Precisely engineered dual-antenna europium MOF with intrinsic dual-state luminescence for sensitive dexamethasone sensing

Dual-emitting combined with dual-mode detection holds great importance in variety of luminescence-based applications. The dual-emitting property of a single metal-organic framework (MOF) is highly attractive due to its stability and the ability to achieve dual emission without requiring additional fluorophores. In this study, a novel dual-emitting dual-state bi-ligand Eu-based MOF (BiL-Eu-MOF) was synthesized exploiting dual-antenna effect. The dual-antenna effect, achieved through precise tuning of the ligands' energy levels in alignment with the empty ⁵D₀ orbitals of Eu³⁺ ions, significantly enhances charge transfer from the ligands to the metal center, resulting in intensified emission. In this regard, dexamethasone (DX) quenches the red emission, while the blue emission remained slightly affected. This phenomenon, led us to design ratiometric-tonality platform for detection of DX using conventional fluorometry and fluorescence tonality visual-based mode. The intrinsic dual-emitting properties of BiL-Eu-MOF enable stable, recyclable, and selective on-site detection DX without the need for encapsulation or functionalization.