Revealing the Buried Metal–Organic Interface: Restructuring of the First Layer by van der Waals Forces

Abstract

With the use of molecular manipulation in a cryogenic scanning tunneling microscope, the structure and rearrangement of sexiphenyl molecules at the buried interface of the organic film with the Cu(110) substrate surface have been revealed. It is shown that a reconstruction of the first monolayer of flat lying molecules occurs due to the van der Waals pressure from subsequent layers. In this rearrangement, additional sexiphenyl molecules are forced into the established complete monolayer and adopt an edge-on configuration. Incorporation of second layer molecules into the first layer is also demonstrated by purposely pushing sexiphenyl molecules with the STM tip. The results indicate that even chemisorbed organic layers at interfaces can be significantly influenced by external stress from van der Waals forces of subsequent layers.

Controlling the electronic and physical coupling on dielectric thin films

“…STM shows 6P molecules arranged in ordered monolayer islands (Figure 2b, Figure 2c), with their long axes aligned parallel to each other and parallel to the substrate surface. This is typical for 6P on atomically clean and ordered substrates obtained from bulk oxides to metal substrates [21][22][23][24][25]. In the submonolayer coverage regime (Figure 2a), we find molecules with different orientations coexisting on the surface.…”

Prototypical Organic–Oxide Interface: Intramolecular Resolution of Sexiphenyl on In2O3(111)

“…Comparable values have been found for 6P on Cu(110) in the densely packed, planar, and flat monolayer (molecular spacing of 0.72 nm) and for the twisted second layer there (molecular spacing of 0.67 nm). 19 An even closer arrangement occurs on O-passivated Cu(110) (2 × 1) with 0.51 nm. This compression of the 6P(203̅) layer (bulk spacing of 0.566 nm and a tilt angle of ∼33° with the 6P long axis as the rotational axis) is realized by a slightly larger tilt of ∼37°.…”

Influence of Relativistic Effects on Assembled Structures of V-Shaped Bispyridine Molecules on M(111) Surfaces Where M = Cu, Ag, Au

“…Surface-assisted fabrication of nanostructures has continuously occupied the research hotspot in recent years for its great potential in functional molecular devices. − The driving forces to assemble nanostructures on surfaces are of rich diversity. Relatively weak interactions such as van der Waals (vdW) forces and hydrogen bonds have been used to fabricate large-area and highly ordered structures. − Robust metal–ligand coordination, covalent bonds, as well as strong ionic interaction are also powerful means in building stable and long-range-ordered nanoarchitectures. − Among these supramolecular architectures, metal–organic structures (MOSs) have drawn much attention due to their potential applications in catalysis, chemical separation, and gas storage . Single-crystalline surfaces of copper, silver, and gold are usually used as supporting substrates to investigate surface reactions including the construction of MOSs .…”