Structural Ion Selectivity of Thia Crown Ether Compounds with a Bulky Block Subunit and Their Application as an Ion-Sensing Component for an Ion-Selective Electrode

Abstract

Several 14-membered thia crown ether ionophores having a bulky block subunit were synthesized, and their chemical structures and ion selectivities were examined in detail when these compounds were used as an ion-sensing component of an ion-selective electrode. The ionophores of both cyclic and noncyclic thia ethers exhibited a high selectivity for silver ion (Ag(+)), in which the sulfur atom in the ionophore molecule plays a role as the effective coordination donor site for the silver ion. The best Ag(+)-selective electrode was prepared with the 14-membered thia crown ether having one sulfur atom, three oxygen atoms, and a bulky pinan subunit. The ion selectivity of this electrode for Ag(+) was over 10(4) times that for other metal cations. In the case where the sulfide in the thia ether ionophore was changed to sulfoxide by oxidation, ion selectivity for mercury ion became higher; therefore, the sulfoxide was found to be an effective coordination site for the mercury ion. The ion selectivity features of noncyclic sulfide, sulfoxide, and sulfone were also examined and compared with the results of the cyclic and noncyclic thia ethers.

Coated-Wire Silver Ion-Selective Electrode Based on Silver Complex of Cyclam

“…3 The substitution of sulfur and/or nitrogen atom for the ether oxygen in the coronand ring reduces the affinity of the ligand for alkali and alkaline earth metal ions. Membrane electrodes based on polythia macrocycles were developed by Casabo et al 4 Several aza macrocycles and thia macrocycles [5][6][7][8] have been tested for their use in the fabrication of Cu(II) and Ag(I) ISEs, respectively. However, it seems that no attempts have been made to make use of aza macrocycles for constructing Ag(I) ISEs.…”

Comparative studies of praseodymium(III) selective sensors based on newly synthesized Schiff's bases

“…The ionophore, membrane composition, nature of plasticizer and additive used affect the potential response of PVC membrane [15,[22][23][24] which is the function of praseodymium ion free concentration. The measured potentials were plotted against active concentration of Pr(III) and shown in Figs.…”

Potentiometric Performance of Silver Ion-Selective Electrodes Based on Tridentate Schiff Base Derivatives

“…That is, the ionophore for an ionselective electrode is generally considered such that a complexing ability with a moderate stability constant is necessary. 8 It is difficult to evaluate the performance of the ionophore only by the complexing ability, since the performance of the ionophore is affected complementarily by the characteristics of the membrane solvent and the coexisting salt. Though a further investigation for these ligands should be carried out, the weak complexing ability of Me-PyO3 seemed to cause promising silver-ion selectivity.…”

“…6,7 We found that the synthesized Schiff bases could coordinate with a silver-ion though the two nitrogen atoms in a diagonal line, and show excellent silver ion selectivity, which is comparable to those of acyclic oligoether, polythiacrown eters and acyclic polythia compounds. [8][9][10][11][12][13] However, for pursuing the practicability of a silver ionophore of N,N′-bis(2′-hydroxyimino-1′-phenylpropyleden)-1,3-propanediamine (PHO3), 6 which is most promising in Schiff bases, the following have remained: control of the hydrolysis of PHO3 in a poly(vinyl chloride) (PVC) membrane, and an improvement in the silver ion selectivity. It was proven that the introduction of a substituent with lipophilicity, such as a butyl group, to the side chain of PHO3 was effective to control the hydrolysis in a PVC membrane.…”