Sen Bhaskar, Sheet Sanjoy Kumar, Patra Sumit Kumar, Koner Debaprasad, Saha Nirmalendu, Khatua Snehadrinarayan
Inorg Chem. 2019 Aug 5;58(15):9982-9991. doi: 10.1021/acs.inorgchem.9b01125. Epub 2019 Jul 24.
A Ru(II) complex () of a substituted pyridyl-1,2,3-triazole ligand () for highly selective "light-up" detection of hypochlorous acid is presented. An unusual anti-Markovnikov HOCl addition to the C═C bond of 1,2,3-triazole and a highly specific C(sp)-H hydroxylation over epoxidation made a highly selective luminescent HOCl probe. The abnormal regio- and stereoselective HOCl addition and subsequent hydroxylation mechanism in detail is supported by the combination of ESI-MS, H/C NMR spectroscopy, and H NMR titration. The hydroxylation at the C5 center in 1,2,3-triazole increases the electron density and makes a better σ-donor as well as π-donor, which in turn increases the MC-MLCT energy gap and inhibits the nonradiative decay from the excited state of and is the key reason for luminescence light-up. Most importantly, the exogenous and endogenous HOCl imaging in the living HEK293T cells is also demonstrated. The probe showed low cytotoxicity and efficiently permeated the cell membrane. The cell-imaging experiments revealed rapid staining of the extranuclear region of HEK293T cells which clearly indicates the presence of cytoplasmic HOCl. The endogenous HOCl generation and imaging, stimulated by lipopolysaccharides (LPS) and paraquat in the HEK293T cells, is also demonstrated.
本文报道了一种用于高选择性“点亮”检测次氯酸的取代吡啶基-1,2,3-三唑配体的钌（II）配合物（）。1,2,3-三唑的C═C键发生了不寻常的反马氏次氯酸加成反应，且在环氧化反应中发生了高度特异性的C(sp)-H羟基化反应，这使得该配合物成为一种高选择性的次氯酸发光探针。电喷雾电离质谱（ESI-MS）、氢/碳核磁共振光谱（H/C NMR）和氢核磁共振滴定相结合，详细支持了异常的区域和立体选择性次氯酸加成及随后的羟基化反应机理。1,2,3-三唑中C5中心的羟基化增加了电子密度，使其成为更好的σ供体和π供体，进而增加了金属-配体电荷转移（MC-MLCT）能隙，抑制了配合物激发态的非辐射衰变，这是发光“点亮”的关键原因。最重要的是，还展示了在活的人胚肾293T细胞中进行的外源性和内源性次氯酸成像。该探针显示出低细胞毒性，并能有效穿透细胞膜。细胞成像实验显示人胚肾293T细胞的核外区域迅速染色，这清楚地表明了细胞质中存在次氯酸。还展示了脂多糖（LPS）和百草枯刺激人胚肾293T细胞产生和成像内源性次氯酸的情况。
