Mechanical conductance tunability of a porphyrin-cyclophane single-molecule junction

Schosser, Werner M. and Hsu, Chunwei and Zwick, Patrick and Beltako, Katawoura and Dulic, Diana and Mayor, Marcel and van der Zant, Herre S. J. and Pauly, Fabian. (2022) Mechanical conductance tunability of a porphyrin-cyclophane single-molecule junction. Nanoscale, 14 (3). pp. 984-992.

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The possibility to study quantum interference phenomena at ambient conditions is an appealing feature of molecular electronics. By connecting two porphyrins in a cofacial cyclophane, we create an attractive platform for mechanically controlling electric transport through the intramolecular extent of pi-orbital overlap of the porphyrins facing each other and through the angle of xanthene bridges with regard to the porphyrin planes. We analyze theoretically the evolution of molecular configurations in the pulling process and the corresponding changes in electric conduction by combining density functional theory (DFT) with Landauer scattering theory of phase-coherent elastic transport. Predicted conductances during the stretching process show order of magnitude variations caused by two robust destructive quantum interference features that span through the whole electronic gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). Mechanically-controlled break junction (MCBJ) experiments at room temperature verify the mechanosensitive response of the molecular junctions. During the continuous stretching of the molecule, they show conductance variations of up to 1.5 orders of magnitude over single breaking events. Uncommon triple- and quadruple-frequency responses are observed in periodic electrode modulation experiments with amplitudes of up to 10 angstrom. This further confirms the theoretically predicted double transmission dips caused by the spatial and energetic rearrangement of molecular orbitals, with contributions from both through-space and through-bond transport.
Faculties and Departments:05 Faculty of Science > Departement Chemie > Chemie > Molecular Devices and Materials (Mayor)
UniBasel Contributors:Zwick, Patrick and Mayor, Marcel
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:Royal Society of Chemistry
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:28 Feb 2022 08:16
Deposited On:28 Feb 2022 08:16

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