A negatively charged pi-electronic system was prepared by the complexation of a dipyrrolyldiketone BF2 complex as an anion receptor with a trialkyl-substituted azobenzene carboxylate. The bulk-state properties and photo-responsive behaviors of the azobenzene carboxylate in the ion-pairing form were controlled by complexation with the receptor molecule. The formation of receptor-carboxylate complexes was found to modulate the sizes, shapes, and electronic states of the anionic pi-electronic systems, exhibiting the potential to form a variety of ion-pairing assemblies.