研究・研究者
研究会・セミナー
| 演 題 | Ultrafast Dynamics in Photochemically Driven Molecular Rotary Motors |
|---|---|
| 日 時 | 2024年11月11日(月) 16:00 |
| 講演者 | Prof. Steve Meech（School of Chemistry, University of East Anglia, UK） |
| 場 所 | 研究棟201室 |
| 概 要 | Molecular motors are critical for the development of molecular machines. Molecular machines that exploit light (which is free, plentiful and wireless) as a source of power will have advantages in terms of ease of use and control of operation. The “Feringa Motor” exploits a unique combination of photochemistry and stereochemistry in sterically overcrowded alkenes to convert light energy into directional molecular motion. These motors operate through successive unidirectional photochemical isomerization and thermal helix inversion steps (see Figure). The first generation motors had a respectable 70% yield of photoisomerization but low (few Hz) rates of thermal helix inversion. Careful synthesis led to a second generation, with greatly improved ground state helix inversion allowing MHz rotation rates, but at the expense of an isomerization yield reduced to less than 10%. Evidently for the most efficient motors some knowledge of and control over excited state processes are needed to optimize the photoisomerization step. In this presentation we will describe some tools for the characterization of ultrafast excited state structural dynamics and apply them to develop a detailed model of excited state evolution in the first two generations of the Feringa motor. Based on that model we designed substituents to modify motor excited state dynamics, exploiting charge transfer configurations. Yields of up to 99% for the photoisomerization were obtained and control over the yield was demonstrated by varying the medium polarity. Coupling two second generation motors led to the development of a third generation, which is capable of molecular crawling in addition to rotation. The structural dynamics of a third generation motor were measured by ultrafast Raman spectroscopy. |
| お問合せ先 |
倉持光（協奏分子システム研究センター） |
