Synthesis of novel dansyl appended cyclodextrins. Self-inclusion and sensor properties
作者:Hubertus F. M. Nelissen、Fokke Venema、René M. Uittenbogaard、Martinus C. Feiters、Roeland J. M. Nolte
DOI:10.1039/a701142c
日期:——
The synthesis of three dansyl appended cyclodextrin derivatives, differing in the spacer length between cyclodextrin and the dansyl moiety, is described. In compound 4 the fluorophore is directly attached to the cyclodextrin. Compound 5 contains an ethyl spacer and compound 6 a triethylene glycol spacer. These compounds are designed to detect neutral organic guest molecules like cyclohexanol and adamantanecarboxylic acid in water by fluorescence spectroscopy. At neutral pH none of the compounds is sensitive towards guest molecules. For compound 4 this is due to the fact that the dansyl group is located outside the cyclodextrin cavity. For compunds 5 and 6 the low sensitivity is the result of a strong self-inclusion of the dansyl group. Lowering the pH results in protonation of the dimethylamino group of the dansyl moiety, which makes the self-inclusion less favourable leading to a strongly increased response towards guests. This phenomenon allows the sensors to be switched on and off by lowering or increasing the pH of the solution. Compound 6 is able to detect adamantanecarboxylic acid at 5 × 10–7 mol–1 dm3 concentration at pH 1.
本文描述了三种包含丹磺酰基团且与环糊精之间空间臂长度不同的丹磺酰修饰环糊精衍生物的合成。在化合物4中,荧光团直接与环糊精相连。化合物5含有乙基间隔臂,而化合物6含有三甘醇间隔臂。这些化合物设计用于通过荧光光谱法在水中检测中性有机客体分子,如环己醇和金刚烷羧酸。在中性pH下,这些化合物对客体分子均不敏感。对于化合物4,这是因为丹磺酰基团位于环糊精空腔外部。对于化合物5和6,低敏感性是由丹磺酰基团的强自包合作用引起的。降低pH会导致丹磺酰部分的二甲氨基团质子化,使得自包合作用变得不那么有利,从而导致对客体分子的响应显著增强。这一现象允许通过降低或增加溶液的pH来开启或关闭传感器。化合物6能够在pH1下检测到浓度为5×10⁻⁷mol–1 dm³的金刚烷羧酸。