Halogen Bonding Ionophore for Potentiometric Iodide Sensing

Iodide (I–) is an essential micronutrient for thyroid function. Hence, rapid and portable sensing is important for I– quantification in food and biological samples. Herein, we report the first example of a halogen bonding (XB) tripodal ionophore (XB1) which is selective for the I– anion. NMR binding studies of XB1 and its H-triazole analog HB2 with I– demonstrated the dominant influence of XB interactions between the ionophore and the I– analyte. The phase boundary model was applied to formulate iodide-selective electrodes with the ionophore XB1. The optimal electrode exhibited a near-Nernstian response of −51.9 mV per decade within a large dynamic range (10–1 to 10–6 M) and notably anti-Hofmeister selectivity for I– over thiocyanate (SCN–), enabling the in situ determination of I– in complex samples. This work establishes XB as a viable supramolecular interaction in the potentiometric sensing of anions.