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Highly conductive 40-nm-long molecular wires assembled by stepwise incorporation of metal centres

An Erratum to this article was published on 10 February 2009

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Abstract

One of the main goals of molecular electronics is to achieve electronic functions from devices consisting of tailored organic molecules connecting two metal electrodes. The fabrication of nanometre-scale spaced electrodes still results in expensive, and often scarcely reproducible, devices1,2,3,4. On the other hand, the ‘conductance’ of long organic molecules—generally dominated by the tunnelling mechanism—is very poor5,6,7,8,9. Here, we show that by incorporating a large number of metal centres into rigid molecular backbones we can obtain very long (up to 40 nm) and highly ‘conductive’ molecular wires. The metal-centre molecular wires are assembled in situ on metal surfaces via a sequential stepwise coordination of metal ions by terpyridine-based ligands10,11. They form highly ordered molecular films of elevated mechanical robustness. The electrical properties, characterized by a junction based on Hg electrodes5,6, indicate that the ‘conductance’ of these metal-centre molecular wires does not decrease significantly even for very long molecular wires, and depends on the nature of the incorporated redox centre. The outstanding electrical and mechanical characteristics of these easy-to-assemble molecular systems open the door to a new generation of molecular wires, able to bridge large-gap electrodes, and to form robust films for organic electronics.

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Figure 1: Schematic representation of the stepwise assembly of the MCMWs in situ on metal surfaces.
Figure 2: Characterization of films for Fe(II)-based MCMWs by ToF-SIMS and ultraviolet–visible spectroscopy.
Figure 3: ToF-SIMS and AFM imaging on micropatterned Fe(II)-based MCMW samples with eight metal centres.
Figure 4: Electrical characterization of MCMWs.
Figure 5: Schematic representation of the energy diagram of the Au-MCMW/Hg juctions.

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Change history

  • 10 February 2009

    In the version of this article originally published, the y axes labels of Fig. 4b and c appeared incorrectly as ln J (A cm−2); they should have been log J (A cm−2). The errors have now been corrected on the HTML and PDF versions.

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Acknowledgements

We thank F. Scandola for discussion. Financial support of MURST (PRIN 2006 2006030320_002), EU (contract STRP-032202—EMDPA) and ‘PROMO’ CNR-INSTM is gratefully acknowledged.

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Contributions

Project planning, A.L., M.A.R.; synthesis of the ligands, M.C., S.Q.; assembly and surface spectroscopy of the MWs, N.T., A.L., G.Z.; electrical measurements and data interpretation, V.F., N.T., M.A.R.

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Correspondence to Antonino Licciardello or Maria Anita Rampi.

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Tuccitto, N., Ferri, V., Cavazzini, M. et al. Highly conductive 40-nm-long molecular wires assembled by stepwise incorporation of metal centres. Nature Mater 8, 41–46 (2009). https://doi.org/10.1038/nmat2332

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