Conformational analysis crystallography

The study of molecular symmetry is the most developed aspect of molecular shape analysis, providing insight as well as computational simplification for most branches of quantum chemistry, conformation analysis, crystallography, spectroscopy, and molecular dynamics. The mathematical and computational techniques for symmetry analysis are usually based on group theory. ... 

Conformational analysis of the novel bicyclo[3.3.0]octasilane and bicyclo[4.2.0]octasilane systems was carried out by X-ray crystallography (Figs. 19-21). The bicyclo[3.3.0]octasilane framework of trans-17 has a trans-fused structure of cyclopentasilane rings. The trans-fused structure is... 

The TRIDIM 80 software was used here in the case of dynamic conformational analysis. Many other applications of such software may be found. In the field of X-ray crystallography, the different steps of a structure refinement could be visualized for checking the quality of this refinement. In astronomy, views of the same portion of the sky at different times treated by TRIDIM 80 could be projected on to a TV screen at any angle so as to magnify all the movements which happen between them. 

Marshall, G. R., H. E. Bosshard, and R. A. Ellis, "Computer Handling of Chemical Structures Applications in Crystallography, Conformational Analysis, and Drug Design," in Computer Representation and Manipulation of Chemical Infor-mation, ed. W. T. Wipke and others, John Wiley 8 Sons, Inc., New York, N.Y., 1974. 

J. C. A. Boeyens, L. Denner, and G. W. Perold, Rotamers and isomers in the fulgide series. Part 2. Stereochemistry and conformational analysis of bis-(j>methoxybenzylidene) succinic anhydrides by X-ray crystallography and molecular mechanics, J. Chem. Soc., Perkin. Trans. 2, 1988, 1999— 2005. 

Andrews PR, Brownlee RTC, Mackay MF, Poulton DB, Sadek M, Winkler DA (1983) Conformational Analysis of Picrotoxinin by N.M.R., X-Ray Crystallography, and Molecular Orbital and Classical Potential-Energy Calculations. Aust J Chem 36 2219... 

The physical, chemical and biological properties of a molecule often depend critically upon the three-dimensional structures, or conformations, that it can adopt. Conformational analysis is the study of the conformations of a molecule and their influence on its properties. The development of modem conformational analysis is often attributed to D H R Benton, who showed in 1950 that the reactivity of substituted cyclohexanes was influenced by the equatorial or axial nature of the substituents [Barton 1950]. An equally important reason for the development of conformational analysis at that time was the introduction of analytical techniques such as infrared spectroscopy, NMR and X-ray crystallography, which actually enabled the conformation to be determined. 

The structure of A -THC was built from the structure of A -tetrahydrocannabinolic acid B as determined by X-ray crystallography. THC analogues were modelled by modifying the basic structure. Aminoalkylindoles and azoles were subject to conformational analysis in order to select initial low energy conformations for all molecules. 

Erythromycin and its derivatives have been extensively studied by NMR. The H and C NMR spectra of erythromycin, measured in a range of solvents and by a variety of techniques, have been completely assigned [31-34]. The combination of NMR spectroscopy and X-ray crystallography has been used for conformational analysis, which found good agreement... 

Preferential conformations of a molecule are studied in conformational analysis. This can be done by microwave, uv, ir, nmr, and Raman spectroscopy, X-ray crystallography, kinetic, equilibrium and dipole moment measurements, etc. The existence and stability of conformers can also be determined by energy calculations. 

Sundaralingam M (1971) Stereochemistry of nucleic acids and their constituents. XVIII. Conformational analysis of a nucleosides by X-ray crystallography. J Am Chem Soc 93 6644-6647... 

The primary structure of P. is elucidated by the standard methods of sequence analysis (see Proteins). The conformation of P. is an important determinant of their biological activity. It is stabilized by peptide and disulfide bonds In P. containing unusual bonds and/or constituents other factors also stabilize the conformation. Although X-ray crystallography (see) was used in the elucidation of the three-dimensional structures of insulin and gramicidin S, the conformational analysis of P. is now by preference carried out in solution, using the spectroscopic methods ORD, CD, IR, NMR and ESR. 

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