Schiff Base Fluorescent Moiety Salicylideneaniline as a Dualchannel Chemosensor: A Hg2+/Cu2+ Switchable Logic Gate

A simple Schiff base (L) fluorescent moiety has been synthesized and characterized using various spectroscopic techniques. It has been tested with several cations, such as alkaline, alkaline earth and transition metal ions. Its micromolar solution in aqueous methanol system discloses discriminatory classification of Hg2+ with emission ON-OFF signaling and selective recognition of Cu2+ with colour changes from yellow to blue. Furthermore, titrations reveal that (L) is a highly sensitive sensor for Hg2+ and Cu2+ with detection limit of 2.8 x 10(-7) M and 7.8 x 10(-5) M, respectively. Job plot analysis supported 1:1 and 1:2 stoichiometries between (L) and Hg2+/Cu2+. The association between metal ion and (L) has been supported using H-1 NMR and DFT studies. Sensor (L) also represents logic circuit operating by integration of AND, NOT and OR gates with fluorescence as output. This is the one of the rare reports in which selective identification of metal ions have been performed using two different recognition techniques.