Charge transport through a cardan-joint molecule.
The charge transport through a single ruthenium atom clamped by two terpyridine hinges is investigated, both experimentally and theoretically. The metal-bis(terpyridyl) core is equipped with rigid, conjugated linkers of para-acetyl-mercapto phenylacetylene to establish electrical contact in a two-terminal configuration using Au electrodes. The structure of the [Ru(II)(L)(2)](PF(6))(2) molecule is determined using single-crystal X-ray crystallography, which yields good agreement with calculations based on density functional theory (DFT). By means of the mechanically controllable break-junction technique, current-voltage (I-V), characteristics of [Ru(II)(L)(2)](PF(6))(2) are acquired on a single-molecule level under ultra-high vacuum (UHV) conditions at various temperatures. These results are compared to ab initio transport calculations based on DFT. The simulations show that the cardan-joint structural element of the molecule controls the magnitude of the current. Moreover, the fluctuations in the cardan angle leave the positions of steps in the I-V curve largely invariant. As a consequence, the experimental I-V characteristics exhibit lowest-unoccupied-molecular-orbit-based conductance peaks at particular voltages, which are also found to be temperature independent.
Ruben
Mario
M
Institute of Nanotechnology, Karlsruhe Institute of Technology, PF 3640, 76021 Karlsruhe, Germany. ruben@int.fzk.de
Landa
Aitor
A
Lörtscher
Emanuel
E
Riel
Heike
H
Mayor
Marcel
M
Görls
Helmar
H
Weber
Heiko B
HB
Arnold
Andreas
A
Evers
Ferdinand
F
D003460:Crystallization; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D015394:Molecular Structure; D012428:Ruthenium / Q000737:chemistry*
D012428:Ruthenium