Structural Changes in Atomically Precise Ag₂₉ Nanoclusters upon Sequential Attachment and Detachment of Secondary...

Area of Science:

• Nanomaterials Science
• Surface Chemistry
• Computational Chemistry

Background:

• Understanding the structural dynamics of ligand-stabilized noble metal nanoclusters (NCs) is crucial for their application.
• Ligand rearrangement significantly influences the structural changes observed in NCs.
• The interaction between primary and secondary ligands on NC surfaces is a key area of investigation.

Purpose of the Study:

• To investigate the dynamic behavior of ligand-protected [Ag29(L)12]3- NCs when interacting with a secondary ligand (L').
• To characterize the structural properties of NC-based adducts [Ag29(L)12]L'n3- for n=1-4.
• To elucidate the nature of noncovalent interactions between NCs and secondary ligands.

Main Methods:

• Experimental techniques: Ultraviolet-visible (UV-vis) spectroscopy, high-resolution electrospray ionization mass spectrometry (ESI MS), and ion mobility mass spectrometry (IM MS).
• Coupled MS/MS IMS experiments were used to probe fragmentation behavior.
• Computational approach: Density functional theory (DFT) calculations were employed to predict structures and interactions.

Main Results:

• Experimentally determined collision cross-sections (CCSs) showed a monotonic increase with the number of secondary ligands (n=1-4).
• DFT calculations indicated weak noncovalent interactions between the NCs and secondary ligands.
• Progressive expansion of the Ag-S staple framework of the NC was observed with increasing secondary ligand addition.

Conclusions:

• Secondary ligand addition induces significant structural modifications in [Ag29(L)12]3- nanoclusters.
• The observed structural changes are consistent with weak noncovalent interactions and framework expansion.
• Gas-phase detachment of secondary ligands by collisional heating leaves persistent structural 'footprints' on the nanocluster surface.