SIR97: a new tool for crystal structure determination and refinement

1999 ◽  
Vol 32 (1) ◽  
pp. 115-119 ◽  
Author(s):  
Angela Altomare ◽  
Maria Cristina Burla ◽  
Mercedes Camalli ◽  
Giovanni Luca Cascarano ◽  
Carmelo Giacovazzo ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Crystal Structures ◽  
Structure Determination ◽  
Direct Methods ◽  
Crystal Structure Determination ◽  
Previous Version

SIR97 is the integration of two programs,SIR92 andCAOS, the first devoted to the solution of crystal structures by direct methods, the second to refinementvialeast-squares–Fourier procedures. Several new features have been introduced inSIR97 with respect to the previous version,SIR92: greater automatization, increased efficiency of the direct methods section, and a powerful graphics interface. The program also provides publication tables and CIF files.

Chemistry and Crystal Structures of Some Constituents of Zingiber cassumunar

1979 ◽  
Vol 32 (1) ◽  
pp. 71 ◽  
Author(s):  
T Amatayakul ◽  
J Cannon ◽  
P Dampawan ◽  
T Dechatiwongse ◽  
RF Giles ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Crystal Structures ◽  
Structure Determination ◽  
Aromatic Compounds ◽  
Crystal Structure Determination ◽  
The Novel ◽  
X Ray ◽  
Zingiber Cassumunar ◽  
Block Diagonal

The novel aromatic compounds cis-3-(2',4',5'-trimethoxyphenyl)-4-[(E)-2''',4''',5'''-trimethoxy-styryl]cyclohex-1-ene(1), cis-3-(3',4'-dimethoxyphenyl)-4-[(E)-3''',4'''-dimethoxystyryl]cyclohex-1-ene (2), a substance assigned the tentative structure cis-3-(3',4'-dimethoxyphenyl)-4-[(E)-2''',4''',5'''- trimethoxystyryl]cyclohex-1-ene (3),(E)-4-(3',4'-dimethoxypheny1)but-3-en-1-ol (5), (E)-4-(3',4'-dimethoxypheny1)but-3-en-1-yl acetate (6), and 8-(3',4'-dimethoxyphenyl)-2-methoxynaphtho-1,4- quinone (7) have been isolated from the rhizomes of Zingiber cassurnunav Roxb. (Zingiberaceae). The crystal structures of the cyclohexene derivative (1) and the quinone (7) have been determined from X-ray diffractometer data at 295 K and refined by block diagonal least squares to residuals of 0.046 (2099 'observed' reflections) and 0.093 (1246), respectively. Crystals of compound (1) are triclinic, P1, a 18.027(12), b 10.037(9), c 6.530(5) α, 84.22 (7), β 81.87 (6), γ 85.72 (6)�, Z 2. Crystals of the quinone (7) are monoclinic, P21/a, a 22.89 (1), b 8.022 (5), c 8.458 (5) �, β 91.98 (5)�, Z 4. Although the latter crystal structure determination is imprecise, due largely to the very small size of the crystal available, the solution is unambiguous. A simple two-step synthesis of the quinone (7) has been achieved.

scholarly journals A Brief History of Fourier Methods in Crystal-structure Determination

1985 ◽  
Vol 38 (3) ◽  
pp. 263 ◽  
Author(s):  
CA Beevers ◽  
H Lipson
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Structure Determination ◽  
Heavy Atom ◽  
Direct Methods ◽  
Crystal Structure Determination ◽  
Fourier Methods ◽  
Isomorphous Replacement ◽  
History Of

Fourier methods for the determination of crystal structures were first suggested by Bragg in 1929, and were then successfully used by Beevers and Lipson for determining the structure of CuS04.5H20 in 1934. It was necessary for methods of summation to be devised, and after some experimentation the Beevers-Lipson strips became established as the best device for the work. They enabled increasingly complicated structures to be derived, but ultimately more elaborate and automatic devices based on digital computers had to be introduced. At the same time, isomorphous-replacement, heavy-atom and direct methods were also developed and these have enabled structures of enormous complexity to be successfully determined.

