Motion Capture and Manipulation of a Single Synthetic Molecular Rotor by Optical Microscopy1. (2nd July 2014)

• Record Type: Journal Article
• Authors: Ikeda, Tomohiro; Tsukahara, Takahiro; Iino, Ryota; Takeuchi, Masayuki; Noji, Hiroyuki
• Is Part Of: Angewandte Chemie. Volume 126:Number 38(2014)
• Page Start: 10246
• Page End: 10249
• Publication Date: 2014-07-02
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.201403091
• Languages: English
• ISSNs: 0044-8249

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>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.</p> </abstract>