Rotaxane or Pseudorotaxane? Effects of Small Structural Variations on the Deslipping Kinetics of Rotaxanes with Stopper Groups of Intermediate Size
作者:Ansgar Affeld、Gosia M. Hübner、Christian Seel、Christoph A. Schalley
DOI:10.1002/1099-0690(200108)2001:15<2877::aid-ejoc2877>3.0.co;2-r
日期:2001.8
Secondly, stopper flexibility has an important influence on the deslipping rate. Thirdly, exchange of a carbonamide for a sulfonamide in the wheel significantly reduces the entropic costs of the deslipping, resulting in a pronounced deslipping rate enhancement. Fourthly, intramolecular hydrogen bonding within the wheel decelerates deslipping by a factor of more than 104.
三个系列的轮烷已通过滑动合成(轴和轮混合熔化)、通过识别大环轮内部的酰胺基团或通过阴离子模板法(其中塞子酚盐与轮以氢键键合)的方式合成。然后通过与半轴的反应连接。大多数这些轮烷使用的 3,5-二叔丁基苯基塞子足够大,可以隔离它们,但在适当的条件下仍允许车轮从轴上滑落。所有轮烷的脱滑活化参数均来自 1 H NMR 动力学测量值,并已根据 Arrhenius 方程和 Eyring 理论进行评估。小的结构变化会对激活参数产生惊人的影响。首先,在一些例子中,轴长影响防滑屏障,但止动器和车轮的尺寸互补性保持不变。其次,塞子的柔韧性对脱滑率有重要影响。第三,在车轮中用碳酰胺交换磺酰胺显着降低了脱滑的熵成本,从而显着提高了脱滑率。第四,车轮内的分子内氢键使滑移减速超过 104 倍。