Crystal structure validation

Platon Single crystal structure validation with the program PLATON, A. L. Spek, J. Appl. Crystallogr., 2003, 36, 7 13 Includes Structure Tidy ... 

Platon/ Single crystal structure validation with the Platon requires Shelx... 

D. Cunningham, R. Dark and M. Mahon, CrystEngComm, 2004, 6, 303 Single crystal structure validation with the program PLATON, A. L. Spek, J. Appl. Crystallogr., 2003, 36, 7 13 and A. L. Spek, 1998, PLATON, A Multipurpose Crystallographic Tool, Utrecht University, Utrecht, The Netherlands... 

Levin EJ, Kondrashov DA, Wesenberg GE, Phillips GN Jr (2007) Ensemble refinement of protein crystal structures validation and application. Structure 15 1040-1052... 

The validity of this approach can be demonstrated by the example of several complex fluoride compounds that exhibit ferroelectric properties, such as compounds that belong to the SrAlF5 family [402, 403]. The crystal structure of the compounds is made up of chains of fluoroaluminate octahedrons that are separated by another type of chains - ramified chains. Other examples are the compounds Sr3Fe2Fi2 and PbsWjOgFio. In this case, the chains of iron- or tungsten-containing octahedrons are separated from one another by isolated complexes with an octahedral configuration [423,424]. 

GPCRs in order to serve as templates and aid in the analysis of ligand-receptor complexes. Thus, the validated structural insights described earlier show that it is not appropriate to utilize the crystal structure of the inactive form of rhodopsin as a universal template if the modeled functional details pertain to an activated (e.g., agonist-bound) state of the GPCR. 

The d-d spectra of copper(II) compounds have provided a fruitful field for practitioners of the AOM. A wealth of structural data is available, and a rich variety of coordination geometries has been revealed. If we can make allowance for the dependence of the AOM parameters on the intemuclear distance, we are provided with excellent opportunities to test the validity of AOM parameters over a range of related systems. However, the progress of such studies over the years has illustrated the fact that a simple model may be very successful in explaining a limited amount of dubious experimental data as more crystal structures appear and as better spectroscopic data become available, the simple model may require considerable refurbishment, perhaps to the extent that it loses some of its appeal and utility. 

However, according to Hyde and Andersson (1989), for instance, the validity extension of this principle is difficult to evaluate. As time passes, crystallographers are able to solve more and more complex crystal structures, and these tend to have low symmetry. The symmetry principle could be restated by observing that a crystal structure has the highest symmetry compatible with the efficient use of space and the specific requirements of chemical bonding between nearest neighbours. 

Another issue is validated by the presented X-ray structures This is related to the pseudoenantiomeric character of the tert-butylcarbamates of quinine and quinidine (Figure 1.19a,b). Except for the vinyl on the backside of the quinuclidine ring, both the complexes that are actually diastereomeric to each other actually look like mirror images with regard to conformations and intermolecular interactions as well so that the pseudoenantiomeric experimental chromatographic behavior for DNB-Leu can be rationalized also on the basis of their X-ray crystal structures. 

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