Probing pi-coupling in molecular junctions.
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.
Seferos
Dwight S
DS
Department of Chemistry, Institute for Polymers and Organic Solids, University of California, Santa Barbara, CA 93106, USA.
Trammell
Scott A
SA
Bazan
Guillermo C
GC
Kushmerick
James G
JG
D004563:Electrochemistry / Q000295:instrumentation / Q000379:methods*; D008280:Magnetics; D008958:Models, Molecular; D008968:Molecular Conformation; D036103:Nanotechnology; D010880:Piperidines / Q000737:chemistry*; D055672:Static Electricity; D013343:Styrenes / Q000737:chemistry*; D013499:Surface Properties
D010880:Piperidines; D013343:Styrenes