Cation binding properties of alkyl calixaryl derivatives. A new family of molecular receptors

Stability constants of the complexes of a lkali cations, Ag+ and T1+, with tetrameric and hexameric calixarenes functionalized on the phenolic oxygens by ester or ketonic groups are reported, in methanol and/or acetonitrile. Four tetramers were investigated (ethylacetate, methylketone, t-butylketone and phenylketone) and one hexamer (ethyl- acetate). Their complexation power is comparable with t hat of DB18C6, but weaker than t hose of cryptands 221 and 222. The remarkable comple- xation selectivities are discussed in terms of the structural features of the free receptors and related to the phase-transfer properties. The ionophoric properties are consistent with the magnitude of the stability constants and the complexation selectivities.