Priya Bhanu, Mahajan Vibha, Kumar Naresh
Department of Chemical Sciences, IKG-Punjab Technical University, Kapurthala, 144603, Punjab, India.
Department of Chemistry, SRM University, Delhi-NCR, Sonepat, 131029, Haryana, India.
J Fluoresc. 2021 May;31(3):853-860. doi: 10.1007/s10895-021-02723-2. Epub 2021 Mar 25.
A xanthene-based probe, Xanth-NPr, is developed as a molecular system that exhibits sensitivity for the highly acidic environments with fluorescence turn-on behavior. Xanth-NPr is designed on the principle of photoinduced electron transfer (PET), which controls the fluorescence profile of the probe. The structure of Xanth-NPr contains the dipropylaniline group as a PET promoting unit. Xanth-NPr exhibited quenched fluorescence as long as it is present in neutral or moderately acidic conditions. However, in the highly acidic pH range, it displayed a strong red-colored fluorescence at 592 nm as the protonation of dipropylaniline moiety inhibits the PET process. A model probe Xanth-M without any PET promoting unit was also synthesized. The model probe along with theoretical calculations was employed to explain the role of the PET process in regulating the fluorescence behavior of Xanth-NPr. Xanth-NPr showed linear fluorescence response as a function of pH in the range of 1 to 4.1 with the pKa value of 2.72. Likewise, its fluorescence profile is not altered by the presence of biologically relevant cations.
一种基于呫吨的探针Xanth-NPr被开发为一种分子体系，它对高酸性环境具有敏感性，并表现出荧光开启行为。Xanth-NPr是基于光诱导电子转移（PET）原理设计的，该原理控制着探针的荧光特性。Xanth-NPr的结构包含二丙基苯胺基团作为PET促进单元。只要Xanth-NPr存在于中性或中等酸性条件下，其荧光就会淬灭。然而，在高酸性pH范围内，由于二丙基苯胺部分的质子化抑制了PET过程，它在592 nm处显示出强烈的红色荧光。还合成了一种没有任何PET促进单元的模型探针Xanth-M。该模型探针与理论计算一起被用于解释PET过程在调节Xanth-NPr荧光行为中的作用。Xanth-NPr在1至4.1的pH范围内表现出作为pH函数的线性荧光响应，其pKa值为2.72。同样，其荧光特性不会因生物相关阳离子的存在而改变。
