A New Molecular Scaffold for the Formation of Supramolecular Peptide Double Helices: The Crystallographic Insight

A series of water-soluble synthetic dipeptides (1−3) with an N-terminally located β-alanine residue, β-alanyl-l-valine (1), β-alanyl-l-isoleucine (2), and β-alanyl-l-phenylalanine (3), form hydrogen-bonded supramolecular double helices with a pitch length of 1 nm, whereas the C-terminally positioned β-alanine containing dipeptide (4), l-phenylalanyl-β-alanine, does not form a supramolecular double helical structure. β-Ala-Xaa (Xaa = Val/Ile/Phe) can be regarded as a new motif for the formation of supramolecular double helical structures in the solid state.