Complexation of 5-aminovaleric acid zwitterions in aqueous/methanol solution by heterotopic tri-cationic receptors.

Heterotopic tri-cationic receptors based on 4,10,16-triaza-18-crown-6 are capable of efficient and selective binding of the zwitterionic form of 5-aminovaleric acid (5-AVA) in aqueous/methanol solution. The cooperative participation of both cation and anion binding domains of this receptor in 5-AVA complexation was established by H NMR experiments and DFT calculations. Heterotopic receptors and fluorescein were used for the preparation of indicator displacement assay and this assembly was applied to selective optical sensing of 5-aminovaleric acid.

A non-multimacrocyclic heteroditopic receptor that cooperatively binds and effectively extracts KAcO salt.

Prepared in only three synthetic steps, a non-multimacrocyclic heteroditopic receptor binds potassium salts of halides and carboxylates with unusually high cooperativity, suggesting salt binding as associated ion-pairs. Unprecedented extraction of highly hydrophilic KAcO salt from water to organic solution is also demonstrated.