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Journal ArticleDOI

Phase annealing in SHELX-90: direct methods for larger structures

George M. Sheldrick
- 01 Jun 1990 - 
- Vol. 46, Iss: 6, pp 467-473
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TLDR
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.

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Citations
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Complexes formed between the quadridentate, heterocyclic molecules 6,6′-bis-(5,6-dialkyl-1,2,4-triazin-3-yl)-2,2′-bipyridine (BTBP) and lanthanides(III): implications for the partitioning of actinides(III) and lanthanides(III)

TL;DR: New hydrophobic, tetradentate nitrogen heterocyclic reagents, 6,6'-bis-(5,6-dialkyl-1,2,4-triazin-3-yl)-2,2'-bipyridines (BTBPs) have been synthesised and show different conformations described as cis, trans, cis and trans, Trans, trans respectively.
Journal ArticleDOI

Deep-Blue-Emitting Heteroleptic Iridium(III) Complexes Suited for Highly Efficient Phosphorescent OLEDs

TL;DR: In this article, the design, synthesis, and characterization of four new heteroleptic iridium(III) complexes bearing 2′,6′-difluoro-2,3′-bipyridine and pyridyl-azole ligands were also investigated.
Journal ArticleDOI

Crystal structure of UvrB, a DNA helicase adapted for nucleotide excision repair.

TL;DR: The location of conserved residues and structural comparisons allow us to predict the path of the DNA and suggest that the tight pre‐incision complex of UvrB and the damaged DNA is formed by insertion of a flexible β‐hairpin between the two DNA strands.
Journal ArticleDOI

Synthesis, structures, and reactivity of weakly coordinating anions with delocalized borate structure: the assessment of anion effects in metallocene polymerization catalysts.

TL;DR: The formation of adducts of tris(pentafluorophenyl)borane with strongly coordinating anions such as CN(-) and [M(CN)(4)](2)(-) (M = Ni, Pd) is a synthetically facile route to the bulky, very weakly coordinatingAnions.
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.