Novel Colorimetric Anthracene-Based Thiosemicarbazone Probe for Selective Cyanide Ion Detection: From Synthesis to Real-Time Applications

A novel thiosemicarbazone, <i>N</i>'-(anthracen-9-ylmethylene) morpholine-4-carbothiohydrazide (<b>MA</b>), was synthesized and characterized for selective cyanide ion sensing. Interaction between the cyanide ion and sensor <b>MA</b> was examined thoroughly with the aid of absorption, emission, and ¹H NMR spectra, and the binding constant was estimated. The detection limit obtained was much lower than those reported recently. The ¹H NMR spectra titration studies clearly indicated that deprotonation occurs from the N-H group of the receptor. The sensing mechanism was further explored by density functional theory (DFT) and time-dependent DFT (TDDFT) methods using Gaussian16 software. <i>In silico</i> investigation reveals that the added cyanide ion abstracts a proton from the N-H group, which supports experimental results. The synthesized receptor <b>MA</b> was found to be a very good candidate for selective sensing of cyanide.