Highly selective colorimetric sensor for Zn2+ based on hetarylazo derivative

An intensely colored hetarylazo derivative 1 possessing thiadiazole derivative as diazo component and m-aminoacetanilide based coupling component has been synthesized and demonstrates a highly selective color change from red to faint orange upon sensing of Zn2+. Other cations of the same group; Cd2+ did not interfere in the sensing process; however, Hg2+ interfered only at very high concentrations but depicted interesting sensing behaviour of its own. Other commonly occurring cations such as Ca2+, Mg2+ and Cu2+ did not respond to the sensing event. The pH stability of the azo derivative offers additional advantage in the sensing process.