University of Pennsylvania , 231 South 34 Street, Philadelphia, Pennsylvania 19104, United States.
J Am Chem Soc. 2017 Oct 18;139(41):14733-14742. doi: 10.1021/jacs.7b08558. Epub 2017 Oct 10.
Boron-dipyrromethene (BODIPY) chromophores have a wide range of applications, spanning areas from biological imaging to solar energy conversion. Understanding the ultrafast dynamics of electronically excited BODIPY chromophores could lead to further advances in these areas. In this work, we characterize and compare the ultrafast dynamics of halogenated BODIPY chromophores through applying two-dimensional electronic spectroscopy (2DES). Through our studies, we demonstrate a new data analysis procedure for extracting the dynamic Stokes shift from 2DES spectra revealing an ultrafast solvent relaxation. In addition, we extract the frequency of the vibrational modes that are strongly coupled to the electronic excitation, and compare the results of structurally different BODIPY chromophores. We interpret our results with the aid of DFT calculations, finding that structural modifications lead to changes in the frequency, identity, and magnitude of Franck-Condon active vibrational modes. We attribute these changes to differences in the electron density of the electronic states of the structurally different BODIPY chromophores.
硼二吡咯亚甲基（BODIPY）发色团具有广泛的应用，涵盖了从生物成像到太阳能转换等领域。了解电子激发的 BODIPY 发色团的超快动力学可以在这些领域取得进一步的进展。在这项工作中，我们通过二维电子光谱（2DES）来表征和比较卤化 BODIPY 发色团的超快动力学。通过我们的研究，我们展示了一种从 2DES 光谱中提取动态斯托克斯位移的新数据分析程序，揭示了超快溶剂弛豫。此外，我们还提取了与电子激发强烈耦合的振动模式的频率，并比较了结构不同的 BODIPY 发色团的结果。我们借助 DFT 计算来解释我们的结果，发现结构修饰会导致Franck-Condon 活性振动模式的频率、身份和幅度发生变化。我们将这些变化归因于结构不同的 BODIPY 发色团的电子态的电子密度的差异。
