Unanticipated Emergence of the Photo-Switchable Cs⁺-Selective Ion Channels From One-Dimensional 18-Crown-6 Arrays

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Ion Transport

Background:

• Artificial ion channels are crucial for understanding biological processes and developing new technologies.
• Designing light-responsive ion channels offers precise control over ion transport.
• The 18-crown-6 motif is known for ion binding but not extensively explored for selective cesium transport.

Purpose of the Study:

• To construct the first photo-regulated artificial cesium ion channel.
• To investigate the Cs+ transport capabilities of azobenzene-functionalized 18-crown-6 units.
• To demonstrate light-induced reversible control over cesium ion transport.

Main Methods:

• Small-molecule self-assembly strategy to create the artificial ion channel.
• Incorporation of azobenzene-modified 18-crown-6 units, amino acid residues, and side chains.
• Photoisomerization of azobenzene units using UV and visible light to control channel activity.

Main Results:

• Successfully constructed a photo-regulated artificial cesium ion channel.
• Identified specific trans-isomers (t-F and t-L) with high Cs+ transport rates.
• Demonstrated significant ion selectivity for Cs+ over K+ and Na+.
• Achieved reversible light-controlled opening and closing of the channel, showing a 4-fold difference in activity.

Conclusions:

• The 18-crown-6 motif can be rationally engineered for selective Cs+ transport.
• This work pioneers the development of photo-regulated artificial ion channels for cesium.
• The findings broaden potential applications in ion transport systems and separation technologies.