A new fluorescent chemosensor for iron(III) based on the β-aminobisulfonate receptor

A simple fluorescent sensor 1 has been developed for the determination of Fe(III) in 100% aqueous solution at pH 7.0. The sensor comprises a novel aminobisulfonate receptor joined to a naphthalene fluorophore via a methylene spacer in the fluorophore-spacer-receptor format of photoinduced electron transfer (PET) based sensors. The fluorescence emission of the sensor was quenched upon addition of Fe(III) ions, most likely due to electron/energy transfer between Fe(III) and the excited naphthalene. The sensor displayed good selectivity for Fe(III) over other physiologically relevant metal ions and can estimate Fe(III) concentration between 16 and 63 μM. Stern Volmer analysis showed the binding stoichiometry to be 1:1 (host–guest) with a binding constant, calculated using the Benesi–Hilderbrand equation, of (7.6 ± 0.6) × 104 M−1.