Tunable Fluorescence from 2D Assemblies of LnW10 and P2 W18 Polyoxometalates Clusters with Quaternary Ammonium-type AIEgens.

Two-dimensional (2D) AIE-inorganic nanocomposites exhibit high stability and high fluorescence activity. However, limited by the types and properties of 2D inorganic materials, it's challenging to realize complex structures and functions. We designed a quaternary ammonium-type AIE ligand, TPECholine. We chose TPECholine and POM clusters as building blocks and synthesized a series of single-layer nanosheets (SLNSs) by assembling LnW10 or P2 W18 POM clusters with TPECholine. By regulating the types of POM clusters and ligands, the morphology and fluorescence intensity of the SLNSs can be finely tuned. Due to the restriction of the intramolecular motions of AIEgens by the SLNSs, nanosheets can exhibit promoted quantum yield (up to 76 %). In addition, thanks to the sub-nanometric sizes and excess surface charges, SLNSs exhibit excellent solvent compatibility, including water, chloroform, ethanol, etc. And the nanosheets showed high fluorescence intensity in these solvents.