There is a correlation between the intramolecular strain energy ∆E strain of the guest within the CS pores and the RMSD in atomic positions between the crystalline guest molecular geometry and the optimised isolated guest (see Fig. ), confirming that large distortions in the molecular geometry are usually associated with a relatively large energetic cost. There are a few cases where significant geometry changes have a relatively low energetic cost, such as risperidone (CSD Refcode: EZEXAL) which has an extended structure; or where a small change in molecular distortion leads to a high strain energy, such as the dithiine guest (GARLAQ). The latter example contains two highly-strained 4membered rings in the molecular structure, for which there is a large energetic penalty for making relatively small geometric changes.