Catenation of calixarene annulus

Area of Science:

• Supramolecular Chemistry
• Organic Synthesis

Background:

• Calixarenes are macrocyclic compounds with unique host-guest properties.
• Catenanes are mechanically interlocked molecules consisting of two or more macrocycles linked like a chain.
• Synthesizing complex catenanes, especially stereoisomers, remains a significant challenge in supramolecular chemistry.

Purpose of the Study:

• To develop a novel method for synthesizing through-the-annulus-catenated calixarenes.
• To achieve the first stereoprogrammed synthesis of an oriented calix[2]catenane isomer.

Main Methods:

• Utilizing the "superweak anion" approach to facilitate the threading of functionalized dialkylammonium axles into the calixarene cavity.
• Employing a directional alkylbenzylammonium axle for macrocyclization to control the orientation of the catenane.

Main Results:

• Successfully synthesized through-the-annulus-catenated calixarenes for the first time.
• Achieved the first stereoprogrammed synthesis of an oriented calix[2]catenane, a specific orientational isomer.
• Demonstrated the efficacy of the "superweak anion" method in constructing complex mechanically interlocked molecules.

Conclusions:

• The "superweak anion" approach is a powerful tool for the synthesis of threaded calixarene structures.
• Stereoprogrammed synthesis of catenane isomers is achievable, opening new avenues for designing sophisticated molecular architectures.
• This work advances the field of mechanically interlocked molecules and their synthetic accessibility.