New Europium(III)-TTA Complex Containing 2-Pyrrolidone as Coligand to Application as Luminescent Sensor: Pb^II and Ethanol in Gasoline

This work describes the synthesis and application of an europium(III) complex, [Eu(TTA)₃(2-pyr) (H₂O)], containing 2-thenoyltrifuoroacetonate (TTA) and 2-pyrrolidone (2-pyr) as ligands, obtained as white solid and soluble in ethanol. In solution, the complex showed red emission, characteristic of the Eu^III emission in the solid state (λ_exc = 375 nm and λ_em = 612 nm). The complex was tested with Pb^II, Cd^II, and Hg^II ions in water. The effect of metal ions was monitored and evaluated by hypersensitive transition ⁵D₀ → ⁷F₂ (612 nm). The results show that Pb^II suppresses the complex luminescence and present high sensitivity, according to the values for the Stern-Volmer constant (K _SV = 2300 L mol⁻¹), showing good linearity, i.e., determination coefficient (R ²) of 0.9913, and low limit of detection (LOD = 6.03 µM). Luminescence quenching increased with the increasing concentration of Pb^II. These results indicate that the synthesized complex is a potential luminescent sensor for detecting Pb^II in a simple and fast way, being applicable for routine environmental analysis. When applied as an ethanol sensor in gasoline, the complex hypersensitive transition intensity decreased with the increasing volume of ethanol in gasoline, reaching the values of R ² = 0.9815 and LOD = 4.94% v/v.

Keywords:
europium(III); 2-pyrrolidone; lanthanides; luminescent sensor