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 D-A pairs enhanced their luminescence intensity in aggregate states, which was beneficial for preparation of conjugated polymer dots (Pdots) 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 AIE-active ECL materials with low potential and high ECL emission intensity via adjusting the D-A electronic structure.