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Electrostatic catalysis of a Diels–Alder reaction

Journal Article


Abstract


  • It is often thought that the ability to control reaction rates with an

    applied electrical potential gradient is unique to redox systems.

    However, recent theoretical studies suggest that oriented electric

    fields could affect the outcomes of a range of chemical reactions,

    regardless of whether a redox system is involved1–4. This possibility

    arises because many formally covalent species can be stabilized via

    minor charge-separated resonance contributors. When an applied

    electric field is aligned in such a way as to electrostatically stabilize

    one of these minor forms, the degree of resonance increases,

    resulting in the overall stabilization of the molecule or transition

    state. This means that it should be possible to manipulate the

    kinetics and thermodynamics of non-redox processes using an

    external electric field, as long as the orientation of the approaching

    reactants with respect to the field stimulus can be controlled. Here,

    we provide experimental evidence that the formation of carbon–

    carbon bonds is accelerated by an electric field. We have designed

    a surface model system to probe the Diels–Alder reaction, and

    coupled it with a scanning tunnelling microscopy break-junction

    approach5–7. This technique, performed at the single-molecule

    level, is perfectly suited to deliver an electric-field stimulus across

    approaching reactants. We find a fivefold increase in the frequency

    of formation of single-molecule junctions, resulting from the

    reaction that occurs when the electric field is present and aligned

    so as to favour electron flow from the dienophile to the diene. Our

    results are qualitatively consistent with those predicted by quantumchemical

    calculations in a theoretical model of this system, and

    herald a new approach to chemical catalysis

Authors


  •   Aragones, Albert C. (external author)
  •   Haworth, Naomi (external author)
  •   Darwish, Nadim A. (external author)
  •   Ciampi, Simone (external author)
  •   Bloomfield, Nathaniel J. (external author)
  •   Wallace, Gordon G.
  •   Diez-Perez, Ismael (external author)
  •   Coote, M L. (external author)

Publication Date


  • 2016

Published In


Citation


  • Aragones, A. C., Haworth, N. L., Darwish, N., Ciampi, S., Bloomfield, N. J., Wallace, G. G., Diez-Perez, I. & Coote, M. L. (2016). Electrostatic catalysis of a Diels–Alder reaction. Nature, 531 (7592), 88-91.

Scopus Eid


  • 2-s2.0-84960119002

Ro Metadata Url


  • http://ro.uow.edu.au/aiimpapers/1803

Has Global Citation Frequency


Number Of Pages


  • 3

Start Page


  • 88

End Page


  • 91

Volume


  • 531

Issue


  • 7592

Place Of Publication


  • United Kingdom

Abstract


  • It is often thought that the ability to control reaction rates with an

    applied electrical potential gradient is unique to redox systems.

    However, recent theoretical studies suggest that oriented electric

    fields could affect the outcomes of a range of chemical reactions,

    regardless of whether a redox system is involved1–4. This possibility

    arises because many formally covalent species can be stabilized via

    minor charge-separated resonance contributors. When an applied

    electric field is aligned in such a way as to electrostatically stabilize

    one of these minor forms, the degree of resonance increases,

    resulting in the overall stabilization of the molecule or transition

    state. This means that it should be possible to manipulate the

    kinetics and thermodynamics of non-redox processes using an

    external electric field, as long as the orientation of the approaching

    reactants with respect to the field stimulus can be controlled. Here,

    we provide experimental evidence that the formation of carbon–

    carbon bonds is accelerated by an electric field. We have designed

    a surface model system to probe the Diels–Alder reaction, and

    coupled it with a scanning tunnelling microscopy break-junction

    approach5–7. This technique, performed at the single-molecule

    level, is perfectly suited to deliver an electric-field stimulus across

    approaching reactants. We find a fivefold increase in the frequency

    of formation of single-molecule junctions, resulting from the

    reaction that occurs when the electric field is present and aligned

    so as to favour electron flow from the dienophile to the diene. Our

    results are qualitatively consistent with those predicted by quantumchemical

    calculations in a theoretical model of this system, and

    herald a new approach to chemical catalysis

Authors


  •   Aragones, Albert C. (external author)
  •   Haworth, Naomi (external author)
  •   Darwish, Nadim A. (external author)
  •   Ciampi, Simone (external author)
  •   Bloomfield, Nathaniel J. (external author)
  •   Wallace, Gordon G.
  •   Diez-Perez, Ismael (external author)
  •   Coote, M L. (external author)

Publication Date


  • 2016

Published In


Citation


  • Aragones, A. C., Haworth, N. L., Darwish, N., Ciampi, S., Bloomfield, N. J., Wallace, G. G., Diez-Perez, I. & Coote, M. L. (2016). Electrostatic catalysis of a Diels–Alder reaction. Nature, 531 (7592), 88-91.

Scopus Eid


  • 2-s2.0-84960119002

Ro Metadata Url


  • http://ro.uow.edu.au/aiimpapers/1803

Has Global Citation Frequency


Number Of Pages


  • 3

Start Page


  • 88

End Page


  • 91

Volume


  • 531

Issue


  • 7592

Place Of Publication


  • United Kingdom