Photochemical Synthesis of Atomically Precise Ag Nanoclusters

Area of Science:

• * Inorganic Chemistry
• * Materials Science
• * Photochemistry

Background:

• * Photochemical synthesis offers control over nanoparticle size and shape.
• * The capability of photochemical methods for fabricating atomically precise silver nanoclusters (Ag NCs) remains largely unexplored.
• * Silver nanoclusters are gaining attention for their unique optical and electronic properties.

Purpose of the Study:

• * To synthesize an atomically precise silver nanocluster using a photochemical approach.
• * To elucidate the mechanism behind the photochemical synthesis of silver nanoclusters.
• * To explore the potential of photochemical methods for developing new silver nanoclusters and sensing applications.

Main Methods:

• * Synthesis of silver nanoclusters ([Ag25(4-MePhC≡C)20(Dpppe)3](SbF6)3) mediated by visible light.
• * Structural determination using X-ray crystallography.
• * Mechanistic investigation involving photoinduced electron-transfer (PET) studies, experimental analysis, and density functional theory (DFT) calculations.
• * Synthesis of additional silver nanoclusters (Ag19, Ag32) and a bimetallic nanocluster (Ag22Au3) by modifying reaction components.
• * Development of a visual amine detection method based on a photochromatic process.

Main Results:

• * Successful synthesis of an atomically precise silver nanocluster, [Ag25(4-MePhC≡C)20(Dpppe)3](SbF6)3 (Ag25), via visible-light-mediated photochemistry.
• * Elucidation of the formation mechanism, revealing a photoinduced electron-transfer (PET) process where amines are oxidized to N-oxides upon light excitation (< 455 nm).
• * Production of three additional nanoclusters (Ag19, Ag32, Ag22Au3) by altering precursor ingredients, showcasing the versatility of the photochemical method.
• * Demonstration of a facile visual detection method for amines, leveraging the photochromatic properties of Ag19.

Conclusions:

• * Visible-light-mediated photochemistry is a viable method for synthesizing atomically precise silver nanoclusters.
• * The photoinduced electron-transfer (PET) mechanism is crucial for the formation of these nanoclusters.
• * The developed photochemical approach can be extended to synthesize diverse silver and bimetallic nanoclusters, with potential applications in chemical sensing.