Halogen bonding and hydrogen bonding fluorescent anion sensing at the solid-liquid interface

Area of Science:

• Supramolecular Chemistry
• Analytical Chemistry
• Materials Science

Background:

• Halogen bonding (XB) is a key interaction for anion recognition in solution.
• Translating XB anion sensing to practical devices, especially in water, requires material integration.
• Current XB sensor applications often face limitations in water and reusability.

Purpose of the Study:

• To develop the first halogen bonding monolayer architecture for anion detection at the solid-liquid interface.
• To enable sensor re-use and anion detection in both organic solvents and pure water.
• To compare the performance of XB interfaces with solution-phase XB receptors and hydrogen bonding (HB) congeners.

Main Methods:

• Covalent immobilization of a BODIPY-bis(iodo)triazole receptor onto glass slides via amide bond formation.
• Development of a XB monolayer architecture on a solid support.
• Fluorescence-based detection of anions at the solid-liquid interface.
• Comparative analysis of XB and HB interfaces in solution and on surfaces.

Main Results:

• Successful creation of a reusable XB monolayer sensor for anion detection.
• Demonstrated anion sensing capability in both organic solvents and pure water.
• Surface immobilization largely retained fluorescence sensing performance compared to solution-phase receptors.
• The XB interface significantly outperformed the HB interface in both binding strength and signal response.

Conclusions:

• The developed XB monolayer architecture enables robust anion sensing at the solid-liquid interface.
• This approach facilitates sensor re-use and overcomes solubility issues common in solution-phase sensing.
• Findings support the translation of solution-phase XB anion receptors into practical molecular film sensing formats.