Two-Dimensional van der Waals Supramolecular Frameworks from Co-Hosted Molecular Assembly and C₆₀ Dimerization

A two-dimensional van der Waals supramolecular framework is created by self-assembled cocrystallization of C60 and octanethiol molecules on the Au(111) surfaces. The framework is characterized by the two-dimensional C60 network, in which the pores are filled by RS-Au-SR (R = CH3(CH2)7S) staples. The framework is stabilized by cooperative interactions involving collective self-assembly instead of the commonly observed pairwise interactions between the nearest neighbors. The pairing of two adjacent C60 molecules and the formation of C60 dimer are visualized by low temperature scanning tunneling microscopic imaging, in conjunction with first-principles calculations, suggesting a charge transfer in each C60 dimer. Such van der Waals C60 supramolecular framework with intermolecular charge transfer, serving a rare example in artificial 2D molecular crystal for inert C60 molecules, is very promising in applications of optics and devices.