A Self‐Assembled Foldamer Capsule: Combining Single and Double Helical Segments in One Aromatic Amide Sequence

Abstract

In this manuscript, we present supramolecular capsules based on a new design relying on both self-assembly and folding of oligomeric strands. We have designed an aromatic amide foldamer in which each monomer encodes three levels of information: a specific cavity size, recognition groups for guest binding, and a propensity to adopt a single or a double helical motif. Thus, a tetradecameric sequence based on four different monomers was encoded so that a wide double helical segment resulting from the hybridization of two strands creates a cavity in which guests, such as 1,10-decanediol, can be bound. Additionally two narrow single helical segments form end-caps and isolate the guest from the solvent. The design, synthesis, solid-state and solution-state characterization of duplex formation and guest binding are presented.

Size Dependence of Nanoscale Confinement on Chiral Transformation

“…Confinement of molecules inside nanoscale pores has become an important method of fabricating new structures and exploiting dynamics that do not occur in bulk systems, such as enhanced catalysis, [33][34][35] and improved stability of the native structure of proteins, [36][37][38] new mechanisms of protein and polymer dynamics, [39][40][41][42][43] excellent on-off gating, and the ability to control the pumping action of permeation behavior. [44][45][46] However, the effect of confinement on the conformational transitions is still far from understood.…”

Structural Tuning and Conformational Stability of Aromatic Oligoamide Foldamers

“…The properties of aromatic foldamers, such as the flexibility, water solubility and overall conformation as well as diameter and chirality of the helix, have been tuned by the addition of different types of monomers. The most common trend has been the addition of aliphatic monomers to make heterogeneous foldamers but also foldamers with different aromatic sequences have been made to create, for example, foldamer capsules and selective receptors . The pyridine‐2,6‐dicarboxamide unit is one of the structural motifs used as a turn unit to impose helical conformations on oligomers .…”

Increasing the Size of an Aromatic Helical Foldamer Cavity by Strand Intercalation

“…Indeed, each monomer makes a predictable contribution to strand curvature, which determines cavity size, and to the interior array of functional groups, which contributes to guest binding. Over the last decade, a variety of foldamer receptors have been described on the basis of various designs, including open-ended helices or shaped-persistent macrocycles that may bind to small [2] or dumbbell-shaped [3] guests, closed helical capsules terminated by narrow helical segments, [4,5] double-helical capsules, [4,6] and sequences with two enantiomeric binding sites. [7] Folding is a dynamic process that may be influenced by external stimuli.…”