Pressure-Stimulated Photopolymerization in Fullerene Layers of a Molecular Complex [{Zn(Et2dtc)}2<middle dot>DABCO]<middle dot>C60<middle dot>(DABCO)2

The behavior of the fullerene molecular complex [{Zn(Et(2)dtc)}(2)<middle dot>DABCO]<middle dot>C-60<middle dot>(DABCO)(2) at high pressure was studied by Raman spectroscopy and X-ray diffraction (XRD) using the diamond anvil cell technique. The Raman spectra taken at room temperature with a green laser of 532 nm showed a peculiarity near 2 GPa related to the formation of interfullerene covalent bonds. However, the XRD study up to 2.6 GPa showed smooth and monotonous pressure dependence of the lattice parameters and cell volume well fitted by the Murnaghan equation of state with K-0 = 10.67 GPa and K ' = 6.96. The changes in the Raman spectra were caused by photoinduced polymerization in fullerene layers that could be suppressed when using a near-infrared laser of 785 nm. The photopolymerization at elevated pressure had a thermal activation character; the activation energy of 1.09 eV at 1.05 GPa decreased to 0.18 eV at 1.85 GPa, which gave rise to a fast photopolymerization at room temperature.