Ion-pairing assemblies of photoresponsive cations and an interlocked [2 + 1]-type π-system-anion complex

Abstract

Abstract Ion-pairing assemblies are formed by the interionic interactions, and the structures and properties of the assemblies can be controlled by the combined negatively and positively charged species in the assemblies. In this study, a negatively charged π-electronic system as the building block for ion-pairing assemblies, arylethynyl-substituted dipyrrolyldiketone BF2 complex was prepared via anion binding; this system provided interlocked [2 + 1]- and planar [1 + 1]-type anion complexes. As a counteranion, the photoresponsive azobenzene moiety was used as a cationic species for ion-pairing assemblies. The single-crystal X-ray structure of the ion pair of the azobenzene-appended tetraalkylammonium cation and [2 + 1]-type π-system-Br– complex showed the formation of a completely charge-segregated assembly containing potential photoresponsive units.