5‐N,N‐Diarylaminothiazoles with Electron‐Accepting Groups: Synthesis, Photophysical Properties, and Their Application for the Detection of Hydrazine Hydrate

Abstract

Abstract5‐N,N‐diarylaminothiazoles containing cyano and nitro groups were synthesized using the Pd‐catalyzed Buchwald‐Hartwig amination reaction with good yields. The cyano group in the resultant thiazole was reduced to a formyl group. This was then subjected to the Knoevenagel condensation reaction, leading to the formation of thiazoles with a dicyanovinyl group. The nitro group in the thiazole was reduced to an amino group, which was subsequently reacted with triphosgene, yielding a thiazole with an isocyanate group. These thiazoles, with their electron‐accepting properties, demonstrated absorption and emission spectra at longer wavelengths. Notably, the thiazole containing the dicyanovinyl group displayed a red emission. Tests for the detection of hydrazine, a hazardous volatile organic compound, were conducted using the synthesized thiazoles. The results showed that the dicyanovinyl group effectively responded to hydrazine hydrate, evidenced by changes in the absorption and emission spectra. This change in color was also visibly detectable to the naked eye.