一种大斯托克斯位移的红光发射荧光探针选择性检测次氯酸

设计、合成了一种基于巴比妥酸衍生物的具有D-π-A结构的光学探针3。该探针能够作为一种高度灵敏和选择性的次氯酸指示剂，快速实现对次氯酸的比色和荧光信号(开-关)的双响应(约15 s)。推测的响应机制是ClO^-与C=C之间发生了亲电加成和氧化裂解反应，导致探针的D-π-A结构遭到破坏，从而阻断了其分子内电荷转移(intramolecular charge transfer，ICT)进程。探针只需一步即可合成，同时具有红光发射(628 nm)和较大的斯托克斯位移(158 nm)，检测限(limit of detection，LOD)低至14 nmol·L^-1。此外，探针还表现出低细胞毒性，并成功应用于活细胞成像。

A red-emitting fluorescent probe with a large Stokes shift for selective detection of hypochlorous acid

An optical probe (3) with a donor-π-acceptor (D-π-A) structure for the detection of hypochlorous acid (HClO) was synthesized by a one-step reaction. It employed a barbituric acid derivative as the electron acceptor and 4-(dimethylamino)cinnamaldehyde as the electron donor. The probe exhibited high sensitivity and selectivity for the detection of HClO, rapidly responding with distinct colorimetric and fluorescent “on-off” signals (about 15 s). The probe displayed a linear relationship between fluorescence intensity and HClO concentration, with a low detection limit (LOD) of 14 nmol·L^-1, which made it suitable for quantitative HClO detection. Moreover, the probe exhibited red light emission (628 nm) with a significant Stokes shift (158 nm) and good photostability, which provided advantages for its application in cell imaging. The proposed reaction mechanism, which was deduced from high-resolution mass spectrometry data, involved electrophilic addition and oxidative cleavage of the C=C bond by ClO^-, which led to the disruption of the probe''s D-π-A structure. Consequently, this effectively halted the intramolecular charge transfer (ICT) process of the probe. MTT cytotoxicity assays demonstrated minimal toxicity of the probe following 12, 24, and 48 h of incubation with HepG2 cells. The probe was successfully applied to living cell imaging and enabled the detection of HClO via fluorescence quenching within the living cellular milieu.