi,Andreas G. Zwahlen +18 more
TL;DR: In this paper, a method for the dehydration of quinic acid to a shikimic acid derivative and for the reduction of a cyclic ketal was found, which led to a doubled overall yield, a 30% reduction in the number of unit operations, and an excellent quality of the resulting epoxide.
Journal ArticleDOI
Two-Dimensional Structural Motif in Thienoacene Semiconductors: Synthesis, Structure, and Properties of Tetrathienoanthracene Isomers
Jaclyn L. Brusso,Oliver D. Hirst,Afshin Dadvand,Srinivasan Ganesan,Fabio Cicoira,Craig M. Robertson,Richard T. Oakley,Federico Rosei,Dmitrii F. Perepichka +8 more
TL;DR: Stille coupling of 2-and 3-thiophene derivatives with tetrabromobenzene followed by oxidative cyclization provides a simple, two-step synthetic route to two isomeric tetrathienoanthracene structures (13 and 14) as discussed by the authors.
Journal ArticleDOI
On the application of the minimal principle to solve unknown structures
TL;DR: This report focuses on algorithmic and parametric optimizations of Shake-and-Bake and the determination of two previously unknown structures that contain 105 and 110 non-hydrogen atoms, respectively.
Journal ArticleDOI
Synthesis, Structure, and Magnetic Properties of Mn(salpn)N3, a Helical Polymer, and Fe(salpn)N3, a Ferromagnetically Coupled Dimer (salpnH2 = N,N‘-bis(Salicylidene)-1,3-diaminopropane)
TL;DR: The preparation, crystal structures, and variable temperature magnetic susceptibility data are presented for two azido-bridged Schiff base complexes of Mn(III) and Fe(III).
References
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Book
Crystallographic Computing 3: Data Collection, Structure Determination, Proteins and Databases
TL;DR: The latest in a series on crystallographic computing, this collection of 33 papers covers the full spectrum of computer applications in crystallography, including the use of micro-, mini-, and mainframe computers.