Quasi 3D polymerization in C₆₀ bilayers in a fullerene solvate

The polymerization of fullerenes has been an interesting topic for almost three decades. A rich polymeric phase diagram of C₆₀ has been drawn under a variety of pressure-temperature conditions. However, only linear or perpendicular linkages of C₆₀ are found in the ordered phases. Here we used a unique bilayer structural solvate, C₆₀·1,1,2-trichloroethane (C₆₀·1TCAN), to generate a novel quasi-3D C₆₀ polymer under high pressure and/or high temperature. Using Raman, IR spectroscopy and X-ray diffraction, we observe that the solvent molecules play a crucial role in confining the [2 + 2] cycloaddition bonds of C₆₀s forming in the upper and lower layers alternately. The relatively long distance between the two bilayers restricts the covalent linkage extended in a single individual bilayer. Our studies not only enrich the phase diagram of polymeric C₆₀, but also facilitate targeted design and synthesis of unique C₆₀ polymers.