ABSTRACT Organic room‐temperature phosphorescence (RTP) materials are promising for bioimaging applications due to their tunable structures, excellent biocompatibility, and long‐lived luminescence. However, the development of highly efficient organic RTP materials for aqueous systems remains challenging, as the organic phosphorescence is prone to being quenched by the dissolved oxygen in water. Herein, heteroaromatic carboxylic acids serve as ligand guests to construct a series of host‐guest composites with nontoxic, dense EDTA‐M (M = Ca, Mg, and Al) coordination polymer in water. These composites exhibit ultra‐long pure RTP of guest molecules with phosphorescence quantum yield up to 53%, and lifetime up to 589.7 ms, due to the synergistic effect of dual‐network structure: a coordinatively cross‐linked network of EDTA‐M, and a non‐covalent bonded network formed by ligands and water molecules. The phosphorescence intensity is more than three times that of the composite with a single coordination network. Notably, the dual‐network configuration can form a rigid and dense structure and block the intrusion of external H 2 O and O 2 molecules to avoid phosphorescence quenching in water. As a result, the RTP of the composites remains unchanged after 1 month in water. Furthermore, the nanoparticles fabricated from composites and anionic surfactants can be successfully applied in in vivo imaging of mice for the stable RTP in water. This work provides a novel strategy for the development of high‐performance RTP materials in aqueous systems.
Zheng et al. (Sun,) studied this question.