The rational design of electrochemical methods for isomer recognition is a focus of research in the molecular recognition and separation fields. In this work, a novel, rapid, and convenient electrochemical approach for recognition of nitrophenol isomers was constructed based on the alternating layer-by-layer (LbL) assembly of water-soluble cationic and anionic pillar [5]arene on a carboxylic graphene (C-Gra) modified glass carbon electrode. The electrochemical recognition of nitrophenol isomers was investigated by differential pulse voltammetry (DPV). The electrochemical results reveal that both the peak currents of m-nitrophenol (m-NP) and p-nitrophenol (p-NP) increased with the increasing of the layer number of the assembled pillar [5]arene, whereas the peak current of o-nitrophenol (o-NP) decreased with the increased layers, which demonstrated an efficient route for discriminating the nitrophenol isomers. The molecular recognition mechanism was studied by 1H NMR spectra, which indicated that the m-NP and p-NP can be included in the cavity of the pillar [5]arene host. However, the o-NP could not enter into the host of pillar [5]arene, which was ascribed to the formation of intramolecular hydrogen bond of o-NP. The LbL assembly modified GCE was used for detecting p-NP and m-NP. A low detection limit of 0.33 μM (S/N = 3) and a linear response range of 1-90 μM for p-NP were obtained by using this method. And the detection limit of 0.16 μM (S/N = 3) and a linear response range of 0.5-70 μM for m-NP were obtained. This method of LbL assembly modified GCE has potential application in molecular recognition and separation.

中文翻译：

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通过组装柱[5]芳烃多膜电化学识别硝基苯酚异构体

异构体识别电化学方法的合理设计是分子识别和分离领域的研究热点。在这项工作中，基于水溶性阳离子和阴离子柱 [5] 芳烃在羧基石墨烯上的交替逐层 (LbL) 组装，构建了一种新颖、快速、方便的电化学方法来识别硝基苯酚异构体。 C-Gra) 改性玻璃碳电极。通过差分脉冲伏安法（DPV）研究硝基苯酚异构体的电化学识别。电化学结果表明，随着组装柱[5]芳烃层数的增加，间硝基苯酚（m-NP）和对硝基苯酚（p-NP）的峰值电流均增加，而o -硝基苯酚（o-NP）随着层数的增加而减少，这证明了一种区分硝基苯酚异构体的有效途径。通过1H NMR光谱研究了分子识别机制，表明m-NP和p-NP可以包含在柱[5]芳烃主体的腔中。然而，o-NP不能进入柱[5]芳烃的主体，这归因于o-NP分子内氢键的形成。LbL 组件改进的 GCE 用于检测 p-NP 和 m-NP。使用该方法获得了 0.33 μM (S/N = 3) 的低检测限和 p-NP 的 1-90 μM 线性响应范围。并且获得了 0.16 μM (S/N = 3) 的检测限和 0.5-70 μM 的线性响应范围对 m-NP。这种 LbL 组装修饰 GCE 的方法在分子识别和分离方面具有潜在的应用价值。