A fluorescent colorimetric azo dye based chemosensor for detection of S2- in perfect aqueous solution and its application in real sample analysis and building a molecular logic gate

摘要

A simple azo-dye based bis-Schiff base chemosensor, L, has been designed, synthesized and characterized by NMR and IR spectroscopy, ESI-MS and elemental analysis. The chemosensor L can successfully detect sulfide ions both visually and spectro-photometrically in perfect aqueous medium as well as in an organic-aqueous mixture through a de-protonation mechanism. The detection limit reaches 16 M in pure aqueous medium (1.7 M by UV-vis titration and 3.35 x 10(-7) M by fluorescence titration in a 1:1 DMSO-H2O mixture), which is the lowest detection limit ever reported in the family of Schiff base chemosensors for sulfide ions. Other interfering anions (F-, Cl-, Br-, HSO3-, N-3(-), PO43-, NO3-, OAc-, CO32- and CN-) exhibited no interference for the detection of sulfide ions. The mechanism of interaction between L and sulphide ions has further been confirmed by DFT studies. The chemosensor L has also been applied for real sample analysis and in building a molecular logic gate.