Meta-aminophenol (m-AP) was used as a guest molecule to be incorporated into the hydrophobic nano-cavity of the host molecule β-cyclodextrin (β-CD) to form host–guest inclusion complex in aqueous medium. For this, we employed spectrometric titration method, i.e., β-CD was added gradually in an aqueous solution of m-AP maintaining a fixed concentration of m-AP. We investigated the changes in the photophysical properties of m-AP through inclusion complex formation in β-CD in aqueous medium by using steady state and time-resolved spectroscopic techniques as well as density functional theory (DFT) computations. Benesi–Hildebrand method was used to find the stoichiometry and association constant at two concentration ranges of β-CD. The average fluorescence lifetime of m-AP was found to increase from 0.17 ns in absence of β-CD to 3.69 ns in presence of β-CD (highest concentration used). DFT computations carried out in water medium clearly indicate that the inclusion complex is more stable for the cis-rotameric conformation of m-AP rather than trans.

中文翻译：

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利用光谱和 DFT 计算研究预测水性介质中 β-环糊精腔中间氨基苯酚的最优选旋转异构体

间氨基苯酚（m-AP）被用作客体分子，结合到主体分子β-环糊精（β-CD）的疏水纳米腔中，在水性介质中形成主客体包合物。为此，我们采用光谱滴定法，即将β-CD 逐渐加入到m-AP 的水溶液中，保持m-AP 的固定浓度。我们通过使用稳态和时间分辨光谱技术以及密度泛函理论 (DFT) 计算，研究了通过在水性介质中 β-CD 中形成包合物形成的 m-AP 光物理性质的变化。Benesi-Hildebrand 方法用于找到两个 β-CD 浓度范围内的化学计量和缔合常数。发现 m-AP 的平均荧光寿命从没有 β-CD 时的 0.17 ns 增加到 3。存在 β-CD 时为 69 ns（使用的最高浓度）。在水介质中进行的 DFT 计算清楚地表明，包合物对于 m-AP 的顺式旋转异构构象比反式更稳定。