文摘
Several 14-membered thia crown ether ionophores havinga bulky block subunit were synthesized, and their chemical structures and ion selectivities were examined indetailwhen these compounds were used as an ion-sensingcomponent of an ion-selective electrode. Theionophoresof both cyclic and noncyclic thia ethers exhibited a highselectivity for silver ion (Ag+), in which the sulfuratomin the ionophore molecule plays a role as the effectivecoordination donor site for the silver ion. The bestAg+-selective electrode was prepared with the 14-memberedthia crown ether having one sulfur atom, three oxygenatoms, and a bulky pinan subunit. The ion selectivityofthis electrode for Ag+ was over 104 timesthat for othermetal cations. In the case where the sulfide in thethiaether ionophore was changed to sulfoxide by oxidation,ion selectivity for mercury ion became higher; therefore,the sulfoxide was found to be an effective coordinationsite for the mercury ion. The ion selectivity featuresofnoncyclic sulfide, sulfoxide, and sulfone were also examined and compared with the results of the cyclic andnoncyclic thia ethers.