Premium
Motion Capture and Manipulation of a Single Synthetic Molecular Rotor by Optical Microscopy
Author(s) -
Ikeda Tomohiro,
Tsukahara Takahiro,
Iino Ryota,
Takeuchi Masayuki,
Noji Hiroyuki
Publication year - 2014
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201403091
Subject(s) - magnetic tweezers , rotational diffusion , optical tweezers , microscopy , optical microscope , chemistry , molecule , resolution (logic) , rotation around a fixed axis , molecular machine , nanotechnology , chemical physics , crystallography , analytical chemistry (journal) , materials science , optics , physics , scanning electron microscope , classical mechanics , chromatography , artificial intelligence , computer science , organic chemistry
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.