Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education, College of Chemistry and Materials Science, Northwest University , Xi'an, 710069, P. R. China.
School of Chemistry and Chemical Engineering, Wuhan University of Science and Technology , Wuhan 430081, P. R. China.
J Org Chem. 2017 Jun 2;82(11):5590-5596. doi: 10.1021/acs.joc.7b00400. Epub 2017 May 19.
As the cucurbit[n]uril (CB[n]) homologue with the largest cavity size, cucurbit[10]uril (CB[10]) can encapsulate big guests to form interesting host-guest complexes/assemblies. Herein, we report the preparation and fluorescence properties of CB[10]-based [2]rotaxane (CB[10]·1) formed from cucurbit[10]uril and dumbbell-like guest 1. This [2]rotaxane (CB[10]·1) is assembled by C═O···N ion-dipole interactions between oxygen atoms of the carbonyl fringed portals of CB[10] and the positively charged pyridinium units of 1 via the slipping method under heating at 95 °C in DMSO. In contrast, other cucurbit[n]uril (CB[n], n = 6-8) homologues cannot form rotaxanes with 1 due to their smaller cavities. The dumbbell-like guest 1 is a poor emitter in DMSO. Interestingly, the formation of CB[10]·1 renders the restriction of intramolecular rotation of TPE, which features a strong fluorescent intensity, long lifetime, and high quantum yield. Furthermore, CB[10]·1 is shown to aggregate plate-like structures with various sizes in different solvents (DMSO, THF, or CHCl), resulting in a stepwise aggregation-induced emission enhancement effect. This kind of CB[10]-based [2]rotaxane may be used to fabricate luminescent systems with unique emission properties.
作为具有最大空腔尺寸的葫芦[n]脲（CB[n]）同系物，葫芦[10]脲（CB[10]）可以包合大客体，形成有趣的主客体配合物/组装体。在此，我们报告了由葫芦[10]脲和哑铃状客体 1 形成的基于 CB[10]的[2]轮烷（CB[10]·1）的制备和荧光性质。这种[2]轮烷（CB[10]·1）是通过在 DMSO 中 95°C 加热下的滑移方法，由 CB[10]的羰基边缘门户的氧原子与 1 的正吡啶单元之间的 C═O···N 离子-偶极相互作用组装而成。相比之下，由于其较小的空腔，其他葫芦[n]脲（CB[n]，n = 6-8）同系物不能与 1 形成轮烷。哑铃状客体 1 在 DMSO 中是一个较差的发射体。有趣的是，CB[10]·1 的形成限制了 TPE 的分子内旋转，从而具有强荧光强度、长寿命和高量子产率。此外，CB[10]·1 被证明在不同溶剂（DMSO、THF 或 CHCl）中聚集形成各种尺寸的板状结构，导致逐步聚集诱导的发射增强效应。这种基于 CB[10]的[2]轮烷可能用于制造具有独特发射性质的发光系统。
