Within the context of this discussion, the hydrophobic effect 179 is (very) broadly defined as the propensity for apolar moieties to aggregate in aqueous solution due to the sum of interactions between solvent and solute being less energetically favourable than interactions between water molecules. This allows relatively weak, and often ill-defined and poorly directional, non-covalent interactions (van der Waals forces, π-π interactions) to exist between the apolar moieties that might be ineffective at directing any semblance of molecular ordering in alternative solvents. Thus, whilst polar solvents can be detrimental to the stability of many other supramolecular capsules due to competing interactions between the components and solvent molecules, exploiting the hydrophobic effect can lead to the formation of capsules in one of the most competitive solvents -water (Fig. ).