Chromo/Fluorogenic Detection of Co2+, Hg2+ and Cu2+ by the Simple Schiff Base Sensor

Herein, we reported the ditriazole Schiff base derivative 1 and evaluated its photophysical properties on induction of varieties of metal ions including Na+, Ag+, Ni2+, Mn2+, Pd2+, Co2+, Hg2+, Cu2+, Pb2+, Cd2+, Zn2+, Sn2+, Fe2+, Fe3+, Cr3+ and Al3+, in order to figure out its potential as ion sensor. The ligand 1 exhibited the strong colorimetric change in the reaction solution as well as absorption spectral shifting with the concomitant appearance of well-defined isosbestic points only upon Co2+, Hg2+ and Cu2+ addition corroborates its applicability as multichannel ion detector. The different extent of spectral shifting as well as unique chromogenic change in the probe solution upon Co2+, Hg2+ and Cu2+ introduction can be used as the discrimination tool for these metal ions. The ligand-metal binding stoichiometry was assessed by their optical response which was further supported by the FT-IR, NMR and mass spectrometric analysis. The association constant and the detection limits of the ligand toward Co2+, Hg2+ and Cu2+ ions were calculated to be 1.52 x 10(-8), 3.26 x 10(-9), 1.16 x 10(-8) and 3.87 x 10(-10), 5.47 x 10(-11), 8.91 x 10(-11) M, respectively, employing the Benesi-Hilderbrand equation and 3 sigma slope(-1) methods. Furthermore, the successive addition of Co2+, Hg2+ and Cu2+ induce the constant decline in the fluorescence emission signal intensity of the probe. The quenching efficiency of the probe upon metallic induction was fitted to the Stern-Volmer equation which yielded the upward curvature in case of all the three metals ions (Co2+, Hg2+ and Cu2+) when (I-o/I-1) was plotted against the quencher concentration indicating the occurrence of both the dynamic and static quenching process in the system with the average Stern-Volmer quenching constant values of 9.25 x 10(-7), 1.14 x 10(-7), 1.829 x 10(-7), respectively.