(Invited) Switchable Electron Transfer Reactivity in Phthalocyanine Sc3n@C80 Supramolecular Ensembles

Abstract

Phthalocyanines (Pcs) are planar, two-dimensional aromatic pophyrinoids which possess outstanding structural, optical and electrical properties as well as stability that render them perfect building blocks for the incorporation into multifunctional materials. Similarly, Ih -Sc3N@C80 fullerene – the most abundant member of the fullerenes family after C60 and C70 – in addition to have excellent electron-accepting properties, provides conditions for an extra stabilization of charge-separated states due to the presence of the internal Sc3N species. This makes Ih -Sc3N@C80 an ideal molecular partner for photo- and electroactive molecular systems such as Pcs. Although several reports have appeared on the preparation of covalent Sc3N@Ih-C80 ensembles, there is no use of Ih -Sc3N@C80 for the preparation of non-covalent assemblies. In this context, plenty of supramolecular systems arranged via coordination interactions have been successfully demonstrated for Pc-C60 supramolecular dimers and trimers. Low accessability of non-covalent supramolecular systems with Ih -Sc3N@C80 is mainly caused by the more sophisticated synthesis and purification of the corresponding fullerene derivatives. Herein, we report a novel example of donor-acceptor Pc/Ih -Sc3N@C80 supramolecular dimers assembled via metal-ligand coordination interactions between Zn(II)Pcs and pyridil-substituted Ih -Sc3N@C80 or C60 fullerene. Photophysical (ground- and excited state) and electrochemical studies on these ensembles showed that depending on the electron-donor or electron-acceptor character of the ZnPcs, a switchable electron transfer reactivity occurs in the case of the Ih -Sc3N@C80 supramolecular systems, revealing the ability for this endohedral metallofullerene to behave either as electron donor or electron acceptor unit.