Specific Ag+ ion binding and transport properties of ‘tripod’ type open-chain cryptands

Abstract

Tripod-type host molecules have shown new and characteristic cation binding and transport properties especially for Ag⁺ ion; they have a flexible open-chain skeleton as well as cryptand-like geometry. ¹H N.m.r. and binding studies have shown that the Ag⁺ ion is completely enveloped by the tripod molecule and, in consequence, barely exchanged with K⁺ and other alkali-metal cations. Such three-dimensional complexation, although similar to that of related double armed crown ethers and cryptands, because of its flexible nature, offers unique and specific transport of Ag⁺ ion.