Discovery a predicted caffeine cocrystal

What is it about?

The cocrystal of caffeine with benzoic acid was previously thought not to form, as it failed to be observed after extensive screening. However, modern crystal structure prediction calculations showed that it should be stable. Templating experiments were designed based in the most probable predicted crystal structure, which led to the material being formed. This is a good example of calculations informing experiments, and leading to materials that might otherwise have never been discovered.

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Why is it important?

Crystal structure prediction methods have been extended beyond prediction of the most likely structures of a compound, to predicting whether two molecules will form a multicomponent crystal (cocrystal or solvate) or not, as well as its energetically preferred composition (see http://goo.gl/XKdP1y and http://goo.gl/7qp for methods). This is an example of the discovery of a cocrystal that was predicted to exist, and how the computational results guide the experiement to produce this new structure.