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10:17am, November 6, 2007
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Researchers have created molecules that spontaneously form sturdy networks on a surface, a step that could bring molecular-scale electronic circuits closer to reality.

Leonhard Grill of the Free University of Berlin and his colleagues synthesized flat, square molecules with arms extending from all four sides. The team engineered the molecules to be either reactive or inert at the tip of each arm, and then temporarily capped the reactive tips with bromine atoms.

Deposited onto a gold surface, the molecules slid around, nudged by random thermal jittering. Heating the surface to 270°C for about 15 minutes drove off the bromine caps. As the molecules continued to wander, their reactive ends began to find one another and form stable, covalent bonds.

Versions of the molecules with just one reactive arm got together in pairs, while those with two or four reactive tips got together in chains and grids, respectively, the researchers report in the November Nature Nanotechnology.

Grill says that the method is more promising than other techniques for self-assembling molecules that rely on weaker chemical bonds. Other molecules could be engineered to form more-complex structures such as circuits, he adds.

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