Ag+ Ion-selective lariat ethers: high pressure syntheses and cation recognition properties

Abstract

A new series of lariat ethers have been prepared by a high pressure S_NAr reaction, in which various heteroaromatics are directly connected to the nitrogens of 12-, 15- and 18-membered aza-crown ethers. Liquid membrane transport studies demonstrated that lariat ethers having thiazole, oxazole, pyrazine and pyridazine rings on their sidearms exhibited excellent Ag⁺ ion selectivity. ¹³C NMR binding experiments revealed that these lariat ethers selectively formed encapsulated Ag⁺ complexes in a different fashion from that of double armed crown ethers. Cooperative action between the heteroaromatic sidearm and the aza-crown ring afforded unique cation recognition.