Selectively Lighting Up Singlet Oxygen via Aggregation-Induced Electrochemiluminescence Energy Transfer

Singlet oxygen (1O2) is an important reactive oxygen species (ROS) that is intensively involved in natural photochemical and photobiological processes. Herein, selectively lighting up 1O2 is achieved in the aggregation-induced emission (AIE) of electrochemiluminescence (ECL) from the Zn2+-mediated AIE assembly of Au nanoclusters (Zn2+-AIE-AuNCs). Zn2+-AIE-AuNCs can exhibit efficient AIE ECL and photoluminescence (PL) along with 1O2 generation in energy and charge transfer routes, respectively. The AIE ECL of the Zn2+-AIE-AuNCs/tripropylamine (TEA) system in carbonate buffer is located around 703 nm with the dimeric aggregate of 1O2 as an emitter because electrochemically oxidizing coexisted Zn2+-AIE-AuNCs and TEA in carbonate buffer would promote the oxygen vacancy (Ov) of Zn2+-AIE-AuNCs, which could selectively enable the generation of emissive singlet oxygen in the energy transfer route by effectively transferring the energy from excited singlet Zn2+-AIE-AuNCs to the triplet ground state of dissolved oxygen (3O2). No emissive 1O2 is detected via electrochemically oxidizing the Zn2+-AIE-AuNCs in the case without either carbonate buffer or TEA, and the Zn2+-AIE-AuNCs/TEA system can only exhibit AIE ECL around 485 nm with Zn2+-AIE-AuNCs as the emitter in carbonate-free buffers. Photoexciting Zn2+-AIE-AuNCs merely brings out band-gap-engineered AIE PL around ∼485 nm with Zn2+-AIE-AuNCs as the emitter, which manifests that the 1O2 generated in the charge transfer route via photoexciting Zn2+-AIE-AuNCs is un-emissive. This work not only proposes an effective strategy for AIE with 1O2 as an emitter but also opens a promising way to selectively light up 1O2.