Friday, November 26, 2010

EU-Funded Team In Nano World First, Build 3D Structures on a Surface

In a world first, scientists in the UK have demonstrated that it is possible to build a three-dimensional (3D) molecular structure on a surface. The experiments, described in the journal Nature Chemistry, represent a major breakthrough in the quest to develop innovative nano devices, such as novel optical and electronic technology and even molecular computers.

EU support for the work came from the COORDSPACE ('Chemistry of coordination space: extraction, storage, activation and catalysis') project, a EUR 2.49 million European Research Council (ERC) Advanced Grant awarded to the University of Nottingham's Martin Schröder under the Ideas Programme of the Seventh Framework Programme (FP7).
Illustration of this article
Scientists have already succeeded in building two-dimensional (2D) self-assembly molecular structures on a surface. These 2D arrays contain pores in which so-called 'guest molecules' can become trapped. Furthermore, these guest molecules do not always simply sit in the 2D array; in some cases, they cause the host framework to switch between two different 2D configurations.

In this study, physicists and chemists at the University of Nottingham created a 2D array of tetracarboxylic acid molecules on a surface. They then introduced a guest molecule - fullerene, also known as the 'buckyball', a football-shaped molecule consisting of 60 carbon atoms.

With their spherical shape, the buckyballs sit above the 2D array. This promotes the growth of a second layer of tetracarboxylic acid molecules above the first layer. This effectively extends the self-assembly structure into the third dimension.

'It is the molecular equivalent of throwing a pile of bricks up into the air and then as they come down again they spontaneously build a house,' explained Professor Neil Champness of the School of Chemistry at the University of Nottingham.

'Until now this has only been achievable in 2D, so to continue the analogy the molecular "bricks" would only form a path or a patio but our breakthrough now means that we can start to build in the third dimension. It's a significant step forward to nanotechnology.'

The newly discovered system is reversible; when coronene (a polycyclic aromatic hydrocarbon) is added as a second guest molecule, the bilayer network involving the buckyballs is replaced by a single-layer network of tetracarboxylic acid with coronene immobilised within its pores.

The scientists conclude: 'The system provides an example of a reversible transformation between a planar and a non-planar supramolecular network, an important step towards the controlled self-assembly of functional, three-dimensional, surface-based supramolecular architectures.'

Sources and contacts:
University of Nottingham:
Nature Chemistry:
European Research Council (ERC):
Citation:  Blunt, M. O., et al. (2010) Guest-induced growth of a surface-based supramolecular bilayer. Nature Chemistry (in press), published online 21 November. DOI: 10.1038/NCHEM.901.

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