Functionalised Metal Nanoparticles for Surface Attachment Reactions

Abstract

Surface attachment of functional molecules to metal nanoparticles can facilitate many useful applications such as molecular electronics.1-2 Preparing size-controlled stable nanoparticles with specific surface functionality to facilitate further chemistry is a significant challenge.3-5 The synthesis of nanoparticles with functional groups that enable versatile attachment reactions such as the CuAAC or olefin metathesis reactions could represent a huge leap forward in the application of these materials.6-7 In the present project, <10 nm gold and silver nanoparticles were synthesised using a microemulsion method with multifunctional capping ligands not previously used in nanoparticle syntheses. Concentrated dispersions of azide-functionalised gold nanoparticles, and alkene functionalised silver nanoparticles were prepared and characterised. Particle size was determined using inductively coupled-mas spectrometry (ICP-MS), transmission electron microscopy (TEM), and ultraviolet-visible (UV-vis) spectroscopy, whereas the attachment, orientation and preservation of functionality of the capping ligands was determined using infrared (IR), and nuclear magnetic resonance (NMR) spectroscopy. Azide-functionalised gold nanoparticles were used in a proof of concept CuAAC reaction to surface attach 1-ethynyl pyrene. Characterisation of the dispersed nanoparticles post CuAAC reaction, which included the use of fluorescence spectroscopy, indicated successful attachment of the pyrene compound to the particle surface. This work paves the way for other functional molecules to be attached to NP surfaces using CuAAC reactions.