Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario, N9B 3P4, Canada.
School of Chemistry, Sun Yat-Sen University, Guangzhou, 510275, P.R. China.
Angew Chem Int Ed Engl. 2017 May 22;56(22):6136-6141. doi: 10.1002/anie.201612549. Epub 2017 Feb 1.
A series of six [2]rotaxane molecular shuttles was designed which contain an axle with a benzo-bis(imidazole) core (in either a neutral or dicationic form) and a single 24-membered, crown ether wheel (24C6, B24C6, or DMB24C6), and the shuttling rates of the ring along the axle were determined. The charged versions showed much slower shuttling rates as a result of the increase in noncovalent interactions between the axle and wheel. The [2]rotaxane with a B24C6 wheel shows a difference in fluorescence between the charged and neutral species, while the [2]rotaxane with a DMB24C6 wheel exhibits a difference in color between the charged and neutral compounds. These changes in optical properties can be attributed to the structural differences in the co-conformations of the [2]rotaxane as they adapt to the changes in acid/base chemistry. This allowed the relative rate of the translational motion of a molecular shuttle to be determined by observation of a simple optical probe.
设计了一系列六个[2]轮烷分子梭，其中包含一个带有苯并双（咪唑）核心（中性或二阳离子形式）和一个单一的 24 元，冠醚轮（24C6、B24C6 或 DMB24C6）的轴，并且确定了环沿着轴的穿梭速率。带电荷的版本由于轴和轮之间的非共价相互作用的增加而表现出较慢的穿梭速率。带有 B24C6 轮的[2]轮烷在带电荷和中性物质之间表现出荧光差异，而带有 DMB24C6 轮的[2]轮烷在带电荷和中性化合物之间表现出色差。这些光学性质的变化可以归因于[2]轮烷的共构构象的结构差异，因为它们适应酸碱化学变化。这使得通过观察简单的光学探针来确定分子梭平移运动的相对速率成为可能。
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