Controlling switching in bistable [2]catenanes by combining donor-acceptor and radical-radical interactions

Zhixue Zhu, Albert C. Fahrenbach, Hao Li, Jonathan C. Barnes, Zhichang Liu, Scott M. Dyar, Huacheng Zhang, Juying Lei, Raanan Carmieli, Amy A. Sarjeant, Charlotte L. Stern, Michael R Wasielewski, J. Fraser Stoddart

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Abstract

Two redox-active bistable [2]catenanes composed of macrocyclic polyethers of different sizes incorporating both electron-rich 1,5-dioxynaphthalene (DNP) and electron-deficient 4,4′-bipyridinium (BIPY 2+) units, interlocked mechanically with the tetracationic cyclophane cyclobis(paraquat-p- phenylene) (CBPQT 4+), were obtained by donor-acceptor template-directed syntheses in a threading-followed-by-cyclization protocol employing Cu(I)-catalyzed azide-alkyne 1,3-dipolar cycloadditions in the final mechanical-bond forming steps. These bistable [2]catenanes exemplify a design strategy for achieving redox-active switching between two translational isomers, which are driven (i) by donor-acceptor interactions between the CBPQT 4+ ring and DNP, or (ii) radical-radical interactions between CBPQT 2(•+) and BIPY •+, respectively. The switching processes, as well as the nature of the donor-acceptor interactions in the ground states and the radical-radical interactions in the reduced states, were investigated by single-crystal X-ray crystallography, dynamic 1H NMR spectroscopy, cyclic voltammetry, UV/vis spectroelectrochemistry, and electron paramagnetic resonance (EPR) spectroscopy. The crystal structure of one of the [2]catenanes in its trisradical tricationic redox state provides direct evidence for the radical-radical interactions which drive the switching processes for these types of mechanically interlocked molecules (MIMs). Variable-temperature 1H NMR spectroscopy reveals a degenerate rotational motion of the BIPY 2+ units in the CBPQT 4+ ring for both of the two [2]catenanes, that is governed by a free energy barrier of 14.4 kcal mol -1 for the larger catenane and 17.0 kcal mol -1 for the smaller one. Cyclic voltammetry provides evidence for the reversibility of the switching processes which occurs following a three-electron reduction of the three BIPY 2+ units to their radical cationic forms. UV/vis spectroscopy confirms that the processes driving the switching are (i) of the donor-acceptor type, by the observation of a 530 nm charge-transfer band in the ground state, and (ii) of the radical-radical ilk in the switched state as indicated by an intense visible absorption (ca. 530 nm) and near-infrared (ca. 1100 nm) bands. EPR spectroscopic data reveal that, in the switched state, the interacting BIPY •+ radical cations are in a fast exchange regime. In general, the findings lay the foundations for future investigations where this radical-radical recognition motif is harnessed in bistable redox-active MIMs in order to achieve close to homogeneous populations of co-conformations in both the ground and switched states.

Original languageEnglish
Pages (from-to)11709-11720
Number of pages12
JournalJournal of the American Chemical Society
Volume134
Issue number28
DOIs
Publication statusPublished - Jul 18 2012

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Catenanes
Oxidation-Reduction
Electron Spin Resonance Spectroscopy
Electrons
Spectrum Analysis
Magnetic Resonance Spectroscopy
Ground state
Nuclear magnetic resonance spectroscopy
Cyclic voltammetry
Paramagnetic resonance
Paraquat
Alkynes
Azides
X Ray Crystallography
Spectroelectrochemistry
Cycloaddition Reaction
Cyclization
Molecules
Cycloaddition
Polyethers

ASJC Scopus subject areas

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

Cite this

Zhu, Z., Fahrenbach, A. C., Li, H., Barnes, J. C., Liu, Z., Dyar, S. M., ... Stoddart, J. F. (2012). Controlling switching in bistable [2]catenanes by combining donor-acceptor and radical-radical interactions. Journal of the American Chemical Society, 134(28), 11709-11720. https://doi.org/10.1021/ja3037355

Controlling switching in bistable [2]catenanes by combining donor-acceptor and radical-radical interactions. / Zhu, Zhixue; Fahrenbach, Albert C.; Li, Hao; Barnes, Jonathan C.; Liu, Zhichang; Dyar, Scott M.; Zhang, Huacheng; Lei, Juying; Carmieli, Raanan; Sarjeant, Amy A.; Stern, Charlotte L.; Wasielewski, Michael R; Stoddart, J. Fraser.

In: Journal of the American Chemical Society, Vol. 134, No. 28, 18.07.2012, p. 11709-11720.

Research output: Contribution to journalArticle

Zhu, Z, Fahrenbach, AC, Li, H, Barnes, JC, Liu, Z, Dyar, SM, Zhang, H, Lei, J, Carmieli, R, Sarjeant, AA, Stern, CL, Wasielewski, MR & Stoddart, JF 2012, 'Controlling switching in bistable [2]catenanes by combining donor-acceptor and radical-radical interactions', Journal of the American Chemical Society, vol. 134, no. 28, pp. 11709-11720. https://doi.org/10.1021/ja3037355
Zhu, Zhixue ; Fahrenbach, Albert C. ; Li, Hao ; Barnes, Jonathan C. ; Liu, Zhichang ; Dyar, Scott M. ; Zhang, Huacheng ; Lei, Juying ; Carmieli, Raanan ; Sarjeant, Amy A. ; Stern, Charlotte L. ; Wasielewski, Michael R ; Stoddart, J. Fraser. / Controlling switching in bistable [2]catenanes by combining donor-acceptor and radical-radical interactions. In: Journal of the American Chemical Society. 2012 ; Vol. 134, No. 28. pp. 11709-11720.
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T1 - Controlling switching in bistable [2]catenanes by combining donor-acceptor and radical-radical interactions

AU - Zhu, Zhixue

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AU - Barnes, Jonathan C.

AU - Liu, Zhichang

AU - Dyar, Scott M.

AU - Zhang, Huacheng

AU - Lei, Juying

AU - Carmieli, Raanan

AU - Sarjeant, Amy A.

AU - Stern, Charlotte L.

AU - Wasielewski, Michael R

AU - Stoddart, J. Fraser

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