Gold nanoparticles are useful because of their use in surface coating, making conductive thin films, surface enhanced Raman spectroscopy (SERS), and catalysis. For successful commercial uses the nanoparticles solutions are required to be monodisperse, stable, high metal content etc. Here a novel approach of gold nanoparticles synthesis in acetonitrile at room temperature has been reported. Here trioctyl amine (TOA) was used as stabilising agent and poly (methyl hydrosiloxane) (PMHS) was used as reducing agent.1 The synthesized nanoparticles are very monodisperse (Fig. 1), which were characterized by UV-vis spectra and transmission electron microscopy (TEM). TEM indicates that the size of the gold nanoparticles in acetonitrile is < 10 nm. The topography and morphology of these nanoparticles were also investigated by AFM and SEM analysis. The stability of these nanoparticles was enhanced by suitable surface modification. Depending upon terminal group attached to the nanoparticles we also synthesized either organic or water soluble gold nanoparticles. The surface bound ligands analysis of the as synthesized surface modified gold nanoparticles was carried out by EDS and elemental mapping. We found that after heating the surface modified gold nanoparticles and subsequent dissolution in appropriate solvent produces more ordered nanoparticles compared to TOA stabilized gold nanoparticles. The mechanistic studies were carried out by FTIR and NMR spectroscopy. Controlled experiment suggests that TOA acts as stabilizing agent and PMHS acts as reducing agent.

[1] Chauhan, B. P. S.; Sardar, R. Macromolecules. 37, 5136-5139, 2004