Rapid Screening of Supramolecular Binding Constants via Active Monomer-Regulated Electrochemiluminescence

Rapid and accurate measurement of host-guest binding constants is crucial for constructing supramolecular assemblies. However, conventional spectroscopic titration methods require high sample consumption, involve lengthy workflows, and demand specific optical properties. Here, we propose a superoxide-triggered luminol electrochemiluminescence (ECL) platform for fast, sensitive, and broadly applicable screening of binding constants in viologen derivative-based supramolecular assemblies. It is disclosed that viologen derivatives could significantly promote luminol ECL by accelerating oxygen reduction and stabilizing the superoxide anion radical at the electrode interface through electrostatic interactions. Upon host-guest complexation, the concentration of active viologen monomers decreased, leading to a measurable reduction in the ECL enhancement. Notably, the ECL intensities of various assemblies exhibited a strong correlation with their binding constants, enabling direct affinity evaluation without the need for traditional UV-vis or fluorescence titration. This work confirms that superoxide-triggered luminol ECL is able to act as a powerful analytical tool for supramolecular screening, offering substantial advantages in speed, sensitivity, and generality.