Multifunctional phosphine stabilized gold nanoparticles: an active catalytic system for three-component coupling...

Area of Science:

• Materials Science
• Nanotechnology
• Catalysis

Background:

• Stabilizing gold nanoparticles (Au(o)-nanoparticles) with small core diameters and narrow size distributions is crucial for their catalytic applications.
• Developing efficient ligands for nanoparticle synthesis and stabilization remains an active area of research.

Purpose of the Study:

• To synthesize and characterize gold nanoparticles stabilized by novel multifunctional phosphine-based ligands: 1,1,1-tris(diphenylphosphinomethyl)ethane [CH3C(CH2 PPh2)3][P3] and 1,1,1-tris(diphenylphosphinomethyl)ethane trisulphide [CH3C(CH2P(S)Ph2)3][P3S3].
• To evaluate the catalytic activity of these stabilized gold nanoparticles in the synthesis of propargylamines via C-H alkyne activation.

Main Methods:

• Gold nanoparticles were synthesized via the reduction of HAuCl4 with NaBH4 in the presence of P3 or P3S3 ligands using a one-pot, two-phase reaction at room temperature.
• Characterization included TEM for particle size and shape, and surface plasmon band analysis.
• Catalytic activity was assessed in a one-pot, three-component (A3) coupling reaction.

Main Results:

• Au(o)-nanoparticles stabilized by P3 exhibited a face-centered cubic (fcc) lattice with single crystallite shapes, while P3S3 resulted in decahedral shapes.
• TEM studies indicated particle sizes below 2 nm for P3-stabilized and 4 nm for P3S3-stabilized nanoparticles.
• P3S3-stabilized nanoparticles demonstrated higher thermal stability compared to P3-stabilized ones.
• The synthesized Au(o)-nanoparticles efficiently catalyzed the A3 coupling reaction, yielding propargylamines in 85-96% yields without additives.

Conclusions:

• Multifunctional phosphine and phosphine sulfide ligands effectively stabilize small gold nanoparticles with controlled morphology and size.
• The stronger interaction between gold (soft) and phosphorus (soft) compared to sulfur (less soft) influences nanoparticle characteristics.
• The synthesized gold nanoparticles are highly effective catalysts for propargylamine synthesis through C-H alkyne activation, showcasing potential for green chemistry applications.