Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Article
  • Published:

Ultrafast dynamics in the power stroke of a molecular rotary motor

Nature Chemistry volume 4, pages 547–551 (2012)Cite this article

Subjects

Abstract

Light-driven molecular motors convert light into mechanical energy through excited-state reactions. Unidirectional rotary molecular motors based on chiral overcrowded alkenes operate through consecutive photochemical and thermal steps. The thermal (helix inverting) step has been optimized successfully through variations in molecular structure, but much less is known about the photochemical step, which provides power to the motor. Ultimately, controlling the efficiency of molecular motors requires a detailed picture of the molecular dynamics on the excited-state potential energy surface. Here, we characterize the primary events that follow photon absorption by a unidirectional molecular motor using ultrafast fluorescence up-conversion measurements with sub 50 fs time resolution. We observe an extraordinarily fast initial relaxation out of the Franck–Condon region that suggests a barrierless reaction coordinate. This fast molecular motion is shown to be accompanied by the excitation of coherent excited-state structural motion. The implications of these observations for manipulating motor efficiency are discussed.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Structure of the molecular motor 1.
Figure 2: Steady-state and time-resolved electronic spectroscopy of 1.
Figure 3: Excited-state dynamics viewed through the time-dependent emission.
Figure 4: Schematic model for the excited-state dynamics of 1.
Figure 5: Comparison of the resonance and off-resonance Raman spectra of 1 with the calculated Raman spectrum.

Similar content being viewed by others

References

  1. Kay, E. R., Leigh, D. A. & Zerbetto, F. Synthetic molecular motors and mechanical machines. Angew. Chem. Int. Ed. 46, 72–191 (2007).

    Article  CAS  Google Scholar 

  2. Balzani, V., Credi, A. & Venturi, M. Light powered molecular machines. Chem. Soc. Rev. 38, 1542–1550 (2009).

    Article  CAS  Google Scholar 

  3. Koumura, N., Zijlstra, R. W. J., van Delden, R. A., Harada, N. & Feringa, B. L. Light-driven monodirectional molecular rotor. Nature 401, 152–155 (1999).

    Article  CAS  Google Scholar 

  4. Koumura, N., Geertsema, E. M., van Gelder, M. B., Meetsma, A. & Feringa, B. L. Second generation light-driven molecular motors. Unidirectional rotation controlled by a single stereogenic center with near-perfect photoequilibria and acceleration of the speed of rotation by structural modification. J. Am. Chem. Soc. 124, 5037–5051 (2002).

    Article  CAS  Google Scholar 

  5. Vicario, J., Meetsma, A. & Feringa, B. L. Controlling the speed of rotation in molecular motors. Dramatic acceleration of the rotary motion by structural modification. Chem. Comm. 5910–5912 (2005).

  6. van Delden, R. A. et al. Unidirectional molecular motor on a gold surface. Nature 437, 1337–1340 (2005).

    Article  CAS  Google Scholar 

  7. Pollard, M. M., Klok, M., Pijper, D. & Feringa, B. L. Rate acceleration of light-driven rotary molecular motors. Adv. Funct. Mater. 17, 718–729 (2007).

    Article  CAS  Google Scholar 

  8. Klok, M. et al. MHz unidirectional rotation of molecular rotary motors. J. Am. Chem. Soc. 130, 10484–10485 (2008).

    Article  CAS  Google Scholar 

  9. Klok, M., Browne, W. R. & Feringa, B. L. Kinetic analysis of the rotation rate of light-driven unidirectional molecular motors. Phys. Chem. Chem. Phys. 11, 9124–9131 (2009).

    Article  CAS  Google Scholar 

  10. Augulis, R., Klok, M., Feringa, B. L. & van Loosdrecht, P. H. M. Light-driven rotary molecular motors: an ultrafast optical study. Phys. Status Solidi C 6, 181–184 (2009).

    Article  CAS  Google Scholar 

  11. Kazaryan, A. et al. Understanding the dynamics behind the photoisomerization of a light-driven fluorene molecular rotary motor. J. Phys. Chem. A 114, 5058–5067 (2010).

    Article  CAS  Google Scholar 

  12. Heisler, I. A., Kondo, M. & Meech, S. R. Reactive dynamics in confined liquids: ultrafast torsional dynamics of auramine O in nanoconfined water in aerosol OT reverse micelles. J. Phys. Chem. B 113, 1623–1631 (2009).

    Article  CAS  Google Scholar 

  13. Glasbeek, M. & Zhang, H. Femtosecond studies of solvation and intramolecular configurational dynamics of fluorophores in liquid solution. Chem. Rev. 104, 1929–1954 (2004).

    Article  CAS  Google Scholar 

  14. Morales, A. R., Belfield, K. D., Hales, J. M., Van Stryland, E. W. & Hagan, D. J. Synthesis of two-photon absorbing unsymmetrical fluorenyl-based chromophores. Chem. Mater. 18, 4972–4980 (2006).

    Article  CAS  Google Scholar 

  15. Nakamura, T., Takeuchi, S., Suzuki, N. & Tahara, T. Revised steady-state fluorescence spectrum and nature of the reactive S(1) state of cis-stilbene in solution. Chem. Phys. Lett. 465, 212–215 (2008).

    Article  CAS  Google Scholar 

  16. Mokhtari, A., Chebira, A. & Chesnoy, J. Subpicosecond fluorescence dynamics of dye molecules. J. Opt. Soc. Am. B 7, 1551–1557 (1990).

