A highly selective and sensitive Fe3+ fluorescent sensor by assembling three 1,8-naphthalimide fluorophores with a tris(aminoethylamine) ligand

A fluorescent dye with three 1,8-naphthalimide units has been readily synthesized from 1,8-naphthalic anhydride and tris(2-aminoethyl)amine. Its photophysical properties in organic solvents with different polarity have been studied and its fluorescent sensor activity to metal ions was carefully investigated. The sensor showed high selectivity to Fe3+ by fluorescence quenching in DMF, and exhibited very good selectivity and sensitivity to Fe3+ in DMF/H2O (volume ratio 4:1 and 2:3) by easily detected fluorescence enhancement. The binding stoichiometry indicated that a 1:1 complex was formed between Fe3+ and the sensor in DMF/H2O (volume ratio 2:3). The binding mechanism was studied by IR and 1H NMR spectroscopic techniques.

► A dendrimer-type “turn-on” Fe3+ fluorescent sensor is reported.
► The sensor is both highly selective and sensitive for Fe3+.
► The detection can be carried out in aqueous DMF solutions.