Supercrystal engineering of atomically precise gold nanoparticles promoted by surface dynamics.

Area of Science:

• Materials Science
• Nanotechnology
• Crystallography

Background:

• Controllable packing of functional nanoparticles (NPs) into crystalline lattices is crucial for developing advanced NP-based materials.
• The size, morphology, and symmetry of NP supercrystals are key properties that dictate their function.
• Understanding the surface dynamics of NPs is essential for controlling their assembly.

Purpose of the Study:

• To demonstrate that adjusting the surface dynamics of constituent NPs can tailor the supercrystal properties.
• To investigate the crystallization of [Au25(SR)18]- NPs in the presence of tetraethylammonium cations.
• To elucidate the formation and stabilization mechanisms of novel supercrystal structures.

Main Methods:

• Synthesis and crystallization of atomically precise [Au25(SR)18]- NPs.
• Experimental characterization of supercrystal structures (e.g., electron microscopy, X-ray diffraction).
• Theoretical modeling to understand interparticle interactions and linker formation.

Main Results:

• [Au25(SR)18]- NPs crystallized into micrometre-sized hexagonal rod-like supercrystals in the presence of excess tetraethylammonium cations.
• The rod-like crystals consist of polymeric chains linked by a linear SR-[Au(I)-SR]4 interparticle linker.
• The linker is formed by conjugation of detached SR-[Au(I)-SR]2 motifs and stabilized by CH⋯π and ion-pairing interactions.
• Supercrystal symmetry, morphology, and size were systematically tuned by varying tetraalkylammonium cation concentration and type.

Conclusions:

• The surface dynamics of NPs, influenced by cations, can be used to control supercrystal formation.
• Atomically precise gold nanoparticles can assemble into tunable, non-conventional supercrystal structures.
• This provides a pathway for designing bespoke NP-based materials with tailored properties.