Oligo(aryleneethynylene)s with Terminal Pyridyl Groups: Synthesis and Length Dependence of the Tunneling-to-Hopping Transition of Single-Molecule Conductances

Abstract

Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractThe synthesis is reported of a new series of olig(oaryleneethynylene) (OAE) derivatives of up to ca. 6 nm molecular length (OAE9) using iterative Pd-mediated Sonogashira cross-coupling methodology.The oligo-p-phenyleneethynylene (OPE) cores of the molecular wires are functionalized at both termini with pyridyl units for attachment to gold leads. The molecular structures determined by single crystal Xray analysis are reported for OAE4, 5, 7 and 8a. The charge transport characteristics of derivatives OAE3 -OAE9 in single-molecular junctions have been studied using the mechanically controlled break junction (MCBJ) technique. The data demonstrate that the junction conductance decreases with increasing molecular length. A transition from coherent transport via tunneling to a hopping mechanism is found for OAE wires longer than ca. 3 nm.

Oligo(p‐phenyleneethynylene) (OPE) Molecular Wires: Synthesis and Length Dependence of Photoinduced Charge Transfer in OPEs with Triarylamine and Diaryloxadiazole End Groups

“…[24,25] Electronic conduction through OPE wires anchored in metal-molecule-metal junctions has also been reported, with length dependent tunneling-to-hopping transitions observed. [26,27] In the present investigation we focus on a new series of five D-B-A complexes 1-5…”

Searching the Hearts of Graphene-like Molecules for Simplicity, Sensitivity, and Logic

“…[1][2][3] Nowadays there is intense interest in utilising these patterns in the optimisation of single-molecule device performance. Indeed, electrons passing through single molecules have been demonstrated to remain phase coherent, even at room temperature [3][4][5] and a series of theoretical and experimental studies have shown that their room-temperature electrical conductance is influenced by quantum interference (QI). [6][7][8][9][10][11][12][13][14][15][16][17][18][19] In practice, the task of identifying and harnessing quantum effects is hampered, because transport properties are strongly affected by the method used to anchor single molecules to electrodes [20][21][22][23][24][25][26][27][28][29][30] .…”

Carbazole‐Based Tetrapodal Anchor Groups for Gold Surfaces: Synthesis and Conductance Properties

“…Given the close proximity to the Au surface, the slightly reduced steric bulk of a pyridine lone pair versus a benzene hydrogen atom could mean that more molecular conformations are possible within the Au–SAM–probe ensemble in the pyridine case. The extent of electronic coupling between the Au surface and the conductive backbone through the pyridine nitrogen, a known anchor group, could vary significantly with conformation, thus affording a broad conductance distribution.…”