Direct synthesis and bonding origins of monolayer-protected silver nanocrystals from silver nitrate through in situ ligand exchange

In this study, we attempt to present a direct synthesis of narrowly dispersed silver nanoparticles in a highly concentrated organic phase (> 2 M) without the use of a size-selection process. The fully organic phase system contains silver nitrate as a silver precursor, n-butylamine as a medium dissolving the silver salt, dodecanoic acid as a capping molecule, toluene as a medium, and NaBH4 as a reducing reagent. Even using only generic chemicals, monodisperse silver nanocrystals with a size of 7 nm were easily synthesized on the 100-g scale in a 1-L reactor. In addition, systematic studies revealed that the silver nanocrystals synthesized through in situ ligand exchange were stabilized through bidentate bridging of carboxyl groups in dodecanoic acid. (c) 2006 Elsevier Inc. All rights reserved.