Speed-controlled molecular shuttles

Martin Bělohradský, Arkadij M. Elizarov, J. Fraser Stoddart*

*Corresponding author for this work

Research output: Contribution to journalArticle

26 Scopus citations

Abstract

Five potential molecular shuttles based on degenerate [2]rotaxanes - wherein the ring component is a bis-1,4-phenylene[34]crown-10 and the dumbbell components are terminated by tetraarylmethane (slippage) stoppers and contain two identical bipyridinium recognition sites and a central 1,3-phenylene unit carrying a CH2OR (R = Me, Et, Ph, i-Pr, and t-Bu) substituent on its C-5 position - have been prepared by acylating the parent hydroxymethyl derivative with the appropriate reagents. Dynamic 1H NMR spectroscopy, carried out on these five potential molecular shuttles in CD3CN solutions, has revealed average Gibbs energy barriers to shuttling of 11.5, 12.0, 14.6, and 14.8 kcal mol-1 for the [2]rotaxanes where R = Me, Et, i-Pr, and Ph, respectively. For the [2]rotaxane where R = t-Bu, the Gibbs energy barrier to shuttling must exceed 17.2 kcal mol-1.

Original languageEnglish (US)
Pages (from-to)1719-1728
Number of pages10
JournalCollection of Czechoslovak Chemical Communications
Volume67
Issue number11
DOIs
StatePublished - Nov 1 2002

Keywords

  • Bipyridinium salts
  • Crown ethers
  • Dynamic NMR spectroscopy
  • Molecular machines
  • Molecular recognition
  • Molecular shuttle
  • Post-assembly covalent modification
  • Rotaxanes

ASJC Scopus subject areas

  • Chemistry(all)

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