The influence of amine functionalities on anion binding in polyamide-containing macrocycles.

Mixed amide/amine macrocyclic anion hosts of varying sizes and with different amine substituents have been synthesized and characterized. Host 2, containing a 28-membered ring and secondary amines, has shown selective binding for HSO(4)(-) over other oxo anions and halides in DMSO-d(6) using NMR titrations. Crystal structures of SO(4)(2-), HPO(4)(2-), H(2)PO(4)(-), and H(2)P(2)O(7)(2-) with the 28-membered ring hosts indicate different macrocyclic conformations depending on the N-substituent. Anion affinities appear to be correlated with macrocycle conformation.