基于芴母核的新型水溶性弱酸性荧光pH指示剂

A water soluable fluorene core pH indicator in weak acidic environments

目的:设计并合成可以检测弱酸性环境的pH荧光探针,为检测溶酶体(pH=4~5)和内涵体(pH=5~6)中的酸性环境提供科学的方法依据。方法:以2,7-二溴芴为荧光母核,分别与电子给体二乙胺基和电子受体苯并噻唑相连,构建供体-π-受体体系,并在芴的亚甲基上引入能够改善水溶性的二乙二醇甲醚乙基得到目标化合物5,并对其进行核磁表征确定结构,采用紫外分光光度计法和荧光光谱法研究目标化合物5对pH值的响应性,计算p Ka。结果:核磁数据与化合物结构相吻合,化合物5紫外吸光度与荧光强度变化具有pH依赖性,通过非线性回归显示p Ka为5.88。结论:基于芴母核结构设计并合成了探针化合物5,紫外和荧光结果表明是一个弱酸性pH荧光指示剂,在弱酸性环境的检测方面应该具有很好的应用前景。

Objective: To design and synthesizethe pH-sensitive fluorescent probes that could detect weak acidic conditions, which would provide a scientific basis fordetecting the acidic environments of lysosomes(pH=4~5) and endosomes(pH=5~6). Methods:Based on a fluorescent core 2,7-dibromofluorene, a donor--acceptor system was developed via conjugation with the electron donor diethylamine and the electron acceptor benzothiazole. The diethylene glycol methyl ether ethyl group was introduced to the methylene position of fluorene to improve the solubility and finally compound 5 was obtained. The compound 5 was characterized by NMR.UV-Vis and fluorescence spectroscopies were used to study itspH-responsive properties andthe p Ka was calculated. Results:The NMR spectradata were well agreement withthe compound 5 as well as the intermediates. The changes of UV-vis absorbance and fluorescence intensity of compound 5 were p H-dependent. The p Ka was calculated to be 5.88 by nonlinear regression analysis. Conclusion: The compound 5 can be designed and synthesized based on thefluorine core. The results from UV-Vis and fluorescence experiments indicate that it may be a weak acidic fluorescent pH indicator, showingagreatpromise in the detection of weak acidic environment.