Self-Enhanced Dual-Emissive Electrochemiluminescent Metallacages Combining Aggregation-Caused Quenching and...

Aggregation-caused quenching (ACQ) and aggregation-induced emission (AIE) represent two opposite but incomplete paradigms in aggregation-dependent luminescence, in which efficient emission is confined to either dispersed or aggregated state. Bridging these regimes within a single system remains challenging. Herein, we report a metallacage (MC)-based electrochemiluminescent (ECL) system, in which a tetraphenylethene (TPE)-based pyridyl ligand and π-extended conjugation derivatives are bridged together to act as AIE and ACQ chromophores within a single structurally well-defined framework. The discrete cage architecture controls chromophore orientation, π-π interactions, and donor-acceptor characteristics, achieving dual-emission from ACQ chromophore in the dispersed state and AIE chromophore in the aggregated state. Moreover, a platinum(II) complex serves as not only the rigid bridging node but also as catalytic center, which promotes the reduction of S₂O₈ ^2- coreactant to generate sulfate anion radical (SO₄ ^•-), establishing a self-enhanced ECL paradigm. In addition, aggregation-dependent redistribution between two emissive channels enables ECL activity in both dispersed and aggregated states. The aggregate formed at a water fraction of 40% shows a 4-fold intensity enhancement relative to the dispersed state. These results demonstrate MC can reconcile ACQ and AIE effects within a single system and provide tunable ECL luminophores for multiplexed sensing and imaging.