Layer-by-Layer Synthesis of Conformal Metal–Organic Framework Shells on Gold Nanorods

Because of their possible use in a number of applications such as sensing and catalysis, hybrid materials of metal–organic frameworks (MOFs) with plasmonic nanoparticles have attracted the attention of many researchers. While there have been reports of the synthesis of MOF shells on colloidal metallic nanoparticles, they often provide little control over the thickness and morphology of the MOF shell. This report presents a layer-by-layer technique for synthesizing conformal shells of the MOF HKUST-1 on gold nanorods. The method described deposits the components of the MOF in a truly layer-by-layer fashion, which allows for subnanometer control over shell thickness. To synthesize conformal MOF shells, it is crucial to control the surface chemistry of the gold nanorods. By using the conjugate base of the organic linker, the surface charge could be controlled during synthesis, helping prevent nanorod aggregation.