Design, synthesis and cation-binding properties of novel adamantane- and 2-oxaadamantane-containing crown ethers

摘要

The synthesis of a series of adamantane- and 2-oxaadamantane-functionalized crown ethers 1-7 is described. Alkali metal picrate extraction profiles have been determined for these novel ionophores. The ability of crown ethers 1-7 to extract the alkali metal picrates was compared with that of benzo-15-crown-5 and 18-crown-6. Also, Na+- and K+-transport, the ability of ionophores 1-3 to transport Na+- and K+ across a bulk liquid membrane was measured. The results of alkali metal cation extraction experiments showed that the complexation properties of crown ethers 1 and 2 are comparable to that of benzo-15-crown-5 and 18-crown-6, respectively. Crown ether 3 showed enhanced extractability for all cations but lower selectivity compared to 18-crown-6. However, adamantano-crown ethers 4-7 showed almost negligible extraction capability toward any of the alkali cations. The observed differences among the complexation abilities of the ionophores 1-3 and 4-7 are rationalized on the basis of the results of a molecular modeling study of their corresponding K+ complexes. (C) 2001 Elsevier Science Ltd. All rights reserved. [References: 29]