Development of color-change indicators using inclusion complex formation

环糊精（CD）在光谱上是惰性的，但它们可以通过用cheomophores修饰而转化为光谱活性化合物。在本研究中，我们制备了几种染料修饰的CD来构建分子的颜色变化指示剂，我们发现生色团修饰的CD在容纳客人时将生色团的位置从其自身的疏水空腔改变到外部水环境。发色团部分周围的这种环境变化通常导致其光谱性质的扰动。在此基础上，甲基红修饰的CD在酸性介质中与客体结合时颜色由黄色变为红色。另一方面，对硝基苯酚修饰的α-CD和β-CD在中性pH条件下发生客体诱导的颜色（黄色）至无色变化。此外，我们制备了酚酞修饰的β-CD，其在客体结合时也经历颜色（紫色）到无色的变化。所有这些主体对客体物种表现出不同的亲和力，因此它们可以用作分子的颜色变化指示剂。

Cyclodextrins (CDs) are spectroscopically inert, but they can be converted into spectroscopically active compounds by modification with cheomophores. In this study, we prepared several dye-modified CDs to construct color-change indicators for molecules.We found that the chromophore-modified CDs change the location of the chromophore from their own hydrophobic cavity to the outside water environment upon guest accommodation. This environmental change around the chromophore moiety usually causes perturbation in its spectroscopic property. On this basis, methyl-red modified CD changes color from yellow to red upon guest binding in acidic media. On the other hand, p-nitrophenol-modified alpha-CD and beta-CD undergo guest-induced color (yellow)-to-colorless change under neutral pH conditions. Futhermore, we prepared phenolphthalein-modified beta-CD,which also undergoes color (purple)-to-colorless change upon guest binding. All these hosts exhibit different affinities for guest species, and consequently they can be used as color-change indicators for molecules.