Deciphering the Role of Energy Transfer Configuration in PFAS Recognition by Metal-Organic Frameworks.

Per- and polyfluoroalkyl substances (PFAS) have attracted widespread attention as persistent environmental contaminants. However, their rapid detection remains challenging due to their weak light absorption capacities. Luminescence sensing provides a rapid and efficient approach for PFAS monitoring, while ratiometric sensing can further amplify signal variations and improve detection sensitivity with self-referenced optical responses. Lanthanide metal-organic frameworks (Ln-MOFs), featuring tunable porous environments, accessible host-guest interactions, and well-defined multicolor emissions, have emerged as promising platforms for constructing ratiometric sensing materials. Nevertheless, current luminescence sensing has primarily focused on optimizing interactions between the framework and analytes, whereas the influence of intraframework energy transfer configuration on sensing performance remains largely unexplored. Here, Eu/Tb spatial organization is deliberately engineered in EuTb-FDA to decipher the role of energy transfer configuration in PFAS recognition. By regulating the spatial distribution of emissive centers, the Tb3+-to-Eu3+ energy transfer pathway is precisely modulated, enabling distinct energy transfer behaviors. The optimized configuration couples PFAS-induced host-guest interactions with directional lanthanide energy redistribution, resulting in enhanced sensing performance, thereby generating an amplified ratiometric response. This work reveals intraframework energy transfer configuration as a critical yet overlooked parameter in luminescence sensing and provides a new design principle for developing high-performance ratiometric sensing materials.