Macrocyclic Polyamines as Specific Receptors for Tricarboxylate-Cycle Anions

Article abstract of DOI:10.1021/ja00401a022

Macrocyclic penta- and hexaamines specifically interact at neutral pH with polycarboxylates having the two CO2^-s at short distances such as succinate, maleate, citrate, malonate, and malate, but they are inert toward the other dicarboxylates fumarate, aspartate or glutarate and also toward the monocarboxylates acetate or lactate.Thus, they are selective receptors for most of the tricarboxylic acid-cycle intermediates and their analogues.The polarographic method showed 1:1 ion-pair association between the macrocyclic polyamines in the triprotonated form and the polycarboxylates in the dianion form ( or the trianion form with citrate) at neutral pH.When the association constants for various membered cyclic and relevant acyclic ligand systems are compared, the macrocyclic effect and the ring size effect are demonstrated.The fact that the ion-pair formation depends on the structural features of both polyamines and carboxylates indicates a steric controlled interaction.The structural relevance is inferred to the receptor sites of biological transporters for the tricarboxylate-cycle polyanions.