Crystal Structure Prediction Methodologies

The subject of this study is particularly challenging for any crystal structure prediction methodology for several reasons. First of all the molecular entity in the solid state (a zwitterion) is different from that in the gas phase. This means that the transfer of molecular information from quantum mechanical... 

The evaluation of the impact of the different crystal structures on the prediction of the site of metabolism by the MetaSite methodology without reactivity correction has been considered. In this case one can conclude that overall the rate of good prediction (number of experimentally determined sites of metabolism among the first three solutions predicted by MetaSite) is similar for the different structures. Nevertheless, there is only a moderate overlap between the compounds that are well predicted by each crystal structure, and a combination of all structures usually yield higher prediction rates. When using the reactivity correction, the difference between the prediction rates for each crystal structure is reduced, suggesting a diminishing rate of the crystal structure used for the analysis. 

AMI calculations on the dimers of nitroanilines and substituted benzoic acids are of considerable value in predicting their crystal structures. In particular, the intermolecular forces that dictate the relative orientations of the individual molecules in the crystal chains can be understood. It is likely that this methodology will be useful for modelling the kinds of interactions that might occur in other crystals. 

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