Clusters of bis- and tris-fullerenes

Bis- and tris-fullerene derivatives [bis-(C60) and tris-(C60)] form suspendable clusters in mixed solvents (80% acetonitrile and 20% toluene). These clusters are optically transparent and exhibit interesting nanostructures with sizes ranging from 100 nm to 1 µm and shapes varying from elongated wires to entangled spheres. Ground- and excited-state properties of the clusters of the mono-, bis-, and tris-fullerene derivatives are compared with the corresponding properties of their monomeric forms through steady-state and time-resolved transient absorption spectroscopy. The singlet excited-state quenching of bis- and tris-fullerene derivatives by N-methylphenothiazine (NMP) occurs with rate constants of 5.5 × 109 and 5.3 × 109 M-1 s-1, respectively. The charge separation in these clustered fullerene derivatives is probed by monitoring the formation and decay of the C60 radical anion and the radical cation of NMP. An increase in the number of fullerene moieties in the molecule helps in the formation of ordered cluster aggregates and this has a beneficial effect in stabilizing the electron-transfer products