Hapticity-dependent charge transport through carbodithioate-terminated [5,15-bis(phenylethynyl)porphinato]zinc(II) complexes in metal-molecule-metal junctions

Zhihai Li, Manuel Smeu, Tae Hong Park, Jeff Rawson, Yangjun Xing, Michael J. Therien, Mark A. Ratner, Eric Borguet

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Single molecule break junction experiments and nonequilibrium Green's function calculations using density functional theory (NEGF-DFT) of carbodithioate- and thiol-terminated [5,15-bis(phenylethynyl)-10,20-diarylporphinato]zinc(II) complexes reveal the impact of the electrode-linker coordination mode on charge transport at the single-molecule level. Replacement of thiolate (-S-) by the carbodithioate (-CS2-) anchoring motif leads to an order of magnitude increase of single molecule conductance. In contrast to thiolate-terminated structures, metal-molecule-metal junctions that exploit the carbodithioate linker manifest three distinct conductance values. We hypothesize that the magnitudes of these conductances depend upon carbodithoate linker hapticity with measured conductances across Au-[5,15-bis(4′-(dithiocarboxylate)phenylethynyl)-10,20-diarylporphinato]zinc(II)-Au junctions the greatest when both anchoring groups attach to the metal surface in a bidentate fashion. We support this hypothesis with NEGF-DFT calculations, which consider the electron transport properties for specific binding geometries. These results provide new insights into the origin of molecule-to-molecule conductance heterogeneity in molecular charge transport measurements and the factors that optimize electrode-molecule-electrode electronic coupling and maximize the conductance for charge transport.

Original languageEnglish
Pages (from-to)5493-5499
Number of pages7
JournalNano letters
Volume14
Issue number10
DOIs
Publication statusPublished - Oct 8 2014

Keywords

  • Linker hapticity
  • NEGF-DFT
  • STM break junction
  • carbodithioate linker
  • molecular electronics

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

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