Donor-Acceptor Conjugated Polymer Dots for Tunable Electrochemiluminescence Activated by Aggregation-Induced Emission-Active Moieties

Low-potential electrochemiluminescence (ECL) luminophores with excellent ECL behavior have attracted considerable interest in biological analysis. Herein, we describe the synthesis of two aggregation-induced emission (AIE)-active conjugated polymers with a donor-acceptor (D-A) system via a Suzuki coupling polymerization reaction. The intramolecular DA pairs enhanced their luminescence intensity in aggregate states, which was beneficial for preparation of conjugated polymer dots (Pdots) as as as ECL materials. The ECL emission of the P-2 Pdots showed obvious red shift from 578 to 598 nm after the fluorene moiety (P-1) was replaced with a stronger electron-donating carbazole moiety. The ECL property could be regulated with intramolecular charge transfer of the D-A moieties, which led to a sharp decline (553 mV) of ECL anodic potential. Furthermore, the ECL intensity significantly increased about 6 times because of the low lowest unoccupied molecular orbital level, which facilitated the electron injection into the conjugated polymer backbone. This work provides an effective strategy for developing potential and high ECL emission intensity via adjusting the D-A electronic structure.