Breaking the catalysis-quenching dilemma in covalent organic frameworks with metal single-atom sites for enhanced electrochemiluminescence

Precise incorporation of metal single-atom (SA) active sites into covalent organic frameworks (COFs) offers a powerful approach to enhance electrochemiluminescence (ECL) by facilitating co-reactant activation and charge transport. However, metal coordination usually triggers intramolecular electron-transfer quenching that degrades the ECL efficiency of COFs. Herein, we construct a pyrene-phenanthroline COF with coordinated Ag SA (AgSA/PP-COF) that breaks the catalysis-quenching dilemma of metals, achieving enhanced ECL performance. Density functional theory calculations reveal that, among the screened metal catalysts, the d10-configurated Ag (I) center exhibits the weakest electron coupling with the nitrogen atoms of PP-COF’s phenanthroline units. This minimal perturbation ensures that the framework’s intrinsic luminescence is largely retained. Specifically, AgSA serves as highly efficient active sites, facilitating co-reactant adsorption and activation while accelerating interfacial electron transfer kinetics. Remarkably, the resultant AgSA/PP-COF exhibits a 4.5-fold enhancement in ECL intensity. Moreover, AgSA/PP-COF enables the construction of a highly sensitive ECL enzymatic biosensor for organophosphorus pesticide detection. This work provides a universal strategy for the design of high-performance solid-state ECL emitters. The incorporation of metal single-atom into covalent organic frameworks facilitates co-reactant activation and charge transport enhancing electrochemiluminescence, however, can also trigger intramolecular electron transfer quenching that degrades the electrochemiluminescence efficiency. Here the authors achieved the coordination of silver atom into pyrene phenanthroline covalent organic frameworks, breaking the catalysis-quenching dilemma of metals and thereby achieving enhanced electrochemiluminescence performance.