Fundamental Properties of the Molecular Au Clusters

Monolayer-protected gold clusters (MPCs) are a very interesting and fascinating class of compounds, from the points of view of both the fundamental science and their possible applications. They are composed of a gold core, with a diameter smaller than a few nanometers, and are surrounded by a protecting organo-thiolate monolayer, bonded by covalent Au-S bonds. Due to their dimensions, these systems exhibit properties in between those of molecules and nanoparticles, therefore displaying unique physical and chemical behaviors. In this Thesis, some properties of the most stable and well-known molecular MPC are addressed and studied. The investigation focuses on fundamental features, including solid-state properties, optical behavior, reactivity and especially their magnetic properties. The investigation of the latter constitutes the major part of this work. Particular attention is dedicated to the effect of ligands on these phenomena. The main tool of our investigation was electron paramagnetic resonance (EPR) spectroscopy, which was used to study these MPCs both in solution and in the solid state. The topics addressed are to understand the magnetic interactions between gold core and the capping ligands in solutions phase and ferromagnetic and antiferromagnetic interactions between clusters in the solid state. Another magnetic resonance technique, nuclear magnetic resonance, was used for the study of the ligand exchange kinetics. The data obtained from a number of experimental techniques and computational calculations were used in conjunction with these two main tools