Impact of Substituent Effects in the Design of β-Sheet Mimetic and β-Double Helix from (E)-Vinylogous γ-Amino Acid Oligomers

Here we are reporting the design, single crystal conformations, impact of the substituents and structural differences of two structurally important motifs, β-sheet and β-double helix. Though β-sheets are common structural motifs in protein structures,β-double helices are not common in proteins and peptides. We found that both β-sheet mimetic and β-double helix can be constructed from the homooligomers of α,β-unsaturated γ-amino acids. Results suggested that introducing gem-dialkyl substitutions at the γ-carbon of the homooligomer of α,β-unsaturated γ-amino acids adopted the β-double helix conformation, while the same oligomer with monosubstitution at the γ-carbon displayed β-sheet structure.