瓜环与喹啉及其衍生物的相互作用

利用荧光光谱分析方法考察六、七及八元瓜环与喹啉、异喹啉、7-甲基喹啉相互作用的结构特征以及光学特性。与核磁共振技术比较,荧光光谱分析方法具有高灵敏性的特点,不仅可观察到喹啉及其衍生物与七元瓜环相互作用而引起的荧光性质变化;还能观察到它们与六元瓜环或八元瓜环相互作用所产生的变化,这是通常的NMR方法所不能实现的。实验表明喹啉、异喹啉、7-甲基喹啉与六、七及八元瓜环有包结作用,形成多种不同包结比的稳定包结配合物。实验也证实,瓜环与客体之间相互作用受到3种效应的协同影响:(1)疏水性的笼体效应(瓜环以其特殊的疏水性笼状结构,可与多种有机物发生疏水性的笼体作用);(2)亲水性的端口效应(瓜环端口环绕的羰基氧通过离子-偶极相互作用来键合金属离子或有机分子的带电部分);(3)相互作用的客体分子或瓜环笼体空间大小,即尺寸效应。

Interaction of Cucurbit[n]urils and Quinoline or Its Derivates

The structures and fluorescence characteristics of cucurbitn=6-8]urils with quinoline, isoquinoline and 7-methyl quinoline have been investigated by fluorescence spectrophotometry. Compared to NMR techniques, the fluorometric analysis method revealed that there are not only obvious interactions of quinoline or its (derivates) and cucurbit7]uril, but also interactions of quinoline or its (derivates) and cucurbit6]uril or cucurbit8]uril which can not be observed by using ~1H NMR technique. The experimental results also revealed that quinoline, isoquinoline and 7-methyl quinoline were included by cucurbit6-8]uril with different ratios. There could be three kinds of interactions of cucurbitn]urils and the guests: a) cavity interaction, including hydrophobic forces and Van der Waals contact forces between macrocycles and cages; b) portals ion-dipole interaction, or electrostatic interaction of the positive charge of the guests and the carbonyl groups at the portals of cucurbitn]uril; c)size interaction which requires the size of the guest matching a (cucurbit)n]uril.