扭曲的半硫靛光致开关:溶剂极性决定了光致旋转的类型。
Twisted Hemithioindigo Photoswitches: Solvent Polarity Determines the Type of Light-Induced Rotations.
机构信息
Department für Chemie, Ludwig-Maximilians-Universität München , D-81377 Munich, Germany.
Institut für Biomolekulare Optik, Ludwig-Maximilians-Universität München , D-80538 Munich, Germany.
出版信息
J Am Chem Soc. 2016 Sep 21;138(37):12219-27. doi: 10.1021/jacs.6b05981. Epub 2016 Sep 13.
Controlling the internal motions of molecules by outside stimuli is a decisive task for the generation of responsive and complex molecular behavior and functionality. Light-induced structural changes of photoswitches are of special high interest due to the ease of signal application and high repeatability. Typically photoswitches use one reaction coordinate in their switching process and change between two more or less-defined states. Here we report on new twisted hemithioindigo photoswitches enabling two different reaction coordinates to be used for the switching process. Depending on the polarity of the solvent, either complete single bond (in DMSO) or double bond (in cyclohexane) rotation can be induced by visible light. This mutually independent switching establishes an unprecedented two-dimensional control of intramolecular rotations in this class of photoswitches. The mechanistic explanation involves formation of highly polar twisted intramolecular charge-transfer species in the excited state and is based on a large body of experimental quantifications, most notably ultrafast spectroscopy and quantum yield measurements in solvents of different polarity. The concept of pre-twisting in the ground state to open new, independent reaction coordinates in the excited state should be transferable to other photoswitching systems.
通过外部刺激控制分子的内部运动对于产生响应性和复杂的分子行为和功能是一项决定性的任务。由于信号应用的简便性和可重复性高,光致开关的结构变化特别受到关注。通常,光致开关在其开关过程中使用一个反应坐标,并在两个或更多定义不太明确的状态之间切换。在这里,我们报告了新的扭曲半硫靛光致开关,这些开关允许使用两个不同的反应坐标来进行开关过程。根据溶剂的极性,可见光可以诱导完全单键(在 DMSO 中)或双键(在环己烷中)旋转。这种相互独立的切换在这类光致开关中建立了对分子内旋转的前所未有的二维控制。这种机制解释涉及在激发态下形成高度极性的扭曲分子内电荷转移物种,并且基于大量的实验量化,特别是在不同极性溶剂中的超快光谱和量子产率测量。在基态预扭曲以在激发态中打开新的、独立的反应坐标的概念应该可以转移到其他光致开关系统。