Chirality Gearing in an Achiral Cage through Adaptive Binding

作者：Qiping Hu, Hao Zhou, Teng-Yu Huang, Yu‐Fei Ao, De‐Xian Wang, Qi‐Qiang Wang · 发表于：Journal of the American Chemical Society · 年份：2022 · DOI：10.1021/jacs.2c02040 · 被引用次数：67 · 研究领域：Supramolecular Chemistry and Complexes、Molecular Sensors and Ion Detection、Supramolecular Self-Assembly in Materials

Herein we report an adaptive, achiral trithiourea molecular cage and its conformational and stereodynamics toward tricarboxylate anion binding. The cage was readily synthesized in four steps with a 44% yield for the irreversible cage-forming reaction. It possesses a flexible conformation and strongly binds 1,3,5-benzene tricarboxylate by forming a sandwich-like inclusion complex, with an affinity up to 10 6 M –1 in acetonitrile. Upon binding, the cage is locked in a twisted helical conformation. By incorporation of three chiral arms on the guest, a gear-like complex dominant in one given helical sense was produced. Due to the steric crowding in the helical grooves, a small change of methyl to ethyl on guest caused a striking difference on binding and chiral induction. The system thus represents a rare example of chiral induction on a flexible, achiral host and provides a decoupled model that the generation of a racemate and following chiral discrimination can be individually probed.