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.