Development of Stable Water‐Soluble Supratomic Silver Clusters Utilizing A Polyoxoniobate‐Protected Strategy: Giant Core‐Shell‐Type Ag₈@Nb₁₆₂ Fluorescent Nanocluster

Abstract

Atomically precise low‐nuclearity (n<10) silver nanoclusters (AgNCs) have garnered significant interest due to their size‐dependent optical properties and diverse applications. However, their synthesis has remained challenging, primarily due to their inherent instability. The present study introduces a new feasible approach for clustering silver ions utilizing highly negative and redox‐inert polyoxoniobates (PONbs) as all‐inorganic ligands. This strategy not only enables the creation of novel Ag‐PONb composite nanoclusters but also facilitates the synthesis of stable low‐nuclearity AgNCs. Using this method, we have successfully synthesized a small octanuclear rhombic [Ag8]6+ AgNC stabilized by six highly negative [LiNb27O75]14‐ polyoxoanions. This marks the first PONb‐protected superatomic AgNC, designated as {Ag8@(LiNb27O75)6} (Ag8@Nb162), with an aesthetically spherical core‐shell structure. The crystalline Ag8@Nb162 is stable under ambient conditions, What’s more, it is water‐soluble and able to maintain its molecular cluster structure intact in water. Further, the stable small [Ag8]6+ AgNC has interesting temperature‐ and pH‐dependent reversible fluorescence response, based on which a multiple optical encryption mode for anti‐counterfeit technology was demonstrated. This work offers a promising avenue for the synthesis of fascinating and stable PONb‐protected AgNCs and sheds light on the development of new‐type optical functional materials.

Kinetically Controlled Self-Assembly of Ag Nanoclusters with Enhanced Luminescence

“…Luminescent metal NCs possess many unique advantages such as ultrasmall size, low toxicity, high photostability, and excellent biocompatibility. They exhibit wide application potentials in biosensing, imaging, phototherapy, photoelectric devices, and environmental detection, ,− which are promising to be the alternatives of conventional luminescent materials such as organic fluorescent dyes and semiconductor quantum dots. However, the commonly low emission efficiency of metal NCs has greatly limited their extensive PL-related applications.…”