Novel allyl-hydrazones including 2,4-dinitrophenyl and 1,2,3-triazole moieties as optical sensor for ammonia and chromium ions in water

It is critical to take safety action if carcinogenic heavy metals and ammonia can be detected quickly, cheaply, and selectively in an environmental sample. As a result, compound 4a [4-(1-(2-(2,4-Dinitrophenyl)hydrazineylidene)-3-(naphthalen-2-yl)allyl)-5-methyl-1-phenyl-1 H-1,2,3-triazole] and compound 4b [4-(1-(2-(2,4-Dinitrophenyl)hydrazineylidene)-3-(naphthalen-2-yl)allyl)-1-(4-fluorophenyl)-5-methyl-1 H-1,2,3-triazole] were prepared. The aldol condensation process of 4-acetyl-1,2,3-triazoles 1a,b (Ar = C₆H₄; 4-FC₆H₄) with 2-naphthaldehyde yields 1-acetyl-1,2,3-triazoles 1a,b (Ar = C₆H₄; 4-FC₆H₄) (5-methyl-1-aryl-1 H-1,2,3-triazol-4-yl) -3-(naphthalen-2-yl)prop-2-en-1-ones 3a,b with a yield of around 95%. The target compounds 4a,b are obtained in around 88% yield by condensation of 3a,b with (2,4-dinitrophenyl)hydrazine in a refluxing acidic medium. Compounds 4a,b exhibited possible colorimetric detection for chromium ion in the range of 0–14 ppm and ammonia in the range of 0–20 ppm. As a result, this research suggests that strong electron-withdraw groups in related probes can improve anion detection ability, while the conjugation effect should also be considered while building structures.