Hisashi Umemoto

A structural diagnostics diagram for metallofullerenes encapsulating metal carbides and nitrides.

Systematic structural studies of 24 different kinds of endohedral metallofullerenes, M(x)C(2n) (M = La, Y, Sc, Lu, Ti, Eu, Er, Hf, Sc(3)N; 34 ≤ n ≤ 43), as 1:1 cocrystals with solvent toluene molecules have been carried out using synchrotron radiation powder diffraction. Thirteen of the 24 molecular structures, including five metal carbides, one metal nitride endohedral fullerene, and one hollow fullerene, have been determined by a combination of the maximum entropy method and Rietveld refinement of the X-ray diffraction data obtained. We have found that the volume for one fullerene and one toluene molecule depends linearly on the number of carbon atoms in the fullerene cage. Fifteen different kinds of metal carbide endohedral fullerenes have been identified, which can be structurally characterized from the obtained lattice constants using only this linear dependence. The linear dependence found in the present study provides a metallofullerene diagnostics diagram that may have universal importance for structural characterization of the so-called cluster endohedral fullerenes.

Grating of single Lu@C-82 molecules using supramolecular network

A supramolecular grating of single Lu@C(82) molecules was obtained by depositing Lu@C(82) molecules onto a room temperature PTCDI-melamine network.

STM TIP-CURRENT-INDUCED POLYMERIZATION OF C60, Ce2@C80 AND Lu2@C76

Polymerization of C60, Ce2@C80, and Lu2@C76 metallofullerenes induced by electron injection from a scanning tunneling microscope (STM) tip has been studied. C60 polymerization has been observed only with C60 multilayer on Au(111) and not with C60 monolayer on Au(111). The Ce2@C80 metallofullerene on Si(111)-7 × 7 also polymerizes by electron injection but has less polymerization reactivity than C60. Interestingly, the Lu2@C76 metallofullerene on Si(111)-7 × 7 does not show any polymerization. Based on these STM observations on the tip-induced polymerization, the direction of the bond formation and the dependence of reactivity on the kind of fullerenes are discussed.