Electron delocalization in a rigid cofacial naphthalene-1,8:4,5- bis(dicarboximide) dimer

Yilei Wu, Marco Frasconi, Daniel M. Gardner, Paul R. McGonigal, Severin T. Schneebeli, Michael R. Wasielewski, J. Fraser Stoddart

Research output: Contribution to journalArticlepeer-review

116 Scopus citations


Investigating through-space electronic communication between discrete cofacially oriented aromatic π-systems is fundamental to understanding assemblies as diverse as double-stranded DNA, organic photovoltaics and thin-film transistors. A detailed understanding of the electronic interactions involved rests on making the appropriate molecular compounds with rigid covalent scaffolds and π-π distances in the range of ca. 3.5 Å. Reported herein is an enantiomeric pair of doubly-bridged naphthalene-1,8:4,5- bis(dicarboximide) (NDI) cyclophanes and the characterization of four of their electronic states, namely 1) the ground state, 2) the exciton coupled singlet excited state, 3) the radical anion with strong through-space interactions between the redox-active NDI molecules, and 4) the diamagnetic diradical dianion using UV/Vis/NIR, EPR and ENDOR spectroscopies in addition to X-ray crystallography. Despite the unfavorable Coulombic repulsion, the singlet diradical dianion dimer of NDI shows a more pronounced intramolecular π-π stacking interaction when compared with its neutral analog. Two are better than one: A doubly-bridged naphthalene diimide (NDI) cyclophane has been synthesized. It shows efficient π-orbital overlap between two rigid cofacial NDI units. The resulting through-space electronic delocalization in the neutral as well as reduced states induces emergent photophysical, electrochemical, and magnetic properties both in solution and in the solid phase.

Original languageEnglish (US)
Pages (from-to)9476-9481
Number of pages6
JournalAngewandte Chemie - International Edition
Issue number36
StatePublished - Sep 1 2014


  • cyclophane
  • excimer emission
  • mixed-valence compounds
  • radical anion dimer
  • π-electron delocalization

ASJC Scopus subject areas

  • General Chemistry
  • Catalysis


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