Highly selective hydrazone based reversible colorimetric chemosensors for expeditious detection of CN- in aqueous media

Herein we have described the design and syntheses of two novel hydrazone based N, O donor Schiff-base colorimetric sensors L-1 and L-2 for selective sensing of cyanide ions in 2:1 CH3CN-H2O mixture. L-1, and L-2 have been characterized by H-1 NMR, IR spectroscopy, HRMS spectrometry and elemental analyses. Interactions of L-1 and L-2 with CN- provide remarkable color change from yellow to red (for L-1) and yellow to pink (for L-2) along with change in the absorption maxima, enabling naked-eye sensing of CN- ion, without use of any expensive equipment. From the job's plot analyses, HRMS spectral studies and H-1 NMR analyses, 1:1 binding stoichiometry of chemosensor L-1, and 1:2 binding stoichiometry of chemosensor L-2 towards cyanide ion have been confirmed. The detection limits reach up to 1.3 JM for L-1 and 1.0 mu M for L-2 which are lower than the maximum permissible level of CN- in drinking water set by WHO. The other competitive anions (OAc-, F-, CI-, Br, I-, H2PO4-, NO2-, NO3-, HSO4-, NO3-, CO2-, PO32-, S2-, and BO3-) showed very negligible interference for detection of cyanide at that concentration level. The sensing mechanism has further been confirmed by DFT studies. Both the chemosensors L-1, and L-2 have been successfully applied for the determination of CN- ions in real water samples and simulated urine samples. (C) 2018 Elsevier B. V. All rights reserved.