Flipping the switch on chloride concentrations with a light-active foldamer.

Area of Science:

• Supramolecular Chemistry
• Photochemistry
• Materials Science

Background:

• Chloride ions play crucial roles in biological and chemical systems.
• Controlling ion concentrations with external stimuli remains a significant challenge.
• Developing light-responsive molecular systems offers precise control mechanisms.

Purpose of the Study:

• To design and synthesize a bioinspired molecular system for light-triggered chloride ion release and reuptake.
• To investigate the mechanism of light-induced conformational changes in a foldamer affecting ion binding.
• To demonstrate the practical application of this system in controlling electrolyte conductivity.

Main Methods:

• Synthesis of a chiral aryl-triazole foldamer functionalized with azobenzene end groups.
• Photoisomerization studies of the foldamer using UV light, inducing conformational changes.
• Binding affinity measurements (equilibrium dissociation constant, K) of the foldamer for chloride ions in nonaqueous solutions.
• Conductivity measurements of electrolyte solutions to demonstrate light-induced ion concentration control.

Main Results:

• A novel foldamer was synthesized, capable of binding chloride ions within a defined pocket.
• UV light induced photoisomerization of azobenzene groups, leading to foldamer unfolding and chloride release.
• Chloride binding affinity decreased approximately 10-fold upon UV light exposure (from K = 3000 M⁻¹).
• The system demonstrated reversible control of electrolyte conductivity by light-induced ion release and reuptake.

Conclusions:

• A light-responsive supramolecular system was successfully developed for precise control of chloride ions.
• The bioinspired foldamer provides a mechanism for wavelength-dependent ion modulation.
• This technology offers potential applications in light-controlled electrolytes and molecular switches.