Halogen Bonding Ionophore for Potentiometric Iodide Sensing

Area of Science:

• Supramolecular Chemistry
• Analytical Chemistry
• Chemical Sensing

Background:

• Iodide (I^-) is a crucial micronutrient vital for thyroid hormone synthesis.
• Accurate and rapid quantification of iodide is essential in food and biological matrices.
• Existing methods for iodide detection may lack portability or selectivity.

Purpose of the Study:

• To report the first halogen bonding (XB) tripodal ionophore (XB1) for selective iodide anion sensing.
• To investigate the role of XB interactions in ionophore-analyte binding.
• To develop and evaluate an iodide-selective potentiometric sensor based on XB1.

Main Methods:

• Synthesis and characterization of the XB tripodal ionophore XB1.
• Nuclear Magnetic Resonance (NMR) spectroscopy to study binding interactions with iodide.
• Fabrication and electrochemical evaluation of iodide-selective electrodes using XB1 and the phase boundary model.

Main Results:

• XB1 demonstrated selective binding with iodide, primarily driven by halogen bonding interactions.
• The developed iodide-selective electrode showed a near-Nernstian response (-51.9 mV/decade) over a wide dynamic range (10^-1 to 10^-6 M).
• The sensor exhibited anti-Hofmeister selectivity for iodide over thiocyanate, enabling *in situ* determination in complex samples.

Conclusions:

• Halogen bonding is a viable supramolecular interaction for designing selective anion sensors.
• The XB1 ionophore enables the development of robust and selective potentiometric sensors for iodide.
• This work advances the field of anion sensing through the application of XB interactions.