Macrocycles prepared from lithocholic acid, piperazine and isomeric pyridine dicarboxylic acids and their selective affinities towards sodium and potassium

Two novel macrocycles prepared from lithocholic acid, piperazine and pyridi ne dicarboxylic acids (2,6- and 3,5-isomers), have been characterized by C- 13 NMR and ESI-MS techniques. In case of the pyridine-2,6-dicarboxylate der ivative, the molecular formula of the cycle was C59H87O6N3 (1), while the p yridine-3,5-dicarboxylate derivative (II) was a trimeric structure by molec ular mass when compared with I. Furthermore, cycle I showed a special affin ity towards potassium cation, while II possessed significant proton and sod ium cation recognition properties. (C) 2001 Published by Elsevier Science B .V.