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Bridge‐Caging Strategy in Phosphorus‐Substituted Rhodamine for Modular Development of Near‐Infrared Fluorescent Probes
Author(s) -
Chai Xiaoyun,
Xiao Jin,
Li Min,
Wang Chaoming,
An Haiyan,
Li Chen,
Li Yuntao,
Zhang Dazhi,
Cui Xiaoyan,
Wang Ting
Publication year - 2018
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201802875
Subject(s) - fluorescence , fluorophore , chemistry , rhodamine , photochemistry , optics , physics
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 2 O 2 ; and fluorogenic enzyme substrate, PRB2‐NTR, respectively.