A 4-phenyl thiophene appended 2,4-dinitrophenylhydrazone as a colorimetric chemosensor for selective detection of cyanide ion and its application for real-life samples

Abstract

A Schiff's base probe PBD was synthesized by the treatment of 4-phenylthiophene-2-carbaldehyde and 2, 4-dinitrophenylhydrazine, which is found to act as a potential colorimetric sensor for CN− ion. The visual color change was noticed from yellow to pink with CN− ion in semi-aqueous medium due to the intra ligand charge transfer (ILCT) and deprotonation mechanism. The PBD-CN− complex formation was supported through NMR, UVVis absorption, and FT-IR spectral studies. The potential binding between probe and CN− ion were determined using Jobs plot (1:1 stoichiometric ratio) and density functional theory (DFT) calculations. The limit of detection was found to be 4.62 × 10−8 M, which is lesser than the permissible levels given by WHO in drinking water. Furthermore, the probe was tested for its reproducibility with various water samples, food samples and smartphone RGB technique to recognize CN− ion. The probe was successfully used for analysis of CN− ion in real samples.