Rational Green Synthesis of Eu MOF for Ratiometric Fluorescence Sensing Cu²

A green-synthesized europium-based metal-organic framework (Eu-ATPA@3RhB) was developed for ratiometric fluorescence sensing of Cu²⁺. Under 245 nm excitation, Eu-ATPA@3RhB exhibits dual emission peaks at 435 nm and 588 nm. When Cu²⁺ is added, the fluorescence at 435 nm is quenched while that at 588 nm remains constant, enabling ratiometric detection based on the I₄₃₅/I₅₈₈ ratio. The method shows a linear range of 1-25 µM (R²=0.99) with a detection limit of 0.25 µM, outperforming drinking water standards. Density functional theory (DFT) calculations elucidate the interaction mechanism between Cu²⁺ and Eu-ATPA@3RhB. The Eu-ATPA@3RhB developed in this study showcases the advantages of green synthesis, simplicity, and swiftness, affirming its potential for Cu²⁺ detection in diverse environmental water samples.