Replacement of the bridging oxygen atom in rhodamine with phosphorus is one of the most efficient ways for bright near‐infrared (NIR) fluorophores with wavelengths over 700 nm. However, the organophosphorus bridge is more versatile than just being a spectrum tuner, it is also a profound solubility booster and photostability enhancer, as proved by a series of phosphorus‐substituted rhodamines (PRBs). A unique bridge‐caging strategy for efficiently manipulating fluorescence has further been innovated in example PRB2. Consistent with theoretical calculations, the formation of organophosphinate by a caging group as a fluorescence‐controller locks the spirolactone into a colorless and nonfluorescent form, whereas decaging, a process induced by a specific stimulus, results in a ring‐opened form, which yields strong fluorescence. The bridge‐caging strategy is feasible for the modular development of NIR probes. Efficient in vivo imaging of photoillumination, hydrogen peroxide, and enzyme have been achieved on the PRB2 scaffold as a photoactivatable fluorophore, PRB2‐hν; fluorescent indicator, PRB2‐H₂O₂; and fluorogenic enzyme substrate, PRB2‐NTR, respectively.

中文翻译：

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磷取代的若丹明的架桥策略用于近红外荧光探针的模块化开发

用磷代替若丹明中的桥接氧原子是波长超过700 nm的明亮的近红外（NIR）荧光团的最有效方法之一。但是，有机磷桥不仅是一种光谱调谐器，而且用途更广，它也是一种出色的溶解度增强剂和光稳定性增强剂，一系列磷取代的若丹明胺（PRB）证明了这一点。示例PRB2中进一步创新了一种有效操纵荧光的独特架桥策略。与理论计算相符，笼基团作为荧光控制剂形成有机次膦酸酯，可将螺内酯锁定为无色和非荧光形式，而通过特定刺激诱导的去壳作用会导致开环形式，从而产生强力的开环反应。荧光。架桥策略对于NIR探针的模块化开发是可行的。在PRB2支架上以光激活性荧光团PRB2-的形式对光照明，过氧化氢和酶进行了有效的体内成像hν ; 荧光指示剂PRB2-H ₂ O ₂；和荧光酶底物PRB2-NTR。