Highly selective probe based on imine linkage for Zn2+ and HSO3− in mixed aqueous media

A simple salicylaldehyde derived Schiff base N, N′- bis (p-chloro salicylidene)-1, 2- ethylenediamine (L) was synthesized and characterized. The receptor demonstrates simultaneous dual channel chromogenic and fluorogenic signaling towards HSO3− and Zn2+ in mixed aqueous media. Solvatochromism was employed systematically for modulating its optoelectronic properties. The probe was successfully assessed to monitor HSO3− detection via UV-vis spectroscopy. DFT calculations and 1H NMR spectroscopy further support the results based on shifting of equilibrium. Moreover, the sensor showed large fluorescence enhancement with blue-shift of 48 nm after addition of Zn2+. The probe exhibits high selectivity over other competitive ions with high detection limit of 6.54×10−5 M and 3.21×10−6 M for HSO3− and Zn2+, respectively. Importantly, this is one of the rare reports in which Schiff base was utilized for the fabrication of chromogenic or fluorogenic sensor using solvent effect for multianalyte detection.