Selective detection of ionic liquid fluorescence probes for visual colorimetry of different metal ions

At present, the fast distinction of different metal ions in pure water media is not only a great challenge, but also drives the protection of water quality in environmental water bodies. In this paper, a novel ionic liquid fluorescent probe Glycolic Acid-L-Arginine (GA-L-Arg) was rationally created and designed through an in-depth study of ionic liquids. It is also used as an innovative multi-ion fluorescent probe for colorimetric detection and separate identification of Fe³⁺ and Co²⁺ in aqueous solutions of various metal ions. GA-L-Arg has excellent water solubility due to the strong hydrophilicity of Glycolic Acid and L-Arginine. The probe showed high sensitivity, extremely significant selectivity, and great pH stability for Fe³⁺ and Co²⁺ in pure water. The GA-L-Arg structure and the mechanism of Fe³⁺ and Co²⁺ detection were analyzed by infrared spectroscopic characterization and quantum chemical calculations. More importantly, the distinct colorimetric partitioning of Fe³⁺ and Co²⁺ was performed by the unique extraction of Fe³⁺ in the presence of the fluorescent probe and buffer solution.