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Zn 2+ Binding‐Enabled Excited State Intramolecular Proton Transfer: A Step toward New Near‐Infrared Fluorescent Probes for Imaging Applications
Author(s) -
Xu Yongqian,
Liu Qin,
Dou Bairui,
Wright Brian,
Wang Jingyun,
Pang Yi
Publication year - 2012
Publication title -
advanced healthcare materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.288
H-Index - 90
eISSN - 2192-2659
pISSN - 2192-2640
DOI - 10.1002/adhm.201200025
Subject(s) - stokes shift , fluorescence , intramolecular force , zinc , excited state , photochemistry , benzoxazole , proton , infrared , ligand (biochemistry) , chemistry , materials science , receptor , stereochemistry , optics , biochemistry , physics , organic chemistry , quantum mechanics , nuclear physics
Abstract In order to facilitate the in vivo study of zinc‐related biology, it is essential to develop a zinc‐selective sensor that exhibits both near‐infrared (NIR) emission and larger Stokes shift. A fluorescent sensor, Zinhbo‐5 , has been constructed by using bis(benzoxazole) ligand with 2, 2'‐dipicolylamine (DPA) as metal ion receptor. In aqueous solution, Zinhbo‐5 exhibits high sensitivity ( K d = 2.58 nM 2 ) and selectivity for Zn 2+ cation, revealing about 14‐fold fluorescence enhancement upon zinc binding to give green emission. Remarkably, Zn 2+ binding to Zinhbo‐5 switches on the excited state intramolecular proton transfer (ESIPT), producing the desirable near‐infrared region (over 710 nm) with large Stokes shift (ca. 240 nm). The new probe is demonstrated to be useful for in vivo imaging of the intracellular Zn 2+ ion. The Zinhbo‐5 is also useful for detecting zinc ion distribution during the development of living zebrafish embryos.