STRIKINGLY SELECTIVE IONOPHORIC PROPERTIES OF RIGID CYCLOPHANES HAVING A SMALL NUMBER OF LIGATING SITES

Ionophores 4 and 5 having two acetate groups and two pyridyl groups, r espectively, on the aromatic rings as well as oligo(oxyethylene) linke d compounds 7a-c were prepared by Williamson ether synthesis between t he corresponding halides or ditosylates and dihydroxycyclophane, which was prepared by Birch reduction of the three-bridged dimethoxycycloph ane, followed by cleavage of the methoxyl groups. On the liquid-liquid extraction, 4 and 5 showed high affinities toward K+ ion and Ag+ ion, respectively. Compounds 7b and c effectively extracted large alkali m etal cations.