Origin of the High Affinity and Selectivity of Novel Receptors for NH₄⁺ over K⁺: Charged Hydrogen Bonds vs Cation−π Interaction

Abstract

[structure: see text]Given the recent report of a novel pyrazole receptor exhibiting a high selectivity for NH4+ over K+, it would be interesting to investigate the origin of this selectivity and affinity so that better receptors could be designed. On the basis of extensive theoretical studies, we conclude that the origin arises from a subtle interplay of charged H-bonds and cation-pi interactions. The approach employed herein would be very useful in the rational design of novel functional molecular systems.