Synthesis and characterization of noble metal nanoparticles stabilized with bifunctional thiols and study of their opto-electronic properties

In the present work the synthesis and characterization of noble metal nanoparticles (MNPs) has been carried out, together with preliminary optoelectronic studies. Organic and organometallic bifunctional thiol ligands have been synthesized for the stabilization of noble metal nanoparticles. In particular, starting from the substrates: 9,9-didodecyl-2,7-dibromo-fluorene, trans-4,4’-dibromo-stilbene and 4,4’-dibromo-1,1’-biphenyl, bifunctional thiolates have beenon purpose prepared. The synthetic products have been characterized by means the spectroscopic techniques (Uv-Vis, FTIR, NMR and Fluorescence) and used as stabilizing ligands for gold and silver nanoparticles (AuNPs and AgNPs) with the aim to obtain interconnected systems of nanoparticles.Noble metal nanoparticles have been prepared by using the Schiffrin–Brust procedure and characterized by means optical, morphological and advanced structural techniques. The optical investigation, carried out by UV-Vis spectroscopy, allowed to observe the presence of the typical Surface Plasmon Resonance of MNPs, and useful information on their size and aggregation state have been achieved; Fluorescence characterization have highlight the emission properties of the MNPs. The morphological studies, carried out by means of scanning and transmission electronic microscopy (FESEM and TEM) and Atomic Force Microscopy (AFM) characterizations, allowed to define MNPs size, shape and their 2D and 3D arrangements in network of interconnected nanoparticles. Synchrotron Radiation X-ray Photoelectron spectroscopy (SR-XPS) and Extended X-ray Absorption Fine Structure (EXAFS) studies defined the surface functionalitystatus and Metal-thiol interface structure. Further structural information have been obtained from Grazing Incidence X-ray Diffraction (GIXD) synchrotron measurements under thermal treatment, that permitted to investigate structural changes in the MNPs network. Preliminary applicative studies have carried out on MNPs, in particular in-situ conductivity measurement have been carried out on Poly-3-hexylthiophene/AuNPs blends, giving evidence on the synergic effect of MNPs on the electrical behaviour of this polymer.