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Cyclodextrin Supramolecular Complex as a Water-Soluble Ratiometric Sensor for Ferric Ion Sensing

2009; American Chemical Society; Volume: 26; Issue: 6 Linguagem: Inglês

10.1021/la9033244

1520-5827

Meiyun Xu, Shuizhu Wu, Fang Zeng, Changmin Yu,

Luminescence and Fluorescent Materials

Heightened concern for human health and environmental protection has stimulated active research on the potential impact of transition-metal ions and their toxic effects, thus it is very demanding to design transition-metal ion detection methods that are cost-effective, rapid, facile, and applicable to the environmental and biological milieus. In this study, we demonstrated an alternative strategy for constructing a water-soluble FRET-based ratiometric sensor for ferric ion detection by forming a supramolecular β-cyclodextrin/dye complex. This water-soluble FRET system consists of a dansyl-linked β-cyclodextrin (β-CD-DNS) and a spirolactam rhodamine-linked adamantane (AD-SRhB). The dansyl moiety serves as the donor, and the spirolactam-rhodamine B derivative (SRhB) was chosen as a sensitive, selective chemosensor for Fe(III) ions and a very efficient ring-opening reaction induced by Fe(III) generates the long-wavelength rhodamine B fluorophore that can act as the energy acceptor. Moreover, the adamantyl (AD) group, which is known for its capability to form stable host−guest inclusion complexes with β-CD derivatives, was covalently linked to the spirolactam rhodamine, thus the adamantyl moiety of the ion-recognition element can be anchored inside the CD cavity. In this way, the donor−acceptor separation can be kept within the critical Förster distance; accordingly, energy transfer can take place from the donor (dansyl) to the acceptor (rhodamine derivative/Fe(III) complex), and thus ratiometric detection for Fe(III) in an aqueous medium can be fulfilled. This FRET-based supramolecular sensor can be readily formed via an inclusion process using the donor part and the acceptor part, hence this strategy could afford a robust approach for constructing a wide range of FRET-based water-soluble sensing systems simply by assembling a specifically predesigned donor-linked CD and acceptor-linked adamantane.