Foldaxanes: Rotaxane-like Architectures from Foldamers.

Area of Science:

• Supramolecular Chemistry
• Organic Chemistry
• Materials Science

Background:

• Mechanically interlocked molecules (MIMs) like rotaxanes and catenanes allow control over molecular motion.
• Pseudo-rotaxanes offer reversible assembly but can dissociate.
• Foldaxanes represent a distinct class of rotaxane-like architectures with unique properties.

Purpose of the Study:

• To introduce and explore the unique characteristics of foldaxanes.
• To demonstrate the rational design and synthesis of foldaxanes with controlled assembly.
• To investigate the dynamic behaviors and potential applications of foldaxanes in molecular machines.

Main Methods:

• Design of helically folded aromatic oligoamide hosts and complementary oligo(alkyl carbamate) guests.
• Synthesis of single, double, and poly[n]foldaxanes with specific binding motifs.
• Characterization of foldaxane structures and investigation of their dynamic motions (translation, rotation, dissociation/reassociation).

Main Results:

• Foldaxanes exhibit significant kinetic stability despite reversible assembly.
• Rational design allows for precise matching of helix and rod components.
• Controlled helix handedness and directional molecular motion (translation, rotation, screw-like motion) were achieved.
• Polyfoldaxanes demonstrated sequential assembly and helix-to-helix handedness transmission.

Conclusions:

• Foldaxanes are a versatile class of rotaxane-like architectures with designer structures.
• They enable the orchestration of supramolecular events and molecular motion on defined timescales.
• Foldaxanes hold significant potential for advanced applications in molecular machinery and nanotechnology.