Hydrogen-bond motifs in the crystals of hydrophobic amino acids

A computer program has been developed to survey a set of crystal structures for hydrogen-bond motifs. Possible ring and chain motifs are generated automatically from a user-defined list of interacting molecular fragments and intermolecular interactions. The new program was used to analyse the hydrogen-bond networks in the crystals of 52 zwitterionic α-amino acids. All the possible chain motifs (repeating 1–4 molecules) are frequent, while the frequency of ring motifs (2–6 molecules) ranges from 0 to 85% of the structures. The list of motifs displayed by each structure reveals structural similarities and it can be used to compare polymorphs. The motifs formed in cocrystals of α-amino acids and in crystals of β- and γ-amino acids are similar to those of α-amino acids.