Radiation & Photochemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, India.
School of Chemical Sciences, Goa University, Taleigao Plateau, Goa 403 206, India.
J Phys Chem B. 2022 Feb 10;126(5):1147-1155. doi: 10.1021/acs.jpcb.1c09780. Epub 2022 Feb 1.
The combination of supramolecular chemistry and aggregation-induced emission-based luminogens (AIEgens) has recently attracted tremendous attention because of its ability to offer large emission enhancement even in substantially dilute solutions. In this work, a new aggregation-induced emission (AIE)-based supramolecular assembly has been reported, which consists of a polyanionic cyclodextrin derivative and a tetracationic tetraphenylethylene (TPE) derivative. Ionic cyclodextrins have attracted significant attention in host-guest supramolecular chemistry and pharmaceutical industry. However, ionic derivatives of β-cyclodextrins have not been explored to establish noncovalent interactions-based aggregation assembly of the most popular class of AIEgens, i.e., tetraphenylethylene derivatives. The current report demonstrates AIE of a tetracationic methyl pyridinium derivative of tetraphenylethylene (TPy-TPE) induced by a polyanionic sulfated β-cyclodextrin (S-βCD). The AIE-based supramolecular assembly has been thoroughly investigated using steady-state fluorescence, ground-state absorbance, and time-resolved fluorescence measurements. Further, the response of the supramolecular assembly towards external stimuli, such as, ionic strength, pH, and temperature, has been investigated. In addition, the complexation behavior of the TPE derivative has also been compared with the native neutral β-cyclodextrin derivative, which delineates the important role of the negatively charged portal of S-βCD in inducing aggregation of the TPy-TPE. The stoichiometry of the complex has been found to be 3:1 for TPy-TPE:S-βCD, using Job's plot analysis. Finally, to get insights into the underlying interactions between the supramolecular assembly components, molecular docking calculations have been performed.
超分子化学和基于聚集诱导发光的发光体（AIEgens）的结合最近引起了极大的关注，因为它能够提供即使在大幅稀释的溶液中也能产生大的发光增强。在这项工作中，报道了一种新的基于聚集诱导发光（AIE）的超分子组装体，它由带负电荷的环糊精衍生物和四阳离子四苯乙烯（TPE）衍生物组成。离子环糊精在主客体超分子化学和制药工业中引起了广泛关注。然而，β-环糊精的离子衍生物尚未被探索用于建立最受欢迎的一类 AIEgens（即四苯乙烯衍生物）的基于非共价相互作用的聚集组装。本报告证明了带正电荷的四苯乙烯甲基吡啶鎓衍生物（TPy-TPE）在带负电荷的磺化β-环糊精（S-βCD）的诱导下具有 AIE。使用稳态荧光、基态吸收和时间分辨荧光测量对基于 AIE 的超分子组装体进行了深入研究。此外，还研究了超分子组装体对外界刺激（如离子强度、pH 值和温度）的响应。此外，还比较了 TPE 衍生物与天然中性β-环糊精衍生物的络合行为，这说明了 S-βCD 的带负电荷的入口在诱导 TPy-TPE 聚集方面的重要作用。使用 Job 图分析发现，TPy-TPE:S-βCD 的络合物化学计量比为 3:1。最后，为了深入了解超分子组装体成分之间的潜在相互作用，进行了分子对接计算。
