Millions of multi stable devices in a network

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PostPosted: Thu Feb 07, 2008 10:43 am    Post subject: Millions of multi stable devices in a network Reply with quote

Scientists from the National Centre of Competence in Research (NCCR) on Nanoscale Science at the Swiss Nanoscience Institute (SNI) have taken a further important step forward in the development of functional addressable supramolecular structures. In collaboration scientists from the University of Basel, the Paul Scherrer Institute ( Villigen, Switzerland) and the Swiss Federal Institute of Technology in Zurich have succeeded in creating a surface with millions of tiny multi stable devices. These switches, made of porphyrin molecules, about one nanometer in size, can be individually operated using the tip of a scanning tunnelling microscope. This work is published in the renowned international science journal Angewandte Chemie.

In its studies, the team around Francois Diederich, Hannes Spillmann and Thomas Jung first set up experimental conditions enabling porphyrin molecules to self-assemble into a network. Each pore in this network is formed from six molecules. Upon continued deposition of porphyrin molecules they self-assemble individually on top of each pore. The porphyrins nested on top of the pores then show an interesting and temperature dependent motion: At 110 K (-160°C) they may be in any of three clearly differentiated positions. When the temperature is increased, they jump randomly back and forth between these three positions. At room temperature, this happens so quickly that they appear to rotate freely. At a temperature of -160°C, the molecules can then be oriented specifically within the porous network while using a scanning tunnelling microscope. This way each porphyrin nested in its hosting pore serves as a supramolecular orientational switch which is potentially useful.

In their studies, the scientists were primarily interested in extending the principles of self-assembly to produce addressable supramolecular structures and thus developing platforms for technical applications. Their research is based on work by Prof. Jean-Marie Lehn, who produced the first supramolecular structures in the 1980s, for which he was awarded the Nobel Prize in 1987.

The research teams from Basel, Villigen, and Zurich have established a well-defined arrangement of supramolecular structures which can be individually addressed. They have thus laid a further foundation stone for the creation of technical functions such as data storage units through the rapid and low-cost self-assembly of molecules. The structures shown here are already completely free of water and are therefore particularly suitable for technical applications.

The scientists from the SNI have also presented other supramolecular structures in the past. For example, they recently published work on a porphyrin network that interacts with “carbon football” molecules of varying sizes. “All these studies will contribute to the future production of data storage units, optical, chemical and logical switching elements on surfaces in extremely small dimensions and at low cost“, says Thomas Jung, commenting on the work of his team.

The Swiss Nanoscience Institute (SNI) emerged from the National Centre of Competence in Research (NCCR) on Nanoscale Science and forms a key focus of research at the University of Basel. The SNI combines basic research with applied research. Researchers are engaged in various projects involving nanoscale structures. They are hoping to provide impetus for life sciences, sustainability, information technology and communications technology. The University of Basel acts as Leading House and coordinates both the NCCR network of university and research institutes and industrial partners, which is run by the Swiss National Science Foundation on behalf of the federal government, and also the Argovia network that is funded by Canton Aargau. With the founding of the SNI, the University of Basel secured its internationally acknowledged position as a centre of excellence for the nanosciences.

Further information:
Dr. Thomas Jung, Paul Scherrer Institute ++41 56 310 45 18 / ++41 61 267 3665

Prof. Dr. Francois Diederich, ETH Zürich, ++41 61 267 37 59

Story posted: 1st June 2007
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