A fluorescent sensor for selective recognition of Al3+ based on naphthalimide Schiff-base in aqueous media

In this paper, a new chemosensor Sl, N-n-buty1-443,3 ' 4(2-aminoethyl)azanediyebis(N '-(2-hydroxybenzylidene) propanehy-drazide)]-1,8-naphthalimide, has been designed and synthesized as an turn-on sensor for the detection of Al3+ with a high sensitivity and an excellent selectivity. The sensor Si comprises 1,8-naphthalimide moiety as the fluorophore and Schiff base as the binding site. The structure of sensor Si has been established by single crystal X-ray structure and common spectroscopic methods. As expected, it exhibited high selectivity and sensitivity for detecting Al3+ over other commonly coexistent metal ions. The 1:1 binding stoichiometry of the metal complex was established on the basis of combined fluorescence titration, Job's plot, UV-vis titration and H-1 NMR spectra analysis. In addition, the sensor Si can be applied to the quantification of Al3+ with a linear range covering from 1.0 to 10.0 M and a detection limit of 1.78 x 10(-7) M. Much more than this, the sensor Si was preliminarily applied for the determination of Al3+ in water samples from the Yellow River and tap water with satisfying results.