One-step synthesis of ordered two-dimensional assemblies of silver nanoparticles by the spontaneous reduction of silver ions by pentadecylphenol Langmuir monolayers

The single-step synthesis of silver nanoparticles by the reduction of silver ions present in the subphase under alkaline conditions by 3-pentadecylphenol (3-PDP) Langmuir monolayer and their assembly into ordered two-dimensional structures is described. The reduction of the silver ions occurs by electron transfer from ionized phenol groups of 3-PDP, which then stabilize the particles against aggregation. Similar reduction of aqueous silver ions was carried out at the interface with toluene bearing 3-PDP and yielded monodisperse silver nanoparticles that may be separated as a dry powder and redispersed in a range of organic solvents. The mechanism of reduction of silver ions by 3-PDP under alkaline conditions was studied by UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) spectroscopy, transmission electron microscopy (TEM), and chemical analysis by X-ray photoelectron spectroscopy (XPS), and is discussed in detail.