NEWS OF THE WEEK
LINKER-FREE MOLECULAR WIRES ELECTRONICS: Metal-carbon bonds
increase electrical conductance
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TRINGING CONJUGATED organic compounds
J. AM. C HEM. SOC.
between two electrodes via direct metal-carbon bonds rather than via linking groups will likely change the way molecular electronic circuits are “wired.” Although circuits made of molecular building blocks are not yet a reality outside research laboratories, they promise to shrink electronics beyond what is possible with silicon-based devices. A research team led by Ronald Breslow and Latha Venkataraman of Columbia University and Mark S. Hybertsen of Brookhaven National Laboratory bonded the terminal methylene groups of oligophenyl compounds directly to two gold electrodes. To form the Au–C bonds, the scientists synthesized the methylene-terminated oligophenyls with trimethyltin end caps. When the molecules come into contact with the electrodes, the A dimethylenebenzene molecule cleaves its trimethyltin end caps to bind between two gold electrodes (yellow). C is gray, H is white, Sn is red.
DOE DEMANDS SOLAR PATENTS INTELLECTUAL PROPERTY: Bankrupt solar firm developed its manufacturing technology with government grant EVERGREEN SOLAR
Evergreen Solar panels on the roof of a high school near Rome.
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HE DEPARTMENT of Energy is claiming owner-
ship of three patents awarded to Evergreen Solar and plans to prevent them from being sold to nonU.S. firms. According to DOE, the technology was developed from 2002 to 2005 with funding from the agency. When Evergreen filed for Chapter 11 bankruptcy in August, it said it would sell its assets at auction, including intellectual property related to its solar wafer manufacturing technology. Evergreen’s wafers are made with what it calls the string ribbon method, which is designed to minimize the use of crystalline silicon. DOE says the firm used a nearly $3 million government grant to refine the method, cutting manufacturing costs by 33%. Even with the innovation, Evergreen—like U.S. solar firms Solyndra and SpectraWatt, which recently both declared bankruptcy—could not compete with lower cost crystalline solar modules made in China. WWW.CEN-ONLINE.ORG
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compounds shed their caps, and each methylene forms a covalent bond with one of the gold electrode surfaces. Since the first measurements of electron transport in single molecules in the late 1990s, researchers have been searching for ways to make highly conductive connections between molecular wires and metal electrodes, says Kristian S. Thygesen, a physicist at the Technical University of Denmark. Typical linking groups such as thiols and amines help organic compounds form strong bonds to metal electrodes, but at the same time suppress electron transport, he says. By eliminating the linkers, the new method enhanced electrical conductance through the methylenelinked oligophenyls by two orders of magnitude (J. Am. Chem. Soc., DOI: 10.1021/ja208020j). In addition, the researchers showed that a single dimethylenebenzene molecule spanning the junction between the gold electrodes achieved 90% of the conductance of a circuit with a gold atom between the electrodes. When the scientists developed the direct Au–C bonding chemistry and tested it on alkanes earlier this year (Nat. Nanotech., DOI: 10.1038/nnano.2011.66), they observed some conductance enhancement, but it was not as large as what they attained with the methyleneterminated oligophenyls. “This is the first demonstration of truly strong coupling dictated by well-defined bonding in a molecular electronic junction,” says Douglas Natelson, a nanotechnology researcher at Rice University. “That’s quite exciting.”—LAUREN WOLF
The Bayh-Dole Act requires Evergreen to inform DOE when grant-supported research results in an invention and whether Evergreen elects to retain title to any inventions. But Evergreen did not notify DOE about three patents resulting from the grant. In such a case, the Bayh-Dole Act says DOE can demand title to the inventions. On Oct. 7, DOE notified Evergreen Solar of its demand for title to the three patents. In an accompanying filing with the bankruptcy court of Delaware, DOE worries that Evergreen has already entered into a joint venture with a Chinese company and established a manufacturing facility in Wuhan, China. It says DOE has a statutory duty “to use the patent system to promote the utilization of inventions arising from federally supported research or development, promote the commercialization and public availability of inventions made in the United States by United States industry and labor, and ensure that the Government obtains sufficient rights in federally supported inventions.” Attorney Charles E. Miller, in the Intellectual Property Group of Dickstein Shapiro LLP, says the government has a good case for ownership rights under Bayh-Dole. Normally, a bankruptcy trustee would decide what to do with the company’s assets, but “the bankruptcy court cannot sell assets that belong to the government,” Miller says.—MELODY BOMGARDNER
OCTOBER 17, 2011
