Electron transport through molecules has received great attention since organic structures have been considered as the active part in electronic nanoscale devices [1]. Different experimental set-ups allowed integrating single molecules and nanocrystals in electronic circuits.
In this talk I will focus on single molecule conductance studies in Au│molecule (cluster)│Au junctions based on STM-BJ, MCBJ and CP-AFM experiments in solution [2]. I will discuss correlations between molecular structure and transport characteristics for several families of molecular wires (OPEs, oligoynes) with a specific focus on molecular length, conformation, quantum interference and the nature of terminal anchoring groups (covalent vs. coordination bonds to the conducting metal leads, pi-stacking) [3-5]. The nature of bond-rupture processes in (single) molecular junctions will be also discussed based on simultaneous conductance and electromechanically CP-AFM experiments. Employing the concept of “electrolyte gating” I will address orientation and conformation changes [2,7] as well as redox-mediated electron transfer [2,8,9]. The experimental data will be compared with simulations based on the phenomenological theory of electron transfer.
The talk will conclude with a perspective outlook towards alternative bonding concepts and addressable functionalities of nanoscale junctions in liquids [9].
Acknowledgement:
Financial support from, DFG (SPP 1243), SNF and FP7 via the FUNMOLS consortium is gratefully acknowledged.
References:
[1] A. Aviram, M. A. Ratner, Chem. Phys. Lett. 1974, 29, 277.
[2] C. Li, A. Mishchenko, Th. Wandlowski, Topics in Current Chemistry. 2012, 313, 121.
[3] A. Mishchenko et al. Nano Letters 2010, 10, 156; A. Mishchenko et al., J. Am. Chem. Soc. 2011, 133, 184; V. Kaliginedi, in peparation (2013).
[4] V. Kaliginedi et al., J. Am. Chem. Soc. 2012, 21, 5262.
[5] W. Hong et al., J. Am. Chem. Soc. 2012, 134, 2292; P. Moreno et al., J. Am. Chem. Soc. 2013, 135, 12228.
[6] I. V. Pobelov et al., J. Phys. Condens. Mater 2012, 24,164210; K. Yoshida, I. Pobelov et al. 2013, in preparation.
[7] L. Cui, B. Liu, Th. Wandlowski, J. Am. Chem. Soc. 2011, 133, 7332.
[8] Z. Li, Y. Liu, S. F. L. Mertens, I. Pobelov, Th. Wandlowski, J. Am. Chem. Soc. 2010, 132, 8187.
[9] B. Liu, Th. Wandlowski, ACS Nano, 2011, 5, 5662; W. Hong et al., J. Am. Chem. Soc. 2012, 134, 19425; D. Roldan et al., J. Am. Chem. Soc. 2013, 135, 5974.