CONFORMATIONAL STUDY OF AMINOCALIXARENES

Chiral calix[4]arenes bearing (R) - (+) or S - (-) (methoxymethyl)pyrrolidin groups (MMP) on the upper ring are synthesized. The conformation is studied by 2D H-1 NMR and by High Temperature Annealed Molecular Dynamics Simulations. A new conformation due to the hydrogen bond between the OH phenolic group and the oxygen atom of the methoxy group is found. These calixarenes exhibit circular dichroism with split Cotton effects as a result of exciton chirality induction. The optical activity is in agreement with the conformation studied by MD simulations which indicate that the MMP groups ate twisted forming, with the aromatic nucleus, the beginning of an helix.