Biogenic Ag-nanoparticles as heterogeneous catalyst for synthesis of 2-aryl benzimidazoles at room temperature

Abstract

A green, straightforward and rapid method of synthesizing silver nanoparticles in an aqueous medium has been developed using Syzygium jambos (L.) Alston (Bogi Jamu) leaves extract and aqueous AgNO₃ solution. The silver nanoparticles were characterized by UV–vis spectroscopy, transmission electron microscopy, X-ray diffraction and scanning electron microscopy. The results indicate the formation of spherical, nano-sized particles, with average particle size of 20 nm based on TEM analysis. The Ag-nanoparticles efficiently catalyze the synthesis of 2-substituted benzimidazoles by the reaction of aldehydes with o-phenylenediamine in DMSO at room temperature. Simple workup, mild reaction conditions, low cost, easy separation, and reusability of the catalyst are some advantages of this method.