Electronic Effects on the Selectivity of Mercuracarborand Ionophores in Ion‐Selective Electrodes and Membrane Formulations for Their Use in High Protein Concentration Environments

Abstract

AbstractIon‐selective electrodes based on the ionophore [9]mercuracarborand‐3 (MC3) have been demonstrated in the past to be highly selective for the chloride ion. This ionophore is macrocyclic and possesses Lewis acidic mercury centers, both of which result in enhanced ionophore binding to spherical anions. Like their charge‐reverse analogs, crown ethers, mercuracarborands offer the possibility to tune binding selectivity through changes in cavity size and/or via the incorporation of functional groups onto the cavity framework. Indeed, this article outlines the effect on ionophore selectivity that results from the addition of methyl groups to the MC3's carborane cages. Our results indicate that this simple functionalization leads to significant changes in selectivity that can be attributed to electronic effects. Furthermore, since MC3‐based electrodes and optodes have previously shown sufficient selectivities to perform physiological analysis, the effect of protein backgrounds and mild exposure to human whole blood on the response of mercuracarborand ISEs is also reported.