A Discrete Four‐Stranded β‐Sheet through Catenation of M2L2 Metal–Peptide Rings

Methods for precisely constructing a β‐sheet assembly with number‐defined strands in solution remains quite limited due to its intense aggregation property. Here, we report the precise construction of a four‐stranded anti‐parallel β‐sheet by utilizing a non‐covalent approach. This was achieved by folding and assembly of Ag+ and a pentapeptide (1) with the Ala‐D3pa‐Gly‐3pa‐Val (3pa: β‐(3‐pyridyl)‐alanine) sequence, which was designed to form an interlocking Ag2(1)2 ring through metal cross‐linking of the side chains. NMR analyses and X‐ray crystallographic studies characterized the structure of the discrete β‐sheet assembly as well as the remarkable structural selectivity in terms of strands’ number, orientation and the sheet type. A discrete four‐stranded β‐sheet was precisely constructed by metal‐induced folding and assembly of a short peptide. This was achieved by folding and assembly of Ag+ and the Ala‐D3pa‐Gly‐3pa‐Val (3pa: β‐(3‐pyridyl)‐alanine) pentapeptide, which was designed to form an interlocking Ag2(1)2 ring through metal cross‐linking of the side chains. The structure was confirmed by X‐ray crystallography and various NMR measurements.