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Single-Molecule Solvation-Shell Sensing

Research output: Contribution to journalJournal article

Published

  • E. Leary
  • H. Hobenreich
  • S. J. Higgins
  • H. van Zalinge
  • W. Haiss
  • R. J. Nichols
  • C. M. Finch
  • I. Grace
  • Colin Lambert
  • R. McGrath
  • J. Smerdon
Article number086801
Journal publication date27/02/2009
JournalPhysical review letters
Journal number8
Volume102
Number of pages4
Pages-
Original languageEnglish

Abstract

We present a new route to single-molecule sensing via solvation shells surrounding a current-carrying backbone molecule. As an example, we show that the presence of a water solvation shell "gates" the conductance of a family of oligothiophene-containing molecular wires, and that the longer the oligothiophene, the larger is the effect. For the longest example studied, the molecular conductance is over 2 orders of magnitude larger in the presence of a shell comprising just 10 water molecules. A first principles theoretical investigation of electron transport through the molecules, using the nonequilibrium Green's function method, shows that water molecules interact directly with the thiophene rings, significantly shifting transport resonances and greatly increasing the conductance. This reversible effect is confirmed experimentally through conductance measurements performed in the presence of moist air and dry argon.