Glassy Porphyrin/C60 Composites: Morphological Engineering of C60 Fullerene with Liquefied Porphyrins

Morphological control of C-60 fullerene using liquefied porphyrins (1 and 2) as the host matrices was explored. Slow evaporation of the solvent of the equimolar mixture of porphyrin and C-60 in toluene afforded the porphyrin/C-60 composite with a 3:1 molar ratio. The stoichiometric binding behaviors suggest that specific porphyrin-C-60 interactions operate the formation of the porphyrin/C-60 composites, as corroborated by spectroscopic and thermal properties, and glazing-incidence wide-angle X-ray diffraction. Under the bulk conditions, the conventional thermodynamic advantage of multiple binding cooperativity for molecular recognition is unlikely to explain the stoichiometric binding behaviors. Instead, we propose a size-matching effect on the porphyrin-C-60 interaction in the bulk porphyrin matrices, i.e., supramolecular solvation. The glassy nature of the porphyrin matrices was transmitted to C-60 through the specific interaction, and the porphyrin/C-60 composites adopted glassy states at room temperature.