Department of Organic Chemistry, College of Pharmacy, Second Military Medical University, Shanghai, 200433, P.R. China.
Department of Chemistry, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai, 200241, P.R. China.
Chemistry. 2018 Sep 25;24(54):14506-14512. doi: 10.1002/chem.201802875. Epub 2018 Aug 29.
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-H O ; and fluorogenic enzyme substrate, PRB2-NTR, respectively.
将罗丹明中的桥氧原子替换为磷原子是获得波长超过 700nm 的明亮近红外（NIR）荧光团的最有效方法之一。然而，有机磷桥不仅是一种光谱调谐器，它还是一种卓越的可溶性增强剂和光稳定性增强剂，这已被一系列磷取代的罗丹明（PRB）所证明。通过对示例 PRB2 的一系列研究，进一步创新了一种独特的桥笼策略，以有效地操纵荧光。与理论计算一致，作为荧光控制器的笼状基团形成有机膦酸酯将螺内酯锁定在无色非荧光形式，而脱笼，即由特定刺激诱导的过程，导致开环形式，从而产生强荧光。桥笼策略可用于 NIR 探针的模块化开发。作为光活化荧光团、PRB2-hν；荧光指示剂、PRB2-H O ；和荧光酶底物、PRB2-NTR，分别在 PRB2 支架上实现了光激发、过氧化氢和酶的高效活体成像。
