Probing pi-coupling in molecular junctions

Proc Natl Acad Sci U S A. 2005 Jun 21;102(25):8821-5. doi: 10.1073/pnas.0500002102. Epub 2005 Jun 14.

Abstract

Charge transport characteristics for metal-molecule-metal junctions containing two structurally related pi-conjugated systems were studied to probe pi-pi interactions in molecular junctions. The first molecule contains a typical pi-conjugated framework derived from phenylene vinylene units, whereas the second has the phenylene vinylene structure interrupted by a [2.2]paracyclophane (pCp) core. Electrochemical investigations were used to characterize the defects and packing density of self-assembled monolayers of the two molecules on gold surfaces and to enable quantitative comparison of their transport characteristics. Current-voltage measurements across molecular junctions containing the two species demonstrate that the pCp moiety yields a highly conductive break in through-bond pi-conjugation. The observed high conductivity is consistent with density functional theory calculations, which demonstrate strong through-space pi-pi coupling across the pCp moiety.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Electrochemistry / instrumentation
  • Electrochemistry / methods*
  • Magnetics
  • Models, Molecular
  • Molecular Conformation
  • Nanotechnology
  • Piperidines / chemistry*
  • Static Electricity
  • Styrenes / chemistry*
  • Surface Properties

Substances

  • Piperidines
  • Styrenes