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

Singlet oxygen ( 1 O 2 ) is an important reactive oxygen species (ROS) that is intensively involved in natural photochemical and photobiological processes. Herein, selectively lighting up 1 O 2 is achieved in the aggregation-induced emission (AIE) of electrochemiluminescence (ECL) from the Zn 2+ -mediated AIE assembly of Au nanoclusters (Zn 2+ -AIE-AuNCs). Zn 2+ -AIE-AuNCs can exhibit efficient AIE ECL and photoluminescence (PL) along with 1 O 2 generation in energy and charge transfer routes, respectively. The AIE ECL of the Zn 2+ -AIE-AuNCs/tripropylamine (TEA) system in carbonate buffer is located around 703 nm with the dimeric aggregate of 1 O 2 as an emitter because electrochemically oxidizing coexisted Zn 2+ -AIE-AuNCs and TEA in carbonate buffer would promote the oxygen vacancy (O v ) of Zn 2+ -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 Zn 2+ -AIE-AuNCs to the triplet ground state of dissolved oxygen ( 3 O 2 ). No emissive 1 O 2 is detected via electrochemically oxidizing the Zn 2+ -AIE-AuNCs in the case without either carbonate buffer or TEA, and the Zn 2+ -AIE-AuNCs/TEA system can only exhibit AIE ECL around 485 nm with Zn 2+ -AIE-AuNCs as the emitter in carbonate-free buffers. Photoexciting Zn 2+ -AIE-AuNCs merely brings out band-gap-engineered AIE PL around ∼485 nm with Zn 2+ -AIE-AuNCs as the emitter, which manifests that the 1 O 2 generated in the charge transfer route via photoexciting Zn 2+ -AIE-AuNCs is un-emissive. This work not only proposes an effective strategy for AIE with 1 O 2 as an emitter but also opens a promising way to selectively light up 1 O 2 .