Toward controllable molecular shuttles

Pier Lucio Anelli, Masumi Asakawa, Peter R. Ashton, Richard A. Bissell, Gilles Clavier, Romuald Górski, Angel E. Kaifer, Steven J. Langford, Gunter Mattersteig, Stephan Menzer, Douglas Philp, Alexandra M.Z. Slawin, Neil Spencer, J. Fraser Stoddart, Malcolm S. Tolley, David J. Williams

Research output: Contribution to journalArticle

150 Scopus citations

Abstract

A number of nanometer-scale molecular assemblies, based on rotaxane-type structures, have been synthesized by means of a template-directed strategy from simple building blocks that, on account of the molecular recognition arising from the noncovalent interactions between them, are able to self-assemble into potential molecular abacuses. In all the cases investigated, the π-electron-deficient tetracationic cyclophane cyclobis(paraquat-p-phenylene) is constrained mechanically around a dumbbell-shaped component consisting of a linear polyether chain intercepted by at least two, if not three, π-electron-rich units and terminated at each end by blocking groups or stoppers. The development of an approach toward constructing these molecular abacuses, in which the tetracationic cyclophane is able to shuttle back and forth with respect to the dumbbell-shaped component, begins with the self-assembly of a [2]rotaxane consisting of two hydroquinone rings symmetrically positioned within a polyether chain terminated by triisopropylsilyl ether blocking groups. In this first so-called molecular shuttle, the tetracationic cyclophane oscillates in a degenerate fashion between the two π-electron-rich hydroquinone rings. Replacement of one of the hydroquinone rings-or the insertion of another π-electron-rich ring system between the two hydroquinone rings-introduces the possibility of translational isomerism, a phenomenon that arises because of the different relative positions and populations of the tetracationic cyclophane with respect to the π-donor sites on the dumbbell-shaped component. In two subsequent [2]rotaxanes, one of the hydroquinone rings in the dumbbell-shaped component is replaced, first by a p-xylyl and then by an indole unit. Finally, a tetrathiafulvalene (TTF) unit is positioned between two hydroquinone rings in the dumbbell-shaped component. Spectroscopic and electrochemical investigations carried out on these first-generation molecular shuttles show that they could be developed as molecular switches.

Original languageEnglish (US)
Pages (from-to)1113-1135
Number of pages23
JournalChemistry - A European Journal
Volume3
Issue number7
DOIs
StatePublished - Jul 1997

Keywords

  • Molecular devices
  • Nanostructures
  • Rotaxanes
  • Self-assembly
  • Translational isomerism

ASJC Scopus subject areas

  • Chemistry(all)

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  • Cite this

    Anelli, P. L., Asakawa, M., Ashton, P. R., Bissell, R. A., Clavier, G., Górski, R., Kaifer, A. E., Langford, S. J., Mattersteig, G., Menzer, S., Philp, D., Slawin, A. M. Z., Spencer, N., Fraser Stoddart, J., Tolley, M. S., & Williams, D. J. (1997). Toward controllable molecular shuttles. Chemistry - A European Journal, 3(7), 1113-1135. https://doi.org/10.1002/chem.19970030719