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George M. Sheldrick

Other affiliations: University of Regensburg
Bio: George M. Sheldrick is an academic researcher from University of Göttingen. The author has contributed to research in topics: Crystal structure & Bond length. The author has an hindex of 58, co-authored 791 publications receiving 151229 citations. Previous affiliations of George M. Sheldrick include University of Regensburg.


Papers
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Journal ArticleDOI
TL;DR: In this paper, the structures of a binuclear and trinuclear gold derivative have been confirmed by X-ray crystallography Crystals of [(C6F5)2Au(Ph2P[graphic omitted]HPPh2]u(C6Fs5)] are monoclinic, space group P21/m, with a= 10003(2), b= 17389(4), c= 11754(3)A, β= 10353(2)°, and Z= 2; R= 0034 for 4 01
Abstract: Reaction of NaH with [Au(C6F5)2(Ph2PCH2PPh2)]ClO4 causes both deprotonation of the methylene group and elimination of the anion and leads to the neutral bis(diphenylphosphino)methanide complex [Au(C6F5)2(Ph2PCHPPh2)], which further reacts with gold(I) or silver(I) derivatives to give bi- or tri-nuclear complexes The structures of a binuclear and a trinuclear gold derivative have been confirmed by X-ray crystallography Crystals of [(C6F5)2Au(Ph2P[graphic omitted]u(C6F5)] are monoclinic, space group P21/m, with a= 10003(2), b= 17389(4), c= 11754(3)A, β= 10353(2)°, and Z= 2; R= 0034 for 4 016 reflections Crystals of [(C6F5)2Au(Ph2P[graphic omitted]HPPh2)Au(C6F5)2]ClO4(CHCl3 solvate) are monoclinic, space group P21/m, with a= 17456(6), b= 17704(6), c= 17749(8)A, β= 9286(5)°, and Z= 2; R= 0096 for 5 230 reflections

22 citations

Journal ArticleDOI
TL;DR: The molecular structure of gaseous trisilyphosphine has been determined by the sector-microphotometer method of electron diffraction as discussed by the authors, and the heavy-atom skeleton is found to be pyramidal.
Abstract: The molecular structure of gaseous trisilyphosphine has been determined by the sector-microphotometer method of electron diffraction. The heavy-atom skeleton is found to be pyramidal; the P–Si distance is 2·248 ± 0·003 A and the Si–P–Si angle 96·45 ± 0·50°. The bond angles at silcon are found to be tetrahedral within experimental error; the Si–H distance is 1·485 ± 0·010 A. These results supersede conclusions from spectroscopic evidence that the molecule has a planar heavy-atom skeleton.

22 citations

Journal ArticleDOI
TL;DR: In this article, the free stannaimine A reacts with methyllithium, 2,6-diisopropylylaniline, and methyl vinyl ketone to give the corresponding 1,2-addition products (to the SnN bond) 2, 3, and 10.
Abstract: Reactions of a Free Stannaimine and of Base-Stabilized Stannylenes The free stannaimine A reacts with methyllithium, 2,6-diisopropylaniline, and methyl vinyl ketone to give the corresponding 1,2-addition products (to the SnN bond) 2, 3, and 10. With 2,6-diisopropylphenyl isocyanate and benzaldehyde [2 + 2] cycloadditions to the CO bonds lead to 4 and 5, while with benzonitrile oxide and acroleine [2 + 3] and [2 + 4] cyclo-additions produce 8 and 9. The pyridine adducts bis-[bis(trimethylsilyl)amino]stannylene and -germylene react with aryl azides to give the corresponding derivatives of tri-amino-2-pyridylstannane 11 and -germane 12. Bis[2-pyridyl-bis(trimethylsilyl)methyl]stannylene upon treatment with aryl azides form the 1-aza-8-stannabicyclo[3.2.0]octa-2,4,6-triene systems 13 and 14 via stannaimine intermediates. X-ray structure analyses are presented for 3, 11, and 13.

22 citations

Journal ArticleDOI
TL;DR: In this article, the cucurbitacin glycosides B(8), C(3), D(9), E(4), F(5), G(6), and H(10), as well as the known compound datiscoside (1) have been isolated and characterized.
Abstract: Datisca glomerata has been systematically fractionated by following cellular toxicity in an effort to identify previously uncharacterized cytotoxic principles. Several new cucurbitacin glycosides, including datiscosides B(8), C(3), D(9), E(4), F(5), G(6), and H(10) and the known compound datiscoside (1), as well as cucurbitacins B(11), D(2), and F(7) have been isolated and characterized. Structures were assigned to the compounds on the basis of their high field 1H n.m.r., 13C n.m.r., high-resolution mass spectra (CI, EI, and FD) and chemical interconversions. The structure of datiscoside C(3) was independently established by single-crystal X-ray analysis at 193 and 293 K.

