We designed and synthesized a simple fluorescent probe, (E)-2-(2-(3,4,5-Trimethoxybenzylidene)hydrazinyl) benzothiazole (probe), which could be applied to the detection of strongly acidic and alkaline pH in DMSO/water (1/4, v/v) system. It could be used to quantitatively detect strong acid in the range of 2.60–3.53 with a pK_a of 2.78. Meanwhile, it also showed an excellent linear relationship between the fluorescence intensity and alkaline pH values over the range of 9.98–10.95 with a pK_a of 9.32. The probe exhibited excellent properties to pH with high selectivity and sensitivity. The mechanism studies showed that the H⁺ binding with the N atom of benzothiazole moiety and hydrazine moiety in acid solution while the deprotonation of N atom in hydrazine group in basic environment. Importantly, the probe was successfully applied for imaging the strongly acidic and alkaline in E.coil cells.

中文翻译：

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用于感应pH值的简单荧光探针及其在大肠杆菌细胞中的应用。

我们设计并合成了一个简单的荧光探针（E）-2-（2-（3,4,5-三甲氧基亚苄基）肼基）苯并噻唑（探针），可用于检测DMSO /中的强酸性和碱性pH水（1 / 4，v / v）系统。它可用于定量检测2.60–3.53范围内的强酸，ap K _a为2.78。同时，在ap K _a为9.32的情况下，荧光强度与碱性pH值在9.98-10.95范围内也显示出极好的线性关系。该探针对pH表现出优异的性能，具有很高的选择性和灵敏度。机理研究表明，H ⁺与碱性溶液中苯并噻唑部分和肼部分的N原子结合，而肼基中的N原子去质子化。重要的是，该探针已成功应用于在大肠杆菌细胞中强酸性和强碱性成像。