Stereodefined Improbable [3]Rotaxane by Post-Interlocking Ring Editing.

Area of Science:

• Supramolecular Chemistry
• Organic Synthesis
• Materials Science

Background:

• Synthesizing complex mechanically interlocked molecules (MIMs) like improbable rotaxanes is challenging due to statistical limitations and lack of recognition between components.
• Racemic or stereolabile ring components further complicate MIM synthesis, leading to undesired stereoisomeric mixtures.

Purpose of the Study:

• To develop a post-interlocking ring editing strategy for creating stereodefined improbable rotaxanes.
• To overcome the challenges associated with synthesizing statistically disfavored MIM architectures.

Main Methods:

• Assembly of nanotubular covalent organic pillar (COP-1) from chiral, stereolabile macrocycles via dynamic covalent imine condensation.
• Chiral resolution of the preorganized COP-1 duplex to enable ring-axle recognition.
• Threading-stoppering protocol to form enantiopure [2]rotaxanes, followed by imine hydrolysis to edit the COP-1 duplex into parent macrocycles, yielding improbable [3]rotaxanes.

Main Results:

• Demonstrated a strategy to overcome statistical limitations in synthesizing improbable rotaxanes.
• Achieved enantiopure [3]rotaxanes by post-interlocking ring editing, preserving stereochemical integrity.
• The mechanical bond successfully maintained the inherited stereochemistry without enantiopurity loss.

Conclusions:

• The post-interlocking ring editing strategy provides a programmable route to stereodefined improbable rotaxanes.
• This approach circumvents direct multiring interlocking limitations for complex MIM synthesis.
• Established design principles for constructing higher-order chiral mechanically interlocked architectures.