Arylpyrrolyldiketone Boron Complexes Exhibiting Various Anion-Binding Modes Based on Dynamic Conformation Changes.

Arylpyrrolyldiketone boron complexes as anion-responsive π-electronic molecules were synthesized by Claisen condensations of acetylpyrrole and corresponding aryl esters. The synthesized π-electronic molecules exhibited anion-binding behavior with various binding modes including pyrrole-inverted and non-inverted [1+1]-type anion complexes as well as [2+1]-type complexes owing to the presence of only a single pyrrole ring. Furthermore, solid-state ion-pairing assemblies, comprising receptor-anion complexes and countercations, were constructed based on fairly planar [2+1]-type complexes.