Redox-Responsive Halogen Bonding as a Highly Selective Interaction for Electrochemical Separations.

Area of Science:

• Materials Science
• Electrochemistry
• Supramolecular Chemistry

Background:

• Selective electrochemical separations are crucial for various applications.
• Current methods often rely solely on electrostatic interactions.
• Expanding separation mechanisms using noncovalent interactions is highly desirable.

Purpose of the Study:

• To explore redox-responsive halogen bonding (XB) for selective electrosorption in nonaqueous media.
• To design and evaluate a novel redox-active XB donor polymer for electrochemically switchable ion binding.
• To investigate the mechanism of redox-mediated enhancement of halogen bonding.

Main Methods:

• Synthesis and characterization of poly(5-iodo-4-ferrocenyl-1-(4-vinylbenzyl)-1H-1,2,3-triazole) (P(FcTS-I)).
• Electrochemical experiments to assess ion binding and release.
• Spectroscopic analysis and Density Functional Theory (DFT) calculations for mechanistic insights.

Main Results:

• The P(FcTS-I) polymer demonstrated electrochemically switchable binding and release of organic and inorganic ions.
• Oxidation of the ferrocene redox center significantly enhanced halogen bonding and ion selectivity.
• Selective uptake of chloride, bisulfate, and benzenesulfonate was observed, outperforming controls.
• DFT calculations provided molecular-level understanding of σ-hole amplification and selectivity modulation.

Conclusions:

• Redox-responsive halogen bonding is a viable strategy for selective electrosorption.
• The designed polymer offers a new platform for redox-mediated electrochemical separations.
• This approach broadens the scope of noncovalent interactions in separation science.