Modular synthesis and dynamics of a variety of donor-acceptor interlocked compounds prepared by click chemistry

Adam B. Braunschweig, William R. Dichtel, Ognjen Š Miljanić, Mark A. Olson, Jason M. Spruell, Saeed I. Khan, James R. Heath, J. Fraser Stoddart

Research output: Contribution to journalArticlepeer-review

85 Scopus citations

Abstract

A series of donor-acceptor [2]-, [3]-, and [4]rotaxanes and self-complexes ([1]rotaxanes) have been synthesized by a threading-followed-by-stoppering approach, in which the precursor pseudorotaxanes are fixed by using Cu I-catalyzed Huisgen 1,3-dipolar cycloaddition to attach the required stoppers. This alternative approach to forming rotaxanes of the donor-acceptor type, in which the donor is a 1,5-dioxynaphthalene unit and the acceptor is the tetracationic cyclophane cyclobis(paraquat-p-phenylene), proceeds with enhanced yields relative to the tried and tested synthetic strategies, which involve the clipping of the cyclophane around a preformed dumbbell containing π-electron-donating recognition sites. The new synthetic approach is amenable to application to highly convergent sequences. To extend the scope of this reaction, we constructed [2]rotaxanes in which one of the phenylene rings of the tetracationic cyclophane is perfluorinated, a feature which significantly weakens its association with π-electron-rich guests. The activation barrier for the shuttling of the cyclophane over a spacer containing two triazole rings was determined to be (15.5 ± 0.1) kcal mol-1 for a degenerate two-station [2]rotaxane, a value similar to that previously measured for analogous degenerate compounds containing aromatic or ethylene glycol spacers. The triazole rings do not seem to perturb the shuttling process significantly; this property bodes well for their future incorporation into bistable molecular switches.

Original languageEnglish (US)
Pages (from-to)634-647
Number of pages14
JournalChemistry - An Asian Journal
Volume2
Issue number5
DOIs
StatePublished - Jul 2 2007

Keywords

  • Click chemistry
  • Cycloaddition
  • Host-guest systems
  • Interlocked compounds
  • Rotaxanes

ASJC Scopus subject areas

  • Biochemistry
  • Organic Chemistry

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