Final published version
Licence: CC BY
Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
}
TY - JOUR
T1 - The single-molecule electrical conductance of a rotaxane-hexayne supramolecular assembly
AU - Milan, David C.
AU - Krempe, Maximilian
AU - Ismael, Ali K.
AU - Movsisyan, Levon D.
AU - Franz, Michael
AU - Grace, Iain
AU - Brooke, Richard J.
AU - Schwarzacher, Walther
AU - Higgins, Simon J.
AU - Anderson, Harry L.
AU - Lambert, Colin J.
AU - Tykwinski, Rik R.
AU - Nichols, Richard J.
PY - 2017/1/7
Y1 - 2017/1/7
N2 - Oligoynes are archetypical molecular wires due to their 1-D chain of conjugated carbon atoms and ability to transmit charge over long distances by coherent tunneling. However, the stability of the oligoyne can be an issue. Here we address this problem by two stabilization methods, namely sterically shielding end-groups, and rotaxination to produce an insulated molecular wire. We demonstrate the threading of a hexayne within a macrocycle to form a rotaxane and report measurements of the electrical conductance of this single supramolecular assembly within an STM break junction. The macrocycle is retained around the hexayne through the use of 3,5-diphenylpyridine stoppers at both ends of the molecular wire, which also serve as chemisorption contacts to the gold electrodes of the junction. Molecular conductance was measured for both the supramolecular assembly and also for the molecular wire in the absence of the macrocycle. The threaded macrocycle, which at room temperature is mobile along the length of the hexayne between the stoppers, has only a minimal impact on the conductance. However, the probability of molecular junction formation in a given break junction formation cycle is notably lower with the rotaxane. In seeking to understand the conductance behavior, the electronic properties of these molecular assemblies and the electrical behavior of the junctions have been investigated by using DFT-based computational methods.
AB - Oligoynes are archetypical molecular wires due to their 1-D chain of conjugated carbon atoms and ability to transmit charge over long distances by coherent tunneling. However, the stability of the oligoyne can be an issue. Here we address this problem by two stabilization methods, namely sterically shielding end-groups, and rotaxination to produce an insulated molecular wire. We demonstrate the threading of a hexayne within a macrocycle to form a rotaxane and report measurements of the electrical conductance of this single supramolecular assembly within an STM break junction. The macrocycle is retained around the hexayne through the use of 3,5-diphenylpyridine stoppers at both ends of the molecular wire, which also serve as chemisorption contacts to the gold electrodes of the junction. Molecular conductance was measured for both the supramolecular assembly and also for the molecular wire in the absence of the macrocycle. The threaded macrocycle, which at room temperature is mobile along the length of the hexayne between the stoppers, has only a minimal impact on the conductance. However, the probability of molecular junction formation in a given break junction formation cycle is notably lower with the rotaxane. In seeking to understand the conductance behavior, the electronic properties of these molecular assemblies and the electrical behavior of the junctions have been investigated by using DFT-based computational methods.
KW - CARBON ALLOTROPE CARBYNE
KW - POLYYNE ROTAXANES
KW - JUNCTIONS
KW - TRANSPORT
KW - WIRE
KW - ELECTRONICS
KW - MODEL
KW - POLYROTAXANES
KW - STABILIZATION
KW - CONDUCTIVITY
U2 - 10.1039/c6nr06355a
DO - 10.1039/c6nr06355a
M3 - Journal article
VL - 9
SP - 355
EP - 361
JO - Nanoscale
JF - Nanoscale
SN - 2040-3364
IS - 1
ER -