Synthesis of coinage-metal nanoparticles from mesityl precursors

An anhydrous route for the synthesis of amine-capped coinage-metal nanoparticles (NP) has been developed using coinage-metal mesityl (mesityl = 2,4,6-Me3C6H2) derivatives. Under an argon atmosphere, crystalline [Cu(mu-mesityl)](5), [Ag(mu-mesityl)](4), and [Au(mu-mesityl)](5) were readily dissolved in octylamine (0.3 M solution) and subsequently injected into a heated hexadecylamine solution (300 degreesC), generating the corresponding metal nanoparticles. After washing with methanol and extracting with toluene, oxide-free coinage NPs were isolated and characterized by UV-vis spectroscopy and transmission electron microscopy. Under these conditions, the spherical NPs were found to be 8-9 nm in size for Cudegrees (no surface oxide present), 9 nm for Agdegrees, and 8-80 nm for Audegrees. Reducing the concentration of the precursor solution, the temperature of the solution, and the time of reaction led to the synthesis of Audegrees NPs that were 12 +/- 1 nm in size.