Atomically dispersed Eu(III) sites in natural deep eutectic solvents based fluorescent probe efficient identification of Fe3+ and Cu2+ in wastewater

Heavy metal ions in wastewater have brought serious environmental pollution. To improve the detection efficiency, it is important to find useful fluorescent probes . The emerging green natural deep eutectic solvents (NADESs) offer attractive option for “green” detection for its good biocompatibility, easy preparation, and high sensitivity. In this study, a multi-functionalized fluorescent probe with atomically dispersed EuCl 3 ·6H 2 O in amino acid-based NADESs ( l -Glutamic acid/Glycerol, l -Glu/Gly) was synthesized by metal-ligand coordination interactions with a mass ratio of 15:1. Combined with the NADESs and rare earth metal , the l -Glu/Gly/EuCl 3 ·6H 2 O could form the amino site and Eu 2+ site fluorescent centers. Under the excitation wavelength of 370 nm, it had dual emission peaks at 425 nm and 470 nm with efficient resonance energy transfer . The stable optoelectronic properties of l -Glu/Gly/EuCl 3 ·6H 2 O under external factors, such as mass ratio (13,1 to 18:1), temperature (30–50 °C), pH (1 to 14) and storage time ( >42 days), approved l -Glu/Gly/EuCl 3 ·6H 2 O an excellent fluorescence probe. In the application of water-quality monitoring, Fe 3+ and Cu 2+ could react with l -Glu/Gly/EuCl 3 ·6H 2 O in different reactive patterns. The blue fluorescence was quenched by Fe 3+ and enhanced by Cu 2+ , thus metal ions could be distinguished with high sensitivity. The detective process was determined and the fluorescent mechanism was also proposed. l -Glu/Gly/EuCl 3 ·6H 2 O fluorescent probe was demonstrated to be an efficient fluorescent probe for metal detection avoiding the hydrothermal process, and the cumbersome of ilter, dialysis, freeze drying.