Abstract

A new anthraquinone appended oxacalix[4]arene (DAQOC) has been synthesized and characterized by different ¹H NMR, IR, ESI-MS and ¹³C NMR spectroscopic techniques. This compound was explored for its sensing abilities towards various anions. DAQOC showed selective anion sensing behaviour towards F⁻ ions which was supported by absorption as well as emission studies. Among other anions, only in the presence of F⁻ ions, a quenching in the fluorescence emission of over 79% was observed due to changes in the intermolecular charge transfer (ICT) process. DAQOC exhibited high selectivity and good sensitivity toward F⁻ ions in the presence of competing ions and the detection limit was found to be 1.23 µM. ¹H NMR titration displays that the peak corresponding to –NH protons (at 12.91 ppm) disappears upon interaction with F⁻, suggesting that the sensing mechanism follows the deprotonation route. The geometrical features of F⁻ bound oxacalixarene species were modelled by the Density Functional Theory (DFT) and NCIPlot calculations. The findings suggested that the appended substituents including nitro groups and anthraquinone can make the calix[4]arene ring electron deficient and thereby more susceptible for F⁻ ions. Moreover, this present chemosensor has been applied for recognition of F⁻ ions from waste water samples which is of direct practical relevance.

Graphic abstract

A new anthraquinone appended oxacalix[4]arene has been explored for its sensing abilities towards F⁻ by absorption and emission studies. An intermolecular charge transfer mechanism has been attributed due to the deprotonation of N–H groups in DAQOC. DAQOC-F⁻ complex is modelled by the Density Functional Theory and NCIPlot calculations.

中文翻译：

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一种高选择性蒽醌附加草酸芳烃受体，用于荧光ICT感应F-离子：实验和计算研究

摘要

合成了一种新的附有蒽醌的氧杂lix [4]芳烃（DAQOC），并通过不同的¹ H NMR，IR，ESI-MS和¹³ C NMR光谱技术进行了表征。探索了该化合物对各种阴离子的感知能力。DAQOC表明朝向˚F选择性阴离子传感行为^-这是由吸收以及发射研究的支持离子。在其他的阴离子，仅在F的存在^-离子，在观察到超过79％的荧光发射猝灭由于分子间电荷转移（ICT）过程中的变化。DAQOC显示出高的选择性和良好的灵敏度朝向˚F ^-在竞争离子的存在离子和检测限被发现是1.23μM。^1个对应于-NH质子峰（12.91 ppm的）H NMR滴定显示相互作用时被F消失^- ，表明感测机构如下所述去质子化的路线。f的几何特征^-结合oxacalixarene种是由密度泛函理论（DFT）和NCIPlot计算建模。这些发现表明，在所附的取代基，包括硝基和蒽醌可以使杯[4]芳烃环缺电子，从而适用于F更敏感^-离子。此外，这种本化学传感器已应用于与F的识别^-从废水样品离子，其是直接的实际相关性。

图形摘要

一种新的蒽醌所附oxacalix [4]芳烃已探索用于朝向˚F其感测能力^-通过吸收和发射的研究。分子间电荷转移机制归因于DAQOC中N–H基团的去质子化。DAQOC-F ^-复用密度泛函理论和NCIPlot计算建模。