Stabilizing Ion and Radical Ion Pair States in a Paramagnetic Endohedral Metallofullerene/π-Extended Tetrathiafulvalene Conjugate

Electron donor–acceptor conjugates of paramagnetic endohedral metallofullerenes and π-extended tetrathiafulvalene (exTTF) were synthesized, characterized, and probed with respect to intramolecular electron transfer involving paramagnetic fullerenes. UV–vis–NIR absorption spectroscopy complemented by electrochemical measurements attested to weak electronic interactions between the electron donor, exTTF, and the electron acceptor, La@C82, in the ground state. In the excited state, photoexcitation powers a fast intramolecular electron transfer to yield an ion and radical ion pair state consisting of one-electron-reduced La@C82 and of one-electron-oxidized exTTF.