Synthesis of 4-(1-(2-(2,4-dinitrophenyl)hydrazineylidene)-5-phenylpenta-2,4-dien-1-yl)-1-(4-methoxyphenyl)-5-methyl-1H-1,2,3-triazole as optical sensor for the toxic heavy metal ions in an aqueous medium

Abstract

Heavy metal ions represented as highly toxic pollutants for the environment. In the search for new optical sensors for heavy metals, here, new organic linker [4-(1-(2-(2,4-dinitrophenyl)hydrazineylidene)-5-phenylpenta-2,4‑dien-1-yl)-1-(4-methoxyphenyl)-5-methyl-1H-1,2,3-triazole] was prepared in 87% yield by simple and facile method. The techniques of synthesis follow the formation of chalcone then condensation with hydrazine moiety to perform hydrazone derivatives. It was synthesized from addition of 1-(1-(4-Methoxyphenyl)-5-methyl-1H-1,2,3-triazol-4-yl)-5-phenylpenta-2,4‑dien-1-one to 2,4-dinitrophenylhdrazine. The chemical structure of prepared linker was established by the IR and NMR spectral data in addition to single-crystal X-ray crystallography. The new linker was used for detection of various metal ions (Cu2+, Zn2+, Cr3+, Co2+, Cd2+, and Hg2+). Interestingly, the new linker showed highly detection level and selectivity toward Hg2+ions. The color of the Hg2+ ions solution was turned from colorless to green when adding the title compound performed excellent naked-eye detection. The binding stoichiometry of the linker to the Hg2+ ions was found to be 1:1, which was confirmed by Job plot. For industrial application, the new linker was mixed with filter paper and used for detection of Hg2+ions. The new fabricated filter paper was identified using scanning electron microscopy (SEM). The present fabricated filter paper produced naked eye colorimetric detection of Hg2+ions.