We desinged seven neutral carriers for hydrophilic anion sensors: four compounds containing one thiourea group and dendritic benzyl ether derivatives, two compounds containing three or four thiourea groups, and a cyclic compound containing three thiourea groups. The association constants with dihydrogen phosphate ion for these thiourea derivatives were determined in organic solvents. The compounds exhibited high association constants with dihydrogen phosphate ion. When these compounds were used as neutral carriers of ion-selective electrodes (ISEs) for phosphate ion, the slopes of the EMF responses were very small in all cases. The ISEs showed better EMF responses for sulfate ion than for phosphate ion. Especially in the case that dendritic and cyclic derivatives containing three thiourea groups were used as neutral carriers, the ISEs exhibited excellent EMF responses for sulfate ion and anion selectivities.
- Anion-selective electrodes
- Dendritic and cyclic thiourea derivatives
- Neutral carriers
- Sulfate ion