Mapping the excited-state potential energy surface of a photomolecular motor

Christopher R Hall, Wesley R. Browne, Ben L. Feringa, Stephen R. Meech

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)
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A detailed understanding of the operation and efficiency of unidirectional photomolecular rotary motors is essential for their effective exploitation in molecular nanomachines. Unidirectional motion relies on light‐driven conversion from a stable (1 a) to a metastable (1 b) conformation, which then relaxes through a thermally driven helix inversion in the ground state. The excited‐state surface has thus far only been experimentally characterised for 1 a. Here we probe the metastable, 1 b, excited state, utilising ultrafast transient absorption and femtosecond stimulated Raman spectroscopy. These reveal that the “dark” excited‐state intermediate between 1 a and 1 b has a different lifetime and structure depending on the initial ground‐state conformation excited. This suggests that the reaction coordinate connecting 1 a to 1 b differs to that for the reverse photochemical process. The result is contrasted with earlier calculations.
Original languageEnglish
Pages (from-to)6203-6207
Number of pages5
JournalAngewandte Chemie International Edition
Issue number21
Early online date6 Apr 2018
Publication statusPublished - 22 May 2018


  • energy conversion
  • excited states
  • molecular motors
  • photochemistry
  • ultrafast dynamics

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