Metal−π Interaction-Enhanced Electrochemiluminescence via U-Shaped Schiff Base Luminophores for Ultrasensitive Clindamycin Detection

The advancement of electrochemiluminescence (ECL) sensing has been increasingly restricted by the lack of rationally designed luminophores that simultaneously support efficient charge transfer, excited-state stability, and catalytic amplification. Herein, we report a Fe(II)-coordinated U-shaped Schiff base luminophore (Fe-PDLILUM) that achieves significantly enhanced ECL via synergistic metal-π interactions and topological rigidification. This luminophore is synthesized through imine-bridged conjugation between isoluminol and 1,10-phenanthroline-2,9-dicarboxaldehyde, forming an extended π-delocalized framework that promotes intramolecular charge transport and suppresses nonradiative decay. Fe2+ coordination further stabilizes the excited state and facilitates reactive oxygen species (ROS) generation, resulting in a 4-fold increase in ECL intensity compared to unmodified isoluminol. On applying to clindamycin (CLM) sensing, this system delivers an ultralow detection limit of 1.62 nM and a wide linear range of 5 nM to 30 μM, with excellent selectivity and robustness in complex matrices including river water and milk. This work establishes a modular and mechanism-driven strategy for constructing high-performance ECL emitters, offering a versatile platform for antibiotic monitoring in both clinical and environmental applications.