Marriage of Heterobuckybowls with Triptycene: Molecular Waterwheels for Separating C<sub>60</sub> and C<sub>70</sub>
Zhe Liu, Wenru Song, Shaojie Yang, Chengshan Yuan, Zitong Liu, Hao‐Li Zhang, Xiangfeng Shao
Abstract
Abstract Exploration of π‐conjugated polycycles, particularly those have π‐frameworks spread over the three‐dimensional space, is essential in materials science and synthetic chemistry as these chemical entities possess featured optoelectronic properties and supramolecular assembly. Herein, the bowl‐shaped trichalcogenasumanenes are fused onto three branches of triptycene through pyrazine units, affording waterwheel‐like three‐dimensional polycycles 4 a/4 b . Because the three branches on 4 a/4 b are chemically equal, the molecular orbitals of 4 a/4 b show degenerate feature that results in the strong UV‐Vis absorbance at steady state. 4 a/4 b exhibit photo‐induced charge‐separation and subsequent charge‐redistribution at transient state, leading to excited state absorption in NIR‐II window (1165–1400 nm). 4 a/4 b are excellent fullerene receptors, and they form 1 : 1 host‐guest complexes with C 60 /C 70 as proved by spectroscopic titrations and single crystal structure analysis. Moreover, 4 a/4 b show much stronger affinity toward C 70 than C 60 . Consequently, 4 a/4 b are able to separate C 60 and C 70 from their mixture, giving the purity of C 60 up to 99.5 %.