NEW CALIX[4]ARENE DIBENZOCROWN ETHERS FOR SELECTIVE SENSING OF CESIUMION IN AN AQUEOUS ENVIRONMENT

1,3-Dialkoxycalix[4]arene dibenzocrown ethers (6-9) were successfully synthesized in the fixed 1,3-alternate conformation, with greater than 90% yields by reaction of the corresponding 1,3-dialkoxycalix[4]arene s 2-5 with dibenzodimesylate 13 in acetonitrile as a solvent in the pr esence of cesium carbonate as a base. In view of the cyclization yield , dimesylate is better than dibenzoditosylate. Because of an unusual A B pattern in the H-1 NMR spectrum for compound 9, it is suggested that the conformational structure of 1,3-diallyloxy calix[4]arene dibenzoc rown ether is less flexible than that of usual 1,3-alternate calixcrow n ether, probably due to steric effects of two allyl groups. Complexat ion of the corresponding calix[4]arene ethers 6-9 to alkali metal ions using the single-flux method through a bulk liquid membrane system wa s found to give high cesium selectivity. (C) 1998 Academic Press.