A novel naphthalimide–glutathione chemosensor for fluorescent detection of Fe3+ and Hg2+ in aqueous medium and its application

By rationally introducing glutathione functionalized 1, 8–naphthalimide, a novel fluorescent chemosensor (NG) was successfully synthesized. NG can high selectively and sensitively recognize Fe3+/Hg2+ ions through quenching of fluorescence among all kinds of common metal ions in aqueous medium. The binding stoichiometry ratio of NG–Fe3+ is verified as 2:1and NG–Hg2+ as 1:2 confirmed by Job's plot method, FT-IR, 1H NMR and ESI–MS spectrum, and the possible sensing mechanism were also proposed. The chemosensor NG toward Fe3+ and Hg2+ displays the excellent advantages of high selectivity and sensitivity, low detection limits (7.92 × 10−8 and 4.22 × 10−8 M), high association constants (3.37 × 108 and 8.14 × 104 M−2), instataneous response (about 10s) and wide pH response range (3.0–8.0). Importantly, the chemosensor NG was successfully applied to determine Hg2+ in tap water. Meanwhile, the test strips based on NG were prepared, which could conveniently and efficiently detect Fe3+ and Hg2+. Moreover, the complex of NG and Fe3+ (NG–Fe3+) showed high selectivity and sensitivity for H2PO4‾ over many other anions in the same medium.