Self-assembly of [n]rotaxanes bearing dendritic stoppers

David B. Amabilino, Peter R. Ashton, Vincenzo Balzani, Christopher L. Brown, Alberto Credi, Jean M J Fréchet, Jeffrey W. Leon, Francisco Raymo, Neil Spencer, J. Fraser Stoddart, Margherita Venturi

Research output: Contribution to journalArticle

120 Citations (Scopus)

Abstract

We have developed a synthetic approach to the self-assembly of [2]-, [3]-, and [4]rotaxanes, incorporating bis-p-phenylene-34-crown-10 as the ring component(s) surrounding bipyridinium-based dumbbell-shaped components bearing dendritic stoppers at both ends. As a result of the hydrophobic dendritic framework, these [n]rotaxanes are soluble in a wide range of organic solvents, despite the polycationic natures of their bipyridinium-based backbones. In all cases, they could be purified by means of column chromatography employing relatively low polar eluants. The molecular shuttling action of the [2]rotaxane containing two bipyridinium units on the rod portion of the dumbbell shaped component has been investigated by variable-temperature 1H-NMR spectroscopy in a range of solvents [CDCl3, CD2Cl2, THF-d8, and (CD3)2CO] for the first time. This investigation reveals a marked dependence of the rate of the shuttling process upon the polarity of the media. On going from CDCl3 to (CD3)2CO, the rate constant increases from ca. 200 to 33000 times per second. Molecular dynamics simulations, performed in CHCl3 and Me2CO on the [2]rotaxane, suggest that significant conformational changes occur upon changing the polarity of the medium resulting in both steric and electronic hindrance of the shuttling process in CHCl3. Three-dimensional representations, as well as the approximate sizes - i.e. overall lengths and molecular volumes which range from 3 to 6 nm and from 4 to 6 nm3, respectively - of these molecular compounds, were obtained by means of molecular modeling studies. Thus, these nanometer-scale dendritic rotaxanes resemble naturally-occurring chemical systems incorporating an active component, in so far as the rotaxane-like core with its distinctive recognition features is surrounded by a molecular shell in the form of the dendritic framework.

Original languageEnglish
Pages (from-to)12012-12020
Number of pages9
JournalJournal of the American Chemical Society
Volume118
Issue number48
DOIs
StatePublished - Dec 1 1996
Externally publishedYes

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Bearings (structural)
Rotaxanes
Column chromatography
Molecular modeling
Organic solvents
Self assembly
Nuclear magnetic resonance spectroscopy
Molecular dynamics
Rate constants
Computer simulation
Temperature
Molecular Dynamics Simulation
Chromatography
Magnetic Resonance Spectroscopy

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Amabilino, D. B., Ashton, P. R., Balzani, V., Brown, C. L., Credi, A., Fréchet, J. M. J., ... Venturi, M. (1996). Self-assembly of [n]rotaxanes bearing dendritic stoppers. Journal of the American Chemical Society, 118(48), 12012-12020. https://doi.org/10.1021/ja962113h

Self-assembly of [n]rotaxanes bearing dendritic stoppers. / Amabilino, David B.; Ashton, Peter R.; Balzani, Vincenzo; Brown, Christopher L.; Credi, Alberto; Fréchet, Jean M J; Leon, Jeffrey W.; Raymo, Francisco; Spencer, Neil; Stoddart, J. Fraser; Venturi, Margherita.

In: Journal of the American Chemical Society, Vol. 118, No. 48, 01.12.1996, p. 12012-12020.

Research output: Contribution to journalArticle

Amabilino, DB, Ashton, PR, Balzani, V, Brown, CL, Credi, A, Fréchet, JMJ, Leon, JW, Raymo, F, Spencer, N, Stoddart, JF & Venturi, M 1996, 'Self-assembly of [n]rotaxanes bearing dendritic stoppers', Journal of the American Chemical Society, vol. 118, no. 48, pp. 12012-12020. https://doi.org/10.1021/ja962113h
Amabilino DB, Ashton PR, Balzani V, Brown CL, Credi A, Fréchet JMJ et al. Self-assembly of [n]rotaxanes bearing dendritic stoppers. Journal of the American Chemical Society. 1996 Dec 1;118(48):12012-12020. https://doi.org/10.1021/ja962113h
Amabilino, David B. ; Ashton, Peter R. ; Balzani, Vincenzo ; Brown, Christopher L. ; Credi, Alberto ; Fréchet, Jean M J ; Leon, Jeffrey W. ; Raymo, Francisco ; Spencer, Neil ; Stoddart, J. Fraser ; Venturi, Margherita. / Self-assembly of [n]rotaxanes bearing dendritic stoppers. In: Journal of the American Chemical Society. 1996 ; Vol. 118, No. 48. pp. 12012-12020.
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