AG-SELECTIVE LARIAT ETHERS - HIGH-PRESSURE SYNTHESES AND CATION RECOGNITION PROPERTIES( ION)

A new series of lariat ethers have been prepared by a high pressure SN Ar reaction, in which various heteroaromatics are directly connected t o the nitrogens of 12-, 15- and 18-membered aza-crown ethers. Liquid m embrane transport studies demonstrated that lariat ethers having thiaz ole, oxazole, pyrazine and pyridazine rings on their sidearms exhibite d excellent Ag+ ion selectivity. C-13 NMR binding experiments revealed that these lariat ethers selectively formed encapsulated Ag+ complexe s in a different fashion from that of double armed crown ethers. Coope rative action between the heteroaromatic sidearm and the aza-crown rin g afforded unique cation recognition.