Motion capture and manipulation of a single synthetic molecular rotor by optical microscopy

Tomohiro Ikeda, Takahiro Tsukahara, Ryota Iino, Masayuki Takeuchi, Hiroyuki Noji

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


Single-molecule imaging and manipulation with optical microscopy have become essential methods for studying biomolecular machines; however, only few efforts have been directed towards synthetic molecular machines. Single-molecule optical microscopy was now applied to a synthetic molecular rotor, a double-decker porphyrin (DD). By attaching a magnetic bead (ca. 200 nm) to the DD, its rotational dynamics were captured with a time resolution of 0.5 ms. DD showed rotational diffusion with 90° steps, which is consistent with its four-fold structural symmetry. Kinetic analysis revealed the first-order kinetics of the 90° step with a rate constant of 2.8 s-1. The barrier height of the rotational potential was estimated to be greater than 7.4 kJ mol-1 at 298 K. The DD was also forcibly rotated with magnetic tweezers, and again, four stable pausing angles that are separated by 90° were observed. These results demonstrate the potency of single-molecule optical microscopy for the elucidation of elementary properties of synthetic molecular machines.

Original languageEnglish
Pages (from-to)10082-10085
Number of pages4
JournalAngewandte Chemie - International Edition
Issue number38
Publication statusPublished - 2014 Sept 15


  • molecular dynamics
  • molecular machines
  • optical microscopy
  • porphyrins
  • single-molecule studies


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