A Hollow Foldecture with Truncated Trigonal Bipyramid Shape from the Self‐Assembly of an 11‐Helical Foldamer

Directing the Self-Assembly of Aromatic Foldamer Helices using Acridine Appendages and Metal Coordination

Folded molecules provide complex interaction interfaces amenable to sophisticated self-assembly motifs. Because of their high conformational stability, aromatic foldamers constitute suitable candidates for the rational elaboration of self-assembled architectures. Several multiturn helical aromatic oligoamides have been synthesized that possess arrays of acridine appendages pointing in one or two directions. The acridine units were shown to direct self-assembly in the solid state via aromatic stacking leading to recurrent helix-helix association patterns under the form of discrete dimers or extended arrays. In the presence of Pd(II), metal coordination of the acridine units overwhelms other forces and generates new metal-mediated multihelical self-assemblies, including macrocycles. These observations demonstrate simple access to different types of foldamer-containing architectures, ranging from discrete objects to 1D and, by extension, 2D and 3D arrays.

Advances in hybrid peptide-based self-assembly systems and their applications

Self-assembly of peptides demonstrates a great potential for designing highly ordered, finely tailored supramolecular arrangements enriched with high specificity, improved efficacy and biological activity. Along with natural peptides, hybrid peptide systems composed of natural and chemically diverse unnatural amino acids have been used in various fields, including drug delivery, wound healing, potent inhibition of diseases, and prevention of biomaterial related diseases to name a few. In this review, we provide a brief outline of various methods that have been utilized for obtaining fascinating structures that create an avenue to reproduce a range of functions resulting from these folds. An overview of different self-assembled structures as well as their applications will also be provided. We believe that this review is very relevant to the current scenario and will cover conformations of hybrid peptides and resulting self-assemblies from the late 20^th century through 2022. This review aims to be a comprehensive and reliable account of the hybrid peptide-based self-assembly owing to its enormous influence in understanding and mimicking biological processes.

Directing Foldamer Self-Assembly with a Cyclopropanoyl Cap

The rational design of self-assembling organic materials is extremely challenging due to the difficulty in precisely predicting solid-state architectures from first principles, especially if synthons are conformationally flexible. A tractable model system to study self-assembly was constructed by appending cyclopropanoyl caps to the N termini of helical α/β-peptide foldamers, designed to form both N-H⋅⋅⋅O and C^α -H⋅⋅⋅O hydrogen bonds, which then rapidly self-assembled to form foldectures (foldamer architectures). Through a combined analytical and computational investigation, cyclopropanoyl capping was observed to markedly enhance self-assembly in recalcitrant substrates and direct the formation of a single intermolecular N-H⋅⋅⋅O/C^α -H⋅⋅⋅O bonding motif in single crystals, regardless of peptide sequence or foldamer conformation. In contrast to previous studies, foldamer constituents of single crystals and foldectures assumed different secondary structures and different molecular packing modes, despite a conserved N-H⋅⋅⋅O/C^α -H⋅⋅⋅O bonding motif. DFT calculations validated the experimental results by showing that the N-H⋅⋅⋅O/C^α -H⋅⋅⋅O interaction created by the cap was sufficiently attractive to influence self-assembly. This versatile strategy to harness secondary noncovalent interactions in the rational design of self-assembling organic materials will allow for the exploration of new substrates and speed up the development of novel applications within this increasingly important class of materials.