Institute of Physical and Theoretical Chemistry , Graz University of Technology , Stremayrgasse 9 , A-8010 Graz , Austria.
Institute of Chemistry, Organic and Bioorganic Chemistry , University of Graz , Heinrichstraße 28 , A-8010 Graz , Austria.
Anal Chem. 2019 Sep 3;91(17):11367-11373. doi: 10.1021/acs.analchem.9b02613. Epub 2019 Aug 20.
We present 1D and 2D NMR experiments that provide in situ insights into photoinduced isomerizations. Irradiation during the mixing period of an exchange spectroscopy (EXSY) experiment leads to characteristic cross peaks in 2D spectra. The phototriggered exchange of magnetization occurring in photoswitchable ()- and ()-isomers of three selected azo compounds provides information on the dynamic / equilibria. We report the dependence of the diagonal-to-cross-peak ratio on concentration, light intensity, and mixing time. In analogy to exchange spectroscopy, this ratio mirrors the efficiency of light induced molecular transformations. Furthermore, we present a time-saving 1D version and a combined light/phase cycle scheme for enhanced detectability of photoinduced changes in the spectrum. This insight into light-induced structural changes is highly suited to study macromolecules, in which photoswitchable units trigger conformational changes.
我们呈现了一维和二维核磁共振实验，这些实验为光诱导异构化提供了实时的见解。在交换光谱（EXSY）实验的混合期进行辐照会导致二维谱中出现特征交叉峰。在三种选定的偶氮化合物的光致可切换（）-和（）-异构体中发生的光触发磁化交换提供了关于动态/平衡的信息。我们报告了对角到交叉峰比与浓度、光强度和混合时间的依赖性。类似于交换光谱学，这个比值反映了光诱导分子转化的效率。此外，我们还提出了一种节省时间的一维版本和一种组合的光/相循环方案，以增强对光谱中光诱导变化的检测能力。这种对光诱导结构变化的深入了解非常适合研究大分子，其中光致可切换单元触发构象变化。
