Predicted crystal energy landscapes of porous organic cages

In principle, the development of computational methods for structure and property prediction offers the potential for the in silico design of functional materials. Here, we evaluate the crystal energy landscapes of a series of porous organic cages, for which small changes in chemical structure lead to completely different crystal packing arrangements and, hence, porosity. The differences in crystal packing are not intuitively obvious from the molecular structure, and hence qualitative approaches to crystal engineering have limited scope for designing new materials. We find that the crystal structures and the resulting porosity of these molecular crystals can generally be predicted in silico, such that computational screening of similar compounds should be possible. The computational predictability of organic cage crystal packing is demonstrated by the subsequent discovery, during screening of crystallisation conditions, of the lowest energy predicted structure for one of the cages.