Molecules are the smallest objects still providing the structural diversity required to tune their properties in order to design their functions. Furthermore, the challenge to assemble these minute nanoscale building blocks has been addressed by organic chemists since more than a century. Considering the ongoing feature size reduction in semiconductor electronics, the increasing interest in molecules as potential functional units in electronic circuits is not surprising.[1] With the development of the experimental tools required to investigate these objects even on the single molecule level by experimental physicists and physical chemists, an outstanding platform to tackle the interdisciplinary challenge of “single molecule electronics” was created and resulted immediately in an inspiring and fruitful cooperation between scientists from these disciplines.
The ability of single molecules integrated in an electronic circuit to modulate the trans¬port current was investigated by comparing structural variations. Following this approach, entire series of molecules varying in a single structural parameter like e.g. biphenyl cyclophanes with a controlled interphenyl ring torsion angle were synthesized [2-4] and investigated [5,6]. The observed correlation of the transport current with the cos2 of the torsion angle further corroborated the single molecule as the origin of the current variation. First examples of single molecule devises have been developed successfully like e.g. a single molecule rectifier [7]. Current investigations are geared towards molecular systems combining optical and electronic signals. In a re¬cent single molecule electroluminescence experiment based on a tailor-made molecular rod in a carbon nanotube junction [8], the optical response from the junction pro¬vides the unambiguous proof of the molecular nature of the junction [9].
To reduce the mismatch between the top-down fabricated electrodes and the bottom-up assembled molecules, a supramolecular approach based on organic / inorganic hybrid materials [10-12] to increase the size of the molecular object which has to be integrated will be presented.
References (ACS format)
[1] N. Weibel, S. Grunder, M. Mayor, Org. Biomol. Chem., 2007, 5, 2343.
[2] D. Vonlanthen, A. Mishchenko, M. Elbing, M. Neuburger, T. Wandlowski, M. Mayor,
Angew. Chem. Int. Ed., 2009, 48, 8886.
[3] D. Vonlanthen, J. Rotzler, M. Neuburger, M. Mayor, Eur. J. Org. Chem., 2010, 120.
[4] D. Vonlanthen, A. Rudnev, A. Mishchenko, A. Käslin, J. Rotzler, M. Neuburger, T. Wandlowski, M. Mayor, Chem. Eur. J., 2011, 17, 7236.
[5] A. Mishchenko, D. Vonlanthen, V. Meded, M. Bürkle, C. Li, I. V. Pobelov, A. Bagrets, J. K. Viljas, F. Pauly, F. Evers, M. Mayor, T. Wandlowski, Nano Lett. 2010, 10, 156.
[6] A. Mischenko, L. A. Zotti, D. Vonlanthen, M. Bürkle, F. Pauly, J. C. Cuevas, M. Mayor, T. Wandlowski, J. Am. Chem. Soc., 2011, 133, 184.
[7] M. Elbing, R. Ochs, M. Köntopp, M. Fischer, C. von Hänisch, F. Evers, H. B. Weber, M. Mayor,
Proc. Nat. Acad. Sci. USA, 2005, 102, 8815.
[8] S. Grunder, D. Muñoz Torres, C. Marquardt, A. Błaszczyk, R. Krupke, M. Mayor;
Eur. J. Org. Chem., 2011, 478.
[9] C. W. Marquardt, S. Grunder, A. Błaszczyk, S. Dehm, F. Hennrich, H. v. Löhneysen, M. Mayor, R. Krupke; Nature Nanotech., 2010, 5, 863.
[10] T. Peterle, A. Leifert, J. Timper, A. Sologubenko, U. Simon, M. Mayor,
Chem. Comm., 2008, 3438.
[11] T. Peterle, P. Ringler, M. Mayor, Adv. Funct. Mater., 2009, 19, 3497.
[12] J. Hermes, F. Sander, T. Peterle, C. Cioffi, P. Ringler, T. Pfohl, M. Mayor, small, 2011, 7, 920.
|