A multistate switchable [3]rotacatenane

Gokhan Barin, Ali Coskun, Douglas C. Friedman, Mark A. Olson, Michael T. Colvin, Raanan Carmielli, Sanjeev K. Dey, O. Altan Bozdemir, Michael R. Wasielewski, J. Fraser Stoddart

Research output: Contribution to journalArticlepeer-review

55 Scopus citations


Rotacatenanes are exotic molecular compounds that can be visualized as a unique combination of a [2]catenane and a [2]rotaxane, thereby combining both the circumrotation of the ring component (rotary motion) and the shuttling of the dumbbell component (translational motion) in one structure. Herein, we describe a strategy for the synthesis of a new switchable [3]rotacatenane and the investigation of its switching properties, which rely on the formation of tetrathiafulvalene (TTF) radical π-dimer interactions-namely, the mixed-valence state (TTF2)+. and the radical-cation dimer state (TTF+.)2-under ambient conditions. A template-directed approach, based on donor-acceptor interactions, has been developed, resulting in an improved yield of the key precursor [2]catenane, prior to rotacatenation. The nature of the binding between the [2]catenane and selected π-electron-rich templates has been elucidated by using X-ray crystallography and UV/Vis spectroscopy as well as isothermal titration microcalorimetry. The multistate switching mechanism of the [3]rotacatenane has been demonstrated by cyclic voltammetry and EPR spectroscopy. Most notably, the radical-cation dimer state (TTF+.)2 has been shown to enter into an equilibrium by forming the co-conformation in which the two 1,5-dioxynaphthalene (DNP) units co-occupy the cavity of tetracationic cyclophane, thus enforcing the separation of TTF radical-cation dimer (TTF +.)2. The population ratio of this equilibrium state was found to be 1:1. We believe that this research demonstrates the power of constructing complex molecular machines using template-directed protocols, enabling us to make the transition from simple molecular switches to their multistate variants for enhancing information storage in molecular electronic devices.

Original languageEnglish (US)
Pages (from-to)213-222
Number of pages10
JournalChemistry - A European Journal
Issue number1
StatePublished - Jan 3 2011


  • molecular switches
  • radical dimerization
  • rotacatenanes
  • template-directed synthesis
  • tetrathiafulvalenes

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry


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