A fluorescent colorimetric azo dye based chemosensor for detection of S2- in perfect aqueous solution and its applications in real sample analysis and molecular logic gate
A simple azo-dye based bis-Schiff base chemosensor L has been designed, synthesized and characterized by NMR, IR spectroscopy, ESI-MS and elemental analyses. The chemosensor L can successfully detect sulfide ion both visually and spectro-photometrically in perfect aqueous medium as well as in organic aqueous mixture through de-protonation mechanism.The detection limit reachesupto 16 µM in pure aqueous medium (1.7 µM by UV-Vis titration, 3.35 x 10-7M by fluorescence titration in 1:1 DMSO-H2O mixture), which is lowest ever known in the family of Schiff base chemosensor for sulfide ion. The other interfering anions (F−, Cl−, Br−, HSO3-, N3-, PO43-, NO3-, OAc−, CO32- and CN-) exhibited no interference for detection of sulfide ion. The mechanism of interaction between the L and sulphide ion has further been confirmed by DFT studies. The chemosensor L has also been applied for real sample analysis and in building molecular logic gate.