Turn-on fluorescent detection of nickel and zinc ions by two related chemosensors containing naphthalimide ring(s)

Abstract

Two rationally designed chemosensors, L1 and L2, conjugated with naphthalimide ring(s) are presented for the “Turn-on” fluorescent detection of Ni2+ and Zn2+ ions. The coordination of Ni2+ and Zn2+ ions to the chemosensors resulted in prominent changes in their emission and absorption spectra. Competitive binding studies, detection limits and binding constants illustrated noteworthy sensing abilities of L1 and L2 toward Ni2+ and Zn2+ ions. Job's plot and high-resolution mass spectra established a 1:1 stoichiometry of chemosensors with Ni2+ and Zn2+ ions which was further supported with the DFT studies. Practical detection methods including colorimetric sensing, paper test-strips and polystyrene films have been utilized for the sensing of Ni2+ and Zn2+ ions in aqueous solutions.