Figure 8: Molecular crystals of peptides I-III. All the hydrogen bonds are shown as dotted lines: (a) I, Boc-Val-Ala-Phe-Aib-Val-Ala- Phe-Aib-OMe; (b) II, Boc-Val-Ala- Phe-Aib-Val-Ala-Phe-Aib-Val-Ala-Phe-Aib-OMe; (c) III, Boc-Aib-Ala-Phe-Aib-Phe-Ala-Val-Aib-OMe.