High-efficiency switching effect in porphyrin-ethyne-benzene conjugates

Yi Peng An*, Zhongqin Yang, Mark A. Ratner

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

42 Scopus citations


We have explored the electronic transport properties of porphyrin-ethyne-benzene conjugates using an ab initio method. The results indicate that these ethyne-bridged phenyl porphyrin molecules can be used as candidates for molecular switching devices. The coplanar conformation of phenyl and porphyrin moieties allows a far larger current than the perpendicular conformation due to the near vanishing overlap of the frontier molecular orbitals (π channels) in the porphyrin and phenyl parts in the latter. Higher current ratios of ONOFF states can be obtained if amino or nitro substituent is placed at the position meta to the bridge connecting the π systems of the molecule. The substituent group affects the electronic state energy of the entire molecule in coplanar conformation, while only affecting the local part in perpendicular conformation. More complex ethyne-bridged diphenyl porphyrin molecules are found to yield more complex and interesting switching effects. Our results suggest that such molecular wires composed of appropriate π-conjugated molecules, can generally display perfect switching function and the efficiency can be tuned flexibly by adding certain substituent groups to the conjugates.

Original languageEnglish (US)
Article number044706
JournalJournal of Chemical Physics
Issue number4
StatePublished - Jul 28 2011

ASJC Scopus subject areas

  • General Physics and Astronomy
  • Physical and Theoretical Chemistry


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