Superatom Pruning by Diphosphine Ligands as a Chemical Scissor

Area of Science:

• Inorganic Chemistry
• Nanomaterials Science
• Supramolecular Chemistry

Background:

• Silver nanoclusters (NCs) are gaining attention for their unique electronic and optical properties.
• Controlling the size and electronic configuration of silver nanoclusters is crucial for tuning their functionality.
• Existing synthesis methods often lack precise control over nanocluster transformation.

Purpose of the Study:

• To demonstrate a novel stepwise synthesis for transforming a larger silver nanocluster into a smaller one.
• To investigate the role of bis(diphenylphosphino)methane (dppm) as a 'chemical scissor' in nanocluster transformation.
• To characterize the resulting two-electron silver superatom and its properties.

Main Methods:

• Synthesis of [Ag6{S2P(OPr)2}4(dppm)2] from [Ag20{S2P(OPr)2}12] by adding dppm.
• Characterization using single-crystal X-ray crystallography, multinuclear NMR spectroscopy, and electrospray ionization-mass spectrometry.
• Computational analysis using density functional theory (DFT) and time-dependent DFT calculations.

Main Results:

• Successful synthesis of a two-electron silver superatom, [Ag6{S2P(OPr)2}4(dppm)2] (1).
• Demonstration of dppm-induced nanocluster-to-nanocluster transformation, reducing size and electron count.
• Observation of fluxional behavior in compound 1 via temperature-dependent NMR spectroscopy.
• Compound 1 exhibits bright yellow emission with a 16.3% quantum yield.

Conclusions:

• Stepwise synthesis using dppm provides a controlled method for nanocluster transformation.
• The transformation involves geometric pruning and electronic reconfiguration of the silver nanocluster.
• The resulting heteroleptic nanocluster possesses interesting photoluminescent properties and dynamic behavior.