Although significant effort has been expended to analyze the binding of pyrene in β-cyclodextrin and γ-cyclodextrin, little has been published on the binding of this guest in β-cyclodextrin derivatives (methyl-β-cyclodextrin and 2-hydroxypropyl-β-cyclodextrin) or in mixtures of such derivatives, despite the fact that these derivatives are known to have different supramolecular properties that facilitate unique modes of complexation. Reported herein is a detailed spectroscopic investigation of the binding of pyrene in β-cyclodextrin derivatives and in binary mixtures of cyclodextrins. Py values, defined as the ratio of representative vibronic bands in the fluorescence emission of pyrene, were used to measure changes in the pyrene microenvironment in the presence of the cyclodextrin hosts, and indicated that unmodified β-cyclodextrin is unique in providing a fully hydrophobic environment for pyrene through the use of two cyclodextrins to bind a single pyrene guest. By comparison, both γ-cyclodextrin and modified β-cyclodextrin analogues bind pyrene in a less hydrophobic environment through 1:1 binding stoichiometries that allow for continued interactions between the incompletely encapsulated pyrene guest and the aqueous solvent system. Binary mixtures of cyclodextrins were also explored and reinforce the unique properties of the unmodified β-cyclodextrin host.

The unique binding geometries of pyrene in beta-cyclodextrin and its derivatives leads to measurable fluorescence emission signals, whose information can be used to elucidate the highly structurally dependent binding geometries and stoichiometries

中文翻译：

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通过荧光光谱法增强混合环糊精系统中芘结合的表征。

尽管已花费大量精力来分析芘在 β-环糊精和 γ-环糊精中的结合，但关于该客体在 β-环糊精衍生物（甲基-β-环糊精和 2-羟丙基-β-环糊精）中结合的报道很少) 或此类衍生物的混合物，尽管已知这些衍生物具有不同的超分子特性，可促进独特的络合模式。本文报道了对芘在 β-环糊精衍生物和环糊精的二元混合物中结合的详细光谱研究。Py 值，定义为芘荧光发射中代表性电子振动带的比率，用于测量在环糊精主体存在下芘微环境的变化，并表明未修饰的 β-环糊精通过使用两种环糊精结合单个芘客体，为芘提供完全疏水的环境是独一无二的。相比之下，γ-环糊精和改性 β-环糊精类似物均通过 1:1 结合化学计量在疏水性较低的环境中结合芘，从而允许未完全包封的芘客体与水性溶剂系统之间持续相互作用。还探索了环糊精的二元混合物并加强了未修饰的 β-环糊精主体的独特性质。1 结合化学计量允许不完全封装的芘客体和水溶剂系统之间的持续相互作用。还探索了环糊精的二元混合物并加强了未修饰的 β-环糊精主体的独特性质。1 结合化学计量允许不完全封装的芘客体和水溶剂系统之间的持续相互作用。还探索了环糊精的二元混合物并加强了未修饰的 β-环糊精主体的独特性质。

β-环糊精及其衍生物中芘的独特结合几何结构导致可测量的荧光发射信号，其信息可用于阐明高度结构依赖的结合几何结构和化学计量