Tuning the electrical conductance of metalloporphyrin supramolecular wires

Noori, M. and Aragonès, A. and Di Palma, G. and Darwish, N. and Bailey, S. and Al-Galiby, Q. and Grace, I. et al. 2016. Tuning the electrical conductance of metalloporphyrin supramolecular wires. Scientific Reports. 6: Article 37352.

Source Title

Scientific Reports

DOI

10.1038/srep37352

School

Nanochemistry Research Institute

Remarks

This open access article is distributed under the Creative Commons license http://creativecommons.org/licenses/by/4.0/

URI

http://hdl.handle.net/20.500.11937/22308

Collection

Curtin Research Publications

Abstract

In contrast with conventional single-molecule junctions, in which the current flows parallel to the long axis or plane of a molecule, we investigate the transport properties of M(II)-5,15-diphenylporphyrin (M-DPP) single-molecule junctions (M=Co, Ni, Cu, or Zn divalent metal ions), in which the current flows perpendicular to the plane of the porphyrin. Novel STM-based conductance measurements combined with quantum transport calculations demonstrate that current-perpendicular-to-the-plane (CPP) junctions have three-orders-of-magnitude higher electrical conductances than their current-in-plane (CIP) counterparts, ranging from 2.10-2 G0 for Ni-DPP up to 8.10-2 G0 for Zn-DPP. The metal ion in the center of the DPP skeletons is strongly coordinated with the nitrogens of the pyridyl coated electrodes, with a binding energy that is sensitive to the choice of metal ion. We find that the binding energies of Zn-DPP and Co-DPP are significantly higher than those of Ni-DPP and Cu-DPP. Therefore when combined with its higher conductance, we identify Zn-DPP as the favoured candidate for high-conductance CPP single-molecule devices.