Theoretical Chemistry Accounts

, Volume 130, Issue 4, pp 815–828

Interference-induced electron- and hole-conduction asymmetry

  • Sören Wohlthat
  • Gemma C. Solomon
  • Noel S. Hush
  • Jeffrey R. Reimers
Regular Article

DOI: 10.1007/s00214-011-1045-2

Cite this article as:
Wohlthat, S., Solomon, G.C., Hush, N.S. et al. Theor Chem Acc (2011) 130: 815. doi:10.1007/s00214-011-1045-2

Abstract

Principles established by Shephard and Paddon-Row for optimizing and controlling intramolecular electron transport through the modulation of interfering pathways are employed to design new molecules for steady-state conduction experiments aimed at manifesting electron–hole conduction asymmetry in a unique way. First, a review of the basic principles is presented through application to a pertinent model system in which a molecule containing donor and acceptor terminal linking groups with an internal multiple-pathway bridge is used to span two metal electrodes. Different interference patterns are produced depending on whether the through-molecule coupling pathways are symmetric or antisymmetric with respect to a topological bisecting plane, giving rise to asymmetric electron and hole conductances at the tight-binding (Hückel) level; this process is also described from a complementary molecular-orbital viewpoint. Subsequently, a new molecular system based on organic polyradicals is designed to allow such asymmetry to be realized in single-molecule conduction experiments. These polyradicals are analyzed using analogous simple models, density-functional theory (DFT) calculations of steady-state transmission, and intermediate neglect of differential overlap (INDO) calculations of intramolecular connectivity, verifying that polyradicals at low temperatures should show experimentally measureable electron–hole conduction asymmetry. A key feature of this system is that the polyradicals form a narrow partially occupied band of orbitals that lie within and well separated from the HOMO and LUMO orbitals of the surrounding molecular scaffold, allowing for holes and electrons to be transported through the same molecular band.

Keywords

Single-molecule conductivityElectron transferInterferencePolyradicalsElectron–hole conduction asymmetry

Supplementary material

214_2011_1045_MOESM1_ESM.pdf (709 kb)
Supplementary material 1 (PDF 709 kb)

Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • Sören Wohlthat
    • 1
  • Gemma C. Solomon
    • 2
  • Noel S. Hush
    • 1
    • 3
  • Jeffrey R. Reimers
    • 1
  1. 1.School of ChemistryThe University of SydneySydneyAustralia
  2. 2.Nano-Science Center and Department of ChemistryUniversity of CopenhagenCopenhagen ØDenmark
  3. 3.School of Molecular BioscienceThe University of SydneySydneyAustralia