Ion-π Interactions Unveil a Universal Mechanism for Boosting Electrochemiluminescence

Improving the electro-oxidation efficiency of neutral tertiary amines has long been considered crucial for achieving efficient electrochemiluminescence (ECL) in physiological environments. However, they are predominantly present as protonated cations at neutral pH. Recognizing this distinction might lead to significant improvements in ECL performance. In this study, we examine the contribution of such protonated amines by introducing electrodes modified with π-conjugated moieties designed to engage in cation-π interactions. Comparative experiments with a series of π-modified electrodes indicate that cation-π interactions can stabilize the amine-derived radical intermediates and facilitate their electro-oxidation, resulting in higher ECL intensities. More interestingly, the effect is most pronounced when the π-conjugated moieties are located at the outermost layer of the electrode/solution interface. The findings of this work highlight the potential of cation-π interactions to improve ECL systems, encouraging further exploration of ion-π interactions across various ECL platforms.