A dual colorimetric chemosensor based on Schiff base for highly selective and simultaneous recognition of CN− and Sn2

[Display omitted] •A new colorimetric chemosensor (SZ) based on azo chromophore containing Schiff base.•Chemosensor exhibited dual ions selectivity towards CN− and Sn2+ over other coexisting ions with lowest limit of detection.•The experimental results theoretically supported by DFT studies.•Test strips coated with SZ can easily detect CN− and Sn2+ ion in aqueous solutions.•Chemosensor was successfully used for quantitative and onsite detection of CN− and Sn2+. A new colorimetric chemosensor 2-methoxy-6-{(E)-[(4-methylphenyl)imino] methyl}-4-[(E)-(4-nitrophenyl)diazenyl] phenol (SZ) was designed and synthesized for simultaneous detection of CN− and Sn2+ in MeCN: bis-tris buffer solution. The sensor SZ showed quick and selective colorimetric response towards CN− and Sn2+ with a change in color from yellow to pink and colorless respectively without any interfering anions or cations. Meanwhile, the binding mode of SZ for CN− and Sn2+ were studied by 1H NMR, ESI-MS, FT-IR spectroscopy, Job’s plot analysis and DFT calculations. The detection limit of SZ towards CN− and Sn2+ was found to be 0.649 µmol/L and 0.754 µmol/L respectively which are lower than the WHO guidelines for drinking water. Furthermore, chemosensor SZ was successfully utilized as a colorimetric chemosensor for the detection of CN− and Sn2+.