Colorimetric and fluorescent sensing of multi metal ions and anions by salicylaldimine based receptors

The salicylaldimine based colorimetric chemosensors R1 and R2 were synthesized and examined for anion and cation sensing property. The chemosensors R1 and R2 show visual changes towards biologically relevant anions like F− and OH− and also towards various cations such as Fe3+, Co2+, Ni2+, Cu2+ and Sn2+. The sensing action was further confirmed by UV–vis titration and fluorescence spectroscopic studies. The binding constant (Ka) and stoichiometry of host-guest complex formed were determined by Benesi–Hildebrand (B–H) plot and Jobʹs plot method, respectively.