Ultrafast Excited State Dynamics in a First Generation Photomolecular Motor
Ultrafast Excited State Dynamics in a First Generation Photomolecular Motor
复制标题
第一代光电分子马达中的超快激发态动力学
作者：
Andy S Sardjan;Palas Roy;Wojciech Danowski;Giovanni Bressan;Laura Nunes dos Santos Comprido;W. Browne;B. Feringa;S. Meech
高效的光分子马达将成为分子机器设计和发展的关键要素。光异构化的量子产率的优化需要对激发电子态的分子动力学有详细的了解。在这里，我们用低于50 ps的时间分辨荧光光谱研究了原型第一代光分子马达中的初级光物理过程。当Franck-Condon态的驰豫速度为100fs时，我们观察到了一个双峰弛豫，用一个减少的跃迁矩填充红移态，然后在皮秒的时间尺度上经历多指数衰变。在超快结构弛豫过程中，由于激发S1态的振动相干态而产生的振荡被认为是幸存的。皮秒弛豫揭示了强烈的溶剂摩擦效应，这归因于围绕C−C轴的扭转。这一行为与第二代光分子马达不同；主要的区别是在第一代马达的激发态表面上存在势垒，而第二代马达没有势垒。这些结果将为今后设计更高效的分子马达提供依据。
Abstract Efficient photomolecular motors will be critical elements in the design and development of molecular machines. Optimisation of the quantum yield for photoisomerisation requires a detailed understanding of molecular dynamics in the excited electronic state. Here we probe the primary photophysical processes in the archetypal first generation photomolecular motor, with sub‐50 fs time resolved fluorescence spectroscopy. A bimodal relaxation is observed with a 100 fs relaxation of the Franck‐Condon state to populate a red‐shifted state with a reduced transition moment, which then undergoes multi‐exponential decay on a picosecond timescale. Oscillations due to the excitation of vibrational coherences in the S1 state are seen to survive the ultrafast structural relaxation. The picosecond relaxation reveals a strong solvent friction effect which is thus ascribed to torsion about the C−C axle. This behaviour is contrasted with second generation photomolecular motors; the principal differences are explained by the existence of a barrier on the excited state surface in the case of the first‐generation motors which is absent in the second generation. These results will help to provide a basis for designing more efficient molecular motors in the future.
影响因子：
3.3
作者：
Heisler, Ismael A.;Kondo, Minako;Meech, Stephen R.
通讯作者：
Meech, Stephen R.
影响因子：
21.8
作者：
Conyard, Jamie;Addison, Kiri;Meech, Stephen R.
通讯作者：
Meech, Stephen R.
影响因子：
15
作者：
Conyard, Jamie;Cnossen, Arjen;Meech, Stephen R.
通讯作者：
Meech, Stephen R.