Here, we report the synthesis of a family of chiral Zn^II₄L₄ tetrahedral cages by subcomponent self-assembly. These cages contain a flexible trialdehyde subcomponent that allows them to adopt stereochemically distinct configurations. The incorporation of enantiopure 1-phenylethylamine produced Δ₄ and Λ₄ enantiopure cages, in contrast to the racemates that resulted from the incorporation of achiral 4-methoxyaniline. The stereochemistry of these Zn^II₄L₄ tetrahedra was characterized by X-ray crystallography and chiroptical spectroscopy. Upon binding the enantiopure natural product podocarpic acid, the Zn^II stereocenters of the enantiopure Δ₄-Zn^II₄L₄ cage retained their Δ handedness. In contrast, the metal stereocenters of the enantiomeric Λ₄-Zn^II₄L₄ cage underwent inversion to a Δ configuration upon encapsulation of the same guest. Insights gained about the stereochemical communication between host and guest enabled the design of a process for acid/base-responsive guest uptake and release, which could be followed by chiroptical spectroscopy.

中文翻译：

---

立体化学和电荷的相互作用控制柔性 ZnII4L4 笼中的客体结合


在这里，我们报道了通过亚组分自组装合成一个手性 Zn^II₄L₄ 四面体笼家族。这些笼子含有灵活的三醛亚组分，使它们能够采用立体化学不同的配置。对映体纯 1-苯乙胺的掺入产生 Δ₄ 和 Λ₄ 对映体纯笼，这与非手性 4-甲氧基苯胺掺入产生的外消旋体形成鲜明对比。这些 Zn^II₄L₄ 四面体的立体化学通过 X 射线晶体学和手性光谱学进行了表征。在结合对映体天然产物鬼臼酸后，对映体纯 Δ 4-Zn^II₄L₄ 笼的 Zn^II 立体中心保持了其 Δ 旋性。相比之下，对映体 Λ 4-Zn^II₄L₄ 笼的金属立体中心在封装相同的客体时发生倒置为 Δ 构型。关于宿主和客体之间立体化学通信的见解使设计了一个酸/碱响应客体吸收和释放的过程，然后可以进行手光谱学。