Bis-pyrene-containing fluorescent receptor for explosive picric acid and Au(III) via dynamic excimer quenching process in aqueous medium: Practical application

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In this paper, we developed a bis-triazole-pyrene sugar derivative 1 to recognize PA and Au(III) in an 80 % aqueous ethanol system. The recognition ability of 1 toward PA and Au(III) was evaluated from spectroscopic studies and DFT calculations. The dynamic excimer emission of 1 was reduced efficiently with PA and Au(III) ions compared to other NACs, metal species and anions. The sugar backbone provides the actual stereochemistry for forming dynamic excimer in aqueous ethanol medium after excitation at 345 nm. The bis-pyrene system 1 generated intramolecular pyrene dynamic excimer emission in the aqueous system. After interacting with PA, the excimer quenching was attributed to the charge and energy shifting from electron-dense pyrene units to electron-lacking PA in the ground state. Receptor 1 demonstrated a 1:1 stoichiometric ratio for PA and Au(III) ion with low micromolar detection limits (0.05 µM for PA and 0.75 µM for Au3+). The quenching and interaction mechanisms were demonstrated from DFT calculations. The recognition property of 1 for PA was also executed in the solid-supported system. Finally, the practical usefulness of the proposed method was described by the PA and Au(III) recovery abilities in various environmental water systems.