Deng Jingjing, Shi Guoyue, Zhou Tianshu
School of Ecological and Environmental Sciences, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China.
Department of Chemistry, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China.
Anal Chim Acta. 2016 Oct 26;942:96-103. doi: 10.1016/j.aca.2016.09.002. Epub 2016 Sep 9.
This study demonstrates a new strategy for colorimetric detection of alcoholic strength (AS) in spirit samples based on dual-responsive lanthanide infinite coordination polymer (Ln-ICP) particles with ratiometric fluorescence. The ICP used in this study are composed of two components: one is the supramolecular Ln-ICP network formed by the coordination between the ligand 2,2'-thiodiacetic acid (TDA) and central metal ion Eu; and the other is a fluorescent dye, i.e., coumarin 343 (C343), both as the cofactor ligand and as the sensitizer, doped into the Ln-ICP network through self-adaptive chemistry. Upon being excited at 300 nm, the red fluorescence of Ln-ICP network itself at 617 nm is highly enhanced due to the concomitant energy transfer from C343 to Eu, while the fluorescence of C343 at 495 nm is supressed. In pure ethanol solvent, the as-formed C343@Eu-TDA is well dispersed and quite stable. However, the addition of water into ethanolic dispersion of C343@Eu-TDA destructs Eu-TDA network structure, resulting in the release of C343 from ICP network into the solvent. Consequently, the fluorescence of Eu-TDA turns off and the fluorescence of C343 turns on, leading to the fluorescent color change of the dispersion from red to blue, which constitutes a new mechanism for colorimetric sensing of AS in commercial spirit samples. With the method developed here, we could clearly distinguish the AS of different spirit samples within a wide linear range from 10% vol to 100% vol directly by "naked eye" with the help of UV-lamp (365 nm). This study not only offers a new method for on-the-spot visible detection of AS, but also provides a strategy for dual-responsive sensing mode by rational designing the optical properties of the Ln-ICP network and the guest, respectively.
本研究展示了一种基于具有比率荧光的双响应镧系元素无限配位聚合物（Ln-ICP）颗粒比色检测酒精饮料样品中酒精度（AS）的新策略。本研究中使用的ICP由两个组分组成：一个是由配体2,2'-硫代二乙酸（TDA）与中心金属离子Eu配位形成的超分子Ln-ICP网络；另一个是荧光染料，即香豆素343（C343），其既作为辅助因子配体又作为敏化剂，通过自适应化学掺杂到Ln-ICP网络中。在300nm激发时，由于C343到Eu的伴随能量转移，Ln-ICP网络本身在617nm处的红色荧光得到高度增强，而C343在495nm处的荧光被抑制。在纯乙醇溶剂中，形成的C343@Eu-TDA分散良好且相当稳定。然而，向C343@Eu-TDA的乙醇分散液中加水会破坏Eu-TDA网络结构，导致C343从ICP网络释放到溶剂中。因此，Eu-TDA的荧光关闭，C343的荧光开启，导致分散液的荧光颜色从红色变为蓝色，这构成了比色传感市售酒精饮料样品中AS的新机制。使用此处开发的方法，我们可以借助紫外灯（365nm）直接通过“肉眼”在10% vol至100% vol的宽线性范围内清楚地区分不同酒精饮料样品的AS。本研究不仅提供了一种现场可见检测AS的新方法，还通过分别合理设计Ln-ICP网络和客体的光学性质提供了一种双响应传感模式的策略。
