Crystallography structure analysis

This structural analysis was later confirmed by Komatsu and co-workers who prepared two new series of dehydroannulenes fused with bicyclo-[2.2.2]octene moieties [58]. In the series of compounds 17-20 (Fig. 2), they showed by X-ray crystallography that trimeric 18 has a planar n-electron peri-... 

The potential application of self-assembled scaffolds offering exact positioning of biological macromolecules within micron- to milimeter-size DNA- or protein-made crystals for structural analysis by x-ray crystallography was also suggested [5,50]. 

Since 1990, more and more structures have been solved from HREM images and electron diffraction and more and more scientists have become interested in structure analysis by electron crystallography (Hovmoller 1992 Zou, 1995). This pushed electron crystallography a big step forward. The term electron crystallography was first introduced and soon been accepted. 

In conclusion, electron crystallography can be used to extend the range of samples amenable to structure analysis beyond those which can be studied by single crystal X-ray diffraction. Moreover, HREM images can supply some initial low resolution phases for X-ray diffraction which may aid in phase determination in X-ray crystallography. 

Electron crystallography provides unique possibilities of studying nanostructured materials. The aims of this course are to show theoretically that electron crystallography can be used for crystal structure analysis to describe different methods of solving crystal structures by electron crystallography and to demonstrate how these methods are used practically. 

Vainshtein B.K., Zvyagin B.B., Avilov A.S. (1992) Electron diffraction structure analysis. In Electron diffraction techniques Vol. 1 (Ed. J. Cowley), lUCr Monographs on Crystallography, Oxford Science Publications, pp. 216-312. 

Klechkovskaya V.V., Imamov R.M. Electron diffraction structure analysis -from Vainshtein to our days. (2001) Crystallography Reports, v.46, N4. pp.598-613. 

Several methods of quantitative structure analysis are known in electron crystallography. These are ... 

Weirich, T. E. (2001), 31ectron crystallography without limits - Crystal structure of Ti45Sci6 redetermined hy electron diffraction structure analysis, /Icta Cryst. A57, 183-191. 

As discussed in section 2.3, the electron diffraction intensities need to be corrected before being employed for structure analysis. An empirical method has been set up to correct simultaneously all kinds of distortions in the diffraction data by referring to the heavy atom method and the Wilson statistic technique in X-ray crystallography. After correction, the intensity of each diffraction beam can approximately lead to the modulus of the corresponding structure factor [26]. 

Weirich, T.E. (2001). Electron crystallography without limits Crystal structure of Xi45Sei6 redetermined by electron diffraction structure analysis. Acta Cryst. A57,183-191. 

Dorset, D. L. Tivol, W.F. and Turner, J.N. Electron crystallography at atomic resolution ab initio structure analysis of copper perchlorophthalocyanine. 

Kenneth Suslick has written several pertinent statements about the study of metalloproteins and their model compounds. This paradigm will guide the study of the varied bioinorganic systems described in this chapter. Additions to Suslick s statement in point 2 stress the importance of modern structural analysis (X-ray crystallography, EXAFS, EPR, and two- and three-dimensional high-held NMR) of the purihed metalloproteins and their model compounds. As paraphrased from reference 19, the following statements outline the steps involved in the study of metalloproteins ... 

The problem of phase determination is the fundamental one in any crystal structure analysis. Classically protein crystallography has depended on the method of multiple isomorphous replacement (MIR) in structure determination. However lack of strict isomorphism between the native and derivative crystals and the existence of multiple or disordered sites limit the resolution to which useful phases may be calculated. 

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