Thiophene aldehyde-diamino uracil Schiff base: A novel fluorescent probe for detection and quantification of cupric, silver and ferric ions

• A novel Schiff base fluorescent chemosensor was easily prepared by a one-step reaction.
• The probe shows significant fluorescence quenching in presence of Ag+, Cu2+ and Fe3+ ions.
• Limits of detection can reach 0.132 μM (Ag+), 0.088 μM (Cu2+) and 0.037 μM (Fe3+).
• The analytical method was validated for the assay of the three cations in real samples.

A new Schiff base from the condensation of 5,6-diamino-1,3-dimethyluracil with 5-methylthiophene-2-carboxaldehyde was synthesized. The compound was characterized by spectral data (UV–Vis, IR, 1H NMR, fluorescence, MS). Ethanolic solutions of the Schiff base exhibit a strong fluorescence emission at 385 nm (λex = 341 nm), and have been employed as a “turn-off” fluorescent probe for selective detection of Ag+, Cu2+ and Fe3+ ions in presence of other cations such as Na+, K+, Ca2+ and Mg2+ ions abundant in natural water. The interaction between the tested compound and copper, silver or iron ions is associated with a significant fluorescence decrease, showing detection limits of 2.1–14.2 ppb. Under optimal conditions, the developed sensor was successfully employed to determine Ag+, Cu2+ and Fe3+ ions in real samples and proved to be selective and sensitive.

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