Multicomponent Rare-Earth Metal–Organic Gels Empowered by Electro-Optical Signal Multi-Source Regulation for Dual-Modal Detection of Propyl Gallate

Propyl gallate (PG) poses a potential threat to human health through dietary exposure. Herein, Eu 3+ /Y 3+ was combined with dual ligands and biomass-derived nitrogen-doped carbon quantum dots (N-CDs) to synthesize multicomponent rare-earth metal–organic gels (N-CDs@Eu 0.05 Y 0.95 -DL-MOGs), achieving electrochemiluminescence (ECL) and fluorescence (FL) visual detection of PG. The dual ligands as antenna molecules collectively displace H 2 O coordination, which sensitizes Eu 3+ via energy transfer. Theoretical calculations indicated that Y 3+ regulates the molecular orbital energy levels and increases the spatial separation between adjacent Eu 3+, thereby suppressing nonradiative energy dissipation arising from cross-relaxation. N-CDs with conductivity and blue FL can sensitize dual-modal sensing. The boronate-affinity units were coupled with molecularly imprinted polymers, providing covalent and noncovalent recognition for PG. The detection limit of ECL sensing mode is 0.267 nM, and the FL emission color response of N-CDs@Eu 0.05 Y 0.95 -DL-MOGs enabled the visual detection of PG. This study provides novel electro-optical signals and multi-source regulation strategies for dual-modal sensing.