Generation of inorganic–organic core-shell crystalline nanoparticles of silver and p-hydroxyacetanilide

Abstract

We report the generation of core-shell crystalline inorganic–organic hybrid nanoparticles (NPs). This has been achieved by the formation of a crystalline layer of p-hydroxyacetanilide (pHA) on metallic Ag NPs. The core-shell NPs formed when an aqueous mixture of Ag NPs and acetone-dissolved pHA was allowed to evaporate at room temperature. UV/Vis spectroscopic measurements exhibited a systematic blue shift of the extinction maximum with time, indicating the changes in the dielectric medium surrounding the NPs. Transmission electron microscopy (TEM) studies of the sample from the medium indicated formation of a thin shell of organic layer over the NPs. The organic moiety was crystalline as established by selected area electron diffraction (SAED) and X-ray diffraction (XRD) studies. The optical properties of the Ag NPs did not show any other significant change in the presence of the crystalline layers of pHA over them. Further, TEM observations indicated melting of the organic layer in the presence of a high energy beam and at longer exposure times. The results also indicated deposition of smaller organic crystals first on the surface of the NPs followed by growth of the organic layer leading to the formation of the shell.