A mutually stabilized host-guest pair.

Zhang, Chi; Wang, Hongye; Zhong, Jie; Lei, Ye; Du, Renfeng; Zhang, Yang; Shen, Libo; Jiao, Tianyu et al. · Sci Adv · 2019

basic_science · Level V

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Abstract

By using click chemistry, a hexacationic cage was synthesized. The cage contains two triscationic π-electron-deficient trispyridiniumtriazine (TPZ<sup>3+</sup>) platforms that are bridged in a face-to-face manner by three ethylene-triazole-ethylene linkers. A diversity of π-electron-rich guests can be recognized within the pocket of the cage, driven by host-guest π-π interactions. The cage cavity acts as a protecting group, preventing an anthracene guest from undergoing Diels-Alder reaction. Under ultraviolet (UV) light, the pyridinium C─N bonds in TPZ<sup>3+</sup> platforms are polarized and weakened, resulting in the occurrence of cage decomposition via β-elimination. Guest recognition could help to prevent this UV-stimulated cage decomposition by suppressing the excitation of the TPZ<sup>3+</sup> units.