Chen Zuoxu, Shimizu Soji, Ji Sheng, Pan Jianming, Wang Yue, Feng Ru
School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013, China.
Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, Fukuoka 819-0395, Japan; Center for Molecular Systems (CMS), Kyushu University, Fukuoka 819-0395, Japan.
Spectrochim Acta A Mol Biomol Spectrosc. 2025 Jan 15;325:125083. doi: 10.1016/j.saa.2024.125083. Epub 2024 Sep 6.
A novel alkaline pH-responsive probe based on an asymmetric aza-BODIPY was synthesized in a one-pot Schiff base formation reaction. This pH-sensitive probe comprises an asymmetric aza-BODIPY as the luminescent core, with a benzothiazole moiety connected via an imine bond serving as the recognition site. The probe exhibits a turn-off fluorescence response upon exposure to alkaline pH (9.6-12.4), while a bathochromic band in the absorption emerges due to its extended π-conjugation system, accompanied by a visible colorimetric change from yellow to orange to red. Furthermore, the probe responds linearly in the highly alkaline region, with a pK of 11.65. The recognition mechanism of the probe towards alkaline pH relies on the deprotonation of the imine group on the aza-BODIPY core, leading to an enhanced degree of π-electron conjugation. The quenched fluorescence intensity is attributed to the increased non-radiative decay of the deprotonated form of the probe. The probe demonstrates high reliability for practical applications due to its photostability and reversibility. This study provides new insights into the design of probes for detecting high alkaline pH levels.
一种基于不对称氮杂硼二吡咯的新型碱性pH响应探针通过一锅法席夫碱形成反应合成。这种pH敏感探针包含一个不对称氮杂硼二吡咯作为发光核心，一个通过亚胺键连接的苯并噻唑部分作为识别位点。该探针在暴露于碱性pH（9.6 - 12.4）时表现出荧光猝灭响应，同时由于其扩展的π共轭体系，吸收光谱出现红移带，伴随着从黄色到橙色再到红色的可见比色变化。此外，该探针在高碱性区域呈线性响应，pK为11.65。该探针对碱性pH的识别机制依赖于氮杂硼二吡咯核心上亚胺基团的去质子化，导致π电子共轭程度增强。荧光强度猝灭归因于探针去质子化形式非辐射衰减的增加。由于其光稳定性和可逆性，该探针在实际应用中表现出高可靠性。本研究为检测高碱性pH水平的探针设计提供了新的见解。
