Aromatic Oligoamide Foldamers: Towards Secondary Structure-Driven Self-Assembly
(2025)
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- Abstract
- Self-assembly is a powerful strategy for designing large, organized molecular structures. In biology, extensive surface interactions enable self-assembly to achieve high selectivity and precision, producing stable, asymmetric assemblies. Mimicking these extensive surface interactions seen in biological systems could enhance synthetic self-assembly methods, and foldamers are a promising tool for this purpose. Aromatic Oligoamide Foldamers (AOF), known for their high stability, predictable folding, and ability to form multi-stranded helical assemblies, are particularly well-suited for this purpose, as they rely on extensive aromatic surface interactions. These folding molecules could be of interest in designing synthetic assembled systems. This PhD thesis aims to develop a new methodology based on AOF self-assembly, leveraging its capacity to form double helices as a new approach to connect molecular components and ultimately create assembled supramolecular structures. However, before reaching this goal, it is essential to first understand how these intermolecular interactions can be selective with each other in order to develop a set of orthogonal AOF self-assemblies. Chapters 3-5 will focus on studying the selectivity of these intermolecular interactions. Since these self-assemblies rely on extensive aromatic surface complementarity, the first hypothesis is that double helix formation between two different helical diameters AOF should not be favorable and should lead to narcissistic self-sorting. To investigate this, a series of aromatic oligoamides with different diameters will be synthesized and examined in both solid-state and solution to determine their helical diameter and analyze the various existing equilibria. Next, attempts will be made to favor social self-sorting by introducing additional intermolecular interactions. With this, orthogonal AOF self-assemblies will be developed, leading either to narcissistic or social self-sorting. Next, since AOF folding and self-assembly processes are spontaneous in solution, controlling these processes will be the focus of chapter 6. A novel reversible strategy, based on modifying the aromatic surface of AOF building block, 1,8-diazaanthracene, through a reversible [4+2] cycloaddition Diels- Alder reaction, will be introduced. This chemical modification will demonstrate control of AOF folding and self-assembly processes by preventing the proper AOF folding into a helix, ultimately preventing double helix formation. Finally, these double helices will serve as connection points to build larger, supramolecular self-assembled structures. In chapter 7, supramolecular polymers will be developed using crosslinked AOF forming double helices. This chapter will emphasize the use of AOF self-assembly as a promising starting point for constructing supramolecular assemblies.
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Citations
SMAL, L. (2025). Aromatic Oligoamide Foldamers: Towards Secondary Structure-Driven Self-Assembly.