<p>Ln-MOFs have garnered significant attention for their potential in metal ion detection, particularly Fe ³⁺ ions, which play a crucial role in biological processes such as the synthesis of hemoglobin, myoglobin, and cytochromes. The development of Ln-MOF-based fluorescent probes with exceptional aqueous stability and efficient Fe³⁺ detection capabilities holds great promise for practical applications. In this study, we designed and synthesized a series of Ln-MOFs: [Ln₂(L)₂(H₂O)₄]·2H₂O (Ln = Tb, Ln = Eu); [Ln₂(L)₂(DMF)(H₂O)] (Ln = Tb), where H₃L is 2-hydroxybenzene-1,3-dicarboxylic acid. These structures exhibit a two-dimensional (2D) layered architecture with a unique coordination configuration. Fluorescence spectroscopy revealed that all the Ln-MOFs display characteristic lanthanide emission peaks, with Ln-MOF1 and Ln-MOF3 showing peaks at 355&#xa0;nm, and Ln-MOF2 at 398&#xa0;nm. Importantly, all Ln-MOFs exhibit significant fluorescence quenching in the presence of Fe³⁺, even with 15 competing metal ions (e.g., Ni²⁺, Cu²⁺, Zn²⁺), achieving a detection limit of 1&#xa0;μM-surpassing most reported Ln-MOFs in sensitivity. XRD and ICP analyses confirmed the structural integrity of the Ln-MOFs after exposure to Fe³⁺, showing no framework degradation and measurable Fe³⁺ adsorption. Stern–Volmer analysis revealed a dynamic quenching mechanism (I/I₀= 1 + K_sv[M]), suggesting that the quenching effect is attributed to the intrinsic luminescent properties and molecular structures, which feature Lewis acid sites from active oxygen atoms. This interaction leads to weak binding with aqueous Fe³⁺ ions, possibly triggering an internal charge transfer process regulated by the coordination field, contributing to the observed fluorescence quenching. Leveraging their optical properties, we also developed filter paper test strips for rapid, on-site detection of Fe³⁺ ions.</p>