Ag₄₄ (EBT)₂₆ (TPP)₄ Nanoclusters With Tailored Molecular and Electronic Structure

Area of Science:

• Materials Science
• Nanotechnology
• Photochemistry

Background:

• Synthesizing atomically precise nanoclusters (NCs) with controlled structures is crucial for understanding structure-property relationships.
• Developing nanoclusters with unique optical and photophysical properties remains a significant challenge.

Purpose of the Study:

• To synthesize a novel, charge-neutral silver nanocluster (Ag NC) with a defined molecular structure.
• To investigate the influence of mixed capping ligands on the optical and photophysical properties of Ag NCs.

Main Methods:

• Synthesis of a charge-neutral Ag NC using phosphine (triphenylphosphine, TPP) and thiol (2-ethylbenzenethiolate, EBT) capping ligands.
• Single-crystal X-ray structure determination to elucidate the NC's core-shell structure (Ag12@Ag20).
• Time-dependent density-functional theory (TD-DFT) calculations to analyze electronic structure and optical properties.

Main Results:

• Successful synthesis of a charge-neutral Ag44 nanocluster with the formula Ag44(EBT)26(TPP)4, featuring a hollow Ag12@Ag20 core and a mixed-ligand shell.
• The Ag44 NC demonstrated a >25-fold enhancement in NIR-II photoluminescence quantum yield compared to all-thiolate stabilized [Ag44(SR)30]4- NCs.
• TD-DFT calculations revealed the Ag44 NC as an 18-electron superatom with a modulated electronic structure, correlating with its enhanced optical properties.

Conclusions:

• The use of mixed phosphine and thiol ligands enables the synthesis of novel Ag NCs with unique structural and electronic properties.
• The charge-neutral Ag44(EBT)26(TPP)4 nanocluster exhibits significantly enhanced NIR-II photoluminescence, paving the way for advanced optical applications.
• Structural and electronic modulation through ligand design is a key strategy for tuning the photophysical properties of metal nanoclusters.