Highly selective fluorescence turn-on chemosensor based on naphthalimide derivatives for detection of copper(II) ions.

A new fluorescent probe, DN-SB, was synthesized. DN-SB was based on the naphthalimide derivatives and exhibited high selectivity and sensitivity for Cu(2+) ions. As a Cu(2+)-amplified fluorescent probe, its fluorescence spectrum showed 4.5-fold enhancement in the intensity of the signal at 519 nm on binding with the Cu(2+). Based on the fluorescence titration spectra and job's-plot, binding mode of DN-SB with Cu(2+) was proposed. Fluorescence intensity was linear with concentration of Cu(2+) cation in a range from 4 μM to 7 μM. DN-SB was also sensitive for copper ions. The detection limit was calculated to be 0.15 μM which indicated DN-SB was sensitive to Cu(2+).