七、八元瓜环与结晶猩红色主客体包结作用的研究

Study on Interaction Between Cucurbit[n=7,8]uril and Crystal Scarlet

利用紫外可见吸收光谱详细考察了七、八元瓜环(Q[7],Q[8])与偶氮染料类客体结晶猩红色的相互作用以及包结配合物受体系pH值影响的情况。实验结果表明,Q[7]与结晶猩红色在作用的pH范围均是以1:1方式相互作用。Q[8]与结晶猩红色相互作用受到体系pH的影响:在“高”或“低”pH条件下,瓜环与客体不发生明显的相互作用;在“较高”和“较低”的pH范围,瓜环与结晶猩红色发生相互作用,主客体存在1:1和1:2两种作用模式的竞争;而在介于“较高”与“较低”的pH范围,Q[8]与客体发生相互作用,形成1:2的包结配合物。不同的瓜环-客体体系,不同作用阶段的pH范围各不相同。本文利用比较简单的实验方法,测定了相应的pH范围,并结合瓜环及客体的结构特征,对体系主客体在不同的pH值区域表现出的不同作用模式进行了初步探讨。

The interaction between cucurbit[n =7, 8]urils（Q[7], Q[8] and crystal scarlet and influence of pH on the interaction were studied by using UV-vis spectroscopy .The experimental results revealed that Q[7] always forms a 1：1 complex with the crystal scarlet respectively in a certain pH. However, there are five interaction stages for Q[8]- crystal scarlet： there is no obvious interaction between Q[8] and the guest at the ＂highest＂ and the ＂lowest＂ pH; the Q [8] could include the guest in a hl ratio and a 1：2 ratio; between the higher and the lower pH, the Q [8] includes the guest in a 1：2 ratio. These certain pHs were determined by using a relevant simple method for the different systems and the different interaction models at different pH were discussed for different systems.