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Developing peptide‐based materials with controlled morphology is a critical theme of soft matter research. Herein, we report the formation of a novel, patterned cross‐β structure formed by self‐assembled C3‐symmetric peptide amphiphiles based on diphenylalanine and benzene‐1,3,5‐tricarboxamide (BTA). The cross‐β motif is an abundant structural element in amyloid fibrils and aggregates of fibril‐forming peptides, including diphenylalanine. The incorporation of topological constraints on one edge of the diphenylalanine fragment limits the number of β‐strands in β‐sheets and leads to the creation of an unconventional offset‐patterned cross‐β structure consisting of short 3×2 parallel β‐sheets stabilized by phenylalanine zippers. In the reported assembly, two patterned cross‐β structures bind parallel arrays of BTA stacks in a superstructure within a single‐molecule‐thick nanoribbon. In addition to a threefold network of hydrogen bonds in the BTA stack, each molecule becomes simultaneously bound by hydrogen bonds from three β‐sheets and four phenylalanine zippers. The diffuse layer of alkyl chains with terminal polar groups prevents the nanoribbons from merging and stabilizes cross‐β‐structure in water. Our results provide a simple approach to the incorporation of novel patterned cross‐β motifs into supramolecular superstructures and shed light on the general mechanism of β‐sheet formation in C3‐symmetric peptide amphiphiles. [ABSTRACT FROM AUTHOR]

The morphology of supramolecular polymer aggregates evolved during normal aging from thin 25-nm-wide nanoribbons into 1-µm-wide nanoribbons and nanotubes thanks to hydrophobic interactions between phenylalanine residues exposed on the edges of nanoribbons. [Display omitted] • Benzene-1,3,5-tricarboxamide decorated with diphenylalanine self-assemble into micrometer-long nanoribbons immediately after dissolution. • Nanoribbons interact laterally via "sticky edges" and gradually merge over the entire length. • After reaching a critical width nanoribbons self-merge, irreversibly forming nanotubes. • Mechanical perturbations cause nanotube fracture and fragmentation similar to analogous inorganic materials. During the aging of supramolecular systems, new stable materials with different morphologies, molecular packing, and hierarchical organization may form from the initial assembly. Understanding the mechanisms and pathways accompanying age-related changes may allow for the controlled synthesis of multiple materials from a single molecule in a nature-inspired manner. Herein, we demonstrate the multi-stage evolution of a single solution of C3-symmetric peptide amphiphile containing diphenylalanine fragment and benzyl-1,3,5-tricarboxamide core. Transmission electron microscopy reveals the rapid formation of 20–40 nm wide nanoribbons in an aqueous solution within 60 s after preparation. The lateral edges of nanoribbons contain solvent-exposed aromatic residues that tend to merge via an unconventional edge-to-edge zipping mechanism, leading to the nanoribbon's growth in width. After reaching a critical width and flexibility, "sticky edges" on the same nanoribbon may merge via a self-zipping mechanism, forming rigid nanotubes. Eventually, mechanical perturbations cause buckling and fracture of nanotubes into shorter nanotubes via flexural or tensile failure. This work reports new evolution pathways in soft 2D assemblies and introduces solution ageing as a promising method to control morphology of peptide amphiphiles. [ABSTRACT FROM AUTHOR]