A multi-mode-driven molecular shuttle

Photochemically and thermally reactive azobenzene rotaxanes

Hiroto Murakami, Atsushi Kawabuchi, Rika Matsumoto, Takeshi Ido, Naotoshi Nakashima

Research output: Contribution to journalArticle

162 Citations (Scopus)

Abstract

The shuttling process of α-CyD in three rotaxanes (1-3) containing α-cyclodextrin (α-CyD) as a ring, azobenzene as a photoactive group, viologen as an energy barrier for slipping of the ring, and 2,4-dinitrobenzene as a stopper was investigated. The trans-cis photoisomerization of 1 by UV light irradiation occurred in both DMSO and water due to the movement of α-CyD toward the ethylene group, while the photoisomerization of 2 occurred in DMSO, but not in water. No photoisomerization was observed for 3 in both water and DMSO. The activation parameters of 1 and 1-ref in DMSO are subject to a compensation relation between ΔS‡ and ΔH‡; however, in water, the ΔS‡ terms are not compensated by the ΔH‡ terms. Alternating irradiation of the UV and visible lights resulted in a reversible change in the induced circular dichroism (ICD) bands of trans-1 and cis-1. In contrast, after the UV light irradiation, the ICD band of trans-2 decreased without the appearance of any bands of c/s-2. The NMR spectra of 2 in DMSO showed coalescence of the split signals for the methylene and for the viologen protons due to the shuttling of α-CyD. Both the NOE differential spectra for cis-1 in water after UV light irradiation and 2 in DMSO after heating to 120 °C showed the negative NOE peaks assigned to interior protons of α-CyD, suggesting that α-CyD in cis-1 exists at the one ethylene moiety, and α-CyDs in cis-2 and 2 heated in DMSO exist at the propylene moieties.

Original languageEnglish
Pages (from-to)15891-15899
Number of pages9
JournalJournal of the American Chemical Society
Volume127
Issue number45
DOIs
Publication statusPublished - Nov 16 2005

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Rotaxanes
Azobenzene
Dimethyl Sulfoxide
Photoisomerization
Ultraviolet Rays
Irradiation
Ultraviolet radiation
Viologens
Dichroism
Water
Ethylene
Protons
Circular Dichroism
Energy barriers
Cyclodextrins
Coalescence
Propylene
Chemical activation
Nuclear magnetic resonance
azobenzene

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

A multi-mode-driven molecular shuttle : Photochemically and thermally reactive azobenzene rotaxanes. / Murakami, Hiroto; Kawabuchi, Atsushi; Matsumoto, Rika; Ido, Takeshi; Nakashima, Naotoshi.

In: Journal of the American Chemical Society, Vol. 127, No. 45, 16.11.2005, p. 15891-15899.

Research output: Contribution to journalArticle

Murakami, Hiroto ; Kawabuchi, Atsushi ; Matsumoto, Rika ; Ido, Takeshi ; Nakashima, Naotoshi. / A multi-mode-driven molecular shuttle : Photochemically and thermally reactive azobenzene rotaxanes. In: Journal of the American Chemical Society. 2005 ; Vol. 127, No. 45. pp. 15891-15899.
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