SELF-ASSEMBLY OF SUPRAMOLECULAR NANOSTRUCTURES: ORDERED ARRAYS OF METAL IONS AND CARBON NANOTUBES - Bio-Inspired and Nanoscale Integrated Computing - page 340

Organic
molecules

Metal
ions

Vacuum system
Single crystal metal
(Au, Ag, Cu)
Substrate

Substrate
Scanning
tunneling
microscope

STM

Pump

Metal ion
networks
(MINs)

Single-molecule
topography

Metal
evaporator

Evaporators of
organic buildings blocks

Metallic surfaces
(Au, Ag, Cu, etc.)
(a)

(b)

Figure 12.9. (a) Schematic representation of the experimental setup of the
UHV-based codeposition of the molecular components (metal atoms and organic
ligands) on metallic substrates. (b) The components self-assemble on metallic
surfaces under UHV 2D confinement to extended metal ion networks (MINs),
which can be investigated in situ by scanning probe techniques [27].

the electronic coupling of the coordinated metal centers to the metallic substrate
or possible counterbalancing of the charges of the assembled molecular struc-
tures by mirror charges within the upper layers of the metallic substrate have to
be taken into consideration to explain the electronic properties of surface-
deposited metal atoms or ions [29]. Looking at the distinct metal/ligand
stoicheometry around the dimeric Fe 2 -nodes, it seems reasonable to believe
that the principle of electro-neutrality persists under near-surface conditions.

Figure 12.10. (a) STM image showing the 2D topography of the extended
Fe-metal ion dicarboxylic acid network on a Cu(100) surface; (b) high resolution
image of the same network indicating the positions of the organic
ligand dicarboxylic acid backbone and the interconnecting dimeric Fe-nod
structures [28].