A novel “on-off-on” switches fluorescence sensor based on TSPP-gallic acid (GA) for S${}^{2-}$-detecting was designed in this article. 5,10,15,20- (4-sulphonatophenyl) porphyrin (TSPP) was synthesized by a modified “one-pot” method. The synthesized TSPP was used as a fluorescence probe for the construction of a fluorescence sensing system. At room temperature, the maximum fluorescence emission wavelength could be obtained at 642 nm when the excitation wavelength was 515 nm when the fluorescence signal was in the “on” mode. The TSPP solution appeared pink in color at this moment. When GA was introduced into the TSPP solution, the fluorescence signal was turned off (fluorescence intensity was quenched) due to the protonation of TSPP, which was caused by the weak acidity of GA. The color of the TSPP solution changed from pink to green. Following that, an acid-base reaction between S${}^{2-}$and GA was initiated when S${}^{2-}$was introduced into the TSPP-GA system, leading to the liberation of TSPP and restoration of fluorescence intensity. The solution color reverted to red, indicating that the fluorescence sensing system had returned to the “on” mode. The TSPP-GA system had good selectivity and sensitivity to S${}^{2-}$, the linear range was 4.52 × 10${}^{-6}$ M $\sim$ 4.34 × 10${}^{-4}$ M, and the detection limit (LOD) was 0.87 $\mu$ M. It could be used to detect sulfur ions in actual samples with satisfactory recoveries and RSD values.

一种基于 TSPP-没食子酸 (GA) 的新型“on-off-on”开关荧光传感器${}^{2-}$-本文设计了检测。 5,10,15,20-(4-磺基苯基)卟啉(TSPP)是通过改进的“一锅法”合成的。合成的 TSPP 作为荧光探针构建荧光传感系统。室温下，当荧光信号处于“on”模式时，激发波长为515 nm，可在642 nm处获得最大荧光发射波长。此时TSPP溶液呈现粉红色。当将GA引入到TSPP溶液中时，由于GA的弱酸性导致TSPP质子化，荧光信号被关闭（荧光强度被猝灭）。 TSPP 溶液的颜色从粉红色变为绿色。随后，S之间发生酸碱反应${}^{2-}$当 S 时，GA 开始${}^{2-}$将其引入TSPP-GA系统中，导致TSPP的释放并恢复荧光强度。溶液颜色恢复为红色，表明荧光传感系统已返回“开启”模式。 TSPP-GA系统对S具有良好的选择性和灵敏度${}^{2-}$，线性范围为 4.52 × 10${}^{-6}$中号$～$4.34×10${}^{-4}$M，检测限（LOD）为0.87$\mu$M.可用于检测实际样品中的硫离子，回收率和RSD值均令人满意。