Alkynide-stabilised gold nanoparticles: a synthetic investigation

Abstract Alkyne compounds have emerged as promising stabilising ligands for gold nanoparticles, with potential applications in sensing, catalysis and biological imaging. Several examples of alkynide-stabilised gold nanoparticles have been reported although most use a mixed-ligand system that requires additional stabilising agents. Thus, a facile and size controllable synthesis of gold nanoparticles stabilised exclusively with alkyne compounds is highly desirable. Here we report dec-1-ynide@AuNPs that were synthesised by reduction of a Au(I) dec-1-ynide complex to give nanoparticles with diameter of ∼3.4 nm and are stable in air for up to 2 months. 1 H NMR spectra indicate that the particles have a shell that contains gold(I) species surrounding a core of gold(0) atoms. The synthetic technique was modified to increase the size of the AuNPs but the larger AuNPs were stabilised predominantly by tetraoctylammonium bromide (TOAB). Methods that utilised reduction of Au(III) chloride with the phase transfer agent TOAB resulted in bidisperse AuNPs with diameters of ∼9 nm and ∼3 nm. Variation of the synthesis conditions did not have a significant effect on the particle sizes and residual TOAB was required to maintain particle stability.