Four calixarene dibenzocrown ether compounds have been prepared and evaluated as Cs+-selective ligands in solvent polymeric membrane electrodes. The ionophores include 25,27-bis(1-propyloxy)calixarene dibenzocrown-6 1, 25,27-bis(1-alkyloxy)calixarene dibenzocrown-7s 2 and 3, and 25,27-bis(1- propyloxy)calixarene dibenzocrown-8 4. For an ion-selective electrode (ISE) based on 1, the linear response concentration range is 1 x 10-1 to 1 x 10-6 M of Cs+. Potentiometric selectivities of ISEs based on 1-4 for Cs+ over other alkali metal cations, alkaline earth metal cations, and NH4/+ have been assessed. For 1-ISE, a remarkably high Cs+/Na+ selectivity was observed, the selectivity coefficient (K(Cs,Na/Pot)) being ca. 10-5. As the size of crown ether ring is enlarged from crown-6 (1) to crown-7 (2 and 3) to crown-8 (4), the Cs+ selectivity over other alkali metal cations, such as Na+ and K+, is reduced successively. Effects of membrane composition and pH in the aqueous solution upon the electrode properties are also discussed.
- Calixarene dibenzocrown ethers
- Cesium-selective ionophore
- Poly(vinyl chloride) membrane
ASJC Scopus subject areas
- Analytical Chemistry