Naphthocage: A Flexible yet Extremely Strong Binder for Singly Charged Organic Cations

Area of Science:

• Supramolecular Chemistry
• Materials Science

Background:

• Development of novel host molecules for selective ion binding is crucial.
• Organic cations play vital roles in biological and chemical systems.
• Stimuli-responsive materials require precisely controlled molecular interactions.

Purpose of the Study:

• To synthesize and characterize a flexible naphthol-based cage (naphthocage).
• To investigate the binding properties of the naphthocage towards singly charged organic cations.
• To explore the potential applications of the naphthocage in ion-selective electrodes and stimuli-responsive materials.

Main Methods:

• Synthesis of the naphthol-based cage.
• Binding affinity studies using equilibrium analysis (Ka).
• Fabrication and electrochemical testing of ion-selective electrodes.
• Electrochemical switching of the naphthocage-ferrocenium complex.

Main Results:

• The naphthocage exhibits a self-inclusion conformation in its free state.
• It demonstrates extremely strong binding of singly charged organic cations (Ka > 10^7 M^-1).
• Ion-selective electrodes incorporating the naphthocage show a super-Nernstian response to acetylcholine.
• A highly stable complex (Ka = 10^10 M^-1) between ferrocenium and naphthocage can be electrochemically switched.

Conclusions:

• The naphthocage is a highly effective host for organic cations.
• Its properties are suitable for developing advanced ion-selective sensors.
• The electrochemical switchability opens avenues for creating novel stimuli-responsive materials.