|
New Method for the Construction of Future Molecular Data Storage Media and Nanoscale Switches
Scientists from the NCCR Nanoscale Science developed a new method which allows the construction
of complex 2-dimensional nanosized structures out of molecular building blocks. Such entities
may be used for future memory devices with high storage densities or as switching
elements in nanoscale technology. As reported in “Angewandte Chemie”, single molecules were
forced to arrange in stable molecular chains and regular pairs on a surface by a self-assembly
process at room-temperature. At present, no other technological method is capable of arranging
that complex supramolecular entities, made of several hundred atoms, in such a precise and
repetitive manner.
It was shown that the formation of the structures is driven by the internal (conformational)
flexibility of the molecular building blocks. Binding of a fullerene molecule (C60)
at the surface blocks selected neighbouring binding sites. Additional molecules therefore only
occupy defined adsorption positions what leads to the observed creation of molecular chains and
pairs. Interestingly, the flexibility of molecules plays also a decisive role in important
biochemical and physiological processes (e.g. oxygen transport in the blood circuit). In this
work, the flexibility of molecules has been used for the first time for the construction of
artificial surface structures.
In order to investigate the nanosized structures with atomic resolution a
Scanning-Tunneling-Microscope was used. This allows the targeted manipulation of single
molecules from one stable position to another one. Especially for the construction of future
memory devices, a detailed understanding of these switching processes is of outmost importance.
|
|
|
Figure 1: Left: Fullerene pairs (bright spots) arranged in two
dimensions on a regular layer of porphyrin type molecules. The extremely large distance
between the pairs (about 7.5 nm) is related to the proper choice of the substrate molecules.
Right: The use of di-porphyrin molecules leads to the formation of 1-dimensional
chains. |
|
|
|
|
Figure 2: Displacement of fullerene molecules on top of a di-porphyrin
layer. Left: The tip of the Scanning-Tunneling-Microscope was moved along the direction of the
green arrow. Right: Situation after the manipulation process. The first two fullerenes of the
original four-membered chain were moved and now form an offset continuation of the left chain.
The molecule marked with a blue circle (left) got lost during the manipulation process. As
indicated by the green ellipse, the fullerene molecules can be displaced without disrupting
the underlying di-porphyrin layer.
|
Supramolecular Patterned Surfaces Driven by Cooperative Assembly of C60 and Porphyrins on Metal Substrates
Davide Bonifazi, Hannes Spillmann, Andreas Kiebele, Michael de Wild, Paul Seiler, Fuyong Cheng, Hans-Joachim Güntherodt,Thomas Jung, and François Diederich
Angewandte Chemie Int. Ed. 2004, Volume 116, Issue 36 , Pages 4863 - 4867
Contact:
Hannes Spillmann |
Thomas Jung |
|
Institute of Physics
University of Basel
Switzerland |
|
