In conclusion, we have uncovered a new foldamer structure in a,d-hybrid peptides -the 13/11(II)-helix which was confirmed by both X-ray diffraction and NMR. These structures are closely aligned, save for the terminal residues, and our studies demonstrate that the helix is very stable. We also show that apolar interactions observed between the ethyl group of one d-residue and the cyclohexyl system of the (i+2) d-residue are responsible for the stabilization of the novel helix type H13/11 II over H13/11 I which was theoretically predicted as most stable for an unsubstitued backbone, by +60.2 kJ/mol. We then demonstrate that replacing two proximal a-residues of the sequence with ornithines leads to a catalyst that is a mimic of an aldolase and accelerates the retroaldol reaction of methodol. The simplicity of the design process for endowing these α,δ-foldamer scaffolds with distinct reactive groups and their unique structure -featuring a deep helical groove -augur well for the development of functional α,δ-foldamers. Further catalyst application and refinement will be the subject of future reports.