Two-Component Fullerene Molecular Layers Assembled on the Au(111) Substrate

Abstract

Self-assembly of binary and multi-component colloidal crystals is an effective approach for the fabrication of structured new materials. The formation of colloidal crystals in most cases is controlled by optimized space occupation by the particles. C 60 and C 70 molecules, when treated as the smallest "colloidal particles", can be used as model systems to study the formation of multicomponent molecular crystals in which the intermolecular forces are mainly of the van der Waals type. By deposition of C 60 and C 70 molecules onto Au(111), the mixing of the two molecules has been investigated. Both C 60 and C 70 form close-packed layers on Au(111), but with different lattice constants. At room temperature, the molecules within the molecular layer have complete freedom to rotate. The boundary between the C 60 and the C 70 domains consists of row dislocations. Adding C 60 onto a C 70 layer has an interesting effect in that C 60 molecules can push their way into the C 70 layer and force the C 70 molecules to take a fixed upright configuration where the long axis of the molecule is perpendicular to the interface. Significant interlayer diffusion takes place at elevated temperatures. When C 70 is added to a C 60 layer, there is little evidence of C 70 getting into the C 60 layer. The second layer C 70 forms a lattice-matched structure by taking the upright orientation.

Self-Defined Transition State in Hybrid C70–Au Clusters Created by the Scanning Tunneling Microscope Tip

“…Addressing the possible mechanisms underlying the stability of the C 70 –Au cluster is similar to C 60 –Au clusters. ,, They are the molecule–molecule close-packing, the molecule–surface adatom, and molecule–2D Au island interactions. Although similar formations between C 70 –Au and C 60 –Au, the intermolecular differences play an important role in the cluster stability due to the rather weak interaction of Au(111) surface to C 70 . To obtain a close-packed arrangement with C 70 molecules, the van der Waals force plays a significant role in the cluster stability .…”

“…For example, C70 charge transfer is 1.1 ± 0.1 electron/molecule [26] and for C 60 1.6 electron/molecule on the Cu(111) surface [27]. While the charge transfer from Au(111) to C 60 is 0.8 electron/molecule [28], it is less for C70 which is observed experimentally [23].…”

“…There are two possible orientations of the C 70 molecule on the Au(111) surface due to its unique rugby ball shape: the molecule can have its long or short molecular axis perpendicular to the substrate. At RT, the C70 molecules are able to rotate around both the long and short axis in the close-packed C 70 layer at [23]. Therefore, the molecule does not take a fixed orientation at RT.…”

Orientational Growth of Flexible van der Waals Supramolecular Networks

“…[50] This approach enriches our fundamental understanding of vdW coassembly on surfaces and offers a promising strategy for creating complex functional nanostructures. [51,52] This work will likely significantly impact the future design and synthesis of molecular nanostructures/nanomaterials, offering enhanced control over their structures and properties.…”