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Several metastable doped C 60 polymers are synthesized under high pressure and high temperature (1.5 GPa, 573 K and 2 GPa, 700 K, respectively), using C 60 /ferrocene(Fc, Fe(C 5 H 5 ) 2 ), C 60 /Ni(OEP) and C 60 /AgNO 3 as starting materials. Raman and IR spectroscopy are used to study the polymerization of these samples after HPHT treatment. It is found that the polymerization degree is always lower than that of pure C 60 treated at the same conditions, which is attributed to the space limitation by the dopants. We also find that even at the same conditions, the three doped materials form different polymeric phases of these doped materials. This is attributed to the unique initial lattice structures and the different degrees of spatial confinement provided by the dopants. [ABSTRACT FROM AUTHOR]

Abstract: High pressure Raman, IR and X-ray diffraction (XRD) studies have been carried out on C70(Fe(C5H5)2)2 (hereafter, “C70(Fc)2”) sheets. Theoretical calculation is further used to analyze the Electron Localization Function (ELF) and charge transfer in the crystal and thus to understand the transformation of C70(Fc)2 under pressure. Our results show that even at room temperature dimeric phase and one dimensional (1D) polymer phase of C70 molecules can be formed at about 3 and 8GPa, respectively. The polymerization is found to be reversible upon decompression and the reversibility is related to the pressure-tuned charge transfer, as well as the overridden steric repulsion of counter ions. According to the layered structure of the intercalated ferrocene molecules formed in the crystal, we suggest that ferrocene acts as not only a spacer to restrict the polymerization of C70 molecules within a layer, but also as charge reservoir to tune the polymerization process. This supplies a possible way for us to design the polymerization of fullerenes at suitable conditions. [Copyright &y& Elsevier]

Abstract: We report a simple synthesis of C70 microcrystals by a fast solvent-assisted evaporation method by selectively using aromatic solvents with halogen radicals as a controller. In a detailed analysis we show that depending on solvent, C70 concentration in the solution, and synthesis temperature both C70 microrods and microcubes can be produced. The samples were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy. From meta-type solvents microrods or microcrystal cubes grow with a single orthorhombic or a monoclinic structure or a mixture of both. These crystals show traces of solvents in the structure. From para-type solvents cubic (or rectangular) crystals grow with a hexagonal structure and with no trace of solvents. Room temperature photoluminescence (PL) of the C70 crystal samples reveals that the PL efficiency of the crystals increases with crystalline order and that the best crystalline C70 cube crystals show 10 times higher PL efficiency than that of pristine C70 polycrystalline samples. [Copyright &y& Elsevier]