Quantitative Evaluation of Anion–π Interactions in Solution

Abstract

Anions included: A series of meso-tetraaryl calix[4]pyrrole receptors have been used as a model system to quantify chloride–π interactions in solution (see picture; green balls are chloride ions). The free energy values are generally indicative of a repulsive interaction; their magnitude depends on the substituent on the aromatic ring.