    Article  CAS  Google Scholar 

  17. Hauer, J., Buckup, T. & Motzkus, M. Enhancement of molecular modes by electronically resonant multipulse excitation: further progress towards mode selective chemistry. J. Chem. Phys. 125, 061101 (2006).

    Article  Google Scholar 

  18. Klok, M., Janssen, L., Browne, W. R. & Feringa, B. L. The influence of viscosity on the functioning of molecular motors. Faraday Discuss. 143, 319–334 (2009).

    Article  CAS  Google Scholar 

  19. Pollard, W. T., Lee, S. Y. & Mathies, R. A. Wave packet theory of dynamic absorption-spectra in femtosecond pump-probe experiments. J. Chem. Phys. 92, 4012–4029 (1990).

    Article  CAS  Google Scholar 

  20. Rubtsov, I. V. & Yoshihara, K. Vibrational coherence in electron donor–acceptor complexes. J. Phys. Chem. A 103, 10202–10212 (1999).

    Article  CAS  Google Scholar 

  21. Sanchez-Galvez, A. et al. Ultrafast radiationless deactivation of organic dyes: evidence for a two-state two-mode pathway in polymethine cyanines. J. Am. Chem. Soc. 122, 2911–2924 (2000).

    Article  CAS  Google Scholar 

  22. Hahn, S. & Stock, G. Quantum-mechanical modeling of the femtosecond isomerization in rhodopsin. J. Phys. Chem. B 104, 1146–1149 (2000).

    Article  CAS  Google Scholar 

  23. Levine, B. G. & Martinez, T. J. Isomerization through conical intersections. Annu. Rev. Phys. Chem. 58, 613–634 (2007).

    Article  CAS  Google Scholar 

  24. Myers, A. B. & Mathies, R. A. Excited-state torsional dynamics of cis-stilbene from resonance Raman intensities. J. Chem. Phys. 81, 1552–1558 (1984).

    Article  CAS  Google Scholar 

  25. Ishii, K., Takeuchi, S. & Tahara, T. A 40-fs time-resolved absorption study on cis-stilbene in solution: observation of wavepacket motion on the reactive excited state. Chem. Phys. Lett. 398, 400–406 (2004).

    Article  CAS  Google Scholar 

  26. Takeuchi, S. et al. Spectroscopic tracking of structural evolution in ultrafast stilbene photoisomerization. Science 322, 1073–1077 (2008).

    Article  CAS  Google Scholar 

  27. Hauer, J., Buckup, T. & Motzkus, M. Quantum control spectroscopy of vibrational modes: comparison of control scenarios for ground and excited states in beta-carotene. Chem. Phys. 350, 220–229 (2008).

    Article  CAS  Google Scholar 

  28. Prokhorenko, V. I. et al. Coherent control of retinal isomerization in bacteriorhodopsin. Science 313, 1257–1261 (2006).

    Article  CAS  Google Scholar 

  29. Flores, S. C. & Batista, V. S. Model study of coherent-control of the femtosecond primary event of vision. J. Phys. Chem. B 108, 6745–6749 (2004).

    Article  CAS  Google Scholar 

  30. Perez-Hernandez, G., Pelzer, A., Gonzalez, L. & Seideman, T. Biologically inspired molecular machines driven by light. Optimal control of a unidirectional rotor. New J. Phys. 12, 1–24 (2010).

    Article  Google Scholar 

  31. Rhee, H. & Joo, T. Noncollinear phase matching in fluorescence upconversion. Opt. Lett. 30, 96–98 (2005).

    Article  Google Scholar 

  32. Pollard, M. M., Meetsma, A. & Feringa, B. L. A redesign of light-driven rotary molecular motors. Org. Biomol. Chem. 6, 507–512 (2008).

    Article  CAS  Google Scholar 

Download references

Acknowledgements

This work was supported by the Engineering and Physical Sciences Research Council (EP/E010466), European Research Council (ERC) Starting Grant (279549; W.R.B.) and ERC Advanced Investigator Grant (227897; A.C., B.L.F.). J.C. was supported by a University of East Anglia studentship.

Author information

Authors and Affiliations

  1. School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK

    Jamie Conyard, Kiri Addison, Ismael A. Heisler & Stephen R. Meech

  2. Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, Groningen, 9747AG, The Netherlands

    Arjen Cnossen, Wesley R. Browne & Ben L. Feringa

Authors
  1. Jamie Conyard
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Kiri Addison
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Ismael A. Heisler
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Arjen Cnossen
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Wesley R. Browne
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Ben L. Feringa
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Stephen R. Meech
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

S.R.M., B.L.F. and W.R.B. conceived and designed the experiments. J.C. and K.A. performed the time-resolved experiments, I.H. constructed the up-conversion apparatus, A.C. and B.L.F. designed and synthesized 1, J.C. and A.C. performed the steady-state electronic spectroscopy, J.C. and I.H. analysed the time-resolved data, A.C. performed the density functional theory calculations, W.R.B obtained and analysed the Raman data, S.R.M. wrote the paper and all the authors commented and contributed to the writing of the manuscript.

Corresponding authors

Correspondence to Ben L. Feringa or Stephen R. Meech.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary information

Supplementary information (PDF 757 kb)

Rights and permissions

Reprints and permissions

About this article

Cite this article

Conyard, J., Addison, K., Heisler, I. et al. Ultrafast dynamics in the power stroke of a molecular rotary motor. Nature Chem 4, 547–551 (2012). https://doi.org/10.1038/nchem.1343

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nchem.1343

This article is cited by

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing