Cavendish Laboratory, University of Cambridge , JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom.
Department of Physics and Astronomy, University of Sheffield , Hounsfield Road, Sheffield S3 7RH, United Kingdom.
J Am Chem Soc. 2017 Aug 30;139(34):12050-12059. doi: 10.1021/jacs.7b06709. Epub 2017 Aug 15.
We have prepared a series of ML tetrahedral cages containing one or the other of two distinct BODIPY moieties, as well as mixed cages that contain both BODIPY chromophores. The photophysical properties of these cages and their fullerene-encapsulated adducts were studied in depth. Upon cage formation, the charge-transfer character exhibited by the bis(aminophenyl)-BODIPY subcomponents disappeared. Strong excitonic interactions were instead observed between at least two BODIPY chromophores along the edges of the cages, arising from the electronic delocalization through the metal centers. This excited-state delocalization contrasts with previously reported cages. All cages exhibited the same progression from an initial bright singlet state (species I) to a delocalized dark state (species II), driven by interactions between the transition dipoles of the ligands, and subsequently into geometrically relaxed species III. In the case of cages loaded with C or C fullerenes, ultrafast host-to-guest electron transfer was observed to compete with the excitonic interactions, short-circuiting the I → II → III sequence.
我们已经制备了一系列包含一个或两个不同 BODIPY 部分的 ML 四面体型笼，以及包含两个 BODIPY 生色团的混合笼。这些笼及其富勒烯包合物的光物理性质进行了深入研究。在笼形成后，双（氨基苯基）-BODIPY 亚基表现出的电荷转移特征消失。相反，在笼子边缘处至少有两个 BODIPY 生色团之间观察到强烈的激子相互作用，这是由于通过金属中心的电子离域。这种激发态离域与以前报道的笼子形成对比。所有笼子都表现出相同的从初始明亮的单重态（物种 I）到离域的暗态（物种 II）的进展，这是由配体的跃迁偶极子之间的相互作用驱动的，随后进入几何上松弛的物种 III。在装有 C 或 C 富勒烯的笼中，观察到超快的主体到客体电子转移与激子相互作用竞争，从而短路了 I → II → III 序列。
