A colorimetric and fluorometric probe for hydrazine through subsequent ring-opening and closing reactions: Its environmental applications

Abstract

Hydrazine (N2H4), as one of the essential industrial chemicals, is main water contaminant and highly toxic for human health. Therefore, the rapid, selective and sensitive detection strategies for hydrazine are needed. The present study describes the first example of a receptor based on pyrazolone and hydrazide formation by subsequent ring-opening and closing reactions displayed distinct naked eye colorimetric and visual fluorescence sensing towards hydrazine with rapid reactivity and very good selectivity over various anions, cations and amines. The probe BC was obtained in good yield by three stages. The sensing mechanism was confirmed by 1H NMR and 13C NMR spectra. Upon interaction with hydrazine, coumarin ring was easily opened and pink color followed by purple was formed. The more hydrazine addition triggered pyrazolone ring formation with yellow colored solution in company with the remarkable cyan blue turn-on fluorescence output. An easy-to-produce TLC test strip enables to determine hydrazine in the solution. The results were successfully shown to be convenient and efficient for hydrazine detection. Therefore, the present strategy is supposed to be widely applied to fabricate fluorescent sensors for detection of hydrazine.