Molecule switch as a "team player"

A prerequisite for complex molecular systems

Nanoscale Molecule Circuit © Jascha Repp, Uni Regensburg
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Molecules are the classic building blocks of nanotechnology, but more complex molecular systems have not been realized so far. This could change soon: Scientists have now succeeded in using certain molecules as switches in a scanning tunneling microscope. As they report in "Science", the connection points to the outside remained unchanged - a prerequisite for complex systems.

In search of ever smaller and more efficient computers and other electronic devices, scientists are looking for new components: molecules as components - switches, memory elements, diodes or transistors - could take the electronics to new dimensions. If a silicon-based transistor currently has a side length of 90 nanometers, molecules with dimensions of only a few nanometers - that is millionths of a millimeter - would be reached. This has already been implemented for individual molecules, but complex molecular systems have not been feasible so far.

So far: Total deformation when switching

The mechanism of the previously known molecular switches is usually based on drastic mechanical deformations. This means that the structure of the molecule also changes to the outside so much that coupling with other elements becomes impossible. This is not the case with scientists from the IBM Research Laboratory in Zurich and the University of Regensburg around Jascha Repp. They used naphthalocyanine molecules, organic dye molecules that are characterized by two hydrogen atoms in the interior of an annular molecule.

These hydrogen atoms were able to change the position of the researchers with the smallest possible surges. The positional shift was accompanied by a change in the conductivity of the molecule. The special thing about this is that the switching does not lead to any movement at the periphery of the molecule, since the hydrogen atoms, which are crucial for the switching position, are located in a protected cavity. Now the conditions for a coupling of several switches were given.

Now: coupling possible

In another experiment, the physicists showed the first step by pushing several molecules together with the help of the scanning tunneling microscope. By injecting current into one molecule, they could then switch an adjacent molecule - a first step on the way to more complex electronic circuits. display

The mechanism found works for a whole class of similarly constructed molecules and thus forms the basis for a number of possible molecular switches of the future.

(University of Regensburg, 03.09.2007 - NPO)