22 citations

Journal ArticleDOI
TL;DR: The structure solution of DNA-binding protein structures and complexes based on the combination of location of DNA -binding protein motif fragments with density modification in a multi-solution frame is described.
Abstract: Protein–DNA interactions play a major role in all aspects of genetic activity within an organism, such as transcription, packaging, rearrangement, replication and repair. The molecular detail of protein–DNA interactions can be best visualized through crystallography, and structures emphasizing insight into the principles of binding and base-sequence recognition are essential to understanding the subtleties of the underlying mechanisms. An increasing number of high-quality DNA-binding protein structure determinations have been witnessed despite the fact that the crystallographic particularities of nucleic acids tend to pose specific challenges to methods primarily developed for proteins. Crystallographic structure solution of protein–DNA complexes therefore remains a challenging area that is in need of optimized experimental and computational methods. The potential of the structure-solution program ARCIMBOLDO for the solution of protein–DNA complexes has therefore been assessed. The method is based on the combination of locating small, very accurate fragments using the program Phaser and density modification with the program SHELXE. Whereas for typical proteins main-chain α-helices provide the ideal, almost ubiquitous, small fragments to start searches, in the case of DNA complexes the binding motifs and DNA double helix constitute suitable search fragments. The aim of this work is to provide an effective library of search fragments as well as to determine the optimal ARCIMBOLDO strategy for the solution of this class of structures.

22 citations


Cited by
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Journal ArticleDOI
TL;DR: This paper could serve as a general literature citation when one or more of the open-source SH ELX programs (and the Bruker AXS version SHELXTL) are employed in the course of a crystal-structure determination.
Abstract: An account is given of the development of the SHELX system of computer programs from SHELX-76 to the present day. In addition to identifying useful innovations that have come into general use through their implementation in SHELX, a critical analysis is presented of the less-successful features, missed opportunities and desirable improvements for future releases of the software. An attempt is made to understand how a program originally designed for photographic intensity data, punched cards and computers over 10000 times slower than an average modern personal computer has managed to survive for so long. SHELXL is the most widely used program for small-molecule refinement and SHELXS and SHELXD are often employed for structure solution despite the availability of objectively superior programs. SHELXL also finds a niche for the refinement of macromolecules against high-resolution or twinned data; SHELXPRO acts as an interface for macromolecular applications. SHELXC, SHELXD and SHELXE are proving useful for the experimental phasing of macromolecules, especially because they are fast and robust and so are often employed in pipelines for high-throughput phasing. This paper could serve as a general literature citation when one or more of the open-source SHELX programs (and the Bruker AXS version SHELXTL) are employed in the course of a crystal-structure determination.

81,116 citations

Journal ArticleDOI
TL;DR: New features added to the refinement program SHELXL since 2008 are described and explained.
Abstract: The improvements in the crystal structure refinement program SHELXL have been closely coupled with the development and increasing importance of the CIF (Crystallographic Information Framework) format for validating and archiving crystal structures. An important simplification is that now only one file in CIF format (for convenience, referred to simply as `a CIF') containing embedded reflection data and SHELXL instructions is needed for a complete structure archive; the program SHREDCIF can be used to extract the .hkl and .ins files required for further refinement with SHELXL. Recent developments in SHELXL facilitate refinement against neutron diffraction data, the treatment of H atoms, the determination of absolute structure, the input of partial structure factors and the refinement of twinned and disordered structures. SHELXL is available free to academics for the Windows, Linux and Mac OS X operating systems, and is particularly suitable for multiple-core processors.

28,425 citations

Journal ArticleDOI
TL;DR: OLEX2 seamlessly links all aspects of the structure solution, refinement and publication process and presents them in a single workflow-driven package, with the ultimate goal of producing an application which will be useful to both chemists and crystallographers.
Abstract: New software, OLEX2, has been developed for the determination, visualization and analysis of molecular crystal structures. The software has a portable mouse-driven workflow-oriented and fully comprehensive graphical user interface for structure solution, refinement and report generation, as well as novel tools for structure analysis. OLEX2 seamlessly links all aspects of the structure solution, refinement and publication process and presents them in a single workflow-driven package, with the ultimate goal of producing an application which will be useful to both chemists and crystallographers.

19,990 citations

28 Jul 2005
TL;DR: PfPMP1)与感染红细胞、树突状组胞以及胎盘的单个或多个受体作用,在黏附及免疫逃避中起关键的作�ly.
Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1(PfPMP1)与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用,在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员,通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

18,940 citations

Journal ArticleDOI
TL;DR: The PHENIX software for macromolecular structure determination is described and its uses and benefits are described.
Abstract: Macromolecular X-ray crystallography is routinely applied to understand biological processes at a molecular level. How­ever, significant time and effort are still required to solve and complete many of these structures because of the need for manual interpretation of complex numerical data using many software packages and the repeated use of interactive three-dimensional graphics. PHENIX has been developed to provide a comprehensive system for macromolecular crystallo­graphic structure solution with an emphasis on the automation of all procedures. This has relied on the development of algorithms that minimize or eliminate subjective input, the development of algorithms that automate procedures that are traditionally performed by hand and, finally, the development of a framework that allows a tight integration between the algorithms.

18,531 citations