π-Electronic ions with appropriate geometries and peripheral substituents would provide assemblies through interactions between building subunits, resulting in fascinating electronic properties. Diverse ion-responsive π-electronic systems and π-electronic ions were prepared, affording dimension-controlled ion-pairing assemblies as crystals, supramolecular gels, and thermotropic liquid crystals (LCs).[1] Structures and properties of the assemblies can be controlled by the combined negatively and positively charged species in the assemblies. Highly ordered arrangement of charged species, not only the ion complexes but also charged π-systems, has been found to be a key factor to exhibit the enhanced performance as fascinating electronic materials.[2] Recently, ion pairs based on porphyrin-Au^III complexes as π-electronic cations were prepared with the combination of various anions including a π-electronic anion. Porphyrin-Au^III complexes possessing aliphatic alkyl chains formed dimension-controlled ion-pairing assemblies as thermotropic liquid crystals, whose ionic components were highly organized by electrostatic and π–π stacking interactions.[3,4]

References

1. A recent review: Haketa, Y.; Maeda, H. Chem. Commun. 2017, 53, 2895.
2. As an example of an anionic porphyrin: Sasano, Y.; Yasuda, N.; Maeda, H. Dalton Trans. 2017, 46, 8924.
3. Haketa, H.; Bando, Y.; Yasuda, N.; Hisaki, I.; Maeda, H. to be submitted.
4. Sasano, Y.; Yasuda, N.; Maeda, H. to be submitted.