scholarly journals Crystal structures of two furazidin polymorphs revealed by a joint effort of crystal structure prediction and NMR crystallography

2020 ◽  
Vol 76 (3) ◽  
pp. 322-335 ◽  
Author(s):  
Marta K. Dudek ◽  
Piotr Paluch ◽  
Edyta Pindelska
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Structure Determination ◽  
Structure Prediction ◽  
Structural Features ◽  
Crystal Structure Determination ◽  
Crystal Structure Prediction ◽  
Crystal Forms ◽  
Space Groups ◽  
Nmr Crystallography

This work presents the crystal structure determination of two elusive polymorphs of furazidin, an antibacterial agent, employing a combination of crystal structure prediction (CSP) calculations and an NMR crystallography approach. Two previously uncharacterized neat crystal forms, one of which has two symmetry-independent molecules (form I), whereas the other one is a Z′ = 1 polymorph (form II), crystallize in P21/c and P 1 space groups, respectively, and both are built by different conformers, displaying different intermolecular interactions. It is demonstrated that the usage of either CSP or NMR crystallography alone is insufficient to successfully elucidate the above-mentioned crystal structures, especially in the case of the Z′ = 2 polymorph. In addition, cases of serendipitous agreement in terms of 1H or 13C NMR data obtained for the CSP-generated crystal structures different from the ones observed in the laboratory (false-positive matches) are analyzed and described. While for the majority of analyzed crystal structures the obtained agreement with the NMR experiment is indicative of some structural features in common with the experimental structure, the mentioned serendipity observed in exceptional cases points to the necessity of caution when using an NMR crystallography approach in crystal structure determination.

Crystal structure determination from powder diffraction data by the application of a genetic algorithm

1997 ◽  
Vol 212 (8) ◽  
Author(s):  
K. Shankland ◽  
W. I. F. David ◽  
T. Csoka
Keyword(s):  
Crystal Structure ◽  
Genetic Algorithm ◽  
Full Advantage ◽  
Crystal Structures ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Structure Determination ◽  
Crystal Structure Determination ◽  
Powder Diffraction Data ◽  
Flexible Molecules

AbstractA genetic algorithm (GA) based method for solving crystal structures directly from powder diffraction data has been developed. The method is based around fitting the diffraction data generated from trial structures against the measured diffraction data and has the ability to handle flexible molecules and multiple fragments. It is computationally highly efficient and takes full advantage of the implicit parallelism of the GA. The method is illustrated with the solutions of three crystal structures of varying complexity.

The Anion [Co(C8H12)2]–. A Comparative Study of the Crystal Structures of [{K(18-crown-6)}2(C5H5)][Co(C8H12)2] and Co(C8H12)(C8H13)

2009 ◽  
Vol 64 (8) ◽  
pp. 985-988 ◽  
Author(s):  
Jian-Qiang Wang ◽  
Thomas F. Fässler
Keyword(s):  
Crystal Structure ◽  
Crown Ether ◽  
Comparative Study ◽  
Single Crystal ◽  
Crystal Structures ◽  
Structure Determination ◽  
Cobalt Complex ◽  
Crystal Structure Determination ◽  
X Ray ◽  
Cyclopentadienyl Anion

The cobalt complex [{K(18-crown-6)}2(C5H5)]- [Co(C8H12)2]・(THF)2 (3) has been synthesized and characterized by X-ray single-crystal structure determination. The crystal structure of Co(C8H12)(C8H13) (2) has been reinvestigated and compared with the structure of 3. The 1,5-cyclooctadiene (C8H12) and C8H13 ligands are coordinated in an η4 and η3 fashion, respectively. The cyclopentadienyl anion in [{K(18-crown-6)}2(C5H5)]+ in 3 is η5-coordinated to the two crown ether-encapsulated potassium cations

Sign in / Sign up

Export Citation Format

Share Document