Simultaneous visual and spectroscopic multi-analyte detection of Al3+ and AsO2− using simple salicylidene based D-π-A chromophore

Abstract

The salicylidene-isoniazide Schiff base D-π-A chromophore ( L1 ) exhibits chromogenic and fluorogenic dual responsive behaviour with multiple ICT-PET-ESIPT interplaying sensing mechanism and provides diverse optical signals promising to selectively and simultaneously track multiple analytes in water rich media. • Salicylidene-isoniazide Schiff base ( L1) exhibited naked-eye detectable distinctive colour changes for Al 3+ and AsO 2 - • It displayed turn-on type distinct fluorogenic response for both Al 3+ and AsO 2 - • Multiple ICT-PET-ESIPT interplaying mechanism provided diverse optical signals to simultaneously track multiple analytes. • Applied for fluorescence imaging of Al 3+ and AsO 2 - in living cells. The present communication reports the efficacy of a salicylidene-isoniazide Schiff base based donor-π-acceptor (D-π-A) chemosensor ( L1 ) for chromogenic and fluorogenic dual mode sensing of Al 3+ and AsO 2 - in water rich semi-aqueous solution. L1 offers multiple benefits of simplicity, ease of synthesis, inexpensive, suitable binding sites for cations and anions, high sensitivity, noteworthy colourimetric response, naked-eye detection, selectivity, and good detection limits of 1.89 μM for Al 3+ and 2.2 μM for AsO 2 - . It shows selective turn-on fluorescence response for both Al 3+ and AsO 2 - , attributed to CHEF due to the combined effect of arrest of PET, inhibition of -CH=N- geometrical isomerization, prevention of ESIPT process and increase in conformational rigidity. Owing to specific interaction between Mo(VI) and arsenite, L1 -Mo(VI) ensemble system is successfully utilized for colourimetric detection of arsenite through displacement approach. The binding modes of the receptor L1 to these analytes are established through Job’s plot and 1 H-NMR spectroscopic analysis. The reversible off-on-off fluorescence switching behaviour of L1 upon binding to Al 3+ and AsO 2 - are applied to construct combinational OR, AND, and NOT molecular logic gates. Fluorescence turn-on sensing, cell permeability and low toxicity of the chemosensor allows monitoring of these analytes in living cells.