A novel fluorescein-based dye containing a catechol chelating unit to sense iron(III)

In the present work we report the synthesis and characterization of a novel fluorescein-based dye containing a catechol chelating unit designed to act as a chemosensor for iron(III). The compound was prepared using conventional and microwave-assisted amide coupling of a catechol derivative with a 5(6)-carboxyfluorescein scaffold. One of the most interesting features of this conjugate structure is a high affinity binding site on the catechol ring close to the fluorophore. As a consequence, the behaviour of the new compound in the presence of metal ions of biological importance was monitored by optical spectroscopy (at physiological pH). The results show that the conjugate is particularly sensitive to iron(III), thus suggesting that it may be used as fluorescent chemosensor for the detection of iron(III) in cellular systems.

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► Fluorescein-based dye containing a catechol chelating unit was synthesised.
► Shorten time reaction was achieved by microwave irradiation.
► Photophysical properties (absorption, fluorescence, quantum yield) were determined.
► Fe(III) and Cu(II) lead to a considerable fluorescence quenching effect.
► Application as an iron(III) sensor in biological media is anticipated.