Triazolophanes: A New Class of Halide-Selective Ionophores for Potentiometric Sensors

Triazolophanes, cyclic compounds containing 1,2,3-triazole units, are a new class of host molecules that demonstrate strong interactions with halides. These molecules are designed with a preorganized cavity that interacts through hydrogen bonding with spherical anions, such as chloride and bromide. We have explored the use of one such triazolophane as a halide-selective ionophore in poly(vinyl chloride) (PVC) membrane electrodes. Different membrane compositions were evaluated to identify concentrations of the ionophore, plasticizer, and lipophilic additive that give rise to the best chloride and bromide selectivity. The lipophilicity of the plasticizer was found to have a great impact on the electrode response. Additionally, the concentration of the lipophilic additive was found to be critical for optimal response. The utility of a triazolophane-based electrode was demonstrated by quantification of bromide in horse serum samples.