An [Ag3(dppy)2(NO3)3] cluster polymer with narrowing fluorescence

Low-dimensional nanomaterials with lattice confinement, including those of nanoclusters (NCs), offer benefits for fluorescence narrowing. Compared to quantum dots of metal NCs, however, one-dimensional structures of such NCs challenge the single-crystal synthesis. Here, we report the synthesis of a novel [Ag₃(dppy)₂(NO₃)₃] _<i>n</i> cluster polymer through the reduction of AgNO₃ with NaBH₄ in a dark environment. This cluster polymer incorporates the coordination and passivation of both diminished nitro groups (NO₃) and diphenyl-2-pyridylphosphine (dppy) ligands. The weak Ag-Ag metallic bonds within this cluster polymer are governed by argentophilic interactions, with each Ag₃ unit connected by a NO₃ group. This cluster polymer exhibits photoluminescence with three emission bands at 308, 352, and 620 nm, aligned with the purple (308/352 nm) and red (620 nm) regions, respectively. We synthesized microfibers of this cluster polymer using reprecipitation, resulting in a fluorescence bandwidth reduction to approximately one-tenth in the microfiber samples relative to the diluted solution.