Assembly of dynamic helical β-peptides with switchable handedness into multiple types of metal-peptide frameworks.

Abstract

Metal-directed assemblies of helical peptides are emerging chiral biomimetic materials, yet dynamic helical peptides remain underexplored. Here we report the coordination-driven assembly of dynamic 12/10-helical β-pentapeptides into distinct metal-peptide frameworks (MPFs) with silver ions. Ligand 1, consisting of cis-2-aminocycloheptanecarboxylic acid with alternating chirality, exhibits solvent-dependent screw-sense preference: (P)-helix in protic and (M)-helix in aprotic solvents. The two helical conformers are not enantiomers and assemble into two distinct MPFs (Ag-1M and Ag-1P), while a racemic ligand mixture (1 and ent-1) yields a third MPF (Ag-rac-1PM). A series of modified ligands (2-5), incorporating various central residues, form MPFs analogous to Ag-1M or Ag-1P, with pore environments modulated by side chains. Particularly, an MPF incorporating polar N-acetyl azepane moieties (Ag-5M) selectively recognizes a chiral guest through post-crystallization. These results highlight dynamic helical β-peptides as versatile building blocks for diverse chiral MPFs, with tunable pore environments through rational peptide design.