Diverse Self-Assembly and Xenon Binding from a Single Mesomeric Macrocycle Component

Xenon binding has received considerable interest, but effective hosts remain rare, and the majority of assembly-type hosts are barely explored. Here, we report the synthesis, self-assembly, and xenon inclusion behavior with a homemade mesomeric bisurea–bisthiourea macrocycle. Compared to its racemic counterparts as recently investigated, the single mesomeric macrocycle forms even more comprehensive dimerization assemblies. From the single macrocycle component, up to two pairs of enantiomeric homochiral dimeric assemblies are formed. In the presence of xenon, the assembly diversity was pushed further, and an additional pair of enantiomeric heterochiral assemblies is induced. The diverse assembly comes from the macrocycle component adopting a folded, dissymmetric chiral conformation and undergoing spontaneous symmetry breaking upon cross-buckling together. The formed capsular assemblies possess a sealed, adaptive cavity for accommodating xenon. The cumulative xenon binding constant with the induced heterochiral capsule is about two times higher than the prior one assembled from racemic counterparts. The xenon-induced heterochiral capsule formation with the mesomeric macrocycle again demonstrates that xenon can find its own preferred host from a dynamic self-assembly system and likes to be accommodated by a more spherical van der Waals surrounding.氙气结合（xenon binding）领域已受到广泛关注，但高性能主体分子仍较为稀缺，且绝大多数组装型主体尚未得到充分探索。本研究报道了一种自主制备的居间双脲-双硫脲大环（mesomeric bisurea–bisthiourea macrocycle）的合成、自组装行为以及氙气包合性能。与近期研究的外消旋（racemic）对应体相比，单一居间异构大环可形成更为完备的二聚组装体。仅由单一大环组分即可形成至多两对对映异构同手性二聚组装体。当体系中存在氙气时，组装体的多样性进一步拓展，且诱导产生了额外一对对映异构异手性组装体。这类多样组装体的形成源于大环组分采取了折叠型非对称手性构象，并在交叉折叠过程中发生了自发对称性破缺。所形成的笼状组装体拥有密闭且可自适应的空腔，可用于容纳氙气分子。诱导形成的异手性笼状组装体的累积氙气结合常数约为外消旋对应体组装产物的两倍。基于居间异构大环的氙气诱导异手性笼状组装体的形成再次证明，氙气可从动态自组装体系中筛选出其偏好的主体分子，并更倾向于被更为球形的范德华（van der Waals）环境所包裹。