There are 8 possible dipeptides arising from all possible combinations of Nle and Phe. Considering that enantiomers will display identical supramolecular behaviour in achiral environments, the 4 non-enantiomeric dipeptides shown in Scheme 1 are representative of the whole series. The 4 compounds were prepared by solid phase, purified by reversed-phase HPLC, freeze-dried, and their identity and purity were confirmed by LC-MS, 1 H-NMR, and C-NMR spectroscopy (see ESI, Sections S1-S4). The HPLC retention times (Table ) can be considered an experimental measure of hydrophobicity, from which it was apparent that heterochirality significantly increased the hydrophobicity of the peptides, regardless of the sequence.