Aggregation-Induced Enhanced Electrochemiluminescence from Organic Nanoparticles of Donor–Acceptor Based Coumarin Derivatives

Organic nanoparticles (NPs) from donor–acceptor based coumarin derivatives, 6-[4-(N,N-diphenylamino)phenyl]-3-ethoxycarbonyl coumarin (DPA-CM), with an average size of 5.82 nm, were synthesized by a facile reprecipitation method using water as a poor solvent and tetrahydrofuran as a good solvent. Red-shifted absorption, blue-shifted photoluminescence emission, and aggregation-induced enhanced electrochemiluminescence (ECL) emission were observed for the DPA-CM NPs in aqueous solution compared with the original DPA-CM in organic solution. The aggregation-induced enhanced ECL emission is ascribed to the combined effects of the small size of the DPA-CM NPs, the restricted conformational relaxation in the NPs, and the good stability of the cationic radical of DPA-CM. A strong and stable ECL emission is obtained at the DPA-CM NPs modified glassy carbon electrode in the presence of tri-n-propylamine, and the ECL intensity of the DPA-CM NPs modified electrode is quenched linearly in the range of 0.05–50 μM with detection limit of 0.04, 0.2, and 0.4 μM for ascorbic acid, uric acid, and dopamine, respectively. This work shows an example of donor–acceptor based organic NPs as ECL emitters and their analytical applications to monitor biomolecules.