OICC Press International Nano Letters 2228-5326 3 1 (December 2013) 2013 09 27 Acacia nilotica (Babool) leaf extract mediated size-controlled rapid synthesis of gold nanoparticles and study of its catalytic activity 10.1186/2228-5326-3-53 EN Rakhi Majumdar Braja Gopal Bag Department of Chemistry and Chemical Technology, Vidyasagar University, Midnapore, WB, 721102, IN Nabasmita Maity Journal Article 2013 09 27 Abstract The leaf extract of Acacia nilotica (Babool) is rich in different types of plant secondary metabolites such as flavanoids, tannins, triterpenoids, saponines, etc. We have demonstrated the use of the leaf extract for the synthesis of gold nanoparticles in water at room temperature under very mild conditions. The synthesis of the gold nanoparticles was complete in several minutes, and no extra stabilizing or capping agents were necessary. The size of the nanoparticles could be controlled by varying the concentration of the leaf extract. The gold nanoparticles were characterized by HRTEM, surface plasmon resonance spectroscopy, and X-ray diffraction studies. The synthesized gold nanoparticles have been used as an efficient catalyst for the reduction of 4-nitrophenol to 4-aminophenol in water at room temperature.