Algorithm Technique For Structure Solution Research Articles

Structural Rationalization Directly from Powder Diffraction Data: Intermolecular Aggregation in 2-(Methylsulfonyl)ethyl Succinimidyl Carbonate

Structural rationalization of molecular materials has relied largely on the application of single crystal X-ray diffraction techniques, although clearly such studies are restricted to those materials that can be prepared in the form of single crystals of appropriate size and quality. To broaden our structural understanding beyond such cases, there is considerable scope for applying techniques that have been developed recently to allow structure determination of molecular materials directly from powder diffraction data. In this light, this paper reports and discusses the structural properties of 2-(methylsulfonyl)ethyl succinimidyl carbonate. The structure determination was carried out directly from powder X-ray diffraction data, using the genetic algorithm technique for structure solution, followed by Rietveld refinement. This material is an example of a molecular crystal that contains several conventional strong hydrogen bond acceptor groups but does not contain any conventional strong hydrogen bond donor groups. The structure is found to contain a number of short C−H···O interactions.

Structural Aspects of High-Efficiency Blue-Emitting 2,5-Bis(trimethylsilyl)thiophene-S,S-dioxide and Related Materials

2,5-Bis(trimethylsilyl)thiophene-S,S-dioxide is a member of a wider family of materials of interest with regard to photoluminescence properties, and has been shown to exhibit a high efficiency of blue fluorescence emission in the solid state. The crystal structure of this material has been determined directly from powder X-ray diffraction data using the Genetic Algorithm technique for structure solution, followed by Rietveld refinement. The structural properties of this material are assessed in the context of a series of related derivatives of thiophene-S,S-dioxide. Potential energy calculations suggest that structural differences within this family of materials can be rationalized in terms of competing intermolecular interactions promoting different structure types.

Ab initio structure determination of a peptide β-turn from powder X-ray diffraction data

Ab initio crystal structure determination of the peptide Piv-Pro-Gly-NHMe directly from powder X-ray diffraction data, using the genetic algorithm technique for structure solution, has allowed the complete structural characterization of the Type II β-turn conformation and the intermolecular interactions in this structure, and highlights the opportunities that now exist for structure determination of peptide systems when single crystals appropriate for single crystal X-ray diffraction experiments cannot be prepared.