Intramolecularly hydrogen-bonded cavity containing macrocyclic/acyclic aromatic pyridone foldarands as modularly tunable ionophores for selective potentiometric sensing of metal ions

Abstract

Abstract Three kinds of intramolecularly hydrogen-bonded cavity containing macrocyclic and crescent-shaped aromatic pyridone foldarands were evaluated as ionophores for polymeric membrane metal ions selective electrodes. Highly selective potentiometric alkali metal ion (such as K+) and heavy metal ions (for example, Cu2+ and Hg2+) determination could be achieved over their environmentally significant interfering cations, owing to the comfortable cavity surrounded by convergently aligned O atoms whose electron density is significantly higher than that of the O/S atoms in crown/thio-crown ethers, which have been traditionally used as metal ions ionophores. To disclose their comprehensive ion-differentiating profiles provide pragmatic guiding principles for designing other potential ion-selective foldarands, the cation-ionophore complex constants in membrane phase were determined and inspected carefully. Optimizing the membrane composition such as lipophilic additives and plasticizers yielded ISEs displaying superior response to K+, Cu2+ and Hg2+ in a wide pH range with good reversibility and long on-shelf time. The analytical results from the proposed ISEs for target ions detection in artificial groundwater, industrial waste water and bottle water samples demonstrate their potential for real-life applications. These results provide pragmatic guiding principles and shed new light on how new ionophores could be designed to broad the scope of potentiometric sensing.