Synthesis of Azosalicylic Aldehyde of Benzoyl Hydrazone Based Sensor and It's Colorimetric Sensing Properties for Cyanide Anions in Aqueous Solutions

A colorimetric anions sensor bearing phenol -OH and -NH groups was synthesized. The binding properties of the receptor with anions such as F-, Cl-, Br-, I-, CH3COO-, H2PO4-, HSO4-, ClO4-, CN-, SCN-, SO42- and NO3- were examined by UV-Vis and H-1 NMR spectra. Upon the addition of CN- anions, the sensor displayed apparent color changes from colorless to yellow while other anions did not cause obvious color changes. The UV-Vis spectroscopic titration experiments and MS data indicated the formation of 1 : 1 addition compound between CN- and the sensor. The results showed that the sensor in DMSO/H2O (volume ratio 5 : 5) solution indicated colorimetric single selectivity for CN- which could be observed by naked eyes due to the nucleophilic addition reaction of cyanide.