Related Experiment Video
Updated: Jun 12, 2026

Capturing the Interaction Kinetics of an Ion Channel Protein with Small Molecules by the Bio-layer Interferometry Assay
Published on: March 7, 2018
Experimental evidence for the functional relevance of anion-pi interactions
Ryan E Dawson1, Andreas Hennig, Dominik P Weimann
1Department of Organic Chemistry, University of Geneva, Geneva, Switzerland.
Abstract:
Attractive in theory and confirmed to exist, anion-pi interactions have never really been seen at work. To catch them in action, we prepared a collection of monomeric, cyclic and rod-shaped naphthalenediimide transporters. Their ability to exert anion-pi interactions was demonstrated by electrospray tandem mass spectrometry in combination with theoretical calculations. To relate this structural evidence to transport activity in bilayer membranes, affinity and selectivity sequences were recorded. pi-acidification and active-site decrowding increased binding, transport and chloride > bromide > iodide selectivity, and supramolecular organization inverted acetate > nitrate to nitrate > acetate selectivity. We conclude that anion-pi interactions on monomeric surfaces are ideal for chloride recognition, whereas their supramolecular enhancement by pi,pi-interactions appears perfect to target nitrate. Chloride transporters are relevant to treat channelopathies, and nitrate sensors to monitor cellular signaling and cardiovascular diseases. A big impact on organocatalysis can be expected from the stabilization of anionic transition states on chiral pi-acidic surfaces.
Related Concept Videos
Basicity of Aliphatic Amines
To measure the basicity of amines, two conventions are generally used. The first defines Kb as the basicity constant for the deprotonation reaction of water by the amine, as presented in Figure 1. Conventionally, lower Kb indicates higher...
Ionic Association
Basicity of Heterocyclic Aromatic Amines
π Electron Effects on Chemical Shift: Overview
MO Theory and Covalent Bonding
π Electron Effects on Chemical Shift: Aromatic and Antiaromatic Compounds

