A semiconducting organic radical cationic host-guest complex

Albert C. Fahrenbach, Srinivasan Sampath, Dattatray J. Late, Jonathan C. Barnes, Samuel L. Kleinman, Nicholas Valley, Karel J. Hartlieb, Zhichang Liu, Vinayak P. Dravid, George C. Schatz, Richard P. Van Duyne, J. Fraser Stoddart*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

42 Scopus citations


The self-assembly and solid-state semiconducting properties of single crystals of a trisradical tricationic complex composed of the diradical dicationic cyclobis(paraquat-p-phenylene) (CBPQT2(•+)) ring and methyl viologen radical cation (MV•+) are reported. An organic field effect transistor incorporating single crystals of the CBPQT 2(•+)⊂MV•+ complex was constructed using lithographic techniques on a silicon substrate and shown to exhibit p-type semiconductivity with a mobility of 0.05 cm2 V-1 s -1. The morphology of the crystals on the silicon substrate was characterized using scanning electron microscopy which revealed that the complexes self-assemble into "molecular wires" observable by the naked-eye as millimeter long crystalline needles. The nature of the recognition processes driving this self-assembly, radical-radical interactions between bipyridinium radical cations (BIPY•+), was further investigated by resonance Raman spectroscopy in conjunction with theoretical investigations of the vibrational modes, and was supported by X-ray structural analyses of the complex and its free components in both their radical cationic and dicationic redox states. These spectroscopic investigations demonstrate that the bond order of the BIPY•+ radical cationic units of host and guest components is not changed upon complexation, an observation which relates to its conductivity in the solid-state. We envision the modularity inherent in this kind of host-guest complexation could be harnessed to construct a library of custom-made electronic organic materials tailored to fit the specific needs of a given electronic application.

Original languageEnglish (US)
Pages (from-to)9964-9971
Number of pages8
JournalACS nano
Issue number11
StatePublished - Nov 27 2012


  • Raman spectroscopy
  • electrochemistry
  • molecular electronics
  • organic field effect transistors
  • quantum mechanics

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)


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